INVESTIGATION OF FUNDAMENTAL PROPERTIES AND TRIBOLOGICAL BEHAVIOR OF HFB2 AND HF(B,N) COATINGS

Thin films of HfB2 and Hf(B,N), including intermediate layers of pure titanium, were sputtered in a rf sputtering unit on steel substrates. The deposition parameters bias-voltage and deposition pressure in the case of HfB2 and the nitrogen flow concerning to Hf(B,N) were systematically varied. The characterization of the coatings includes fundamental properties such as thickness, hardness, adhesion and cohesion, structure, morphology, residual stresses and wear resistance of the coatings resulting from the plate on cylinder tribometer. The hardness values, analysed with the Vickers and the indentation depth method (Universal hardness),were extremely high for HfB2 films, deposited with low deposition pressure or high bias voltage applied on the substrate. These results are probably caused by high residual stresses in the coating. The best wear properties could be obtained by testing the hardest coatings.