Enhancing High Temperature Mechanical Performance of Aluminate Cement with Plasma-Modified MgO Whisker

High brittleness and low tensile strength at elevated temperatures of set cement limits its use in thermal production of heavy oils. In laboratory study, a plasma-modified magnesium oxide (MgO) whisker was used to enhance the high temperature mechanical properties of aluminate cement. It was found through the study that the surface microstructure of the plasma-modified MgO whiskers is rougher than that of the original MgO whiskers, and are thus better bonded with cement to form set cement with improved mechanical properties. After aging at high temperature for 7 days, the set cement containing 2% plasma-modified MgO whiskers has more significant improvement in mechanical performance than the set cement containing 2% MgO whiskers without plasma-modification; the compressive strength and tensile strength of the set cement containing 2% plasma-modified MgO whiskers are 24.5% and 14.1% higher than those of the set cement containing 2% MgO whiskers without plasma-modification, respectively. It was also found that the set cement containing 2% plasma-modified MgO whiskers has better stress-strain performance; it has higher peak stresses and lower elastic modulus. Characterization of the micro morphology of the set cement with whickers with SEM and EDS indicated that the whiskers act on the matrix of cement through crack deflection, whisker fracture and bridging, thereby enhancing the mechanical performance of set cement.