Degradation of mechanical properties of MgO-spinel bricks after pre-treatment in hydrogen-containing atmospheres at different temperatures

The current climate policy raises targets to reduce CO 2 emissions, i.a. by using “green” hydrogen as a power source. However, the resulting water vapor-containing atmosphere raises uncertainties regarding its impact on the properties of refractory materials during their production and application. Therefore, this study investigates the effect of pre-treatment of unsintered MgO-spinel bricks with flue gas from firing with hydrogen, natural gas and a mixture of both at different temperatures followed by sintering in an industrial furnace as well as during differential scanning calorimetry (DSC). While the splitting tensile strength of the bricks was unaffected for a pre-treatment at 200 °C, the samples pre-treated with hydrogen at 600 °C revealed a decreased strength of about 14.5% compared to those pre-treated with natural gas at 600 °C. DSC results indicated that, besides brucite formation, the formation of additional phases (probably magnesium-silicates) also play a non-negligible role for this strength degradation. • Pre-treatment of MgO-spinel bricks with hydrogen affects their mechanical properties. • The hydrogen effect on the splitting tensile strength (STS) depends on temperature. • At 200 °C, the STS after hydrogen pre-treatment was improved compared to natural gas. • At 600 °C, the STS after hydrogen pre-treatment was reduced compared to natural gas. • Besides brucite, the formation of magnesium-silicates also plays an important role.