Interfacial Microstructure and Shear Strength Improvements of Babbitt–Steel Bimetal Composites Using Sn–Bi Interlayer via Liquid–Solid Casting

Abstract

To enhance the performance of Babbitt–steel bimetallic composites, bismuth (Bi) was incorporated into the Tin (Sn)-interlayer. Babbitt–steel bimetallic composites were created using the liquid–solid compound casting method in this study. Sn–Bi interlayer alloys with varying levels of Bi (1, 2, 3, and 4 wt.%) were created. The Babbitt-steel bimetallic composite’s bonding strength and interfacial microstructure were examined in relation to Sn-Bi interlayer alloys. The structure of the interface layer at the Babbitt–steel interface’s edge and center are significantly altered when Bi is added to the Sn interlayer. The relatively higher cooling rate near the edge led to the formation of clear unsolved Sn/Sn–Bi interlayers. Otherwise, the Sn–Bi interlayers in the middle were completely dissolved. By increasing the amount of Bi in the Sn–Bi interlayer alloy, the interfacial hardness of Babbitt-steel bimetallic composites increases by increasing Bi content in Sn–Bi interlayer alloy. Babbitt-steel bimetal composites’ shear strength increased to 28.27 MPa by adding Bi to the Sn interlayer using 1 wt.% alloying, with a 10.3% increase when compared with the reference pure Sn interlayer. Future research that aims to improve the production of Babbitt-steel bimetallic composites with high-quality and long-lasting bi-metal bonding ought to take into consideration the ideal pouring temperature, the preheating of the mold, and the addition of a minor amount of Bi (Bi ≤ 1) to the Sn-interlayer.