INFLUENCE OF PLASMA NITRIDING ON WEAR PERFORMANCE OF TIN COATING

The wear properties of uncoated, TiN-coated and plasma-nitrided-TiN-co ated samples made of steel grades AISI M2 and AISI 4140 were studied. A wheel 50 mm in diameter made of cementation steel grade AISI 5115 wa s used as a countermaterial for sliding wear tests against samples mad e in cubic form. The sliding speed was 56.5 m min-1 and the normal loa d used was 10 or 50 N. Under the conditions used in these experiments it was found that plasma-nitrided-TiN-coated samples have superior wea r resistance. The wear mechanism depends strongly on the surface treat ment of the samples. Abrasive wear dominates in the case of uncoated s amples, while in the case of TiN-coated samples cracking and plucking of parts of the coating dominate in the initial stage of the wear test and no gradual wear of the coating itself was found. The formation of a protective glassy layer on TiN coatings deposited on high speed ste el substrates was observed.