CONTINUOUS COMPOSITE METAL FOAM PRODUCTION AND METHOD AND DEVICE FOR STIRRING PARTICLE REINFORCED COMPOSITE METAL

Technical Field of the Invention

This invention is related to a method and a device that performs said method in order to carry out in one go, the production of closed cell, and continuous form composite metal foam production without the necessity to perform pre-processes thereon; to increase the quality and strength of the material, to distribute the reinforcement and/or foam material homogenously within the material, to be able to produce foam material having the desired density and to provide a homogenous inner structure, moreover, to be able to mix homogenously at the desired ratios, the reinforcement material and the matrix material during the production of particle reinforced composite metal, to distribute the ceramic particles used as reinforcement material into the material homogenously and in order for the material to be wetted better by the matrix material and in order to increase the quality of the material.

Prior Art related to the art of metal foams

The publications (articles and thesis) within the known state of the art related to the method and device for producing continuous composite metal foam have been listed below.

[1] Ashby, M. F., Evans, A., Fleck, N. A., Gibson, L. J., Hutchinson, J. W. and Wadley, H. N. G., Metal Foams: A Design Guide", Butterworth-Heinemann Woburn, USA,ISBN 0-7506- 7219-6,2000

[2] Wassim Elias Azzi, "A Systematic Study On The Mechanical And Thermal Properties Of Open Cell Metal Foams For Aerospace Applications" Ph.D. Thesis, North Carolina State University, Raleigh, ,2004.

[3] John Banhart, "Manufacture, Characterization and Application of Cellular Metals and Metal Foams" John Banhart & Denis Weaire, "On the road again: Metal foams find favor". Physics Today, 2002. [4] H.P. Degischer, Handbook of Cellular Materials - Production, Processing, Applications,H.P. Degischer y B. Kriszt (Eds.), Wiley-VCH, Weinheim, pp. 5-7.,2000

[5] Matijasevic-Lux, B. (2006). Characterization and optimization of blowing agent for making improved metal foams, Doctor Eng. Science thesis, Technical University of Berlin [6] S. Elbir, S. Yilmaz, A. K. Toksoy, M. Guden "SiC-Particulate Aluminum Composite Foams Produced By Powder Compacts: Foaming And Compression Behavior" Journal Of Materials Science 38,4745-4755,2003

[7] S. Esmaeelzadeh A, A. Simchi, "Foamability And Compressive Properties Of AlSi7-3 Vol.% SiC-0.5 Wt.% TiH2 Powder Compact", Materials Letters, 2008

[8] Wang Deqing, Shi Ziyuan, "Effect Of Ceramic Particles On Cell Size And Wall Thickness Of Aluminum Foam", Materials Science And Engineering A361,45-49,2003

[9] F. Simancik, L. Lucan And J.Jerz, "Reinforced Aluminium Foams" Institute Of Materials And Machine Mechanics, Sas, Bratislava, Slovak Republic

[10] B.P.Neville,A.Rabiei,"Comp. Metal Foams Processed Through Powder Metallurgy", Mat. And Des.29-388-396,2008

[11] Rabiei, A.T. O'neill, "A Study On Processing Of A Composite Metal Foam Via Casting", Materials Science And Engineering A 404,159-164,2005

[12] Lakshmi J. Vendra, Afsaneh Rabiei, "A Study On Aluminum-Steel Composite Metal Foam Processed By Casting" Materials Science And Engineering A 465,59-67,2007

[13] Banhart, J., Fleck, N. and Mortensen, A., "Cellular Metals: Manufacture, Properties, Applications", Verlag Metall Innovation Technologie MIT Berlin, Germany,ISBN 3-935538-12- X,2003

[14] Ashby,M.F.,"Materials Selection in Mechanical Design",Butterworth-Heinemann Oxford,UK,ISBN 0 7506 6168 2,2005

[15] Stadler, C, Hosnedl, S. and Lasova, V., "Organ Features Incorporating Metal Foams- their Properties and their Relationships and Evaluation", Proc.of the 4th Int. Conf. on Porous Metals and Metal Foaming Tech.-MetFoam05, , Japan, 2005.

[16] John Banhart, Manufacture, "Characterization And Application Of Cellular Metals And Metal Foams", Progress In Materials Science, 46, 559-632, 2001 [17] Esmaeelzadeh,S., Simchi, A., Lehmhus, D., "Effect of Ceramic Particle Addition on the Foaming Behavior, Cell Structure and Mechanical Properties of P/M AISi7 Foam", Materials Science and Engineering, A424, 290-299,2006

[18] Yu, S., Luo, Y., Liu, J., "Effects of Strain Rate and SiC Particle on the Compressive Property of SiCp/AISi9Mg Composite Foams", Materials Science and Engineering, 487, 394- 399,2008

[19] Gui, M.C., Wang, D.B ^" , Wu, J.J., Yuan, G.J., Li, C.G., "Deformation and Damping Behaviors of Foamed Al-Si-SiCp Composite", Materials Science and Engineering, A286, 282- 288,2000

[20] Esmaeelzadeh, S., Simchi, A., "Foamability and Compressive Properties of AISi7 - 3 Vol.% SiC- 0.5 Wt.% Tih2 Powder Compact", Materials Letters, 62, 1561-1564,2008

[21] Jeon, Y.P., Kang,C.G., Lee, S.M., "Effects of Cell Size on Compression and Bending Strength of Aluminum-Foamed Material by Complex Stirring in Induction Heating", Journal of Materials Processing Technology, 2 0 9, 435-444,2009

[22] Luo, Y., Yu, S., Li, W., Liu, J., Wei, M., "Compressive Behavior of SiCp/Alsi9Mg Composite Foams", Journal of Alloys and Compounds, 460, 294-298,2009

[23] Yu, C.J., Banhart, J., "Mechanical Properties of Metallic Foams", Fraunhofer USA Metal Foam Symposium, 37-48,1997

[24] Haesche, M., Weise, J., Garcia-Moreno, F., Banhart, J., "Influence of Particle Additions on The Foaming Behaviour of AISill/TiH2 Composites Made by Semi-Solid Processing", Materials Science And Engineering, 480, 283-288,2007

Metal foams (Metal Foam) can be used in several fields from mechanical applications to thermal applications due to their perfect durability /weight ratios [1-4,13,15]. Metal foams, form interesting physical and mechanical characteristics when high durability is combined with very low specific gravity or high gas permeability is combined with heat treatment conduction.

They are characterized with cell topologies, structurally, or by the fact that they are open or closed cells, according to their specific intensities, to their cell sizes, cell shapes, and anisotropics. They can be produced from different materials such as aluminum, titanium and nickel. As a result the field of application determines the type of material from which the metal foam should be produced from. [4,13].

Due to their low densities, perfect specific durability, noise insulation, and impact and flame damping characteristics, studies that have increased recently especially regarding closed cell Metal Foams in sectors such as space, aviation, and automotives attract attention [3,4]

Mainly two methods are used to produce Metal Foam's which are the liquid phase and the solid phase. The structural and durability characteristics show difference in connection with the production method. There are several studies related to the problems that arise during production. [5-9,16,18-23].

The main problems that are faced during the production of metal foams that are produced using liquid phase methods, are not being able to provide sufficient resistance in the cell walls, not being able to control cell sizes and distribution, combining of cells, and the obligation to perform heat treatment on powders that are used as foaming agents [11- 13,21]. In the patent publications numbered US2005161188, HU0800736, WO2006021082, it has been explained that reinforcement material is added into liquid metal prior to the foaming process in order to increase resistance and foam stability and to thicken the walls of cells. This application has been described in the publication numbered WO2008003290.

It is said that that in these studies where composite foam production is carried out, the matrix and reinforcement materials are in contact with each other for a long time and due to this reason unwanted brittle phases occur in inter surfaces, and that homogenously distributing the reinforcement material within the liquid phase is a difficult task on which studies are still being carried out. [6,8-12,17,18].

Although production is possible using liquid phase production methods, due to weak resistance characteristics they have limited usage in structural applications [5,7,8,and 9]. Cell size and distribution control can be relatively carried out in metal foams that have been produced by first forming a preform by means of sintering and then heating in a furnace or in limited volumes; however the product sizes and numbers obtained with these kind of methods are limited (WO2010127668 and WO201010106883). Moreover the sintering procedure is quite long. The precautions taken in order to prevent these kinds of disadvantages also increase process costs. [10,11]. The method and device, developed by means of the present invention, in order to produce a continuous composite metal•foam or particle reinforced composite metal overcomes the disadvantages mentioned above and the method and device developed according to the present invention is characterized by the following:

• Closed cell composite foam materials reinforced with ceramic particles added in different ratios can be directly produced using the semi solid production method,

• Ceramic particles and foaming powders are mixed into the semi solid metal or metal alloys,

• The stirring procedure is carried, out when the material is semi solid by means of stirrers having different profiles, prepared from graphite rods,

• The semi solid mixture is added to movable molds by means of a piston after the stirring process has been completed,

• The size of the product is determined by the section of the mold and the volume of the crucible,

• Following the foaming procedure that has been carried out inside a furnace the product is taken out of the furnace by means of a pushing mechanism,

• It is quickly cooled by a cooling system located outside of the furnace, and as a result the metal foam production having the desired characteristics is produced.

KNOWN STATE OF THE ART RELATED TO PARTICLE REINFORCED COMPOSITE METAL

The publications (articles and thesis studies) within the known state of the art related to the method and device for particle reinforced composite metal stirring developed by means of this invention have been listed below.

[1] Naher,S., Brabazon,D., Looney,L, "Development and assessment of a new quick quench stir caster design for the production of metal matrix composites", Journal of Material Processing Technology, 166,430-439., 2004

[2] Zhou, W. and Xu, Z.M., "Casting of SiC reinforced metal matrix composites", J. of Mat. Proc.Tech., 63, 358-363.,1997 [3] D.O.D., "Department of Defense Handbook", Comp. Mat. Handbook, Metal Matrix Composites, Vol.4., 1999

[4] Kaczmar, J.W., Pietrzak, K. , Wlosinski, W., "The production and application of metal matrix composite materials", Journal of Materials Processing Technology 106, 58-67,2000 [5] William, C, Harrigan, Jr. "Commercial processing of metal matrix composites", Mat. Sci. and Eng. A244,75-79,1998

[6] Evans, A., San Marchi, C, Mortensen, A., "Metal Matrix Composites in Industry, An Introduction and a Survey", 440 p., Hardcover, ISBN: 978-1-4020-7521-6,2003

[7] O'Donnell, G., Looney, L, "Production of Aluminium Matrix Composite Components Using Conventional PM Technology", Materials Science and Engineering A303,292-301,2001

[8] Hashim, J. Looney, L, Hashmi, M.SJ,. "The Wettability of SiC Particles by Molten Aluminium Alloy", Journal of Materials Processing Technology 119, 324-328,2001

[9] Hashim, J., Looney,L, Hashmi, M.S.J., "Particle distribution in cast metal matrix composites— art I", Journal of Materials Processing Technology 123, 251-257,2002

[10] Hashim, J., Looney,L, Hashmi, M.S.J., "Particle distribution in cast metal matrix composites— Part Π", Journal of Materials Processing Technology, 123 ,258-263,2002

[11] Shi, Z., Ochiai, S. , Gu, M., Hojo, M. and Lee, J.C., "The formation and thermostability of MgO and MgAI204 nanoparticles in oxidized SiC particle-reinforced Al-Mg composites", Applied Physics A: Materials- Science & Processing Springer Berlin / Heidelberg, 74, 97- 104,2002

[12] Contreras, A., Bedolla, E. , Perez, R., "Interfacial phenomena in wettability of TiC by Al- Mg alloys", Acta Material ia ,52 985-994,2004

[13] Vaucher, S., Beffort, O., "Bonding and interface formation in Metal Matrix Composites", Vol. 9, EMPA Swiss Federal Laboratories for Materials Testing and Research Thun Switzerland,2000

[14] Tham, L.M., Gupta, M. and Cheng, L, "Effect Of Limited Matrix-Reinforcement Interfacial Reaction On Enhancing The Mechanical Properties Of Aluminium-Silicon Carbide Composites", Acta mate., 49 3243-3253,2001

[15] Kevorkijan, V.M. , Sustarsic, B., "A New Production Technology for Discontinuously Reinforced Al-SiC Composites", Key Engineering Materials (Volumes 127 - 131),471-478,1997 [16] aher, S., Brabazon D., Looney L., "Simulation of The Stir Casting Process, Journal of Materials Processing Technology", 143-144 ,567-571,2003

[17] Yarandi, F.M. , Rohatgi, P.K. , Ray, S., Settling, "Casting Fluidity and Solidification Behavior of Aluminum-SiC Particle Composite", Journal Key Engineering Materials (Volumes 79 - 80), 91-104,1993

[18] J. Hashim, L. Looney* and M. S. J. Hashmi, "Metal matrix composites: production by the stir casting method", Journal of Materials Processing Technology,Volumes 92-93, Pages 1-7,1999

[19] Balasivanandha S. P., , Karunamoorthy, L, Kathiresan, S., Mohan, B., "Influence of stirring speed and stirring time on distribution of particles in cast metal matrix composite", Journal of Materials Processing Technology, Volume 171, Issue 2, , Pages 268-273,2006

[20] A. Ourdjini, K.C. Chew, B.T. Khoo, "Settling of silicon carbide particles in cast metal matrix composite", J. Mater. Process. Technol. 116,72-76.,2001

[21] Aklaghi, F., Lajevardi, A., Maghanaki, H.M., "Effect of Casting Temperature On The Microstructure And Wear Resistance of Compocast A356/SiCp Composites:A Comparison Between SS and SL Routes", J. Mat. Proc. Tech,2004

[22] Hallen, J.M. , Balmori, H.M. , Jaramillo-Vigueras, D. , Estrada, J.L , Gonzalez J.L , Manzano-Ramirez, A., "Influence of Mg and Stirring on the Strength of an Aluminium Matrix Composite Obtained by Compocasting", Journal Key Engineering Materials (Volumes 127 - 131), 495-502,1997

[23] Wang,H., 2007, In-Situ Si/Al "Composite Produced by Semisolid Metal Processing, Materials and Manufacturing Processes", 22, 696 - 699,2007

[24] Qin, Q.D., Zhao, , Y.G., Cong, P.J. W. Zhou and Xu, B., "Semisolid microstructure of Mg2Si/AI composite by cooling slope cast and its evolution during partial remelting process", Materials Science and Engineering: A, 444, 99-103,2007

[25] Ghomashchi,M.R.,Vikhrov,A.,"Squeeze casting: an overview",J. of Materials Processing Technology 101,1-9,2000

[26] Vijayaram, T.R., Sulaiman, S., Hamouda, A.M.S. and Ahmad, M.H.M., "Fabrication of fiber reinforced metal matrix composites by squeeze casting technology", Journal of Materials Processing Technology,178,34-38,2006 [27] Yong, M. S. and Clegg, A. 1., "Process optimization for a squeeze cast magnesium alloy", J. of Mat. Proc. Tech., 145, 134-141,2004

[28] Zheng,M., Wu, ., Yao, C, "Characterization of interfacial reaction in squeeze cast SiCw/Mg composites", Materials Letters,47, 118-124,2001

[29] Reihani, S.M.S., "Processing of squeeze cast AI6061-30vol% SiC composites and their characterization", Materials and Design,27, 216-222,2006

[30] Long, S., Beffort, O., Cayron, C, Bonjour C, "Microstructure and mechanical properties of a high volume fraction SiC particle reinforced AICu4MgAg squeeze casting", Mat. Sci. and Eng. A269 175-185,1999

[31] Vicens,!, Chedru, M., Chermant, J. L., "New AI-AIN composites fabricated by squeeze casting: interfacial phenomena", Composites Part A: Applied Science and Manufacturing, Volume 33,Issuel0,2, Pages 1421-1423,2002

[32] Spencer, K., Corbin, S.F., Lloyd, D.J., "The Influence of Iron Content on the Plane Strain Fracture Behaviour of AA 5754 Al-Mg Sheet Alloys", Materials Science and Engineering A325,394-404,2002

[33] Valdez,S., Campillo,B., Perez,R., Martinez,L, Garcia H. A.,"Synthesis and microstructural characterization of Al-Mg alloy-SiC particle composite", Materials Letters, 62, 2623-2625,2008

[34] Clrkmez, N., "AIMg3/SiCp ompozitlerinin Llretimi ve Mekanik Ozelliklerdeki Degisjmlerin incelenmesi", Doktora Tezi, YTU F.B.E., Istanbul, 2004

[35] Skolianos,S.M., Skolianos, S.M., Kiourtsidis, G. and Xatzifotiou, T. "Effect of Applied Pressure on the Microstructure and Mechanical Properties of Squeeze-Cast aluminium AA6061 alloy",Material Sci. and Engineering A231,17-24,1997

Various methods are used during the production of Metal Matrix Composites (MMC), depending on the type of reinforcement and its geometry. [1]. These methods are liquid, solid and double phase methods. [2-4]. Each method has its own advantages and disadvantages during its application [1,5-7].

Quite a high amount of resistance, homogenous reinforcement distribution, and controlled inter surface reactions can be provided as a result of solid phase production methods in especially particle reinforced metal matrix composite (PRMMC) materials. However the procedure is difficult and quite costly due to additional processes. The particle sizes that can be obtained are limited. [1]

As liquid phase production methods are relatively cheaper, easier and more adaptable they are commercially preferred. During the production of PRMMC materials with liquid phase methods, problems that are difficult to overcome occur at the stirring and solidification processes[4, 8-10]. Some of the main problems that can occur are, not being able to homogenously distribute the reinforcement material into the liquid phase, not being wetted by the matrix material, being pushed beyond the mixture, flocculation, accumulation, occurrence of unwanted chemical reactions between the matrix and reinforcement material, inter surface problems and formation of pores [11-14].

There are several studies that research for solutions of the present problems in literature. Reinforcement pre processes and metallurgical procedures that increase wetting are carried out in order to improve the inter surface connection between the reinforcement and the matrix[15].

Different stirring profiles, stirring speed and durations have been tried in order to overcome problems such as the reinforcement being pushed out of the mixture, flocculation and sedimentation [19,20]. Although these solutions provide homogenous reinforcement, unwanted inter surface reactions are also faced as stirring duration is extended in high temperatures and the rate of pore formation is also increased. [2, 12, 15-20].

The methods using double phase for production are being preferred by investigators recently. These methods have several advantages that can be explained with the ticsotropic behavior of metal materials. Main advantages of said method can be listed as: (a) Lower energy consumption relative to other liquid stirring methods due to short time stirring procedures in low temperatures; (b) reducing chemical waste in the reinforcement material from the alloy (c) longer mold life; (d) laminar flow of the viscose semi solid material; (e) lower solidification shrinkage; (f) lower tendency to hot tearing; (g) faster process conversion; (h) less formation of reaction products that reduce the resistance of composite material; Q) reducing abrasion in the stirrers, and reducing the unwanted elements inside the mixture; (k) less porous inner structure as the gas intake rate from the environment is reduced; (I) solid phase formation having co axial particles which are not dentritic [21-22]. The main disadvantages of the semi solid production methods are; stirring difficulty due to high viscosity and trying to ensure that the procedure parameters are kept fixed (temperature, shear stresses etc.) [21-24]. A method and device for the method of particle reinforced composite metal stirring developed according to the present invention can overcome the disadvantages mentioned above and the characteristics of the method and device developed according to the present invention is as follows:

• Ceramic particles with different ratios are added directly into metal matrix material using the semi solid stirring method,

• Ceramic particles are homogenously distributed into metal or metal alloys which are semi solid,

• The stirring procedure is carried out by means of stirrers having different profiles, prepared from graphite rods when the material is at a semi solid state,

• When the stirring procedure is completed the semi solid mixture is transferred into molds either at a semi solid state or under high temperatures,

• Particle reinforced composite metal production can be performed using the desired casting or production method,

• The product sizes are determined by the mold section and the volume of the crucible; and as a result the particle reinforced composite metal production having the desired characteristics can be carried out.

Description of the Drawings

The figures that have been drawn in order to further explain the method and device for the production of continuous composite metal foam and particle reinforced composite metal stirring method have been attached to this document. The definitions of the figures are given below.

Figure 1 Process line sectional view

Figure 2 Process line mold movement view

Figure 3 The view of the crucible and the crucible bottom

Figure 4 Schematic view of the furnace

Figure 5 The schematic view of the kneading and stirring apparatus and the stirring system Figure 6 Schematic view of the bottom of the crucible Figure 7 View of the aluminum composite foam that has been prepared by adding %25 SiCp reinforcement

Figure 8 SiC reinforcement rate-linear expansion change graphic

Figure 9 View of the non reinforced, %10 SiC reinforced and %20 SiC reinforced samples that have been produced with 5754 alloy

Figure 10 View of the aluminum foam samples that have been produced using TiH ₂ powders having different particle sizes,

Figure 11 View of %1 TiH2 and %20 SiC reinforced 5754 alloy that has been foamed at different durations

Figure 12 Resistance graphic according to heat treatment application of composite foam produced with 7075 Aluminum alloy

Figure 13 Resistance graphic of 15% SiC reinforced composite foam not treated with heat and resistance graphic of 20% SiC reinforced composite foam treated with heat

Figure 14 Resistance graphics of 15% SiC reinforced composite foam treated with heat Figure 15 Resistance graphics of composite foam with variable densities but whose aluminum 5754 aluminum materials and reinforcement rates are the same

Figure 16 Resistance graphics of composite foam whose 5083 aluminum materials and reinforcement rates are the same but whose densities are variable

Figure 17 Resistance graphics of composite foam whose 7075 aluminum materials and reinforcement rates are the same but whose densities are variable

Figure 18 Surface images that have been obtained as a result of SEM examinations

Figure 19 Micro rigidity test results of naturally aged and heat treated composite foam samples

Figure 20 View of the characteristic curves of furnace sections

Figure 21 The inner structure sectional view of the composite foam obtained as a result of a graphite mold foaming procedure

Figure 22 The inner structure sectional view of the composite foam obtained as a result of a gas concrete foaming procedure.

Figure 23 The inner structure sectional view of the composite foam produced in a continuous form foam production device Descriptions of the parts shown in the figures

The components (parts, elements) within the drawings (figures) that have been prepared in order to further desc be the method and device developed by means of the invention for continuous composite metal foam production and particle reinforced composite metal stirring have each been numbered. The descriptions of each number have been listed below.

1 Front heating section

2 Stirring section

3 Foaming section

4 Mold entrance cover

5 Mold exit cover

6 Top stirring cover

7 Resistance groups

8 Moving molds (Material resistant to high temperatures and having low heat transfer)

9 Mold bed

11 Crucible

12 Crucible bottom (Material resistant to high temperatures and having low heat transfer)

13 Reinforcement powder oxidization vessel

14 Protective gas inlet ( N ₂ or argon)

15 Pushrod

16 Fan

17 Piston

18 Kneading and stirring apparatus

19 Heat sensor

20 Pressure sensor

21 Foaming powder vessel (TiH ₂ or CaC0 ₃ )

22 Foaming powder inlet. 23 Matrix material inlet (Particle or powder form)

24 Matrix material vessel

25 Reinforcement powder.inlet ( SiC, TiC,B ₄ C or Al ₂ 0 ₃ )

26 Reinforcement powder vessel

27 Stirring mechanism

27a Stirring mechanism rotating means

27b Up and down movement of stirring mechanism means

Detailed description of the Invention

The present invention is a new method and device used in composite metal foam production; wherein the developed device comprises the following characteristics.

The device that has been developed in order to produce metal foam comprises three sections which are the front heating ^¾ section (1), the stirring section (2) and the foaming section (3). All sections are heated with separate resistance groups (7). The temperature control of the sections is carried out separately.

The temperatures of the furnace front heating (1) section are temperatures that are below 40 - 60 °C, of the molting temperatures of the metal or metal alloy that is to be foamed.

The temperatures of the foaming section (3) aretemperatures that are 50 - 70 °C higher than the molten temperature of the metal or metal alloy that is to be foamed.

The temperatures of the- stirring section (2) are 100 - 300 °C higher than the molten temperatures of the metal or metal alloy that is to be foamed.

The movable molds (8) and the reinforcement powders at the front heating section are tried to be brought to process temperatures.

The stirring section (2) comprises a crucible (11), metal or metal alloy material inlet (23) that is to be foamed, reinforcement powder inlet (25), foaming powder inlet (22), protective gas inlet (14) and top stirring cover (6), kneading and stirring apparatus (18) and a stirring mechanism (27). Protective gas (IM ₂ or argon) is continuously sprayed on a crucible (11). Reinforcement material, foaming metal or metal alloy (matrix material), foaming powder and powder inputs (25,23,22,and 14) are poured through the inlets located on said stirring section (2).

Protective gas (N ₂ or- argon) are present all the time in the environment and the protective gas is continuously sprayed on the crucible (11). The reinforcement and matrix material and foaming powder inputs (25,23 and 22) are provided by the automatic control unit according to the information obtained from the sensors (19 and 20). The material inside the metal or metal alloy (matrix material) vessel (24) that is to be foamed, is divided into parts. Said material, can be processed by preparing it in particle or powder form from metal plate, ingot or recycled materials. The materials can be formed of aluminum, copper, titanium, nickel or other metals.

The stirring process with kneading and stirring apparatus (18) is again carried out through the top stirring cover located at again the top alignment of the crucible. Moreover the gas used as protective atmosphere (N ₂ or argon) is also blown onto the crucible from this cover section.

The kneading and mixing apparatus (18) are operated by the kneading and stirring mechanism (27). The pressure sensor (20) and the temperature sensor can be located within the stirring mechanism (27). Besides this the temperature sensor (19) can also be located in the crucible (19). The stirring procedures are carried out by controlling the viscosity/consistency and temperature information obtained from the pressure and temperature sensors (19 and 20). One of the most important aspects of the invention is to keep the mixture at a semi solid state during the whole of the stirring process. If the viscosity is low (at the phase of being semi solid to being liquid) the viscosity is increased by adding foaming metal or metal alloy to the mixture. If the viscosity is high (at the phase from being semi solid to solid) the stirring procedure is continued without adding metal to the mixture. The mixture is checked to see if it is at a semi solid state by means of the pressure and temperature sensors (19 and 20) which are controlled by the control unit and the addition of metal is provided by commands submitted to the stirrer by the control unit.

The pressure sensor (20) of the stirring mechanism (27), submits the pressure

(viscosity) information that enables to control the up and down movement of the stirrer at the pressure value, to the automatic control unit. The temperature sensor (19) which measures the temperature inside the crucible (11) submits the temperature information which enables the movement of the stirrer by ensuring that the mixture is kept at a certain temperature, to the automatic control unit.

The stirring mechanism (27) is a system that can operate in connection with a tool changer such that it can provide the changing of different stirrers and that can ensure that the required stirrer at the stirring section is chosen and attached. After the stirrer is attached the down and up (27b) and rotational (27a) movement is carried out. The stirring durations, the selection of stirrers, their attachment or dismantling is controlled by an electronic system.

The end parts of the kneading and stirring apparatus (18) connected to the stirring mechanism (27) can be flat, spiral or could have holes inside it. The holes within the kneading and stirring apparatus with holes, can be circular, elliptical, or can have a square shapes or a polygonal geometrical shapes, and the holes could each be the same size or could be in different sizes.

The kneading and stirring apparatus (18) can be resistant to high temperatures and can have different diameters depending on the crucible diameter. In the case that the bottom of the crucible has a different geometry, the kneading and stirring apparatus (18) can also have different geometries and sizes compliant to the geometry of the crucible.

The material of the stirrers (18) can be made of graphite or said stirrers could be coated with high temperature resistant materials such as ceramic. Besides this, the surface of the apparatus (18) can be coated with a mixture comprising silicium carbide powder and colloidal silica. By this means, the life span of the stirrer is also extended.

More than one crucible (11) can be used which can be moved in sequence in order to provide a mixture that is continuously at a semi solid state. The crucible (11) which is empty is pushed outside of the stirring section (2) by moving it forward and a new crucible (11) is pushed in place to replace the preceding crucible. The next crucible with a mixture prepared inside is brought to an alignment with the movable crucibles and this procedure is repeated constantly to provide a ready mixed mixture.

The bottom parts of the crucibles (11) are open and the front part of the movable mold also functions as a crucible bottom (25) and is at a closed position during the stirring procedures. The movable molds move along the mold bearing (9) made of firebrick that extends from the cover (4) of the movable mold to the mold outlet cover. The material of the crucible (11) can be SiC, Al ₂ 0 ₃ , graphite etc. The crucible bottom (12) is made of high temperature resistant and heat conducting material. Preferably graphite is used to form crucible bottoms (12). The vessel (13) is made of high temperature resistant and low heat conductive material such as gas, concrete, ceramic foam etc.

A fan (16) mechanism is present on the mold outlet cover so that the foam material exiting out of the furnace can be cooled.

The continuous metal foam production or particle reinforced composite metal production method developed according to the present invention, has been listed below:

1- The movable molds (8) and reinforcement powders at the front part of the furnace (1) is subjected to pre-heating and are brought to process temperatures. Reinforcement powders can be SiC, B ₄ C, Al ₂ 0 ₃ , TiC, and other carbides, oxides, nitrides and ceramic powders.

2- The pre heating section (1) of the furnace is brought to a temperature approximately below 40-60 °C of the metal or metal alloy melting temperature which is to be turned into foam. The temperature of the foaming section (3) is brought to a temperature 50 - 70 °C higher than the melting temperature of the metal or metal alloy that is to be foamed.

3- The crucible (11) containing metal or metal alloy that is to be turned into foam, is taken into the stirring section (2) of the pre-heating section (1) of the furnace. The temperature of the stirring section (2) is 100 - 300 °C higher than the metal or metal alloy melting temperature that is to be turned into foam.

4- The metal or metal alloy (matrix material) present inside the stirring section (2) of the crucible (11) is kept until the temperature of said mixture rises to the temperature range in which said mixture is at a semi solid state.

5- The movable molds (8) are inserted into the pre-heating section (1) from the mold entry cover (4) and is brought to the temperature of the pre-heating section (1)

6- When the material inside the crucible (11) is softened and begins to be crushed, the reinforcement material that has been pre-heated, is added into the crucible (11) through the reinforcement material inlet (25).

7- The metal or metal alloy (matrix material) that is to be turned into foam is poured in from the crucible inlet (11) in order to ensure that the material stays between the semi solid temperature ranges, when the temperature exceeds the semi solid state temperature range. Metal or metal alloy addition, is carried out by the automatic control unit according to the information obtained from the pressure sensors (20). The viscosity of the mixture is controlled by means of adding metal or metal alloy in accordance with the information obtained from the pressure and temperature sensors (19 and 20). At this point the aim is to ensure that the mixture is kept at a semi solid state. The aim or the mixture to be kept at a semi solid state is to ensure that the material does not flocculate or sedimentation is not created when the reinforcement material is added, and to ensure that the reinforcement material is homogenously distributed into the mixture. If the viscosity of the mixture is low (at the phase from being at a semi solid state to being liquid), the viscosity is increased by adding metal or metal alloy that is to be converted into foam in order to keep the mixture at a semi solid state. If the viscosity of the mixture is high (at the phase from being at a semi solid state to becoming solid) the stirring procedure is continued without adding metal to the mixture. When the temperature of the mixture increases, and when the viscosity is low, reinforcement material is not added to the mixture and only metal or metal alloy is added.

8- The mixture is checked if it is at a semi solid state or not by determining by means of the pressure and temperature sensors (19 and 20) controlled by the control unit, and again the semi solid state is ensured by the commands submitted to the stirrer and metal addition mechanism.

9- After the reinforcement material is added, kneading and mixing procedures are carried out together until the material is homogenously mixed. The stirring process is carried out by the up and down movement of the stirrer(s) depending on the viscosity/stability (or in other words depending on the mixture being at a semi solid state or not) of the material found inside the crucible (11). Besides this the stirrers) (18) also change orbits by zig zag or elliptical or radial movement inside the crucible (11).

10- After the mixture is prepared at the desired amount, the foaming powder inside (TiH ₂ and CaC0 ₃ and compounds comprising gas) the foaming powder vessel (21) is added to the mixture through the foaming powder inlet (22) and the quick stirring procedure is repeated. At this moment metal or alloy is continued to be added to the mixture.

11- After the mixture is prepared at the desired amounts, the foaming powder inside the foaming powder vessel (21) is added to the mixture from the foaming powder inlet (22) and the quick stirring process is continued. During this time metal or alloy is continued to be added to the mixture.

12- When a homogenous mixture is obtained, the movable mold is shifted and the bottom of the crucible (11) is opened, the mixture is transferred into the mold cavity (8) from the bottom of the crucible (11) by means of a thrusting piston (17). 13- Whilst the mixture is being pushed by the piston (17) the movable mold is moved at a constant speed on the mold bed (9) by means of a pushrod (15) and the mixture fills the cavity of the movable mold.

14- The movable mold (8) is taken into the foaming section (3) having a temperature which is 50 - 70 °C higher than the melting temperature of the metal or metal alloy that is to be foamed.

15- When the waiting period depending on the mixture amount, is completed the mold (8) is taken out of the furnace by means of the pushrod (15), after the mold exit cover (5) is opened.

16- The foaming material inside the mold which has been taken out of the furnace is cooled quickly by means of cooling fans (16).

TESTS CARRIED OUT FOR THE PRODUCTION METHOD DEVELOPED ACCORDING TO THE INVENTION

Several tests have been carried out regarding the continuous composite metal foam production developed according to the invention or method developed for the production of metal foam using the particle reinforced metal production method and device developed for the continuous production of metal foam. The tests that have been conducted for the product that was produced .using the method subject to the invention have been listed below.

1- Determining the reinforcement powder ratios that could be added into the semi solid material. (Up to 25% reinforcement powder can be added into semi solid material) (Figure 7).

2- Determining the effect of the foaming powder amount to linear expansion (The linear expansion rate is 5-8 when the foaming powder is added at a percentage of 1-2%) (Figure

8)

3- Examining the effect of the reinforcement rate to the formation of foam. The effects of SiC powders to the formation of foam have been mentioned below. When the SiC reinforcement amount increased;

· Linear expansion increased

• Homogenous pore distribution was provided • Drainage formation was prevented

• The thickness of the cell walls increased

• The resistance of the cell walls increased and pore combining was prevented

The effects mentioned above are performed by the selection of the foam formation temperature distinctive to the material. When the waiting period at a high temperature has been exceeded, combining of the pores, thinning of the cell walls and sedimentation occurs.

4- Examining the effect of the foaming powder size to the formation of foam, (when foaming powder having particle sizes larger than ~40 pm was used it was harder for a homogenous inner structure to be obtained. The test results are shown in Figure 10).

5- Examining the effect of the type of foaming powder used to the production of foam.

Similar results have been obtained with tests carried out with TiH ₂ and CaC0 ₃ powders. The process parameters change for such procedures.

6- Examining the effect of the foaming duration to the foam structure. As the duration for the foaming procedure increased the cell sizes increased, and the cells are combined with each other and a non homogenous inner structure is obtained. The pore structure in stirring and foaming procedures carried out under protective gas by means of the metal foam production apparatus passes through different phases depending on time. The time also changes depending on material. The %1 TiH ₂ and %20 SiC reinforced 5754 alloy foam which have been foamed in different durations can be seen in Figure 11.

7- Measuring the densities of the products that have been produced. Aluminum composite foam materials having a density between 0.3 gr/cm ³ to 0.8 gr/cm ³ have been obtained. The results of the tests carried out in relation to specific weight and relative densities (EN AW 5754) have been given in the table below.

TiH21SiC20TB44pmKS10min 0,399 0,149 TiH21 SiC10TB4Mm KS 8min 0,618 0,231

-heat tr

TiH21SiC20TB44pmKS12min 0,388 0,145 TiH21SiC10TB4pm KS lOmin 0,652 0,244

-heat tr

TiH21SiC0TB44MmKS8min- 0,497 0,186 TiH21 SiC10TB4MmKS 12min 0,550 0,205 heat tr

TiH21SiC0TB44Mm S10min 0,497 0,186 TiH21SiC10TB4pmKS8min- 0,769 0,288 heat tr heat tr

TiH21SiC0TB44pmKS12rnin- 0,410 0,153 TiH21SiC10TB4pmKS10min 0,662 0,247 heat tr heat tr

TiH21SiC0TB44pmKS lOmin 0,389 0,145 ΤΪΗ21 SiCIO TB4pmKS 0,683 0,255

12min-heat tr

ΤΪΗ21 SiC20TB44 m KS 0,324 0,121 TiH21 SiC 20 ΤΒ4μηι 8min 0,613 0,229

8min

ΤΪΗ21 SiC20TB44pm KS 0,380 0,142 TiH21SiC20TB4pmKS lOmin 0,773 0,289 lOmin

TiH21SiC20TB44pm KS 0,311 0,116 TiH21 SiC 20TB4pmKS 12min 0,960 0,359

12min

TiH21SiC10TB44MmKS8min- 0,704 0,263 TiH21SiC10TB100pmKS 8min 0,648 0,242 heat tr.

TiH21SiC10TB44pmKS10min 0,683 0,255 TiH21SiC10TBlOOMmKS10mi 0,521 0,195 .

-heat tr. n

TiH21SiC10TB44MmKS12min 0,482 0,180 TiH21SiC10TB100pmKS 0,499 0,186

-heat tr. 12min

TiH21SiC10 ΤΒ44μηη KS8min 0,473 0,177 TiH21SiC20TBlOOpmKS 8min 0,334 0,125

TiH21 SiCIO TB44pm 0,380 0,142 TiH21SiC20TBl00pm 0,371 0,138 KSlOmin KSlOmin

ΤΪΗ21 SiC10TB44Mm KS 0,413 0,154 TiH21SiC20TBlOOpmKS 0,450 0,168

12min 12min TiH21SiC20TB44pmKS8min 0,900 0,337 TiH21SiC10TB100Mm KS 0,493 0,184

800°C 8min-heat tr.

TiH21SiC20TB44 m S10min 0,665 0,249 TiH21SiC10TB100pmKS10mi 0,260 0,097

800 °C n-heat tr.

ΤϊΗ218ϊε20ΤΒ44μιτι 812Γηίη 0,616 0,230 TiH21SiC10TB100pmKS12mi 0,290 0,108

800 °C n-heat tr.-

TiH21 SiC10TB30pmKS 0,564 0,211 TiH21SiC20TB100Mm KS 0,408 0,152

8min-heat tr. 8mi n-heat tr.-

TiH21SiC10TB30MmKS10min 0,365 0,136 TiH21SiC20TB100MmKS10mi 0,772 0,289

-heat tr. n-heat tr.-

TiH21SiC10TB30 mKS12min 0,418 0,156 TiH21SiC20TB100 mKS12mi 0,575 0,215

-heat tr. n -heat tr.

TiH21SiC 10 ΤΒ30μηη KS 0,300 0,112 TiH20,5SiC20TB^m KS 0,424 0,158

8min 8min

ΤΪΗ215ϊΟ10ΤΒ30μπΐ KS 0,249 0,093 TiH20,5SiC20TB44MmKS10mi 0,301 0,112 lOmin n

TiH21SiC10 ΤΒ30μπηΚ5 0,346 0,129 TiH20,5SiC20TB44MmKS12mi 0,378 0,141

12min n

TiH2 SiC 20 ΤΒ30μΓΠ KS 0,482 0,180 ΤιΗ225!θ20ΤΒ44μηι KS 8min 0,456 0,170

8min

TiH21SiC 20ΤΒ30μηιΚ5 0,590 0,22 ΤΪΗ22 5ϊΟ20ΤΒ44μΓη 0,355 0,132 lOmin KSlOmin

TiH21SiC20TB30pm KS 0,550 0,205 ΤϊΗ225ίΟ20ΤΒ44μηηΚ8 12min 0,368 0,137

12min

ΤϊΗ215ϊΟ20ΤΒ30μηιΚ5 8min- 0,480 0, 179 TiH20,5 SiC 5 ΤΒ44μηΐ 0,572 0,214 heat tr. KSlOmin

ΤϊΗ215ϊΟ20ΤΒ30μιτιΚ510Γηίη 0,643 0,240 TiH20,5 SiC 10 ΤΒ44 0,689 0,258

-heat tr. KSlOmin

ΤΪΗ21 SiC 20 ΤΒ30μιη KS(Foaming Time) lOmin-heat tr.-T800 °C→ %1 TiH2-%20 SiC- 30μιη Particle Size-10 minutes Foaming Time- heat tr. Heat Treatment TiH2 - T800Furnace temperature- All tests besides T800 have been carried out at a furnace temperature of 750 °C).

8- Determining the compressive strengths of the obtained products (Aluminum composite foam materials between the range of 5 MPa- 35 MPa have been produced.

5 Figure 12, shows that the resistances of the composite foam produced with 7075 aluminum alloy can be increased by means of heat treatment.

Figure 13, shows that the resistance of the composite foam produced using heat treated %20 SiC reinforcement is much higher than non heat treated %15 SiC reinforced composite foam.

it ⁾ Figure 14, shows the effect of the reinforcement rate on resistance. It shows that the composite foam which has been subjected to heat treatment having a higher reinforcement rate is more resistant.

Figure 15, 16 and 17, shows that the resistance of the composite foams with higher density is more resistant in comparison to composite foams having the same material and 15 reinforcement rate but having different densities.

9- The surface images obtained as a result of SEM examinations are shown in Figure 18.

10- The results of the micro rigidity tests have been shown in Figure 19.

TESTS CARRIED OUT ON THE DEVICE ON WHICH THE PRODUCTION METHOD

0 DEVELOPED ACCORDING TO THE INVENTION IS APPLIED:

The tests related to the device on which the continuous composite metal foam production or particle reinforced composite metal production method developed according to the invention is carried out have been listed below.

1 - Forming the temperature characteristic curves of furnace sections: As it can be seen in5 Figure 20, the furnace sections rise up to 750°C temperature in 3 hours. The characteristics of the device used for measurements are described below.

Technical features of the AFM05 device

Maximum temperature: 1200 °C

0 Constant usage temperature: ^' 750 °C Temperature deviation: + 3 °C

Inner dimensions: 2x (30x30x60) + (40x40x70) (cm)

Heating means: Kanthal (d=2mm) On the ceramic rod, on the side walls of the partitions Temperature control devices: 3x (PC 442/6, Dual Display,PID.6 step programming)

Energy distribution

Pre-heating section: 3.85 kW,

Stirring Section: 7.7 kW,

Retention section: 3.85 kW

Total 15.4 kW

Atmosphere: Gas metal protection environment (Nitrogen gas)

2- It has been noted that during the foaming procedures carried out using graphite and gas concrete blocks in tests determining the foam mold materials, low heat conducting material needs to be used as mold material. The inner structure sectional views of the composite foams obtained in tests have been shown in Figures 21 and 22. Heterogeneous pores are present and drainage sections are established inside the inner structure of the composite foam produced in graphite molds. Pores which are homogenous and do not have drainage sections are formed inside the inner structure of the composite foam foamed with gas concrete molds.

The inner structure sectional view of the composite foam in constant from obtained by means of the AFM05 device has been shown in Figure 23. The important issue here is for the composite foam to be produced continuously. The inner structure and density of the foam is controlled by selecting suitable parameters (such as waiting time, TiH ₂ size, SiC amount/rate).

The method developed according to the present invention can also be used during the stirring phase of the particle reinforced composite metal production. The steps of the particle reinforced composite metal stirring method have been listed below.

1- The reinforcement powders at the pre heating part of the furnace (1) are subjected to pre-heating and are brought to process temperatures. Reinforcement powders can be SiC, B ₄ C, Al ₂ 0 ₃ , TiC, and other carbides, oxides, nitrides and ceramic powders. - The pre heating section (1) of the furnace is brought to a temperature approximately below 40-60 °C of the metal or metal alloy melting temperature which is to be turned into particle reinforced composite metal.

- The crucible (11) containing metal or metal alloy that is to be turned into particle reinforced composite metal, is taken into the stirring section (2) of the pre-heating section (1) of the furnace. The temperature of the stirring section (2) is 100 - 300 °C higher than the metal or metal alloy melting temperature that is to be turned into particle reinforced composite metal.

- The metal or metal alloy used to produce composite metal production inside the crucible (11) located at the stirring section (2) is kept until the temperature thereof is increased to the temperature range wherein said metal or metal alloy is at a semi solid state,- When the material inside the crucible (11) is softened and begins to be crushed, the reinforcement material that has been pre-heated, is added into the crucible (11) through the reinforcement material inlet (25).

- The metal or metal alloy (matrix material) that is to be turned into composite metal production is poured in from the crucible inlet (11) in order to ensure that the material stays between the semi solid temperature range, when the temperature exceeds the semi solid state temperature range. Metal or metal alloy addition, is carried out by the automatic control unit according to the information obtained from the pressure sensors (20). The viscosity of the mixture is controlled by means of adding metal or metal alloy in accordance with the information obtained from the pressure and temperature sensors (19 and 20). At this point the aim is to ensure that the mixture is kept at a semi solid state. The aim or the mixture to be kept at a semi solid state is to ensure that the material does not flocculate or sedimentation is not created when the reinforcement material is added, and to ensure that the reinforcement material is homogenously distributed into the mixture. If the viscosity of the mixture is low (at the phase from being at a semi solid state to being liquid), the viscosity is increased by adding metal or metal alloy that is to be cpnverted into foam in order to keep the mixture at a semi solid state. If the viscosity of the mixture is high (at the phase from being at a semi solid state to becoming solid) the stirring procedure is continued without adding metal to the mixture. When the temperature of the mixture increases, and when the viscosity is low, reinforcement material is not added to the mixture and only metal or metal alloy is added. 7- The mixture is checked if it is at a semi solid state or not by determining by means of the pressure and temperature sensors (19 and 20) controlled by the control unit, and again the semi solid state is ensured by the commands submitted to the stirrer and metal addition mechanism.

8- After the reinforcement material is added, kneading and mixing procedures are carried out together until the material is homogenously mixed. The stirring process is carried out by the up and down movement of the stirrer(s) depending on the viscosity/stability (or in other words depending on the mixture being at a semi solid state or not) of the material found inside the crucible (11). Besides this the stirrer(s) (18) also change orbits by zig zag or elliptical or radial movement inside the crucible (U).

9- When a homogenous mixture is obtained, the composite mixture inside the crucible (11) is taken out and poured into molds thereby a particle reinforced composite material production is obtained by means of a casting or production method.