Tribological Properties of O-Doped Zr-B-N Coatings Grown by Pulsed Magnetron Sputtering

The O-doped Zr-B-N coatings were synthesized by pulsed magnetron sputtering on substrates of Si-wafer and 304 stainless steel.The influence of the content of O-dopant on the microstructures and tribological behavior was investigated with X-ray diffraction,scanning/transmission electron microscopies,and conventional mechanical probes.The O-content was estimated by measuring the ratio of O₂/(O₂+N₂+Ar) flow-rates.The results show that the O-content had a major impact.To be specific,as the O₂/Ar flow-rate ratio increased,the deposition-rate decreased because of the target surface oxidation; the grain-size decreased,accompanied by crystallinity deterioration; the hardness and average friction coefficient of the O-doped Zr-B-N coatings,comprising(ZrO₂,Zr₃N₄) grains enclosed by amorphous(BN,B₂O₃),changed in a decrease-increase manner; and the increasing density of a-B₂O₃,a solid lubricant,accounted for the transfer wear mechanism and the lowest friction coefficient of 0.7.