Fabrication of porcelain foam substrates coated with SiC, Ni, and Cr using the dip-coating technique

This report presents a study on the properties of porcelain foam substrate fabricated via the sponge replication technique. The sintered porcelain foam substrates were dip-coated with SiC-, Cr-, and Ni-based coating slurries, and sintered again at 900–1250°C. The XRD results of coated samples show existence of secondary phases (Cr2O3, Al3Cr7, NiO2, and NiAl2O4) due to sintering, mostly at higher temperatures. The porosity of the plain substrate was reduced significantly after dip-coating and proportionally decreased as the sintering temperature increased, therefore influencing the compressive strength value. Furthermore, the thermal conductivity of coated substrate sintered at 1250°C was obtained in the range of 0.0921–0.1358W/mK, when compared to the plain substrate at 0.0461W/mK. In general, a reduction in the number of pores, cracks and open cells was observed, with significant improvement in the compressive strength of the coated substrate.