MICROSTRUCTURE AND WEAR-RESISTANCE OF CP TITANIUM LASER ALLOYED WITH A MIXTURE OF REACTIVE GASES

Laser processing is a promising technique for alloying and synthesis o f wear resistant layers. In this work, commercially pure titanium was laser alloyed with various proportions of nitrogen and carbon monoxide in order to produce a composite surface layer. The following gas mixt ures were selected: 100% N-2, 67% N-2 + 33% CO, 50% N-2 + 50% CO, 33% N-2 + 67% CO and 100% CO. The microstructure, roughness and compositio n of coated specimens were characterized. The presence of Ti(C,N,O) in the surface layer was assessed by X-ray diffraction, X-ray photoelect ron spectroscopy and Auger electron spectroscopy. The abrasive wear re sistance of coatings was determined and related to their surface hardn ess. The abrasive wear resistance of the laser alloyed coating was sub stantially improved compared to untreated titanium and appears to be s uperior when composed of Tit C,N,O) prepared from a mixture of gases. (C) 1997 Elsevier Science S.A.