In this report, the effect of refractory coating agent on the oxidation of molten aluminum alloy was investigated. Cup-shape refractories were molded, sintered, and coated. AD12.1 molten alloy was poured into them and they were observed by SEM-EDX after four and six days. The surface of the refractories was rough in the order of no-coated ＜ Zr-coated ＜ P-coated. Moreover, the amount of Mg oxide on the surface of the refractory increased in the same order. On the other hand, the amount of Mg in the molten metal became depleted in the same order. These findings suggest that the microscopic unevenness of the refractory surface affects the surface area of the molten metal and changes the amount of oxides produced dominantly.
It has already been reported that the use of a chiller which suppresses the occurrence of internal casting defects in cast products of 27%Cr cast iron results in the deterioration of impact-wear resistance in the as cast state. In this paper, impact-wear behavior of 27%Cr cast iron was investigated after quenching at various temperatures to improve the impact wear resistance. Evaluation of impact-wear resistance was based on wear loss and decrease of thickness using air blasting machine. Microstructural analysis was performed using a scanning electron microscope with energy dispersive X-ray spectrometer, X-ray diffractometer and ferrite meter. Quenching at temperatures over 1323K results in improved impact wear resistance, as compared with the as cast state. Below that temperature, impact-wear becomes severe. This can be explained by the change in the volume fraction of retained austenite and martensite in the matrix and the self-temper softening of martensite caused by the generation of impingement heat between abrasive media and experimental samples.