# Microstructure and Properties of Conventional Cast Versus Annular Laser-Clad Babbitt Alloy Layers for Sliding Bearings

## TL;DR

Laser cladding improves the microstructure and performance of Babbitt alloy layers used in sliding bearings compared to conventional casting.

## Contribution

This study demonstrates the benefits of annular coaxial laser cladding for fabricating tin-based Babbitt alloys with refined microstructure and better tribological properties.

## Key findings

- Laser cladding reduces grain size of SnSb phase from ~100 μm to 10-20 μm.
- Tribological performance improves with a 38.19% decrease in friction coefficient and 10.46% reduction in wear volume.
- Hardness increases from 25.3 HB to 27.6 HB with laser-clad Babbitt layers.

## Abstract

Sliding bearing alloy layers must combine excellent tribological performance with reliable metallurgical bonding, but conventional fabrication methods often suffer from coarse grains, chemical segregation and poor interface adhesion. Annular coaxial laser wire-feed cladding, by providing more uniform heat input and rapid solidification, is expected to mitigate these deficiencies; however, systematic studies of this technique applied to tin-based Babbitt alloy layers remain limited. In this work, Babbitt layers produced by conventional casting and by annular coaxial laser wire-feed cladding were compared in terms of microstructure, phase constitution, hardness and tribological behavior. The results indicate that laser cladding can produce continuous, dense and well-bonded coatings and markedly refine the SnSb phase, reducing grain size from approximately 100 μm in the cast material to 10-20 μm. Hardness increased from 25.3 HB to 27.6 HB, while tribological performance improved substantially: the coefficient of friction decreased by about 38.19% and the wear volume was reduced by approximately 10.46%. These improvements are attributed mainly to the rapid solidification, low dilution and more uniform phase distribution associated with annular coaxial laser cladding, demonstrating the strong potential of this process for fabricating high-performance tin-based Babbitt bearing layers.