THE ROLE OF TITANIUM IN THE ABRASIVE WEAR-RESISTANCE OF PHYSICALLY VAPOR-DEPOSITED TIN

The use of physically vapour-deposited TiN coatings for tribological applications is now commonplace, though the reasons for the improvements in wear behaviour they produce are not fully understood. In order to promote good adhesion between substrate and coating a thin titanium interlayer is often used. The presence of this interlayer in the case of sputtered coatings, or the presence of any unreacted titanium in the case of arcevaporated coatings, can have significant effects on the abrasive wear resistance of a coated component. Abrasive wear tests have been performed on sputtered TiN coatings on stainless steel with a range of titanium interlayer thicknesses. Best wear properties are obtained for the thickest interlayer due to the increased interface toughness in this system. Arc-evaporated coatings perform better than similar sputtered coatings under mild abrasive conditions, but the behaviour is reversed for more severe abrasive conditions. A model is proposed to account for these observations, but clearly the presence of titanium can have both advantages and disadvantages for the production of abrasion resistant coatings by physical vapour decompositon techniques. © 1990.