# Sustainable development of copper matrix hybrid composites using waste stainless steel chips: a physical and tribological investigation

## TL;DR

This study explores using waste stainless steel chips to create copper-based hybrid composites with improved hardness and wear resistance.

## Contribution

A novel approach to repurpose waste stainless steel chips in copper composites, enhancing their mechanical and tribological properties.

## Key findings

- Hybrid composites with waste stainless steel chips showed lower density and higher hardness than pure copper.
- Tribological tests revealed improved wear resistance in composites with higher stainless steel chip content.
- AFM and SEM analyses identified wear mechanisms on the composite surfaces.

## Abstract

Stainless steel is widely used in manufacturing industries, and its machining generates large quantities of metallic chips that are typically discarded as waste. In view of this, the present study aims to fabricate copper-based hybrid composites using waste stainless steel chips (WSSCs) via the stir-casting process. Four hybrid composites were produced by reinforcing the copper matrix with WSSCs, tungsten carbide (WC), and chromium (Cr). These composites were labelled HC-WSSC1, HC-WSSC2, HC-WSSC3, and HC-WSSC4, corresponding to 1, 2, 3, and 4 wt% WSSCs, respectively, while maintaining constant proportions of WC and Cr. Microstructural analysis confirmed a fair distribution of the reinforcement phases within the copper matrix. The measured density of the fabricated hybrid composites was lower than that of pure copper and decreased with increasing WSSC content. In contrast, Brinell hardness values increased progressively with higher WSSC reinforcement. Tribological performance, including friction and wear behaviour, was systematically evaluated under dry sliding conditions using a pin-on-disk tribometer. The results demonstrated that the hybrid composites possess superior wear resistance compared to the copper matrix, with further improvement observed at higher WSSC contents. Additionally, the worn surfaces were investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM) to reveal the dominant mechanisms of wear.