Improvement of Mechanical, Tribological, and Fricative Reduction Properties of Pure Titanium by Boriding

Abstract

Surface boriding of pure titanium was performed using dissolved salt impregnation to modify the surface hardness and improve wear performance. The effect of boriding temperature (950–1150 °C) on the microstructure, composition, and room-temperature tribological properties of the borided samples was investigated by X-ray diffraction, scanning electron microscopy, and ball-on-disc tribometry, respectively. Gibbs free energy was also calculated to evaluate the compounds generated during the boriding at different temperatures. After a detailed analysis of the crystal structures and the growth morphologies of TiB, the diffusion mechanisms for B atoms in TiB and TiB2 were discussed in the present report. The boriding temperature had a large effect on the microstructure, mechanical properties, and room-temperature tribological behavior of the borided samples, attributed to the changes in the composition and the increased hardened layer under elevated boriding temperature. The modeling of layer growth kinetics was also discussed in this paper. The actual value of hardened layer thickness was compared to the calculated value, and the difference was analyzed. The fricative value of the borided samples showed a minimum value of 88.9 dB for a boriding temperature of 1050 °C. The depth and width of the wear tracks decreased gradually with increasing boriding temperature. The worn surface of the samples borided at higher temperatures showed very good wear resistance. A boriding condition of 1050 °C was considered optimal, as it provided sufficiently high surface hardness and a low fricative value to reduce vibrations during practical use.

Evaluation of Boride Layers on C70W2 Steel Using a New Approach to Characterization of Boride Layers

“…This is also consistent with the boronizing kinetics studies, which confirmed the diffusive nature of boronizing. It was found that boronizing obeys the parabolic law where the square of the layer thickness is proportional to the duration of boronizing, and the proportionality coefficient represents the growth rate constant [ 1 , 4 , 5 , 7 , 9 , 13 , 24 , 30 , 32 , 39 , 40 ]. Since boronizing obeys the parabolic law, this would imply that diffusion slows down over time.…”

“…Regarding hardness, previous studies on the cross-sectional hardness of boride layers determined the hardness as the arithmetic mean of five or more measurements at each depth [ 2 , 3 , 4 , 5 , 9 , 37 , 39 ]. This method is suitable for layers parallel to the surface, and it can be said that reliable results are obtained in this case.…”

Influence of Laser Texturing and Coating on the Tribological Properties of the Tool Steels Properties

“…Methods that improve the integrity of the surface and at the same time reduce the coefficient of friction between the contacting surfaces can be included among the options that allow the reduction of the coefficient of friction and the reduction of the thermal load. This includes options such as surface hardening, chemical-heat treatment (carburizing, nitriding and boriding), laser welding, laser texturing and, finally, coating (PVD, CVD) and others [11][12][13][14][15][16][17][18].…”

Investigation of the Effect of Stress on Oxygen Diffusion in Pure Titanium Using a Phase-Field Model

“…However, its hardness and wear resistance are low, which limits its use. Various processing methods, including severe plastic deformation [16][17][18], thermal oxidation [19][20][21], carburization [22][23][24], nitriding [7,25,26], and boriding [7,27,28], have been proposed to improve its mechanical properties. During the processes of thermal oxidation, carburization, nitriding, and boriding, the atom diffusion behavior in pure titanium plays a key role in achieving good mechanical properties.…”