The effect of the Ar/N-2 gas ratio on the structure and properties of Ta-Si-N coatings produced by magnetron sputtering of TaSi2 target

Coatings in the Ta-Si-N system were deposited by magnetron sputtering in the Ar, N-2 atmosphere and Ar+N-2 gas mixtures. Coatings have been studied in terms of structure and composition, optical characteristics, adhesion strength, fracture toughness, mechanical and tribological properties, as well as oxidation resistance. Nitrogen added to the coatings inhibits the columnar grain growth of the h-TaSi2 phase due to formation of amorphous nitrogen-containing interlayers. The coating deposited in an atmosphere of nitrogen was characterized by optical transmittance up to 90% and reflectivity up to 32% in the visible and infrared spectra. Extremal dependence of adhesion strength, fracture toughness and hardness on nitrogen concentration was observed, with the maximum (Lc(2) >31 N, L=20 N and H=26.7 GPa) corresponding to the Ar:N-2 gas ratio = 1:2. The coating fabricated in an atmosphere of Ar had the lowest friction coefficient (similar to 0.6) and wear rate (< 0.2 x 10(-4) mm(3)N(-1)m(-1)). The coatings with high nitrogen content were resistant to oxidation at temperatures up to 1200 degrees C because of the higher volume fraction of the amorphous phase with the composition close to Si3N4.