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Laser surface processing is a promising technique for alloying and synthesis of wear resistant coatings. To this end, commercially pure titanium was laser gas-alloyed with a mixture of nitrogen and carbon monoxide, and the influence of processing parameters was studied. The surface treatments were performed using a 400 W Nd:YAG pulsed laser. The composition of the gas mixture was set at either 100% N2, 67% N2 + 33% CO, 50% N2 + 50% CO, 33% N2 + 67% CO or 100% CO. The microstructure of the reacted layer of specimen was studied by optical and scanning electron microscopy. Their thickness was characterized and surface hardness profiles were determined. X-ray diffraction, Auger electron spectroscopy and X-ray photoelectron spectroscopy were used for determination of crystalline structure and chemical composition of phases. The study of processing parameters such as incident power density, pulse length and pulse rate showed that the optimum conditions for wear resistance were influenced by the composition of the gas mixture. Abrasive and erosive wear tests on laser-treated surfaces showed a substantial improvement in wear resistance over untreated titanium. This reduction in wear rate is attributed to the formation of the hard compounds TiN, TiCO and TiCNO in the resolidified layer.
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