Microstructural and Tribological Characterization of Stainless Steel-Reinforced Aluminum Matrix Bimetal Composites Produced at Various Mold Burnout Temperatures

Abstract

This study aims to identify the optimal burnout temperature (BT) of a plaster mold that was used in bimetal composite production. To achieve this goal, the mold was gradually heated up to 600, 650, 700, and 750 degrees C prior to melt infiltration casting. Molten A356 aluminum alloy was cast into mold at 730 degrees C for each casting process. Fifty percent porous 304 stainless steel (SS) preforms, obtained by assembling recycled SS shavings, were placed in a mold and infiltrated by A356 alloy until solidification was completed. The produced bimetal composites were subjected to a ball-on-disc tribometer with loads of 5, 10, and 15 N for 100 m sliding distance using an Al2O3 ball as a counterpart. theta-Fe4Al13 and eta-Fe2Al5 phases were formed at A356 Al-304 SS interfaces for all samples. Wear rates increased with increasing load and decreased with increasing BT, except at 750 degrees C. At this temperature, interfacial phases with excessively increased layer thickness, hardness, and brittleness were fragmentized during the test, and these cracked particles decreased wear resistance by participating in the wear process. The most suitable BT of the mold was found to be 700 degrees C, considering the microstructure and wear results of bimetal composites.