Background of the Invention There is a need for lightweight impact resistant plate in applications such as body armour. The present approach with body armour is to have a polyimide e. g.

Kevlafrm matt material as a vest and then slip into pockets of this vest ceramic plates. The ceramic plate is generally penetrated and shattered by projectiles traveling at high velocity but, in this process, the projectile becomes badly distorted which then prevents it successfully penetrated the Kevlar matt. If a ceramic plate is penetrated it shatters. This makes the vest significantly less effective should the person be struck by a second or further projectile.

Objects and Summary of the Invention The invention seeks to make plates which are a combination of flexible and hard materials. The process by which the plate is constructed is in an evacuated chamber.

In one embodiment of the invention, material is deposited either by sputtering or by plasma polymerization onto a substrate which may or may not be kept with the plate at the end of the process.

Best Mode and Other Embodiments of the Invention Sputtering is a process well known in the coatings industry. It involves firing a high-energy beam of electrons at a target thereby dislodging atoms which comprise the target. These atoms then fall under the action of gravity to recombine on a surface of our substrate.

Plasma polymerization involves introducing a monomer into a highly evacuated chamber. The plasma is caused by a charge traveling between a negative and positive plate separated by some distance. In the evacuated atmosphere is argon gas, which facilitates the movement of the electrons from one plate to the other. Theses electrons knock electrons off the monomer molecules causes these molecules then to bond with each other plus other substances in the chamber.

It is possible to lay down alternate layers of target material and polymer in this process without breaking the vacuum. If the target material is a ceramic then one arrives at a material which is very hard but which is held together by a highly flexible series of laminates of polymer.

Experiments have shown that numerous materials can be sputtered at the same time and that these will form amalgams which would otherwise not occur in nature. For example, a ceramic can be mixed with magnesium metal to form a tough lightweight material. Experiments have also shown that polymers created in

the process, described above, are hyper cross-linked. This causes them to exhibit a good memory when deformed and have exceptional strength and elastic modulus. When deposited in this fashion, they adhere well to the deposited target material and so provide a tenacious interface bond. The temperature resistance of this polymer is also far superior to that of the same polymer created by more conventional means.

For example, Hexamethyldisoloxane usually has a temperature resistance of 150°C before it starts to deteriorate. When made using this process, the polymer can withstand temperatures in excess of 405°C.

Plates or membranes produced by this process will withstand high levels of impact but will have the necessary hardness to deform any projectile which attempts to penetrate it. Additionally, the surface energy required to penetrate an interface layer is known to be greater than that required to penetrate the matrix of each material. The end result of this is that the kinetic energy of the projectile is more vigorously dissipated as it attempts to make its way through each layer than would otherwise be the case with a solid material.

In this same manufacturing environment it is possible to produce various substances such as amorphous diamond and nanotubes. There is also in existence processes which can deposit materials, of the type described in this and the previous specification, at a greatly accelerated rate.

The present invention contemplates depositing, for example, amorphous diamond and encapsulating it in a polymer; the end result is a material with exceptional hardness but also with flexibility and energy absorbing characteristics. The polymer, being hyper cross-linked would have exceptional memory, heat resistance and strength.

Similarly, using nanotubes, one can construct materials which are analogous to glass reinforced plastics. These exhibit exceptional strength, elastic modulus and impact resistance.

Using these processes, one may construct structural members or components to a machine capable of withstanding extreme operating environments whilst being of very lightweight. An example of this would be aircraft parts and blades.

In preferred embodiments, it is desirable that there be a strong interfacial bond between the hard and the tough laminates. When laying down substances in a plasma reactor, the substance is polar active when it deposits on the surface and remains that way for many days thereafter. This is a very useful characteristic in that one achieves covalent bonding of substances or, at the very least, strong nuclear bonding. The preference is to achieve strong covalent bonding.

Some preferred embodiments use amorphous diamond and a polymer such as Hexa-Methyl-Di-Sil-Oxane. It is possible by varying the strength of the RF field to change the composition of both the diamond and the HMDSO. In the case of the diamond, the deposit can be more carbon than diamond crystals. In the case of the HMDSO, the deposit can have a higher or lesser level of silicon. By varying these it is possible to have carbon rich diamond at the interface and a more tenacious polymer thereby achieving a better bonding of the two layers.

It is also possible to lay down an interfacial layer to improve the bonding of the two substances by performing the operation at elevated temperatures or by introducing a different monomer such as a styrene into the reactor. Research in this field has sought to improve the adhesion and dispersion on or of nano tubes (particles). In one study of interfacial particle-to-particle bonding mechanisms, an ultrathin film of pyrrole was deposited on alumina nanoparticles using a plasma

polymerization treatment. High resolution transmission electron microscopy experiments showed that an extremely thin film of the pyrrole layer (2 nm) was uniformly deposited on the surfaces of the nanoparticles. In particular, the particles of all sizes (10-150 nm) exhibited equally uniform ultrathin films indicating well-dispersed nanoparticles in the fluidized bed during the plasma treatment. Time-of-flight secondary ion mass spectroscopy experiments confirmed the nano-surface deposition of the pyrrole films on the nanoparticles.

The pyrrole-coated nanoparticles were consolidated at a temperature range (approximately 250 °C), much lower than the conventional sintering temperature.

The density of consolidated bulk alumina has reached about 95% of the theoretical density of alumina with only a few percent of polymer in the matrix.

After low-temperature consolidation, the micro-hardness test was performed on the bulk samples to study the strength that was related to particle-particle adhesion. The underlying adhesion mechanism for bonding of the nanoparticles is discussed.

In another study of particular interest, ultrathin films of polystyrene were deposited on the surfaces of carbon nanofibers using a plasma polymerization treatment. A small percent by weight of these surface-coated nanofibers were incorporated into polystyrene to form a polymer nanocomposite. The plasma coating greatly enhanced the dispersion of the nanofibers in the polymer matrix.

High-resolution transmission-electron-microscopy (HRTEM) images revealed an extremely thin film of the polymer layer (-3 nm) at the interface between the nanofiber and matrix. Tensile test results showed considerably increased strength in the coated nanofiber composite while an adverse effect was observed in the uncoated composites; the former exhibited shear yielding due to enhanced

interfacial bonding while the latter fractured in a brittle fashion. This is of particular interest as the same applies to granules of crystallised amorphous carbon. Styrene monomer then forms a good bond to HMDSO. The use of HMDSO is preferred to styrene because of its ability to withstand higher elevated temperatures.

Commercially available deposition machines provide deposition rates of up to 300 nanometers per second. This is achieved by using a strong microwave RF agitation field to cause disassociation of the monomer. The same techniques can be used when introducing methane into the chamber for the purposes of creating amorphous diamond. The degree of vacuum and the amount of argon present to allow transmission of electrons across the space between the two electrodes may be varied to achieve an optimum effect. These settings are well known by anyone skilled in the art of plasma polymerization and are provided by the makers of the machines.

It is also possible to increase deposition rates by increasing the time that the monomer has to become disassociated. This is done by having the monomer travel down a rectangular"chute", the sides of which comprise the positive and negative electrodes. The monomer is admitted from the top of the"chute".

When the monomer begins to chain to form a polymer under the action of the RF it falls from the gaseous situation downwards to land on the surface being coated.

In this manner, one achieves higher rates of deposition.

It is possible to have more than one"chute"and to have the arrangement wherein these chutes may move over the surface or to have the surface move relative to the chute. In this manner, one multiplies the deposition rates considerably. Likewise, it is possible to have number of different compounds

being introduced into the process at the same time. For example, one could have styrene coming down one chute and HMDSO down another.

The present invention is suitable for making complex shapes. Polymer may be deposited on any substrate. This substrate could be made in the shape of, for example, a helmet inner. By mounting the helmet inner on a stand or mount and then moving it such that it is uniformly coated by precipitating polymer and other substances, it is possible to build up a complex shape.

Making a shaft is a related activity to making a complex shape. The shaft can be made of hollow polystyrene. The shaft is mounted between two co-linear points, like the headstock and tailstock of a lathe. The shaft is then rotated during the deposition of the polymer and nanotubes; the nanotubes being sprinkled from above in a system not unlike a flour sifter. Particles which do not fall on the shaft are recycled to fall again. During this process, styrene monomer and HMDSO are entered through separate chutes, the arrangement being that the styrene is deposited prior to the deposition of the HMDSO. In this manner, we achieve a strong interfacial bond and then have a bond between the styrene coating and the HMDSO. At the end of the process, the polystyrene may be melted out of the shaft or dissolved using a petroleum spirit. In a similar vein, it is possible to make the shaft pattern out of paraffin wax or a similar high melting point substance. Once the shaft has been coated to the desired thickness, the substance is melted and recycled to cast as new pattern.

The current art contains teachings which allow for the cost affordable production of nanotubes of boron nitride which are a suitable substitute for carbon in this invention. These particles compete well with carbon in terms of

their hardness, elastic modulus and strength. Additionally, nanotubes made of boron nitride can stand far higher temperatures than nanotubes made of carbon.

While the present technology has been disclosed with reference to particular details, these should not be construed as limitations to the scope or spirit of the invention as expressed in the claims.