Influence of deposition energy and C2H2-doping on HiPIMS deposition of hard ta-C coatings

The tetrahedral amorphous carbon coatings (ta -C) deposited on the cemented carbide surface by high power impulse magnetron sputtering (HiPIMS) were investigated in the present study. The adhesion and friction properties of ta -C coatings, which is significantly influenced by deposition parameters using in the field of cutting tools and wear-resistant parts, was commonly influenced by the deposition energy directed toward the growing coatings and structures. The results showed that adjusting the deposition energy of ta -C coating based on frequency and bias voltage could improve the electric field intensity in the cathode potential drop region, and the higher energy electrons were therefore obtained, which further promoted the increase of gas ions impacting the cathode target and the number of secondary electrons emitting, and significantly reduced the number and size of large particles on the surface of ta -C coatings. On this basis, C2H2 doping can effectively improve the deposition rate, structure, hardness, adhesion and wear resistance of ta -C coatings. When the flow rate of C2H2 was 15 sccm, the ta -C coatings thickness was 872.3 nm, the sp3 bond content was 70.19 %, the adhesion was 21.2 N, the hardness was 43.6 GPa, and the friction coefficient can be reduced to 0.109, while the surface of ta -C coating was uniform and dense.