INVESTIGATION OF FUNDAMENTAL PROPERTIES A ND TRIBOLOGICAL BEHAVIOR OFHFB2 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 systemat ically varied. The characterization of the coatings includes fundament al properties such as thickness, hardness, adhesion and cohesion, stru cture, morphology, residual stresses and wear resistance of the coatin gs resulting from the plate on cylinder tribometer. The hardness value s, analysed with the Vickers and the indentation depth method (Univers al hardness),were extremely high for HfB2 films, deposited with low de position 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 coa tings.