Liquid-phase oxidation joining of oxide ion conducting ceramics via Al/heat resistant alloy/Al multilayer interlayers

Abstract

A joining technique for oxide ion conducting ceramics, such as yttria-stabilized zirconia, was developed, utilizing oxidation of transiently formed aluminum melt. Two yttria-stabilized zirconia (YSZ) blocks were joined via Al/Ni alloy/Al interlayers at 1273 to 1473 K for 3.6 to 28.8 ks in a vacuum (< 0.2 Pa) with an applied load of 80 MPa. The average fracture strength increased with increasing the joining time and temperature. A strong four-point bend strength of 170 MPa was obtained for the specimen joined at 1473 K for 14.4 ks, which was fractured at YSZ block. Alumina interlayer, which is expected to act as a protective layer for further oxidation of Ni alloy, was formed between YSZ and Ni alloy in the specimen after joining.

Oxygen Gas Sealing between YSZ and Fe-Cr Alloy by Liquid-Phase-Oxidation Joining via ZrO2-Dispersed Al Interlayer

“…Figure 1 shows Arrhenius plot for oxygen permeation rate, V O2 , at a constant applied voltage of 0.9 V. Apparent activation energy for the oxygen permeation in this experiment was 1.11 eV, which was greater than that of 0.88 to 1.01 eV for oxygen ion conduction [3,4], and smaller than that of 1.87 eV and 1.67 eV for the transport of electron and hole [5] in YSZ. The apparent activation energy was independent of applied voltage between 0.5 V and 0.9 V. Figure 2 shows voltage dependence of pumping current at 1073K.…”

“…[1] Recently, Yokokawa et al reported that silicon in components of SOFCs evaporates into SiO(g) or Si(OH) 4 gas species, and deposits at anode, leading a severe degradation of anodes. [2] In the previous study, we carried out siliconfree gas sealing, employing liquid-phase-oxidation (LPO) joining [3] of yttria-stabilized zirconia (YSZ) plate and Fe-Cr alloy (SUS430) tube via Al interlayer. In the LPO joining, the aluminum interlayer is designed to melt, fill gap along the YSZ/Fe-Cr alloy interface, and achieve good contact between YSZ and alloy.…”

Microwave Joining Alumina Ceramics Using Al-Si Alloy Powders at Low Temperature

“…However, material degradation during joining and interfacial reactions that produce undesirable and structurally defective reaction layers can limit the properties and reliability of joined assemblies. The extent of degradation or reaction often increases with increasing joining temperature [2][3][4]. So it becomes increasingly important to reduce the joining temperature below some critical threshold temperature to mitigate such problems.…”

Liquid-Phase Oxidation Joining of Yttria-Stabilized Zirconia via Al/Fe-Cr Alloy/Al Interlayers

“…(1,2) However, compounds including Si, such as Si(OH) 4 and SiO evaporates from glass and deposits SiO 2 on the triple point at anode. The deposition of SiO 2 at anode will cause severe degradation of SOFCs for a long term operation.…”