Effect of silicon carbide particle size and CaO content on foaming properties during firing and microstructure of porcelain ceramics

Porcelain green bodies were prepared using porcelain stoneware tile powder as the major raw material, with silicon carbide (SiC) and CaO as additives. These were fired at 1000-1200 °C. The effects of SiC particle size and CaO content on the microstructure and foaming properties of porcelain ceramics were investigated in detail, with a view to further clarify the dominant factors linking foaming behavior to SiC oxidation during firing of a porcelain tile matrix. The results reveal that the size of the SiC particles has a significant influence on the number, size, and interconnectivity of the pores formed in the samples; this effect becomes more pronounced as the SiC particle size is reduced. The addition of a small amount of CaO is shown to significantly accelerate the foaming of a porcelain green body containing SiC, but this effect is gradually inhibited by an increasing formation of anorthite. Finally, the foaming mechanism is also discussed in detail.