Synthesis of titanium carbide and titanium diboride for metal processing and ceramics production

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 4 2021 Fig. 1. Diffraction patterns of titanium carbide samples Ta b l e 1 Results of X-ray fl uorescence analysis of samples 1-3 and 1-4 Sample Content, wt. % Ti С total Residual elements 1-3 79.49 19.6 1.69 1-4 79.42 19.8 1.71 process of carbide formation is completed, as evidenced by the presence of only one phase (TiC) in the sam- ples. The results of the X-ray spectral fl uorescence analysis of one-phase samples are presented in Table 1. The content of elements with the atomic weight higher than for fl uorine (Al, Ni, Cu, Si, Са , Fe, Nb, Cr, Zr) is negligible in impurities. As seen from Table 1, the similarity is found between the samples with regard to the content of titanium and total carbon. The calculated content of titanium carbide of the composition TiC is: titanium – 80.00 wt.%; carbon – 20.00 wt.%. Calculated impurities content in titanium carbide is equal to 1.92 wt.%, with regard to impurities con- tent (1 wt.%) in titanium oxide and NFC . The data given in the table are very close to the calculated ones, and it gives evidence of high purity of the received products despite negligible content of impurities. When taking into account possible content of unreacted titanium dioxide and carbon, the content of impurities in the obtained titanium carbide could be estimated as ~ 2 wt.%. According to cumulative results of X-ray phase and elemental analyses, we can come to conclusion that the process of carbide formation is nearly completed at the temperature of 2,000 ° С or more. If NFC is used as a reducing agent, optimum conditions of titanium carbide synthesis will be the following: 1) TiO 2 /C mass ratio by stoichiometry versus TiC, 2) the process should take place in a weak reductive gaseous medium (N 2 + CO mixture) at 2,000…2,100 ° С . Figure 2 shows SEM images of samples obtained by the interaction of titanium dioxide with carbon at different temperatures. Samples 1-3 and 1-4 essentially consist of homogeneous particles. It appears to be an indirect proof of the carbide formation completion. It should be noted that titanium carbide particles are mainly aggregated, their boundaries are even (without shape fragmentation), that is a characteristic feature of compounds obtained by chemical reactions.