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Gokhan Kara, Akgun Alsaran, Gencaga Purcek, ''Microstructure and wear behaviour of β-Ti alloy borided by electron beam evaporation technique '', ICETAT 2016, November 4-6, International Conference on Engineering Tribology and Applied Technology, Taipei, Taiwan
Abstract: In this study, it is aimed to achieve hard and protective layer on β-type Ti-45Nb alloy substrates by electron beam evaporation (EBE) technique. A two-stage process was applied during boriding of Ti alloy. The first stage included the deposition of boron atoms onto the Ti alloy samples using EBE technique. During this stage, the boron atoms were vapourised first using a source of amorphous boron and then was deposited on the Ti substrate. Deposited boron was diffused towards substrate by annealing the sample at various temperatures and time intervals. Consequently, a hard and adhered layer on the surface of the substrate was achieved.The layer is a mixture of monolithic TiB2 and Nb2B and TiB whiskers which anchors monolithic layer towards the substrate.Annealing of deposited samples at higher temperatures (> 1000ºC ) resulted in deterioration of boride layer which may be attributed to limited boron source at the deposition of boron during electron beam evaporation stage.Dry wear test together with micro-indentation study were performed after morphological analyses of boride layers. The top monolithic layer has high hardness up to 30 GPa which serves high wear resistance and TiB whisker layer, anchors the ceramic layer to substrate, has hardness nearly 20 GPa.Especially hard monolithic boride layer exhibited higher wear resistance along with higher friction coefficient as compared to un-borided one under the same conditions.
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