BACKGROUND

[0001] Electronic devices, such as laptops and mobile phones, include various components located within a metal alloy housing. Such a metal alloy housing is made of a metal alloy substrate, which may have at least one chamfered edge that has been formed by a CNC diamond cutting process. The metal alloy housing should have a good metallic lustre and should be able to withstand wear and tear from regular use and exposure to the natural environment.

BRIEF DESCRIPTION OF DRAWINGS

[0002] Figure 1 is a flowchart as an example of a process for producing a coated metal alloy substrate for an electronic device.

[0003] Figure 2 is a cross-sectional diagram showing an example of a coated metal substrate formed by the process set out by the flowchart in Figure 1.

[0004] Figure 3 is a flowchart as an example of a process for producing a coated metal alloy substrate for an electronic device.

[0005] Figure 4 is a cross-sectional diagram showing an example of a coated metal substrate formed by the process set out in the flowchart in Figure 3.

[0006] Figure 5 is a flowchart as an example of a process for producing a coated metal alloy substrate for an electronic device.

[0007] Figure 6 is a cross-sectional diagram showing an example of a coated metal substrate formed by the process set out In the flowchart in Figure 5.

[0008] Figure 7 shows an example housing for a laptop.

[0009] The figures depict several examples of the present disclosure. It should be understood that the present disclosure is not limited to the exampies depicted in the figures. DETAILED DESCRIPTION

[0010] Before the water-based carbon nanotube cutting fluid for use in a CNC diamond cutting process; process for producing a coated metal alloy substrate for an electronic device; and electronic device with a housing comprising a coated metal alloy substrate are disclosed and described, it is to be understood that this disclosure is not limited to the particular process details and materials disclosed herein because such process details and materials may vary somewhat. It is also to be understood that the terminology used herein is used for the purpose of describing particular examples. The terms are not intended to be limiting because the scope of the present disclosure is intended to be limited by the appended claims and equivalents thereof.

[0011] It is noted that, as used in this specification and the appended claims, the singular forms “a", "an" and “the" include plural referents unless the context clearly dictates otherwise.

[0012] If a standard test is mentioned herein, unless otherwise stated, the version of the test to be referred to is the most recent at the time of filing this patent application.

[0013] As used herein, the term "about" is used to provide flexibility to a numerical range endpoint by providing that a given value may be "a little above" or "a little below" the endpoint The degree of flexibility of this term can be dictated by the particular variable and would be within the knowledge of those skilled in the art to determine based on experience and the associated description herein.

[0014] Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include the numerical values explicitly recited as the limits of the range and also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. As an illustration, a numerical range of “about 1 wt.% to about 5 wt.%” should be interpreted to include the explicitly recited values of about 1 wt.% to about 5 wt.% and also include individual values and subranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3.5, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This same principle applies to ranges reciting a single numerical value. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described.

[0015] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be constated as a de facto equivalent of any other member of the same list based on their presentation in a common group without indications to the contrary.

[0016] As used herein, the term “deposited” when used to refer to the location or position of a layer includes the term “disposed" or "coated”.

[0017] As used herein, the term “engraving" when used to refer to the formation of a chamfered edge includes the term “etching" or "cutting*.

[0018] As used herein, the term “water-based cutting fluid”, refers to any cutting fluid that comprises water.

[0019] As used herein, the term "carbon nanotube” refers to a network of carbon atoms assembled into a cylindrical structure. The “inner diameter" of the carbon nanotube refers to the diameter of the cylindrical structure.

[0020] As used herein, the term “cutting fluid", refers to any fluid used when mechanically processing, cutting or engraving metals.

[0021] As used herein, the term “CNC” refers to computer numerical control, which may be referred to simply as “numerical control”. A CNC process involves automated control of machining tools, wherein the machine tools may follow pre-coded programmed instructions.

[0022] As used herein, “diamond cut process” refers to any machine process which uses diamond as a cutting tool.

[0023] As used herein, “hydrophobic” or “hydrophobicity” is a physical property of a molecule, wherein the molecule has a tow affinity towards water.

[0024] As used herein, “hydrophilic” or "hydrophilicity” is a physical property of a molecule, wherein the molecule has a high affinity towards water.

[0025] As used herein, the term “LogP" refers to the logarithm of the partition coefficient, abbreviated P. LogP is a measure of the hydrophobicity or hydrophillicity of a chemical substance. For example, components with a LogP of greater than 5 are considered to be hydrophobic compounds. LogP may be defined as the ratio of the concentrations of a solute in a diphasic system of n-octanol and water at equilibrium and at 25 °C and standard pressure. The LogP can be determined by calculation, for example, using a fragment-based and/or atom-based approach, for example, using Cambridge Soft software such as ChemDraw Ultra 12.0.

[0026] As used herein, the term “chamfered edge” refers to an edge of a substrate that has resulted from engraving or cutting.

[0027] As used herein, the term "biocide" refers to any compound that destroys or inhibits the growth or activity of living organisms.

[0028] As used herein, the term "HLB” refers to the hydrophilic lipophilic balance of a molecule. HLB may be determined by the formula HLB - 20 * M _h /M wherein Mi, is the molecular mass of the hydrophilic portion of the molecule, and M is the molecular mass of the whole molecule.

[0029] As used herein, the term “silicone oil” refers to any liquid polymerized siloxane with organic side chains.

[0030] As used herein, the term "contact angle" refers to the angle, measured through the liquid, where a liquid-vapour interface meets a solid surface. The contact angle quantifies the wettability of a solid surface by a liquid using the Young equation. A given system of solid, liquid, and vapour at a given temperature and pressure has a unique equilibrium contact angle. However, in practice a dynamic phenomenon of contact angle hysteresis is often observed, ranging from the advancing (maximal) contact angle to the receding (minimal) contact angle. The equilibrium contact angle is within these maximal and minimal values, and can be calculated from these minimal and maximal values. The equilibrium contact angle reflects the relative strength of the liquid, solid, and vapor molecular interaction. The contact angle may be measured using a Drop Shape Analyzer, such as DSA100.

[0031] As used herein, the term "comprises" has an open meaning, which allows other, unspecified features to be present. This term embraces, but is not limited to, the semi-closed term “consisting essentially of” and the closed term "consisting of". Unless the context indicates otherwise, the term "comprises" may be replaced with either “consisting essentially of or "consists of.

[0032] Unless otherwise stated, any feature described herein can be combined with any other feature described herein. [0033] The present inventors have found that certain CNC diamond cutting processes, used to form chamfered edges on metal alloy substrates, may lead to chamfered edges which have poor aesthetic properties, such as poor metallic lustre. Chamfered edges can also be susceptible to corrosion. During the CNC cutting process, metal alloy substrates may be engraved to expose a shiny non-oxidised edge. However, this edge can quickly oxidise or corrode when exposed to air and/or other environmental factors. In some cases it has been found that known cutting fluids, used for lubrication and heat dissipation in the CNC process contributed to dullness at the chamfered edge. This dullness has is some case been attributed to the lubricating fluids or other hydrophobic components of the cutting fluid, which can be difficult to remove without compromising the aesthetic properties of the metal alloy substrate.

[0034] The present inventors have found that engraving metal alloy substrates using the water-based carbon nanotube cutting fluid described herein during the diamond cut process can lead to a more glossy or and/or lustrous metallic chamfered edge. The application of a passivation layer, followed by an electrophoretic deposition layer, may further protect and retain the attractive and shiny appearance of the underlying metallic substrate. The passivation layer and electrophoretic deposition layer applied may also enhance corrosion resistance of the metal alloy substrate.

[0035] The present inventors also found that the engraving process using the water-based carbon nanotube cutting fluid described herein, may extend the life-time of the CNC diamond cut knife. The water-based carbon nanotube cutting fluid can provide good lubrication properties and/or can prevent overheating of the diamond in the CNC diamond cut process. Water-based carbon nanotube cutting fluid

[0036] In some examples, there is provided a water-based carbon nanotube cutting fluid for use in a CNC diamond cut process. The water-based carbon nanotube cutting fluid comprises a carbon nanotube, a dispersant and water. For example, the water-based carbon nanotube cutting fluid is free from components with a LogP of greater than 5, in other words, the water-based carbon nanotube cutting fluid is free from very hydrophobic components. In an example, the water-based carbon nanotube cutting fluid is free from any liquid components that have a contact angle of greater than about 90". [0037] Components with a LogP of greater than 5 may include oils, fatty acids or esters thereof, hydrophobic alkanes, hydrophobic alkenes, isodecyl pelargonate, dipropylene glycol dipelargonate, dimethyl silicone fluid and silicone fluid. In an example, the water-based carbon nanotube cutting fluid is free from components with a LogP of greater than about 4.5, or free from components with a LogP of greater than about 4.

[0038] The water-based carbon nanotube cutting fluid herein may comprise at least about 40 v/v% water-based on the total volume of the water-based carbon nanotube cutting fluid. For example, the water-based carbon nanotube cutting fluid herein may comprise at least about 50 v/v%, or at least about 60 v/v%, or at least about 70 v/v%, or at least about 80 v/v%, or at least about 85 wt v/v% water based on the total volume of the water-based carbon nanotube cutting fluid. The water-based cutting fluid may comprise water as a solvent, or the water-based cutting fluid may further comprise a water-miscible solvent.

[0039] in an example, the water-based carbon nanotube cutting fluid is free from oil, which may include, for example, animal oils, vegetable oils (such as palm oil, soybean oil, rapeseed oil, sunflower oil, peanut oil, cottonseed oil, palm kernel oil, coconut oil, olive oil, canola oil, corn oil, linseed oil, rice bran oil, safflower oil, sesame oil), mineral oils (such as paraffin, transformer oil, or group I, II, III, IV or V oils), or combinations thereof. The water-based carbon nanotube cutting fluid is free from oil with a LogP of greater than about 5. For example, the water-based carbon cutting fluid is free from oils with a LogP of greater than about 4.5, or greater than about 4, or greater than about 3.5, or greater than about 3. or greater than about 2.5.

[0040] For example, the water-based carbon nanotube cutting fluid is free from fatty acids or esters thereof. The fatty acids or esters thereof may include medium chain, long chain or very long chain fatty acids. The fatty acids or esters thereof may be saturated or unsaturated. The fatty acids or esters thereof may include, for example, perlargonic acid, capric acid, undecyclic acid, lauric acid, tridecyiic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, myristoleic acid, palmitoieic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, pauilinic acid, gondoic acid, erucic acid, nervonic acid, mead acid, or combinations thereof. In an example, the water-based cartoon nanotube cutting fluid is free from isodecyl pelargonate, dipropeylene glycol dipelargonate, methyl stearate, diol oleate, oleic acid, or combinations thereof. The water-based carbon nanotube cutting fluid is free from fatty acids or esters thereof with a LogP of greater than about 5. For example, the water-based carbon nanotube cutting fluid is free from fatty acids or esters thereof with a LogP of greater than about 4.5, or greater than about 4, or greater than about 3.5, or greater than about 3, or greater than about 2.5.

[0041] For example, the water-based carbon nanotube cutting fluid is free from hydrophobic alkanes. The hydrophobic alkanes may be unsubstituted or substituted, for example, halo-substituted (iodo-substituted, bromo-substituted, chloro-substituted or fluoro-substituted). The hydrophobic alkanes may be branched or unbranched. The hydrophobic alkanes may include, for example, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane or combinations thereof. The water-based carbon nanotube cutting fluid is free from alkanes with a LogP of greater than about 5. For example, the water-based carbon nanotube cutting fluid is free from hydrophobic alkanes with a LogP of greater than about 4.5, or greater than about 4, or greater than about 3.5, or greater than about 3, or greater than about 2.5.

[0042] For example, the water-based carbon nanotube cutting fluid is free from hydrophobic alkenes. The hydrophobic alkenes may be unsubstituted, alkyl-substituted, or halo-substituted (iodo-substituted, bromo-substituted, chloro-substituted or fluoro- substituted). The hydrophobic alkenes may contain a single double bond, or more than one double bond, which may be present at any position in the alkyl chain. The hydrophobic alkenes may be branched or unbranched. The hydrophobic alkenes may indude hexene, heptene, octene, nonene, decene, undecene, dodecene, tridecene, tetradecene, pentadecene, hexadecane, heptadecene or combinations thereof. The water-based carbon nanotube cutting fluid is free from hydrophobic alkenes with a LogP of greater than about 5. For example, the water-based cartoon nanotube cutting fluid is free from hydrophobic alkenes with a LogP of greater than about 4.5, or greater than about 4, or greater than about 3.5, or greater than about 3, or greater than about 2.5.

[0043] For example, the water-based carbon nanotube cutting fluid is free from silicone oils. The silicone oils may include any polydialkyl, aryialkyl, fiuoroalkyi or ether- modified siloxane polymers, which may include PDMS (also referred to as dimethyl silicone fluid). The water-based carbon nanotube cutting fluid is free from silicone oils with a LogP of greater than about S. For example, the water-based carbon nanotube cutting fluid is free from silicone oils with a LogP of greater than about 4.5, or greater than about 4, or greater than about 3.5, or greater than about 3, or greater than about

2.5. Carbon nanotube

[0044] The water-based carbon nanotube cutting fluid comprises a carbon nanotube. In some examples, the carbon nanotube may be present in an amount from about 0.01 to about 10 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example, the carbon nanotube may be present in an amount of from about 0.5 to about 9 percent by weight, or from about 2 to about 8 percent by weight, or from about 3 to about 7 percent by weight, or from about 4 to about 6 percent by weight, or from about 4.5 to about 5.5 percent by weight, or about 5 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. For example, the carbon nanotube may be present in an amount greater than about 0.01 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example, the carbon nanotube may be present in an amount greater than about 0.1 percent by weight, or greater than about 0.25 percent by weight, or greater than about 0.5 percent by weight, or greater than about 1 percent by weight, or greater than about 2 percent by weight, or greater than about 3 percent by weight, or greater than about 4 weight percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. For example, the carbon nanotube may be present in an amount less than about 10 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example, the carbon nanotube may be present in an amount less than about 9 percent by weight, or less than about 8 percent by weight, or less than about 7 percent by weight, or less than about 6 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid.

[0045] The carbon nanotube has a LogP of less than 5. In an example, the carbon nanotube has an inner diameter of from about 0.4 nm to about 50 nm, or about 1 nm to about 45 nm, or about 2 nm to about 40 nm. In an example, the carbon nanotube has an inner diameter greater than 0.4 nm, or greater than 0.6 nm, or greater than 0.8 nm, or greater than 1 nm, or greater than 1.2 nm, or greater than 1.4 nm, or greater than 1.6 nm, or greater than 1.8 nm. In an example, the carbon nanotube has an inner diameter of less than 50 nm, or less than 48 nm, or less than 46 nm, or less than 44 nm, or less than 42 nm. In an example, the carbon nanotube may have a length of from about 4 nm to about 1000 μm, or about 50 nm to about 50 μm, or about 100 nm to 20 μm. In an example, the carbon nanotube may have a length of greater than 4 nm, or greater than 8 nm, or greater than 15 nm, or greater than 25 nm, or greater than 40 nm, or greater than 50 nm, or greater than 65 nm, or greater than 80 nm, or greater than 100 nm. In an example, the carbon nanotube may have a length of less than 1000 μm, or less than 500 μm, or less than 200 μm, or less than 100 μm, or less than 50 μm, or less than 20 μm.

[0046] The carbon nanotube may be a single walled carbon nanotube or a multi walled carbon nanotube. In an example, the carbon nanotube is water-dispersible. The carbon nanotube may be non-functionalised or functionalised. In an example, the carbon nanotube is functionalised with hydrophilic groups, for example, carboxyl groups, hydroxyl groups, or a combination thereof.

Dispersant

[0047] The water-based carbon nanotube cutting fluid comprises a dispersant. The dispersant has a LogP of less than 5.

[0048] For example, the dispersant may comprise at least one of polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, sodium caseinate, sodium polyacrylate, sodium hexametaphosphate, sodium silicate, sodium polyoxyethylene alkyl ether carboxylate, sodium dodecyl sulfate, alcohol sulfates, aikyibenzene sulfonates or a combination thereof. In an example, the water-based carbon nanotube cutting fluid comprises polyvinyl alcohol and sodium dodecyl sulfate.

[0049] In some examples, the dispersant may be present in an amount from about 0.5 to about 5 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example, the dispersant may be present in an amount from about 1 to about 4.5 percent by weight, or from about 1.5 to about 4.2 percent by weight, or from about 2 to about 4 by weight, or from about 3 to about 3.6 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. The dispersant may be present in an amount greater than about 0.5 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example, the dispersant may be present in an amount greater than about 0.75 percent by weight, or greater than about 1 percent by weight, or greater than about 1.5 percent by weight, or greater than about 2 percent by weight, or greater than about 2.5 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. The dispersant may be present in an amount less than about 5 weight percent based on the total weight of the water-based carbon nanotube cutting fluid. For example, the dispersant may be present in an amount less than about 4.5 percent, or less than about 4 percent by weight, or less than about 3.5 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. [0050] in an example, the dispersant may have a solubility of greater than about 0.1 mg/ml in water at 25 °C, or greater than about 1 mg/ml in water at 25 °C, or greater than about 5 mg/ml, or greater than about 10 mg/ml, or greater than about 25 mg/ml, or greater than or equal to about 50 mg/ml in water at 25 °C.

[0051] In some examples, the dispersant may comprise an anionic compound. The anionic compound may comprise a sulfate, sulfonate, phosphate, silicate or carboxylate. The anionic compound may be present in an amount of from about 0.3 to about 2 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example, the anionic compound may be present in an amount of from about 0.5 to 1.7 percent by weight, or from about 0.8 to about 1.5 percent by weight, or from about 1.0 to about 1.4 percent by weight, or from about 1.1 to about 1.3 percent by weight, or in an amount of about 1.2 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. In an example, the anionic compound may be selected from sodium caseinate, sodium polyacrylate, sodium hexametaphosphate, sodium silicate, sodium polyoxyethylene alkyl ester carboxylate, sodium dodecyl sulphate, alcohol sulfates, alkyfbenzylsulfonates or a combination thereof. In an example, the anionic compound is sodium dodecyl sulphate.

[0052] In an example, the dispersant may comprise a polymer. The polymer may be water-soluble. The polymer may have a HUB value between about 10 and about 20, or between about 12 and about 19. The polymer may have a HLB value greater than about 10, or greater than about 11 , or greater than about 12, or greater than about 13, or greater than about 14, or greater titan about 15, or greater than about 16, or the polymer may have a HLB value greater than about 17. The polymer may be an oxygen-containing or nitrogen-containing polymer. The polymer may be selected from polyvinyl alcohol (PV A), polyvinylpyrrolidone (PVP), polyacrylamide or combinations thereof. The polymer may be present in an amount from about 0.2 to about 3 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example, the polymer may be present in an amount from about 0.5 to about 4 percent by weight, or from about 1 to about 3 percent by weight, or in an amount of about 2.2 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. In an example, the polymer used is polyvinylalcohol. In some examples, the polymer may act as a thickener, in addition to having dispersing properties.

[0053] The dispersant may comprise both a polymer and an anionic compound. In an example, the dispersant comprises a polymer with a HLB value between about 12 and about 19, and an anionic compound comprising a sulfate. Other components of the water-based carbon nanotube cutting fluid

[0054] In an example, the water-based carbon nanotube cutting fluid further comprises at least one further component. The at least one further component has a LogP of less than 5. In an example, the at least one component may be selected from a carboxylate salt, an alcohol amine, a diamine, an aliphatic amine salt, an alkenyl succinic acid, or a combination thereof, for example, the at least one component may be selected from sodium acetate, potassium butyrate, sodium benzoate, aliphatic amine salt, alkenyl succinic acid, diethanolamine, tiigiycolamine, ethylenediamine, triethanolamine, methyl isopropanolamine or a combination thereof. The at least one further component may be present in an amount of about 0.5 to about 6 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example, the at least one further component may be present in an amount of about 1 to about 5.5 percent by weight, or about 1 to about 5 percent by weight, or about 2 to about 4 percent by weight, or about 3 to about 3.8 percent by weight, or in an amount of about 3.5 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. In an example, the water-based carbon nanotube cutting fluid comprises potassium butyrate. The at least one further component may inhibit corrosion of the diamond cut knife.

[0055] The at least one further component may have a solubility of greater than about 0.1 mg/ml in water at 25 °C, or greater than about 1 mg/ml, or greater than about 5 mg/ml, or greater than about 10 mg/ml, or greater than about 25 mg/ml, or a solubility of greater than or equal to about 50 mg/ml in water at 25 °C,

[0056] In an example, the water-based carbon nanotube cutting fluid may further comprise at least one biocide. The at least one biotide has a LogP of less than 5. The at least one biotide may be a heterocyclic sulphur-containing compound, an aldehyde, a sodium phenoxide, a free-radical initiator or a combination thereof, for example, the biocide may be selected from 2-mercaptobenzothiazole, sodium salicylamide, hydrogen peroxide, glutaraidehyde or a combination thereof. The at least one biocide may be present in an amount of about 0.1 to about 1 percent by weight based on the total weight of the water-based carbon nanotube cutting fluid. For example the at least one biocide may be present in an amount of about 0.25 to about 0.75 percent by weight, or about 0.4 to about 0.6 percent by weight, based on the total weight of the water-based carbon nanotube cutting fluid. Process for producing a coated metal alloy substrate

[0057] The present disclosure also relates to a process for producing a coated metal alloy substrate for an electronic device. Examples of processes for producing a coated metal alloy are described below and shown in the flow chart in Figure 1.

[0058] In some examples, there is provided a process for producing a coated metal alloy substrate for an electronic device comprising: engraving the metal alloy substrate using a CNC diamond cut process to form at least one chamfered edge; applying a passivation layer to the at least one chamfered edge; and applying an electrophoretic deposition layer to the passivation layer; wherein the CNC diamond cut process uses a water-based carbon nanotube cutting fluid described herein, that is, a water-based carbon nanotube cutting fluid comprising a carbon nanotube, a dispersant and water, which is free from components with a LogP of greater than 5.

[0059] in some examples, there is a coated metal alloy substrate producible according to the processes described herein.

[0060] In some examples, the process may be repeated any number of times. In other words, after applying an electrophoretic deposition layer to the passivation layer, there is provided a second process comprising: engraving the metal alloy substrate using a CNC diamond cut process to form at least a second chamfered edge; applying a passivation layer to the at least a second chamfered edge; and applying an electrophoretic deposition layer to the passivation layer.

[0061] By producing a coated metal alloy substrate containing at least one chamfered edge according to the process described herein, it may be possible to protect and retain the attractive, shiny appearance of the underlying metallic substrate at the chamfered edge. Unlike coatings formed by electroplating processes, the layers may protect the exposed, underlying surface from corrosion. The coated chamfered edges disclosed herein may show good resistance as tested using a salt fog test, such as ASTM B117, particularly when compared to coating formed by electroplating. In addition, the engraving process used in the process described herein, may result in chamfered edges which have a glossy or natural metallic lustre, particularly when compared to CNC cutting processes that use commercial cutting fluids, such as those that comprise oils or other very hydrophobic components.

Metal altoy substrate

[0062] The metal alloy substrate may comprise a metal selected from aluminium, magnesium, lithium, titanium, niobium, zinc and alloys thereof. For example, the metal alloy substrate may comprise a metal alloy selected from an aluminium alloy, a magnesium alloy, a lithium alloy, a titanium alloy and stain steel. These metals may be light-weight and can provide a durable housing. In an example, the metal alloy substrate comprises a magnesium alloy.

[0063] Generally, the metal alloy comprises a content of metal of at least about 75 wt.%. For example, when the metal alloy is a magnesium alloy, the magnesium alloy may comprise at least about 80 wt.% magnesium, or at least 85 wt.% magnesium, or at least about 90 wt.% of magnesium, based on the total weight of the metal alloy.

[0064] The magnesium alloy may further comprise aluminium, zinc, manganese, silicon, copper, a rare earth metal or zirconium. The aluminium content may be about 2.5 wt.% to about 13.0 wt.%. When the magnesium alloy comprises aluminium, then at least one of manganese, zirconium, or silicon is also present Examples of magnesium alloys include AZ31, AZ31B, AZ61, AZ60, AZ80, AM60, AZ91D, LZ91, LZ14, ALZ691 alloys according to the American Society for Testing Materials standards.

[0065] In one example, the metal alloy comprises at least one of the following list including, Al: about 0.02 wt.% to about 9.7 wt.%, Zn: 0.02 wt.% to about 1.4 wt.%, Mn: about 0.02 wt.% to about 0.5 wt.%, a component selected from Si: about 0.02 wt.% to about 0.1 wt.%, Fe: about 0.004 wt.% to about 0.05 wt.%, Ca: about 0.0013 wt.% to about 0.04 wt.%, Ni: about 0.001 wt.% to about 0.005 wt.%, Cu: about 0.008 wt.% to about 0.05 wt.%, Li: about 9.0 wt.% to about 14.3 wt.%, Zr: up to about 0.002 wt.%, or combinations thereof, all based on the total weight of the metal alloy, and the balance being Mg and inevitable impurities.

[0066] The metal alloy substrate may be an insert molded metal substrate to form a metal substrate with sections comprising a further material, such as plastics. Fey example, the insert molded metal substrate may be formed by using the metal substrate as a mold. This metal mold may have a section into which a material, such as plastic, is injected to form a plastic insert. Plastics used for insert molded metal substrates may be selected from polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyamide (nylon), polyphthalamide (PPA), acrylonitrile butadiene styrene (ABS), polytheretherketone (PEEK), polycarbonate (PC) and acrylonitrile butadiene styrene with polycarbonate (ABS/PC) with about 15 to about 50 wt.% glass fibre filler.

Engraving

[0067] The metal alloy substrate is engraved by a Computer Numeric Control (CNC) diamond cut process to form at least one chamfered edge, using the water-based carbon nano-tube cutting fluid described herein.

[0068] The chamfered edge formed by the engraving may be an exposed non- oxidized surface of the metal alloy substrate. The non-oxidized surface of the substrate exposed in this way is an uncoated surface of the substrate that has not undergone substantial oxidation. The engraving process removes a part of the metal alloy substrate, including, for example, any oxidized layers to expose a shiny surface of the underlying substrate. In some examples, the metal alloy substrate has been pre-coated or pretreated before the engraving process, for example, using the processes described herein. If the metal alloy substrate has been pre-coated or pre-treated, the engraving process removes a part of the coating to expose a shiny surface of the underlying substrate.

[0069] Engraving the metal alloy substrate to form at least one chamfered edge may be carried out to form a predefined pattern or shape. The engraving process may allow the formation of patterns that will provide a surface of the chamfered edge with a texture or finish that is different to the texture or finish of the metal alloy substrate that has not been engraved. The surface of the metal alloy substrate that has not been engraved may be referred to as the non-chamfered surface.

[0070] Using this process, parts of the metal alloy substrate may be cut away and each resulting chamfered edge may form an edge, a sidewall, a logo, a gap for a click pad, a gap for a fingerprint scanner.

[0071] The engraving process described herein, using the water-based carbon nanotube cutting fluid described herein, is found to increase the lifetime of the CNC diamond cut knife. The water-based carbon nanotube cutting fluid may effectively dissipate the heat from the CNC diamond cut knife during CNC cutting, and may simultaneously provide good lubrication. Applying a passivation layer

[0072] A passivation layer is applied to the at least one chamfered edge. The passivation layer may be sprayed, rollered, dipped, or brushed onto the metal alloy surface.

[0073] The passivation layer may be transparent The passivation layer may comprise a chelating agent and a metal ion or chelated metal complex thereof, or a mixture of the chelating agent, the metal ion and the chelated metal complex. The chelated metal complex comprises a ligand coordinated to the metal ion. The ligand is the chelating agent.

[0074] The chelating agent may be selected from ethylenediamioetetraacetic acid (EDTA), ethylenediamine (EN), nitrilotriacetic acid (NTA), diethylenetriaminepenta(methylenephosphonic acid) (DTPPH), nitrilotris(methylenephosphonic acid) (NTMP), 1-hydroxyethane-1,1-dtphosphonic acid (HEDP) and phosphoric acid. In one example, the chelating agent is DTPPH.

[0075] The metal Ion may be selected from an aluminium ion, a nickel ion, a chromium ion, a tin ion, an indium ion, and a zinc ion. In one example, the metal ion is selected from an aluminium ion, a nickel ton and a zinc ton.

[0076] In one example, the chelated metal complex may comprise DTPPH chelated to an aluminium ton. In another example, the chelated metal complex may comprise DTPPH chelated to a nickel ion. In a further example, the chelated metal complex may comprise DTPPH chelated to a zinc ion.

[0077] The passivation layer may have a thickness of from about 30 nm to about 3 μm, such as from about 200 nm to about 2 μm, or from about 500 nm to about 1 μm.

[0078] The thickness of the passivation layer can be measured after it has been applied using, for example, a micrometre screw gauge or scanning electron microscope (SEM).

Applying an electrophoretic deposition layer

[0079] An electrophoretic layer is deposited on at least part of the passivation layer. [0080] To carry out the electrophoretic deposition, the metal alloy substrate is made an electrode of an electrochemical cell. The electrochemical cell also has an inert electrode as the counter electrode and an electrolyte comprising an electrophoretic polymer. A potential difference is applied across the electrodes of the electrochemical cell to deposit the electrophoretic polymer over the coating layer. The electrolyte may have a concentration of from about 1 wt.% to about 25 wt.%, such as from about 5 wt.% to about 20 wt.%, or from about 10 wt.% to about 15 wt.% of the electrophoretic polymer. The polymer, in general, has ionizable groups. When the polymer is a negatively charged material, then it will be deposited on the positively charged electrode (anode). When the polymer is a positively charged material, then it will be deposited on the negativeiy charged electrode (cathode).

[0081] The electrophoretic deposition layer comprises an electrophoretic polymer selected from polyacrylic polymer, polyacrylamide-acrylic copolymer and epoxy- containing polymer.

[0082] The electrophoretic deposition layer may be transparent. In one example, the electrophoretic deposition layer is colourless. In another example, the electrophoretic polymer layer may comprise a colorant.

[0083] A “colorant'' may be a material that imparts a colour to the electrophoretic deposition layer. As used herein, “colorant" includes pigments and dyes, such as those that impart colours, such as black, magenta, cyan, yellow and white to an electrophoretic deposition layer. The pigment particles may be dispersed throughout the electrophoretic deposition layer. The pigment may be selected from carbon blade, titanium dioxide, clay, mica, talc, barium sulfate, calcium carbonate, synthetic pigment, peart pigment, metallic powder, aluminium oxide, dye, graphene, graphite, pigment colorants, magnetic particles and an inorganic powder. Although the present description primarily exemplifies the use of pigment colorants, the term "pigment” can be used more generally to describe pigment colorants and also other pigments such as organometallics, ferrites and ceramics. In one example, the pigment is a dye. The dye may be dispersed throughout the electrophoretic deposition layer.

[0084] The colorant can be any colorant compatible with the electrophoretic polymer and useful for providing an electrophoretic deposition layer. For example, the colorant may be present as pigment partides, or may comprise a resin and a pigment. The pigments can be any of those standardly used in the art. In some examples, the colorant is selected from a cyan pigment, a magenta pigment, a yellow pigment and a black pigment. For example, pigments by Hoechst including Permanent Yellow DHG, Permanent Yellow GR, Permanent Yellow G, Permanent Yellow NCG-71, Permanent Yellow GG, Hansa Yellow RA, Hansa Brilliant Yellow 5GX-02, Hansa Yellow X, NOVAPERM® YELLOW HR, NOVAPERM® YELLOW FGL, Hansa Brilliant Yellow 10GX, Permanent Yellow G3R-01, HOSTAPERM® YELLOW H4G, HOSTAPERM®

YELLOW H3G, HOSTAPERM® ORANGE GR, HOSTAPERM® SCARLET GO, Permanent Rubine F6B; pigments by Sun Chemical including L74-1357 Yellow, L75- 1331 Yellow, L75-2337 Yellow; pigments by Heubach including DALAMAR® YELLOW YT-858-D; pigments by Ciba-Geigy including CROMOPHTHAL® YELLOW 3 G, CROMOPHTHAL® YELLOW GR, CROMOPHTHAL® YELLOW 8 G, IRGAZINE® YELLOW 5GT, IRGALITE® RUBINE 4BL, MONASTRAL® MAGENTA, MONASTRAL® SCARLET, MONASTRAL® VIOLET, MONASTRAL® RED, MONASTRAL® VIOLET; pigments by BASF including LUMOGEN® LIGHT YELLOW, PALIOGEN® ORANGE, HELIOGEN® BLUE L 690 IF, HELIOGEN® BLUE TBD 7010, HELIOGEN® BLUE K 7090, HELIOGEN® BLUE L 710 IF, HELIOGEN® BLUE L 6470, HELIOGEN® GREEN

K 8683, HELIOGEN® GREEN L 9140; pigments by Mobay including QUINDO® MAGENTA, INDOFAST® BRILLIANT SCARLET, QUINDO® RED 6700, QUINDO® RED 6713, INDOFAST® VIOLET; pigments by Cabot including Maroon B STERLING® NS BLACK, STERLING® NSX 76, MOGUL® L; pigments by DuPont including TIPURE® R- 101; and pigments by Paul Uhlich including UHLICH® BK 8200. If the pigment is a white pigment particle, the pigment particle may be selected from TiOa, calcium carbonate, zinc oxide, and mixtures thereof. In some examples, the white pigment particfe may comprise an alumina-TiO2 pigment. In some examples the colorant may be Pacific Blue dye.

[0085] The colorant or pigment may be present in the electrophoretic deposition layer in an amount of from about 0.1 wt.% to about 15 wt.%, based on the total weight of the electrophoretic deposition layer. For example, the colorant or pigment may be present in the electrophoretic deposition layer in an amount from about 0.5 wt.% to about 13 wt.%, or from about 1 wt.% to about 12 wt.%, or from about 1.5 wt.% to about 10 wt.%, or from about 2 wt.% to about 9 wt.%, or from about 2.5 wt.% to about 8 wt.%, or from about 3 wt.% to about 7 wt.%, or from about 3.5 wt.% to about 6 wt.%, or from about 4 wt.% to about 5 wt.%, based on the totai weight of the eiectrophoretic deposition layer. In some examples, the colorant or pigment particle may be present in the electrophoretic deposition layer in an amount of at least 5.5 wt.% based on the total weight of the electrophoretic deposition layer, for example at least 4.5 wt.% based on the total weight of the electrophoretic deposition layer. [0086] In one example of an electrophoretic deposition layer comprising a colorant, the electrophoretic deposition layer comprises, based on the total weight of the electrophoretic deposition layer, 10 wt.% polyacrylic copolymer resin, 0.1 wt.% Pacific Blue dye, 0.3 wt.% of an anionic compound, such as sodium dodecylbenzene and 89.6 wt.% de-ionized water.

[0087] In one example of a transparent electrophoretic deposition layer, the electrophoretic deposition layer comprises, based on the total weight of the electrophoretic deposition layer, 10 wt.% polyacryiic copolymer resin, 0.3 wt.% of an anionic compound, such as sodium dodecylbenzene and 89.6 wt.% de-ionized water.

[0088] The electrophoretic deposition layer may have a thickness of from about 5 μm to about 60 μm, for example from about 10 μm to about 55 μm, or from about 15 μm to about 50 μm, or from about 20 μm to about 45 μm, or from about 25 μm to about 40 μm, or from about 30 μm to about 35 μm.

[0089] The thickness of the electrophoretic deposition layer can be measured after it has been applied using, for example, a micrometre screw gauge or scanning electron microscope (SEM).

Pre-treatment of the metal alloy substrate to form a first layered surface

[0090] In some examples, the metal alloy substrate may be pre-treated to form a first layered surface before engraving the metal alloy substrate using a CNC diamond cut process to form at least one chamfered edge. This is described below and shown in the flow chart in Figure 3.

[0091] The first layered surface may comprise a single layer or a combination of layers. The first layered surface may comprise, an oxidized layer, a protective layer or a combination thereof.

[0092] When the first layered surface comprises an oxidized layer, this layer may comprise a preliminary passivation layer, an oxidized layer of the metallic substrate, or both an oxidized layer of the metallic substrate and a preliminary passivation layer. The preliminary passivation layer may also be referred to herein as an inorganic layer.

[0093] The inorganic layer may comprise a salt selected from a molybdate salt, a vanadate salt, a phosphate salt, a chromate salt, a stannate sail and a manganese salt. In one example, the inorganic layer comprises a phosphate salt. The inorganic layer may contain oxidic salts that can provide the first surface with a dark grey appearance. In one example, the inorganic Iayer may be non-transparent

[0094] The oxidized Iayer of the metallic substrate may be a micro-arc oxide (MAO) layer, such as a micro-arc oxide Iayer of the magnesium alloy. For example, when the substrate comprises a magnesium alloy, the oxidized Iayer of the metallic substrate is an oxidized Iayer of the magnesium alloy. The micro-arc oxide Iayer may be obtainable from the method described herein.

[0095] The oxidized layer of the metallic substrate, including the micro-arc oxide layer, can have a thickness of from about 3 μm to about 15 μm, such as from about 5 μm to about 12 μm, from about 7 μm to about 10 μm. The inorganic layer may have a thickness of from about 0.5 μm to about 5 μm, such as from about 1 μm to about 4 μm, or about 2 μm to about 3 μm.

[0096] In one example, both an oxidized iayer of the metallic substrate and an inorganic Iayer may be present. In one example, the inorganic Iayer can be deposited or coated on the surface of the metal alloy substrate.

[0097] In one example, the oxidized Iayer or the inorganic Iayer can be a single layer, wherein the oxidized Iayer is a micro-arc oxide Iayer. By itself, the micro-arc oxide Iayer or the passivation Iayer may prevent corrosion of the metal alloy substrate.

[0098] The first layered surface may further comprise at least one protective Iayer, such as two, three or four protective layers. Each protective Iayer may be selected from a primer coating layer, a base coating layer, powder coating Iayer and a top coating Iayer. The protective Iayer may be deposited or coated directly on to the oxidized Iayer or the inorganic Iayer. Each of these protective layers may be made of different materials and may provide different functionality, such as heat resistance, hydrophobicity, and anti- bacterial properties.

[0099] The primer coating Iayer may comprise a polyurethane or a filler selected from carbon black, titanium dioxide, clay, mica, talc, barium sulfate, calcium carbonate, a synthetic pigment, a metallic powder, aluminium oxide, carbon nanotubes (CNTs), graphene, graphite, and an organic powder. The organic powder may, for example, be an acrylic, a polyurethane, a polyamide, a polyester or an epoxide. The primer coating Iayer may, for example, comprise a polyurethane and a filler as described above. [00100] A heat resistant material may be included in the primer coating layer. In an example, the primer coating layer contains a heat resistant material, a filler as described above and may further comprise a polyurethane.

[00101] The primer coating layer can have a thickness of from about 5 μm to about 20 μm, such as from about 7 μm to about 18 μm, or from about 10 μm to about 15 μm.

[00102] The base coating layer may comprise polyurethane-containing pigments. The base coating layer may further comprise at least one of carbon black, titanium dioxide, clay, mica, talc, barium sulfate, calcium carbonate, synthetic pigment, metallic powder, aluminium oxide, an organic powder, an inorganic powder, graphene, graphite, plastic beads, a colour pigment or a dye. The organic powder may, for example, be an acrylic, a polyurethane, a polyamide, a polyester or an epoxide.

[00103] The base coating layer may comprise a component selected from barium sulfate, talc, a dye and a colour pigment. In one example, the base coating layer comprises a colour pigment or a dye.

[00104] The base coating layer may further comprise a heat resistant material, such as a silica aerogel. The base coating layer can comprise a heat resistant material and a component as described above.

[00105] The base coating layer can have a thickness of from about 10 μm to about 25 μm, such as from about 15 μm to about 20 μm.

[00106] By using a base coating layer, other different protective layers can easily be deposited on the first layered surface. For example, when the first layered surface has been coated with an oxide layer, the use of a base coating layer may improve adhesion between different protective layers.

[00107] The powder coating layer may comprise a polymer selected from an epoxy resin, a poly(vinyl chloride), a polyamide, a polyester, a polyurethane, an acrylic and a polyphenylene ether.

[00108] In an example, the powder coating layer is an electrostatic powder coating layer. The powder coating layer may be electrostatically deposited or coated onto a first surface of the substrate and then the polymer may be cured.

[00109] The powder coating layer may further comprise a filler selected from carbon black, titanium dioxide, clay, mica, talc, barium sulfate, calcium carbonate, a synthetic pigment, a metallic powder, aluminium oxide, carbon nanotubes (CNTs), graphene, graphite, and an organic powder. The organic powder may, for example, be an acrylic, a polyurethane, a polyamide, a polyester or an epoxide. In one example, toe fillers may be selected from talc, clay, graphene and high aspect ratio pigments.

[00110] The powder coating layer may be applied and may be cured at a temperature of about 120 ºC to about 190ºC.

[00111] The powder coating layer can have a thickness of from about 20 μm to about 60 μm, such as from about 30 μm to about 50 μm, or from about 35 μm to about 45 μm.

[00112] The top coating layer may comprise a bottom layer and a top layer coated or deposited on the bottom layer. The bottom layer may comprise a polyurethane polymer. The top layer may comprise a UV top coat. The UV top coat may, for example, be a resin, such as a polyacrylic resin, a polyurethane resin, a urethane acrylate resin, an acrylic resin or an epoxy acrylate resin.

[00113] When the top coating layer comprises a bottom layer and a top layer, then both the bottom layer and the top layer may be transparent. The top coating layer may be transparent The top coating layer can have a total thickness of from about 10 μm to about 25 μm, such as about 15 μm to about 20 μm.

[00114] The first layered surface may comprise multiple layers on the metal alloy substrate. In an example, the first layered surface comprises an inorganic layer, a primer coating layer, a base coating layer and a top coating layer. In an example, the first layered surface comprises an inorganic layer, a power layer, a primer coating layer, a base coating layer and a top coating layer.

[00115] The first layered surface may also comprise a hydrophobic anti- fingerprint layer. The hydrophobic anti-fingerprint layer may be transparent. The hydrophobic anti-fingerprint layer may comprise a fluoropolymer. The fluoropolymer may be selected from fiuorinated olefin-based polymers, fluoroacrylates, fluorosilicone acrylates, fluorourethanes, perfiuoropolyethers, perfluoropoiyoxetanes, C1 to C6 fluorotelomers, polytetrafluoroethylene, polyvinylidenefluoride and ftuorosiloxane. In one example, the fluoropolymer is polyvinylidenefluoride. The fluoropolymer comprised in toe hydrophobic anti-fingerprint layer may be a UV polymer, which may be cured at about 80 to about 120 ºC. The fluoropolymer comprised in the hydrophobic anti-fingerprint layer may be a hydrophobic polymer, comprising 7-carbons or more. The hydrophobic anti- fingerprint layer comprises at least 20 wt.% of a fluoropolymer, based on the total weight of the hydrophobic anti-fingerprint layer. For example, the hydrophobic anti-fingerprint layer may comprise at least 25 wt.% of fluoropolymer, or at least 30 wt.% of fluoropolymer, or at least 40 wt-% of fluoropolymer, or at least 50 wt-% of fluoropolymer, or at least 60 wt-% of fluoropolymer, or at least 70 wt-% of fluoropolymer, based on the total weight of the hydrophobic anti-fingerprint layer, in addition to the fluoropolymer, tee hydrophobic anti-fingerprint layer may further comprise components selected from isophorone, cyclohexanone, acrylic resin and combinations thereof. In one example, the hydrophobic anti-fingerprint layer comprises 20 wt.% polyvinylidenefluoride, 40 wt.% isophorone, 5 wt.% cyclohexanone and 35 wt.% acrylic resin, based on the total weight of the hydrophobic anti-fingerprint layer. The hydrophobic anti-fingerprint layer may have a high contact angle. In one example, the hydrophobic anti-fingerprint layer may have a contact angle of about 100º or more, such about 105 º or more, or about 110 ° or more. The hydrophobic anti-fingerprint layer may have an anti-smudge function and provide a smooth touch feeling. In one example, the hydrophobic anti-fingerprint layer may be on a painted layer and may cause the water based paint not to adhere to the painted layer. The hydrophobic anti-fingerprint layer may have a thickness of about from 10 nm to about 1 μm, such as from about 50 nm to about 900 nm, or from about 100 nm to about 800 nm, or from about 200 nm to abort 700 nm, or from about 300 nm to about 600 nm, or from about 400 nm to about 700 nm. In one example, the hydrophobic anti-fingerprint layer may be applied to the whole surface of the metal alloy substrate prior to the engraving process to form a chamfered edge.

Pre-treatment of metal alloy substrate to form a first treated surface

[00116] In some examples, the metal alloy substrate may be pre-treated with a cleaning treatment followed by electrophoretic deposition, to form a first treated surface, before engraving the metal alloy substrate using a CNC diamond cut process to form at least one chamfered edge. This is described below and shown in the flow chart in Figure

5.

[00117] The metal alloy substrate subjected with a cleaning treatment may be untreated, or may have been pre-treated with a preliminary passivation layer, an oxidized layer of the metallic substrate, or bom an oxidized layer of the metallic substrate and a preliminary passivation layer.

[00118] The first treated surface may be treated with a cleaning treatment selected from degreasing, chemical polishing and deionized water cleaning. The cleaning treatment may even out the surface of the metal alloy substrate. [00119] In one example degreasing is carried out in an ultrasonic vibration bath: comprising an alkaline cleaning process using 0.3-2.0 wt% sodium caseinate, sodium polyacrylate, sodium polyoxyethylene alkyl ether carboxylate, and sodium dodecyl sulfate in an ultrasonic vibration degreasing bath at pH 9-13 to remove organic impurities, grease and oil from a surface.

[00120] in one example, chemical polishing is carried out using 0.1-3 wt.% acid solution selected from hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid and combinations thereof.

[00121] An electrophoretic polymer may then be applied to the cleaned metal alloy substrate surface. The electrophoretic polymer layer Is formed by an electrophoretic deposition (EPD) process, for example, as described herein. The electrophoretic polymer may be selected from polyacrylic polymer, polyacrylamide-acrylic copolymer and epoxy- containing polymer. Electronic device having a housing

[00122] The present disclosure also provides for an electronic device having a housing. The electronic device of the present disclosure may be a computer, a laptop, a tablet, a workstation, a cell phone, a portable networking device, a portable gaming device and a portable GPS.

[00123] The electronic device has an electrical circuit, such as a motherboard or display circuitry. The housing may be external to the electrical circuit.

[00124] In some examples there is provided an electronic device having a housing, wherein the housing comprises a metal alloy substrate with at least one chamfered edge, a passivation layer deposited on the at least one chamfered edge, and an electrophoretic deposition layer deposited on the passivation layer. The at least one chamfered edge is engraved by a CNC diamond cut process using the water-based carbon nanotube cutting fluid described herein.

[00125] The housing comprises a coated metal alloy substrate disclosed herein. The metal alloy substrate can be light-weight and may provide a durable housing. The housing of the present disclosure may have cosmetic features that are visually appealing to a user, such as an attractive surface finish. The housing according to the present disclosure may have chamfered surfaces that are glossy or have a natural metallic lustre. The glossy surface and/or metallic lustre can be determined by visual examination. The housing according to the present disclosure has a chamfered surface that has good resistance to corrosion and/or metal oxidation.

[00126] The housing may provide an exterior part of the electronic device, such as a cover or a casing of the electronic device. The housing may include a support structure for an electronic component of the electronic device. The housing may include a battery cover area, a battery door, a vent or combinations thereof.

[00127] The housing may provide a substantial part of the cover or the casing of the electronic device. The term “substantial part” in this context refers to at least about 50 %, such as at least about 60 %, at least about 70 %, at least about 80 % or at least about 90 %, of the total weight of the cover or the casing. The housing may provide the entire cover or casing of the electronic device.

[00128] The housing can be a cover, such as a lid, the casing or both the cover and the casing of the electronic device. The casing may form a bottom or lower part of the cover of the electronic device. For example, the housing is the casing of a laptop, a tablet or a cell phone.

[00129] The chamfered edge may provide an edge or peripheral area in the housing for a touchpad, a fingerprint scanner, a trackball, a pointing stick, or a button, such as a mouse button or a keyboard button.

[00130] The main non-engraved surface, in other words non-chamfered surface, of the metal alloy substrate may provide a bezel for a display screen, a casing, or wrist rest for a keyboard.

[00131] Examples of housings of the present disclosure are shown in Figures 2, 4 and 6, which are partial cross sections through the housing. The housing shown in Figure 2 is a cross-section of the housing at the chamfered edge (1 ). The chamfered edge (1) has a passivation layer deposited thereon (2) and an electrophoretic deposition layer deposited on the passivation layer (3). In a further example, the housing shown in Figure 4 shows a metal alloy substrate that was first pre-treated with an inorganic layer (4), a primer layer (5), a base coat layer (6) and a top coat layer (7) to form a first-coated surface. The pre-treated metal alloy substrate was then engraved to form a chamfered edge (1). The chamfered edge has a passivation layer deposited thereon (2) and an electrophoretic deposition layer deposited on the passivation layer (3). In a further example, the housing shown in Figure 6 shows a metal alloy substrate that was first pretreated with an inorganic layer (4) and a first electrophoretic deposition layer (8) to form a first-treated surface. The pre-treated metal alloy substrate was then engraved to form a chamfered edge (1). The chamfered edge has a passivation layer deposited thereon (2) and an electrophoretic deposition layer deposited on the passivation layer (3).

[00132] Figure 5 shows an example of a housing of the present disclosure. The housing is a casing (9) for a keyboard of a laptop. The non-engraved coated surface of the metal alloy substrate (10) provides a wrist rest and cover for the laptop. Chamfered edges form further surfaces such as (11), (12) and (13). The chamfered edges of this housing are found to have good metallic lustre. Along with a high metallic lustre, the surfaces are also found to be corrosion resistant and have a durable coating. EXAMPLES

[00133] The following illustrates examples of the water-based carbon nanotube cutting fluids, methods and other aspects described herein. Thus, these Examples should not be considered as limitations of the present disclosure, but are merely in place to teach how to make examples of the present disclosure.

Examole 1

[00134] A keyboard casing for a laptop was manufactured from a magnesium alloy substrate comprising the magnesium alloy AZ31 B, which comprises, based on the weight of the total alloy: Al: 2.5-3, 5 wt.%, Zn: 0.6-1.4 wt.%, Mn: 0.2 wt.%, Si:0-1 wt.%, Cu: 0.05 wt.%, Ca: 0.04 wt.%, Fe: 0.005 wt.%, Ni: 0.005 wt.% and the remainder being Mg and inevitable impurities.

[00135] An oxidized surface layer was formed on the magnesium alloy substrate by micro-arc oxidation. The oxidized surface layer was then coated with a primer coating layer of polyester polyurethane. The primer coating layer was coated with a base coating layer of polyurethane and a top coating layer of urethane acrylate.

[00136] Chamfered edges were cut into the coated substrate using a CNC cutting process. This process uses a diamond cutting procedure, using a lathe, to remove a thin Mg alloy layer to expose a non-oxidised surface of the coated metal alloy substrate. This cuts an opening in the casing for a touchpad. The machine used was a Brother Speedio S500 Z1 (machine dimensions 61.4" x 87.4” x 98.3”). The dimensions of the touchpad were between 0.3-2mm in width. [00137] The water-based carbon nanotube cutting fluid used had the composition as shown in Table 1, and contained no components with a LogP of 5 or above. After cutting, the chamfered edge was then cleaned with deionized water. Table 1

[00138] The exposed chamfered edge was coated with a solution comprising a chelated metal complex wherein the chelating agent is DTTPH and the metal ion Is zinc. The solution was dried and formed a transparent passivation layer which comprises DTTPH and zinc. The transparent passivation layer protects the underlying metallic surface of the substrate and prevents it from undergoing atmospheric oxidation. [00139] To the passivation layer was applied a transparent electrophoretic deposition layer. The electrophoretic deposition layer comprised 10 wt.% polyacrylic polymer, 0.5 wt% sodium polyacrylate, and 0.3 wt.% glutaraldehyde, based on the total weight of the electrophoretic deposition layer. The substrate was then heated at 170 °C for 45 minutes. Excess passivation layer and electrophoretic deposition layer around the chamfered edges was then washed out using deionised water.

Example 2

[00140] A keyboard casing for a laptop was manufactured from a magnesium alloy substrate as described in Example 1, except that a yellow coloured electrophoretic deposition layer was applied onto the passivation layer.

[00141] The yellow-coloured electrophoretic deposition layer comprised 10 wt.% polyacrylic polymer, 5 wt% pigment yellow 191, 0.5 wt% sodium polyacrylate, and 0.3 wt.% glutaraldehyde, based on the total weight of the electrophoretic deposition layer. The substrate was then heated at 170 “C for 45 minutes.

Example 3

[00142] A keyboard casing for a laptop was manufactured from a magnesium alloy substrate as described in Example 2.

[00143] Further chamfered edges were then cut into a second area of the coated metal alloy substrate using a CNC cutting process to expose a non-oxidised surface of the coated metal alloy substrate to cut an opening in the casing for a fingerprint scanner. The CNC cutting process used the same water-based carbon nanotube cutting fluid as described in Example 1.

[00144] To the second chamfered edge was applied a transparent passivation layer, as described in Example 1.

[00145] Using electrophoretic deposition, a red-coloured electrophoretic layer was applied to the transparent passivation layer. The electrophoretic deposition layer comprised 10 wt.% polyacrylic polymer, 5 wt% Pigment Red 168 MF, 0.5 wt% sodium polyacrylate, and 0.3 wt.% glutaraldehyde, based on the total weight of the electrophoretic deposition layer. The substrate was then heated at 170 ⁶ C for 45 minutes. [08146] The resultant substrate had two chamfered edges, both of which are coloured. The laptop housing had a yellow-coloured touchpad and a red-coloured fingerprint scanner.

Results The chamfered edge(s) formed by the processes described herein have been found to have an attractive metallic lustre, as determined by visual determination, and have been found to have good corrosion resistance properties. The cutting knife used was also found to have an increased life-time when used repetitively in the examples above.