In the PACVD technique, temperature and gas flow rate are two important parameters affecting the coating characteristics. Effect of these parameters on mechanical behaviors of TiC coating that was deposited on hot work tool steel (H13) was investigated in this paper. We analyzed TiC coating composition and structure with grazing incidence X-ray diffraction (GIXRD) and Fourier transformation infrared spectroscopy (FTIR). The mechanical properties of the coatings, such as microhardness, wear resistance, and surface roughness, were studied with Knoop hardness indentation, pin on disk wear tests, and atomic force microscopy, respectively. When the deposition temperature decreased from 490°C to 450°C and the CH4 to TiCl4 flow rate ratio was also increased from 1.5 to 6, TiC coating color changed from dark gray to silver. The best mechanical properties such as a high hardness (27？GPa), wear resistance, and low surface roughness were related to the coating that was deposited at 450°C. 1. Introduction Hard coatings such as titanium carbide (TiC) and titanium nitrocarbide (TiCN) have been used in various industries such as microelectronics and aerospace due to the unique properties such as high hardness and Young’s modulus, low friction coefficient, proper resistance to corrosion and wear, good electrical and thermal conductivity, and high melting temperature [1–3]. Thin and hard coatings can be deposited by different methods such as physical vapor and thermal chemical vapor techniques. In the first method due to the low temperature, the coatings adhesion strength decreases and in the second method, due to low deposition rate, the cost waste and the time waste occur [4]. Thus, plasma assisted chemical vapor deposition (PACVD) can be a proper technique for depositing thin coatings on different substrates, due to possibility to achieve the same properties in lower temperatures and higher deposition rate. Controlling the composition and the thickness of coatings by adjusting plasma parameters is easy. Additionally, rotating of the complex sample is not necessary [4–6]. Thus, PACVD is used to deposit various coatings for casting and extruding mold even with irregular geometry and complexity [7]. In TiC coating deposition via PACVD technique, the temperature, plasma power, duty cycle, and CH4 and TiCl4 flux rates are the fundamental parameters, because the amount of excess carbon is a very effective factor on the coating properties. It was shown by Stock et al., in 1998, that increasing the level of excess carbon can decrease coating hardness [4, 8, 9]. It is
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