Impregnation of Tungsten-Carbide Substrates with Low-Carbon Steel

Abstract

The interaction of tungsten carbide and low-carbon steel in contact and contact-free is investigated in systems with contact and contact-free heating. Substrates of pressed tungsten-carbide powder sintered in a vacuum furnace are impregnated with low-carbon steel of specific chemical composition. A high-speed video recording of the process permits measurement of the contact wetting angle at any time during the experiment. The experiment is conducted at the Center for High-Temperature Studies, Foundry Research Institute, Krakow, Poland. The microstructure of the substrates obtained is investigated. The chemical composition of the reaction products is studied by means of a Jeol JSM-6460 LV scanning electron microscope. All the samples are successfully impregnated. The same structure is observed throughout the substrate cross section. It consists of three phases: tungsten-carbide grains; and iron–tungsten–carbon compounds with different iron content (86.72 and 22.86–23.68%). At the edges adjacent to the upper face, large quantities of the iron–tungsten–carbon compound with 22.86–23.68% Fe may be observed. This is explained in that such regions are impregnated last, and the iron dissolves the carbide more than in other regions. At points of direct substrate–iron interaction, grains of tungsten carbide are clearly identified; they are bound together by iron-based melt (with different iron content in different phases). Partial coverage of the sample surface by an iron film is seen on both samples at the horizontal face of the substrate adjacent to the impregnation region. The edges of the substrate’s horizontal face are completely covered with iron film, under which lie tungsten-carbide grains. Despite the use of different methods to study the interaction of tungsten carbide with low-carbon steel (contact and contact-free heating), no great difference in sample structure is observed.