TiC Coating on Titanium by Carbonization Reaction Using Spark Plasma Sintering

Abstract

Hard TiC coating layer is formed on commercially pure titanium by heat treatment in a spark plasma sintering (SPS) mold filled with graphite powder. In case of heat treatment at 1243 K for 3600 s, the obtained thickness of the coating layer is about 10 µm and almost uniform. This coating itself consists of TiC and graphite, and there is no titanium oxide detected by X-ray diffractometer (XRD). Vickers hardness tests have revealed that the hardness of titanium coating is 1600 HV, which is much higher than that of the titanium substrate (130 HV). The hard TiC coating on titanium is considered to be advantageous when applied to load bearing parts of hard tissue replacements. The growth behavior of TiC is parabolic with an activation energy of 218.6 kJ/mol. This value is close to the activation energy of carbon diffusion in TiC. Therefore, the growth rate of TiC is rate-controlled by inward diffusion of carbon in the TiC phase.

Spark plasma sintering of a commercial TiAl 48-2-2 powder: Densification and creep analysis

“…2. In this case, the linear relationship achieved confirms diffusion control of the reaction and is in agreement with the work of Hayashi et al [14].…”

“…From our measurements, an average activation energy of 232.52 kJ/mol was determined. This result is close to the Hayashi et al [14] estimation of 218.6 kJ/mol for TiC layers grown on pure titanium. Consistently, Khina et al [15] evaluated the value of the activation energy for TiC layers grown on Ti 3 Al samples immersed in carbon powder at between 240 and 460 kJ/mol.…”

“…The growth of such a reaction layer has already been studied by Sudo et al [13], and more recently by Hayashi et al [14], on pure titanium samples sintered using SPS under 10 MPa pressure and 5 min to 1 h dwell times at temperatures ranging between 770 and 970°C. According to these studies, and considering that TiC reaction layer thickness is controlled by diffusion phenomena, results obtained on TiAl were post-processed using the well-established diffusion-ratecontrolled parabolic equation x 2 = kt.…”

“…The dense state is obtained during a densification of a commercial [14]; this study done at 1250°C). Fig.…”

Kinetic Models for the in Situ Reaction between Cu-Ti Melt and Graphite

“…Ti atoms migrate to the reaction interface within the layered TiC x via solid-state diffusion [35]. This point was also followed by some other researchers [36], and we think it needs to be further studied to give clear evidence in later work. As the TiC x generation reaction proceeds, the diameter of the C source particles decreases steadily, the reaction interface advances toward the core of the particles, and the layered TiC x advances toward the C source.…”