The Effect of Vacuum Carburizing on the Mechanical and Wear Properties of Fe-C-Cu Composite Materials Produced via Powder Metallurgy

Abstract

This study investigated the effects of the direct vacuum carburizing process on sinterability, mechanical, and wear properties applied to the composites produced via the powder metallurgy (PM) method and containing of Fe-C-Cu. Direct sintering (DS), sintering + vacuum carburizing (S + VC), and direct vacuum carburizing (DVC) heat treatment processes were applied to the samples, respectively, and these processes were compared in terms of the results of the hardness measurements, three-point bending tests, and wear tests applied after the treatments. The material characterization results were interpreted via field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) analyses. It was found that the samples' hardness and bending strength increased with the graphite and copper ratio in the composite material, and copper also increased the ductility. Wear split and micro-cracks were observed on worn surfaces with increase in hardness. After the sintering process, necks had formed between the powder grains in the DVC-treated samples and through the DVC process, greater carbon diffusion depth was achieved in the samples. The highest hardness increase was observed in the surface areas of the samples subjected to the DVC heat treatment, whereas the lowest increase was seen in the central zones of the DVC samples. The highest bending strength values were determined in the S + VC samples and the lowest in the DVC samples. The wear test results revealed that the highest volume loss and friction coefficient had occurred in the DS samples, whereas the S + VC and DVC treatments had significantly increased the wear resistance.