Sealing performance and chemical compatibility of SrO–La2O3–Al2O3–SiO2 glasses with bare and coated ferritic alloy

Abstract

Sealing performance and chemical compatibility of SrO–La2O3–Al2O3–SiO2 glass sealants with bare and Mn–Co spinel coated SUS430 ferritic alloys are investigated. The low–SrO glasses (≤40mol%) show good wettability and adherence to the bare SUS430 alloy due to their lower viscosity and negligible reactions with the alloy. The high–SrO glass (e.g. 45mol%) exhibits higher viscosity and more serious reactions with the bare SUS430 alloy. The formation of SrCrO4 with higher CTE causes obvious delamination and dramatic oxidation of the alloy at the glass/alloy interface. In contrast, Mn–Co spinel coating has good compatibility with both SrO–La2O3–Al2O3–SiO2 glasses and Fe–Cr ferritic alloy. Moreover, the Mn–Co spinel coating on the alloy can effectively restrain the diffusion of Fe and Cr and the reactions between the glasses and the alloy. Due to the ameliorated interfacial microstructure, sealing performance can be improved by applying the Mn–Co spinel coating on SUS430 alloy, especially for the bonded couple with high–SrO glass.