2Dispersion and Fabrication of ZrO/SUS316 Functionally Graded Material by Tape Casting process

Abstract

When two materials are joined, it is likely to be a step-like structure at the heterogeneous interface. The internal stress at interface and the difference in material properties are strongly related to thermal degradation of materials. It is necessary to minimize the sintering defects and the internal stress caused by the thermal mismatch particularly in FGM. Zirconia(ZrO2) and stainless steel 316(SUS316) functionally graded material(FGM) was fabricated by tape casting method in an aqueous system. For the stable dispersion of ZrO2 and SUS316, we observed zeta-potential of each phase with pH variation and investigated the effect of organic additives on dispersion. Tetragonal zirconia polycrystal(TZP) and monolinic zirconia polycrystal(MZP) could be dispersed with addition of polymethacrylic acid(PMAA) as dispersant. SUS316 could be dispersed with carboxymethylcellulose sodium salt (Na-CMC) as suspending agent. ZrO2 and SUS316 were dispersed as the optimal condition established from the electrokinetic sonic amplitude (ESA). ZrO2/SUS316 FGM was fabricated by sintering at 1350°C in Ar/H2 atmosphere. As a result, the microstructure and the interface of the FGM showed the continuous compositional gradient and also, the adjustment of the particle size and the phase type of ZrO2 made sintering defects reduced or eliminated.