Thermal cycling study of prospective fuel-cell sealants from silica-sand/alumina composites

Abstract

As excellent alternatives for cleaner energy production evaluated against conventional nonrenewable energy sources, fuel-cells have now been commercially viable. However, efforts to improve their efficiency are always important. By high temperature and sandwich model of fuel-cells, sealing materials play an important role to prevent air leakage and entirely lock the hydrogen inside to achieve high efficiency. In this study, we reported the phase stability of purified silica- sand/alumina composites under heat cycling treatment within the fuel-cells working temperatures. The composites, containing commercial Al2O3 and purified SiO2 from Indonesian silica sand, were prepared using a simple solid-state reaction approach. X-ray diffraction data collection and evaluation were performed to check the phase formation of the compact ceramic composites. Herein, we focused on the composites’ phase stability under heat treatment for several times. As a result, the phase content in the composites remained unchanged. This stable characteristic also applied to the density- porosity behaviors and the coefficient of thermal expansion (CTE) of the composites. In addition, the CTE of the composites was evaluated theoretically and experimentally. Both results agreed that the CTE values of the composites are suitable for sealing materials. From the crystalline structures, physical and thermomechanical stabilities, it is therefore concluded that the silica-sand/alumina composites can be proposed as fuel-cell seal materials.