An economical process for applying nitride layers to titanium and titanium alloys. Within a short time, layer thicknesses of 20 .mu.m are obtained by pressure-nitriding in an ammonia atmosphere. To this end, temperatures of 500.degree. to 1000.degree. C. and pressures of 0.2 to 9 MPa are used.
CONTINUING APPLICATION DATA
This application is a continuation in part of U.S. patent application Ser. No. 07/665,652, filed Mar. 7, 1991, abandoned which application is entirely incorporated herein by reference.
A decorative item and method for making same, such as an exterior part of a timepiece, wristwatch band and the like, includes a basis material of stainless steel having a carburized hardened later thereon in which carbon is diffused so as to form a solid solution in which crystalline chromium carbide is not formed and at least one hard coating is deposited on the carburized hardened layer of basis material, wherein the hard coating has a surface hardness greater than that of the carburized layer.
Method for passivating a layer of titanium that has been deposited on a substrate in a reaction chamber to coat the titanium thereby reducing the likelihood of contamination by byproducts of the deposition process or ambient oxygen or similar reactants. The method includes adding a flow of hydrogen and a flow of nitrogen to the chamber. The flows of hydrogen and nitrogen are approximately 800 sccm and continue for approximately 10-30 seconds respectively. The method may further comprise the step of forming a nitrogen plasma in the chamber for approximately 10 seconds wherein such case the flows of hydrogen and nitrogen continue for approximately 8 seconds respectively. The plasma is formed by applying RF power to an electrode located within said chamber or by a remote plasma source and channeled to said reactor chamber. Alternately, the passivation layer may be formed just by using a nitrogen plama alone for approximately 10-30 seconds at the same RF power level. The plasma in either case may further comprise hydrogen and argon and the layer of titanium has been deposited by CVD.