Failure Analysis And Material Reverse Design Of Brake Discs For High-Speed Trains

The failure mechanism of the brake disc basing on the crackles on the surface was analysed in this paper. Then design the Basic scheme of brake disc coating. The Y₂O₃ part stabilize ZrO₂ ceramic coating, YPSZ for short in later paper, have been prepared by plasma spraying and laser remelted. The morphology and phase structure have been studied by SEM and XRD. The capability of thermal shock resistance and the wear resistance of the YPSZ coating and NiCr-Gr₃C₂ coating have been compared too.The results showed that the failure mechanism of the brake disc is the thermal fatigue resulted by the heat stress producing during brake course.The result of coating also showed:plasma spraying coating have typical by layer structure, the layer have mechanical bond with substrate and each other. Laser remelted coating have a more thinner morphology structure and a more uniformity structural constituent compared to the plasma spraying coating. There is almost no pore in laser remelted coating.Comparing to the plasma spraying coating, laser remelted YPSZ coating have a better capability of thermal shock resistance, and the capability of thermal shock resistance have a relation with the processing parameter of the laser remelted process. When the value of specific energy is 28.05 J/mm²,the capability of thermal shock resistance is best, and the more value of specific energy approaching to 28.05 J/mm²,the better capability of thermal shock resistance is.The wear resistance of laser remelted coating is about 1.4-1.8 times higher than the plasma spraying ones. And under the load 25N the wear resistance of laser remelted coating is about 1.8 times higher than the plasma spraying ones in this paperComparing the YPSZ coatings to the NiCr-Gr₃C₂ coatings ,the result showed: laser remelted YPSZ coating are better in capability of thermal shock resistance and laser remelted NiCr-Cr₃C₂ coating are better in capability of wear resistance. Based on the failure mechanism, take different kinds of factors in condersation, the laser remelted YPSZ coating has a best combination property.