Fabrication and performances of WC‐Co cemented carbide with a low cobalt content

Abstract

WC-Co cemented carbides with a low cobalt content (≤3 wt.%) were successfully manufactured by the powder metallurgy method. The cobalt content is lower than conventional cemented carbide (3-30 wt.%), which makes the prepared alloys possess excellent hardness. The effects of cobalt content on the densification behavior, phase composition, micromorphology, and mechanical performances of cemented carbides were investigated in detail. The results revealed that all the sintered alloys were almost completely consolidated with a relative density of greater than 98.0%. Moreover, abnormal grain growth was observed, and the inhomogeneity of WC grains decreased with the increment in cobalt content. In order to obtain cemented carbides with homogeneous microstructure and outstanding performances, VC was added to inhibit grain growth. Microstructure and performances were significantly affected by the addition of VC. The maximum Vickers hardness of cemented carbides without the addition of vanadium was 2234 HV30, while the fracture toughness was 7.96 MPa⋅m 1/2 after sintering WC-2 wt.%Co. After adding VC, the ultimate hardness and fracture toughness of WC-3 wt.%Co-0.5 wt.%VC alloy could reach 2200 HV30 and 8.61 MPa⋅m 1/2 , respectively. In addition, the obvious crack deflexion and transgranular behavior can be noticed, which can prevent the extension of crack and achieve an increase in fracture toughness of cemented carbides.

Effect of carbon nanotubes additives on mechanical properties of WC–6Co cemented carbide

“…Traditional additives include oxides, 1-3 nitride, 4 borides, and carbides, such as Mo 2 C, TaC, NbC, VC, Cr 3 C 2 , TiC, and SiC. [5][6][7][8][9][10][11][12][13] These additives can inhibit the growth of the WC grains. As a result, the hardness is generally improved but the fracture toughness often decreases.…”

“…In recent years, many scientists have revealed the effect of additives on the properties of WC–Co cemented carbide. Traditional additives include oxides, 1–3 nitride, 4 borides, and carbides, such as Mo 2 C, TaC, NbC, VC, Cr 3 C 2 , TiC, and SiC 5–13 . These additives can inhibit the growth of the WC grains.…”

Application of U-FAST Technology in Sintering of Submicron WC-Co Carbides

“…Co = 1494 °C) is much lower than that of the tungsten carbide (T melt. WC = 2785 °C), which makes it possible to obtain sintered materials at low temperatures, as well as limiting the growth of WC grains [ 5 , 6 , 7 ]. Apart from the WC grain size, the cobalt content plays an important role, influencing the hardness and durability of carbide blades, at the same time.…”

Effects of Nb/TiC/TaC/VC and Co addition on the microstructure and properties of WC‐based cemented carbides

“…The characteristics, content, and distribution of the additive are the main factors that affect the microstructure and properties of WC‐based cemented carbides. The Co addition can significantly improve the toughness of WC‐based cemented carbides but extremely weaken its hardness, which limits its application under high temperature, high load, and in an easily oxidized and corroded environment 4–6 . Nanocrystalline WC–12Co fabricated by microwave sintering shows a high fracture toughness of 12 MPa·m 1/2 in combination with a low hardness of 14.66 GPa 5 …”

“…The Co addition can significantly improve the toughness of WC-based cemented carbides but extremely weaken its hardness, which limits its application under high temperature, high load, and in an easily oxidized and corroded environment. [4][5][6] Nanocrystalline WC-12Co fabricated by microwave sintering shows a high fracture toughness of 12 MPa⋅m 1/2 in combination with a low hardness of 14.66 GPa. 5 To overcome the trade-off between hardness and toughness, the development of cemented carbides with low Co content and Co-free materials has gradually attracted the attention of researchers.…”