Study on the microstructure and mechanical properties of reactive plasma sprayed TiCxN1_x composite coatings with different Ti/graphite powders

In this present paper, the effects of Ti/graphite mass ratio (4:1, 6:1, 8:1 and 10:1) on the composite, grain size and mechanical properties of TiCN coatings were investigated. Based on the solid-solid reaction of Ti with graphite and solid-gas reaction of Ti with N-2 in plasma jet, TiCN phase were in situ synthesized. Results show that all coatings consist of TiCxN1_x(0 < x < 1) main phase, small amount of Ti2O, amorphous graphite and CNx phases. The amount of TiCN phase firstly increases and then decreases along with mass ratio increases, and the content reachs the maximum when the Ti/graphite ratio is 6:1. Besides, the highest sp(3)C-N fraction (about 36.22%) is detected in the coating, which is benefical to improve hardness and elasticity modulus. Therefore, the value of H/E (0.095) and H-3/E-2 (0.23 GPa) are higher than other three coatings, which is conductive to improve mechanical and tribological properties. A joint wear mechanism of abrasive wear and adhesive wear is found for TiCN coatings.