Performance Evaluation of SiC-DPF Sintered with Sintering Additive

SiC is well known as a ceramic with high mechanical strength and thermal conductivity, and the R-SiC-DPF (recrystallized SiC-DPF) used these excellent properties is widely recognized as the substrate material for DPF. DPF system requires the material possessing high thermal shock resistance against an unexpected accident, such as an uncontrolled regeneration. One of the indices indicating the thermal shock resistance of the DPF is soot mass limit, which is an important factor determining the penalty of vehicle fuel consumption. In order to further increase the soot mass limits of R-SiC-DPF, this paper covers the attempts of IBIDEN to promote the sintering of the neck part of a SiC porous body using a sintering additive. Al₂O₃, well known as a sintering additive for a SiC dense body, was selected as the sintering additive. Consequently, the SiC-DPF obtained through the addition of Al₂O₃ was found to be increased, particularly in terms of the soot mass limit and thermal oxidation resistance, more than the conventional R-SiC. The reason for such increased soot mass limits was due to the reinforcement of the SiC neck, while the increase in thermal oxidation resistance was due to the formation of a passive film of nano order including Al on the surface of the SiC. On the other hand, when Al₂O₃ was added, such events were clearly seen to cause a drop in high temperature strength and a broader pore diameter distribution, resulting in the increased pressure loss. However, these problems were be improved by optimizing the amount of the additive and the sintering temperature used.