The quality of various commercial silicon nitride raw powders was compared and evaluated. Various powder characteristics and sinterability of low-cost Chinese powders were compared with those of powders from advanced manufacturers. Powder characteristics such as particle size, agglomeration, impurity content, and β phase fraction, as well as bulk characteristics such as β phase fraction and sintered density were investigated. The Chinese powder showed characteristics that were inferior to the E10 powder from UBE, Japan in most evaluated characteristics, but were comparable to the powders from other advanced manufacturers. However, at high temperature sintering of 1,800 °C, the sintered density of the Chinese powder was noticeably lower than that of the other powders. The correlation between various powder characteristics and sintered density was also quantified using the Pearson correlation coefficient. In the 1,700 °C sintered specimens, the particle size and β phase fraction were found to have a strong negative correlation with the sintered density. In contrast, the 1,800 °C specimens did not show any powder properties with a strong correlation to the sintered density.

Al2O3-SiC ceramic composites are produced using pressureless sintering, and their plasma resistance, electrical resistance, and mechanical properties are evaluated to confirm their applicability as electrostatic-discharge-safe components for semiconductor devices. Through the addition of Mg and Y nitrate sintering aids, it is confirmed that even if SiC content exceeded 10%, complete densification is possible by pressureless sintering. By the uniform distribution of SiC, the total grain growth is suppressed to about 1 μm; thus an Al2O3-SiC sintered body with a high strength over 600 MPa is obtained. The optimum amount of SiC to satisfy all the desired properties of electrostatic-discharge-safe ceramic components is obtained by finding the correlation between the plasma resistance and the electrical resistivity as a function of SiC amount.

The synthesis behavior of nanoporous silica aerogel in the macroporous ceramic structure was observed using TEOS as a source material and glycerol as a dry control chemical additive (DCCA). Silica aerogel in the macroporous ceramic structure was synthesized via sono-gel process using hexamethyldiazane (HMDS) as a modification agent and n-hexane as a main solvent. The wet gel with a modified surface was dried at under ambient pressure. The addition of glycerol appears to give the wet gel a more homogeneous microstructure. However, glycerol also retarded the rate of surface modification and solvent exchange. Silica aerogel completely filled the macroporous ceramic structure without defect in the condition of surface modification (20% HMDS/nhexane at 36hr).