Design of alternative binders for hard materials

Abstract

In the last years, a special interest has emerged towards the total or partial substitution of traditional cemented carbides composing elements. In this study, a systematic methodology is presented and used to design iron-based binders for WC and Ti(C,N) ceramic phases. First, metal alloy phase diagrams were simulated by means of Thermo-Calc® software, combining several alloying elements (Ni, Al, Cr, Mo and C) to fulfil the following criteria: provide high corrosion resistance, least number of phases present at room temperature and solidus-liquidus temperatures below 1500 °C. Two final compositions were chosen: Fe15Ni10Cr and Fe15Cr10Al. Next step was to validate the critical temperatures by means of differential thermal analysis tests and, finally, high-temperature wetting experiments were conducted to measure the contact angle between molten metal and ceramic phases. Resultant metal-ceramic region was studied by means of field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and nanoindentation techniques. As a proof of concept, samples with 80 vol% of Ti(C,N) and WC ceramic phases were prepared for a basic characterization. Both ceramic reinforcements were compared, and the presented methodology could satisfactorily be validated as a design procedure of alternative binders for hard materials.