Revisão bibliográfica sobre metais duros: processamento, propriedades e aplicações

Abstract

The hard metal is a material obtained from carbides of refractory metals such as tungsten, molybdenum, titanium, niobium and chromium. It is a metallic matrix composite composed of a hard phase, the carbides, and a ductile phase, the binder metal, which can be cobalt, nickel or iron, which acts as a binder of the hard phase, giving the material the appropriate toughness. The unique combination of carbide and binder produces a material of high hardness and good fracture toughness, with many applications in engineering, such as: tools for machining, industrial cutting, molds, forming dies, mining, civil and oil industry, wear-resistant components, among others. Tungsten carbide (WC) is the most widely used, with 70% of the cutting tools being WC-binder carbides. Cobalt is the most used binder in the production of conventional hard metals, however, economic factors have motivated the search for new alternatives aiming at the total or partial replacement of cobalt by other elements as a binder phase. The processing of these composites is done through powder metallurgy, which is a process used to transform metallic and non-metallic powders into finished parts or components. This technique has unique characteristics such as obtaining the desired chemical composition and, consequently, distribution of varied phases. Powder metallurgy has the following steps: mixing of components, compaction and sintering. The main objective of this work is to carry out a bibliographic survey on the types of hard metals, their elements, main binders, their properties, processing and applications, correlating each of these factors.