TiB whisker coating on titanium surfaces by solid-state diffusion: Synthesis, microstructure, and mechanical properties

Abstract

The study demonstrates the feasibility of synthesizing TiB whiskers on titanium (Ti) surfaces by solid-state diffusion to form a hard and wear-resistant coating. The microstructural and mechanical properties of the TiB coating layer have also been investigated. The TiB coating was formed by the solid-state diffusion of boron (B) from a powder mixture containing amorphous boron, Na 2 CO 3 powder, and charcoal (activated) powder. The diffusion process was carried out at various temperatures ranging from 800 ЊC to 1000 ЊC for various periods of time ranging from 1 to 24 hours. The amount of Na 2 CO 3 in the mixture was also varied. It has been found that pristine and extremely fine TiB whiskers form on the surfaces of titanium, with the whiskers growing more or less normal to the surface. A maximum coating thickness of about 218 m was observed for the pack diffusion conditions at 850 ЊC for 24 hours with 15 pct Na 2 CO 3 . The kinetics of TiB formation was found to follow the growth rates in bulk composites. The X-ray diffraction (XRD) patterns of the coatings revealed the dominant TiB peaks with a very few TiB 2 peaks, with small intensity at higher temperature and time. The surface hardness of the coated layer increased to a Vickers hardness of about 550 kgf/mm 2 due to the presence of TiB whiskers in the coating. It is shown that pack diffusion of boron in the solid state is a simple and very effective means of generating hard and wear-resistant coatings on titanium.

Characteristics and wear performance of borided Ti6Al4V alloy

“…3, Ti 3 B 4 was not detected by the XRD analysis in accordance with the results of previous studies [11][12][13][14][15][16][17][18][19][20]. The peaks of α and β titanium also appeared on the XRD pattern.…”

“…The cross-section SEM micrographs along with the results of EDX analysis and XRD pattern of the borided alloy are given in Table 1 The characteristics of Ti and Ti6Al4V alloy surfaces after diffusional boriding techniques Authors Boriding technique Base Metal Surface Layer Hardness Brandstötter and Lengauer [11] Pack Ti TiB and TiB 2 Kaestner et al [12] Plasma-assisted Ti and Ti6Al4V TiB and TiB 2 2800 HK Anthymidis et al [13] Fluidized bed Ti6Al4V TiB and TiB 2 Aich and Ravichandran [14] Pack Ti TiB whiskers 550 HV Anthymidis et al [15] Fluidized bed Ti and Ti6Al4V TiB and TiB 2 Tsipas et al [16] Fluidized bed Ti and Ti6Al4V TiB and TiB 2 1925 HV Prytula et al [17] Pack Ti TiB and TiB 2 1440 HV He et al [18] Pack Ti TiB, TiB 2 and TiC 820 HV Tikekar et al [19] Pack Ti6Al4V TiB 2 3200 HV Lee et al [20] Pack Ti6Al4V TiB 2 3300 HV Figs. 1 and 2, respectively.…”

“…Even though titanium borides exhibit excellent combination of hardness and wear resistance in many tribological systems, only a few publications exist on boriding of titanium and titanium alloys as an alternative diffusion technique [11][12][13][14][15][16][17][18][19][20]. Table 1 presents the characteristics of Ti and Ti6Al4V alloy surfaces after diffusional boriding.…”

Mechanical behavior of porous commercially pure Ti and Ti–TiB composite materials manufactured by selective laser melting

“…Similar chemical reaction also occurs between Ti and TiB 2 during other manufacturing technologies [17,35]. Moreover, TiB particles exhibit a growth direction parallel to the [010] axis of the B27 cell as this direction has higher growth speed compared to other directions, leading to the formation of needle-shape morphology in TiB particles [36,37]. The contents of B in the starting Ti-TiB 2 powder as well as in the SLMproduced Ti-TiB composite samples were measured by chemical analysis (inductively coupled plasma atomic emission spectroscopy) to be 1.50 wt%, indicating that neither Ti nor B was potentially lost by evaporation during SLM processing and, consequently, the ratio of Ti to B atoms remained constant.…”

Microstructure and wear properties of WC particle reinforced composite coating on Ti6Al4V alloy produced by the plasma transferred arc method

“…However, their relatively poor tribological properties, such as high friction coefficient and low hardness, are barriers to their use in applications that require high surface hardness and wear resistance [1][2][3][4][5][6]. Surface modification techniques, including chemical vapor deposition (CVD) [7][8][9][10][11], physical vapor deposition (PVD) [12][13][14][15][16], laser and plasma surface treatment [17][18][19][20], thermal oxidation [21][22][23][24][25][26], sol-gel processing [27,28] and nitriding [29][30][31][32], have been applied to improve the tribological and wear properties of Ti alloys.…”