Wear resistance of KhVG tool steel hardened with composite coatings based on titanium-chromium double carbide

Wear resistance of KhVG tool steel hardened with composite coatings based on titanium-chromium double carbide is studied by means of an automatic wear-measurement system. The influence of deposition methods—electrical discharge alloying and plasma spraying—as well as process variables on the wear resistance of coated steel is discussed. The composition and structure of specimen friction surfaces are examined. The authors of the paper have established the optimal operating conditions for the coatings as well as the most efficient deposition methods for the operation under experimental conditions studied.     

Oxidation of nickel-molybdenum coatings on diamond

Conclusions The main processes causing oxidation in air of pure and nickel-alloyed molybdenum coatings on diamond are: build up of oxides in the scale; removal of molybdenum and carbon in the composition of volatile oxides MoO₃ CO, and CO₂; renewal of the carbide layer on the boundary with the diamond as a result of the oxidation-reduction reactions taking place in this zone; enrichment of the scale with nickel as a result of selective oxidation of the molybdenum-nickel phases which reduces the rate of removal of molybdenum from MoO₃. The contribution of each component is determined by the oxidation conditions and the nickel content of the molybdenum coatings. The described mechanisms make it possible to predict the behavior of components made of molybdenum metallized diamond powders under specific service conditions.Translated from Poroshkovaya Metallurgiya, No. 4(340), pp. 53–58, April, 1991.