Effect of Al molar ratio on formation of Ti3AlC2
Due to TiC as an impurity phase existing in the final products, as shown in sections 3.2 and 3.3, it is also reported that Al may be deficient due to its evaporation by the synthesis of the traditional methods. Hence, increasing the Al content in the starting powder may compensate for the Al loss due to the high-temperature evaporation. Therefore, four sets of the starting elemental powders according to the Ti:Al: C molar ratios of 3:0.9:2, 3:1:2, 3:1.1:2, and 3:1.2:2 were well mixed with the dried NaCl‒KCl and then heating at 950 °C holding for five h, the corresponding XRD patterns and the detailed XRD patterns of samples obtained. 5(A) and (B), respectively. The result reveals that with increasing Al molar ratio from 1.0 to 1.1, a certain amount of Ti2AlC as the new impurity is observed, as shown in curves b and c. This suggests that excessive Al would facilitate the formation of the Ti2AlC phase. In addition, the amount of Ti2AlC phase increases with the increase of Al content in the starting elemental powders. However, when insufficient Al was used in the starting elemental powders, large amounts of TiC and Ti2AlC phases were obtained as impurities and Ti3AlC2 as the main phase. Hence, The Al content in starting elemental powders would not facilitate the formation of Ti3AlC2. On the contrary, it reacts with TiC and enhances the formation of Ti2AlC. The result is different from that reported by Wang et al. And Yang et al. The reason is as follows, on the one hand, the melting point of eutectic NaCl‒KCl, and Al is 657 and 660 °C, respectively; on the other hand, the density of Al is higher than NaCl‒KCl molten salt. Therefore, the liquid Al is under the molten salt, and the evaporation of Al is prevented by the liquid molten salt when the temperature is above 660 °C. Additionally, TiAl and Ti3Al alloy even forms at 700 °C. one curve a, which further prevents the evaporation of Al. Therefore, the optimal molar ratio of Ti:Al: C is 3:1:2 for synthesizing Ti3AlC2 powders in NaCl‒KCl molten salt. If you are looking for high quality, high purity, and cost-effective Ti3AlC2, or if you require the latest price of Ti3AlC2, please feel free to email contact mis-asia.