PSI - Issue 40

M.V. Fedorov et al. / Procedia Structural Integrity 40 (2022) 136–144

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Fedorov M. V. at al. / Structural Integrity Procedia 00 (2019) 000 – 000

The thermal analysis of the WC-Co(8%) powder revealed the presence of an endothermic peak within room temperature – 100 ○ C, 800 – 1000 ○ C due to the removal of physical combined water present in the powder and the beginning removal of some of the carbide phases at a high temperature. An exothermic peak within 1250 ‑ 1350 ○ C revealed the creation of a phase by decay characterized by loss of mass in contrast to the peaks found within 200 ‑ 350 ○ C, 350 ‑ 450 ○ C, 650 ‑ 750 ○ C, accompanied by saturation of the total mass. Thermal analysis results are presented in Figure 3 as DSC, DDSK, TG and DTG curves.

Fig. 3. Thermal analysis of WC- С o(8%) powder within room temperature to 1450 ○ C.

Thermal analysis of tungsten carbide powders was carried out using DSC, DDSK, TG, and DTG, as shown in Figure 4. During heating, endothermic processes are detected within room temperature to 100 ○ C, 150 ‑ 200 ○ C, 800 ‑ 900 ○ C, 1050 ‑ 1150 ○ C, 1180 ‑ 1250 ○ C and 1300 ‑ 1400 ○ C. During the analysis, weight loss occurs depending on the actual temperature. The total weight loss is approximately 0.7% by weight. X-ray diffraction analysis of heated samples of tungsten carbide powder revealed tungsten (W), tungsten carbide (WC), and a compound, most likely, Co 3 W 9 C 4 . The results of X-ray phase analysis of heated WC powder to 1450 ○ C are shown in Figure 5. Thermal analysis of cobalt powder (Figure 6) revealed exothermic processes within 250 ‑ 350 ○ C, 500 ‑ 600 ○ C, 950 ‑ 1100 ○ C and 1290 ‑ 1360 ○ C, accompanied by an increase in the total mass of approximately 5.5% wt. The TG mass loss curve within the 250 ‑ 400 ○ C section indicates a rapid increase in the sample mass. Further, the growth of the curve stabilizes until the end of the analysis. Thermal analysis was carried out in an inert argon atmosphere on corundum and platinum-rhodium crucibles with a heating rate of 10 ○ C/min. According to Gabelkov et al. (2011), Barry (2014), Manouchehri et al. (2013), Yılmaz et al. (2013), Kudlash et al. (2008) cobalt tends to be α -stable at temperatures from room temperature to 400 ○ C; then transitions from α - to β - cobalt begin. As a result, it can be argued that a chemical reaction occurs between the cobalt and the crucible, coloring the surfaces of their contact. X ray diffraction analysis of heated samples of cobalt powder revealed cobalt (Co) and cobalt oxide (Figure 7).