Scientists at the Fraunhofer Institute produce diamond ceramic composite for seals

The coating, developed at the Fraunhofer Institute, has been used on axial face seals inserted in pumps for critical environments, such as conveyors for oil, sand and gas mixtures. In one case, the diamond coating extends the durability for each application by a factor of 4 to 1,000.

The composite is made of a silicon-nitride or carbide ceramic. The composite is made by placing components and tools in a vacuum reactor for the hot wire chemical vapour deposition (CVD) technology applied for the coating process, and methane and hydrogen are added. In order for the diamond coating to grow, wires are spread at intervals of just a few centimetres across the objects that were going to be coated. The wires are heated until they reach incandescence. This activates the gases, and carbon is deposited on the surface in crystalline diamond form.