Abstract This study investigates the effect of graphene addition on the mechanical an‎d tribological properties of WC-FeAl-based cermets produced by the spark plasma sintering (SPS) method. Considering the challenge of simultaneously achieving high hardness an‎d desirable fracture toughness in cermets, especially for use in cutting tools, the main objective of this study is to optimize new combinations of cermets with improved mechanical an‎d thermal performance. In this regard, three types of samples, including WC-Co (as a reference sample), WC-FeAl, an‎d WC-FeAl-G (with graphene addition), were prepared an‎d eva‎luated. The hardness of the samples was measured by the Vickers test, an‎d the results showed that the hardness of WC-FeAl-G cermet is 19.55% higher than WC-FeAl, an‎d the hardness of WC-FeAl is 18.06% higher than the reference WC-Co sample. Microstructure examination using scanning electron microscopy (SEM) an‎d X-ray diffraction (XRD) showed that the addition of graphene resulted in a finer grain structure an‎d reduced dissolution of carbide phase in the metal matrix. The four-point bending test showed that the maximum bending failure stress for WC-Co, WC-FeAl an‎d WC-FeAl-G cermets was 392.4, 114.2, an‎d 274.3 MPa, respectively. The wear test also indicated a significant improvement in the wear resistance of the samples containing graphene an‎d FeAl binder, such that the weight loss was measured to be 0.015, 0.002, an‎d 0.001 g for WC-Co, WC-FeAl, an‎d WC-FeAl-G, respectively. The oxidation resistance was eva‎luated by isothermal oxidation test an‎d DSC-TG thermal analysis. The results showed that WC-FeAl cermet has the highest oxidation resistance, which is attributed to the formation of stable complex phases such as Al₂(WO₄)₃ an‎d FeWO₄. The weight gain present in the DSC-TG test was reported to be 15.41% for WC-Co, 12.90% for WC-FeAl-G, an‎d only 6.02% for WC-FeAl, respectively, indicating that the oxidation resistance of the graphene-containing sample is higher than that of WC-Co. Overall, the findings of this study show that although the addition of graphene causes a slight decrease in oxidation resistance compared to WC-FeAl, it still has higher oxidation resistance than WC-Co cermet. In addition, the addition of graphene increases hardness an‎d wear resistance. Also, the recovery of a significant part of the lost flexural strength in the WC-FeAl sample by adding graphene overcomes one of the main challenges of using alternative binders instead of cobalt an‎d provides a positive outlook for the development of cobalt-free cermets.

مرتضي هادي

مهدي رفيعائي , محمد خدائي