Wettability and thermal shock resistance of novel h-BN based ceramic seals for nitrogen oxide sensor

Abstract

In this study, the novel h-BN based ceramic seals are investigated for nitrogen oxide sensor. The alkaline-free glass (H4) exhibited good wettability on the Fe-16Cr alloy and yttria stabilization zirconia (YSZ) chip and the wetting rate obviously accelerated when the temperature exceeds 940 ℃. The shape parament Ɛ and wetting area of the H4 glass on the substrate of Fe-16Cr alloy and YSZ chip reach the maximum value at 900 °C that Ɛ was 1.46 and wetting area was 146.58 mm2 for Fe-16Cr alloy while Ɛ was 0.89 and wetting area was 165.99 mm2 for YSZ chip. In addition, the addition of 20 wt% H4 glass to hexagonal boron nitride (h-BN) formed BN-20 composite seal that can be effectively reduce the formation of substrate pores, microcracks and exhibited excellent chemical compatibility and stability, which shows that BN-20 seal is can be considered as a promising seal for nitrogen oxide sensors.