Fabrication of transparent AlN ceramics by spark plasma sintering
放电等离子烧结制备透明AlN陶瓷

AIN powders containing deliberating amounts of calcium fluoride (CaF2) were consolidated by spark plasma sintering (SPS) technique and transparent AIN ceramics were fabricated. Samples obtained by SPS achieved high densities in short time, which indicated SPS was an efficient method for the fabrication of transparent AIN ceramics. Heterogeneity in the color of the sintered pure AIN ceramics was observed. With the increase of CaF2, density and transmittance of the sintered AIN were improved. An increase in the amount of CaF2 to 3% in mass did not further increase the density, but did improve the transmittance. The sample doped with 3% CaF2 yielded the highest maximum transmittance of 54.7%. The high transmittance was attributed to high purity, the homogenous mi-crostructures and the less-grain boundary phases, which was confirmed by the results from XRD, SEM, TEM and EDX.