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M50 steel was implanted with nitrogen at elevated temperatures ranging from 260 [degrees]C to 420 [degrees]C using plasma-based ion implantation. The effect of implantation temperature on surface microstructure, hardness, and wear resistance was investigated. It is observed that nitrogen penetrates very deeply from the surface as a result of implantation and thermal diffusion at elevated temperatures. The amount of nitrides and their distribution depth as well as the hardness and the wear resistance in the surface layer increase with the processing temperature. As the implantation temperature increases, the wear mechanism changes from adhesive wear to abrasive wear. Index Terms--Elevated temperature ion implantation, plasma-based ion implantation (PBII), structure, wear.

Very hard and wear-resistant layers are formed after energetic nitrogen insertion into stainless steel. Here, a systematic investigation of the influence of the microstructure is presented. Nitrogen implantation was performed in austenitic, martensitic, and ferritic steels with the samples investigated with respect to formation of expanded phase, nitrogen depth distribution, hardness, and wear. Microstructure strongly affects the diffusion in austenite and has negligible effect in the case of martensitic/ferritic transformations. Index Terms--Microstructure, nitrogen implantation, stainless steel, wear.

To synthesize good diamond-like carbon (DLC) films on the inner surface of a cylinder, [C.sub.2][H.sub.2] plasma should be generated uniformly in the cylinder. In this study, glow discharge [C.sub.2][H.sub.2] plasma was generated by a high pulsed bias voltage applied on the cylinder, and ions were accelerated and implanted into the sample by the same bias. The effect of pulse frequency of the bias and working pressure on the discharge characteristics was investigated. In addition, the ball-on-disk test and Raman spectroscopy were used to characterize the as-deposited DLC films. The test results show that wear resistance of samples increases with the applied voltage, and the friction coefficient of DLC films lies in the range of 0.15-0.20. Index Terms--Diamond-like carbon (DLC) film, inner surface modification, plasma immersion ion implantation (PIII), wear resistance.