Elbow Deep in Pink Snapper (gynostretcher) wrote,
Elbow Deep in Pink Snapper

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Vacuum Plasma Spraying (VPS)

VPS is a fabrication technique used to build up solid parts from powdered metals and ceramics. The fabrication is performed by a robot arm wielding a plasma torch inside a vacuum chamber. The low pressure permits a rarefied plasma, which has a high temperature but very little hot material, to lay down a coating on a part without melting the target. The technique is useful when working with metals that do not alloy when melted and stirred together (e.g. titanium alumnide, because the metals are like oil and water when liquid, so other techniques are required to alloy them.) VPS is also effective when building up Metal Matrix Composites (MMC) or Metal Ceramic Composites (MCC), by shooting a metal plasma through a mesh of metal or ceramic fibers. VPS is also well suited to combining reactive materials, since the temperature and pressure of the plasma across precipitation to a solid is controllable, the conditions provide an ideal environment for materials to uniformly react. Since most engineered ceramics are unit solids with covalent bonds, VPS is suited to reactive ceramic coating of finished parts [e.g. diamond coating, or inlay of sapphire and spinel crystals into "holes" in metal parts. New missile nose-cones made from spinels allow forward-looking radar to pass, but withstand the stress and heat encountered when closing on a target at speeds above Mach 6 in an atmosphere.]

Fabrication of parts to near-net dimensions in a vacuum chamber, followed by grinding or electro-polishing to finished tolerances, is an expensive way to build. The size of vacuum chambers, and the time required for contaminants to "out gas" from the inner walls of the vacuum chamber, limit the scale of production. Currently, the technique is suitable for parts up to 20cm on the longest dimension. However, this is acceptable for low volume (one-off) production of high spec parts, such as combustion chamber and thruster nozzle units for communication satellites. Research is underway to scale the technique to larger dimensions or faster cycle rates.

If you'd like to geek out, you can read about it at http://www.google.com/search?hl=en&lr=&safe=off&q=ceramic+matrix+vps

Or if you're not a material science geek, check out _taraisawesome's boyfriend's band. Their initials are VPS but she didn't say what that stands for.

I also mentioned spinel mineral crystals, which are a class of minerals including ruby. http://www.google.com/search?hl=en&lr=&safe=off&rls=GGLD%2CGGLD%3A2003-33%2CGGLD%3Aen&q=spinel+armor&btnG=Search These minerals are the subject of a great deal of research for military applications, because they make excellent armor glass. The aluminum based spinels are especially promising for multi-hit survivability, and may be hot-press or sinter processed from powdered raw materials. If you need a windshield for a rocket car, this class of materials is a good candidate.
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