Effect of Plasma Nitriding Treatment on the Chromium Layer applied on Space Construction to Avoid Cold Weld

Although regarding low density and high ratio of strength to weight of titanium, the application of this metal is restricted in space industry due to its low surface properties including low wear resistance which could lead to the cold weld. For improving this property of titanium, applying protective coatings are effective. Physical parameters, wear resistance, adhesion of applied layer, and surface microhardness are impressive and could avoid occurrence of the cold weld. Therefore, by applying plasma nitriding on chromium layer in titanium used in space constructions, tribological properties (wear resistance, adhesion and surface microhardness) were studied. Results confirmed the formation of nitride chromium phase on titanium substrate due to the applying plasma nitriding on chromium layer and increasing the surface microhardness up to 1109 HV and improving the wear resistance and adhesion subsequently. The value of the friction coefficient was decreased down 0.16 which could avoid the cold weld occurrence.