Liquid–Solid Reactions and Microstructure of SiC-5120 Steel Composite Brake Material

摘要

This study investigated solid–liquid reactions between SiC preform and molten 5120 steel during infiltration casting of SiC-steel composite for heavy duty brake applications. The reactions between SiC and the molten steel resulted in the formation of three distinctive microstructural regions, including the α ₁-Fe(Si)-graphite region, the pearlite region, and the ferrite-pearlite region. The phase structures were identified by means of X-ray diffraction, X-ray energy dispersive spectrometry, and metallographic examination. These observations reveal that SiC was decomposed via reactions with the molten steel. The diffusion of C and Si into the molten steel and selective solidification led to the formation of different regions with varied C and Si contents. The microstructures produced during the solidification sequence are identified to be the ferrite-pearlite → pearlite → α ₁-Fe(Si) + graphite and cementite.