FIGURE 2 The digital images of (a) SCG, (b)NSCG , and (c) ASCG; The SEM images of (d) SCG,(e) NSCG, and (f) ASCG
Through the microscope, we observed the SCG under different atmospheres and statistically analyzed its particle size distribution, as shown in Figure 3. Figure 3 ( a-c ) shows that the original SCG is brown, and the color after heat treatment in different atmospheres is black. This is the same as the color reflected in the digital camera. Figure 3 ( d-f ) corresponds to the particle size distribution of SCG, NSCG , and ASCG, respectively. From the distribution map, the particle size of the three SCG showed a normal distribution, and the average particle size of the SCG was 0.204 mm, while the average particle size of the SCG after heat treatment in different atmospheres decreased to 0.188 and 0.186, respectively. The decrease of particle size indicates that heat treatment can effectively improve the grindability of SCG under the same grinding time, especially in air atmosphere.