Improvement in heat resistance of electric heating alumite carriers

Abstract

Alumite carriers were prepared by using Al/Ni-Cr-Alloy/Al clad materials with different Pore widening treatment (PWT) durations of 0, 2, 4, 6 and 8 h to observe its effect on the alumina surface structures and the overall heat resistance. Aluminum clad materials were first anodized in 298 K 4 wt% oxalic acid with 50 A/m2 electric current. Subsequently, PWT was carried out in the same oxalic acid solution at 298 K. After calcination at 623 K for 1 h, samples underwent Hot water treatment (HWT) in 358 K hot water for 2 h before lastly calcinated at 773 K for 3 h. It was found that heat resistivity improved drastically when PWT was carried out for longer than 6 h. Results also showed that alumite carriers’ surface structure changed drastically after 6 h of PWT from fragment structure into a sponge-like structure. By manipulating the PWT durations, alumite carriers produced successfully withstood up to 1223 K without needing to induce diffusion layers by preheating. Therefore, alumite carriers produced with 6 h and 8 h of PWT showed promising potential for the usage in high temperature steam reforming reactions with electric heating.