A study of the wear performance of TiN, CrN and WC/C coatings on different steel substrates

In this study, the performance of the coatings TiN, CrN and WC/C applied on steel substrates that were subjected to sliding wear was analyzed. These materials normally exhibit an efficient performance in applications such as coatings of cutting tools, stamping processes, forming and plastic injection tooling where the contact and sliding conditions are severe. Due to this fact, this research was conducted to characterize the materials in relation to the wear process. The sliding wear test was performed using a reciprocating wear test machine. All tests were conducted in dry conditions with a room temperature between 20 °C and 23 °C and 45% to 50% relative humidity. A sliding velocity of 0.08 m/s and 2 mm amplitude were used. The applied loads were 11.76 N (Po = 1.74 GPa) and 7.84 N (1.52 GPa), respectively. Optical microscopy and scanning electron microscopy (SEM) were used to observe and analyze the wear mechanisms. Additionally, the variation of the friction coefficient versus the number of cycles was obtained. This was used to determine with a higher precision the time (presented as number of cycles) where the coating presented the initial signs of wear damage. In addition, energy dispersive X-ray analysis (EDS) was performed to obtain the chemical composition of the materials and hardness tests on the wear tracks were also carried out. It was possible to know the wear life of these coatings and possible causes of life variations. The load was an important factor in the variation of the wear life results, although other factors such as surface roughness and coating thickness were also significant.