Influence of boriding temperature on microstructure and tribological properties of titanium

Abstract

In the current study, we added the cross section with different boriding temperatures and researched the microstructural using SEM. The line analysis results of the sections were shown as below. It is apparent from the micrograph that a dual boride layer consisting of monolithic TiB 2 and needle-like TiB whiskers form beneath the surface. No discontinuity and lack of adhesion are observed between boride layer and substrate which means that TiB whiskers anchor boride layer formed on the substrate. According to the results of the line analysis, when the boriding temperature was raised at 950 °C, the thickness of the hardened layer was 2.6 μm. The thickness of the total boride layer in this study was about 30 μm, which consists of 7.5 μm thick continuous and smooth monolithic TiB 2 and remaining TiB layers at 1150 °C. This apparent improvement in boriding of Ti can be attributed to the boriding mixture content. • The microscopic morphology of the hardened layer was observed. It reveals that the composition of hardened layers. • The relationship between the thickness of the hardened layer and the hardness result was discussed. • It is concluded, when the treating temperature was increased to 1050 °C and higher, a continuous boride layer formed on the pure titanium surface and the overall tribological properties had been improved. • The relationship between the boriding temperature and mechanical properties such as hardness and Young's modulus were also discussed. • Comparing the calculated value of the wear depth and the measured value. It was found from these results that the abrasion of the ball surface was caused in addition to the surface of the hardened layer.