Cemented carbide is a kind of alloy material prepared by powder metallurgy, which is composed of refractory metal carbides (mainly tungsten carbide and vanadium carbide) as hard phase and bonded metal (cobalt, iron and nickel as representative). Cemented carbide has not only good strength, but also excellent toughness. It is one of the most widely used tool materials. As the application of cemented carbide covers many fields such as cutting tools, dies, mining and road construction machinery, it is no exaggeration to say that the emergence and development of cemented carbide is closely related to the prosperity of the global economy.
At the end of the 19th century, Americans invented high-speed steel. As a high hardness material and high wear-resistant material, high-speed steel was rapidly used as cutting tools and die materials, which won tremendous economic benefits for the production of machinery industry in the United States at that time.
However, the hot plasticity of HSS is not good, and it is prone to edge collapse under hot working conditions. People began to try to find new hard materials to replace HSS. At that time, researchers have found that carbides formed by transition elements (tungsten, titanium, niobium, etc.) in the fourth, fifth and sixth groups of the periodic table of elements have some common characteristics, including high hardness, high melting point and good chemical stability. Early work focused on the study of tungsten carbide. Among them, the Germans used tungsten trioxide and sugar to heat to high temperature together in the electric furnace to produce WC, and tried to use it to make drawing die. However, because of the brittleness of WC, the drawing die is easy to crack.
This is mainly because hard materials are generally brittle materials, brittle materials toughness is not good. Bricks, stones and ceramics are the representatives of brittle materials in life. A little deformation will lead to cracks or even brittle fracture. In order to solve the brittleness problem of hard materials, people began to try to achieve the combination of rigidity and flexibility by adding materials.
In 1923, Schlertel of Germany added 10%-20% cobalt to tungsten carbide powder as binder, and invented a new alloy of tungsten carbide and cobalt, which is the first cemented carbide manufactured in the world.
At present, the method of making WC-Co cemented carbide tools by powder metallurgy in Germany is still in use. Its principle and operation are very simple, including the following three steps:
1. W powder was obtained by hydrogen reduction of WO3 in the temperature range of 700-900 C.
2. WC powders were obtained by carbonization of W and C powders in the temperature range of 1400-1600 C.
3. WC-Co composite powder was prepared by mixing WC powder with CO powder.
Today's research has proved that cobalt powder is the best binder for cemented carbide. On the one hand, cobalt powder can completely infiltrate tungsten carbide and hold tungsten carbide well, thus improving the strength of cemented carbide; on the other hand, cobalt powder with uniform particle size distribution and spherical shape can achieve high uniformity in mechanical mixing and plastic flow, thus improving the toughness of cemented carbide.
Langsun Carbide has all kinds of shapes and sizes of cemented carbide products including carbide rods, carbide plates, carbide rings, carbide bushings, carbide nozzles, carbide balls, valves and nonstandard carbide parts. We feel very pride that our tungsten carbide products are widely used in the following fields, Mechanical seals, oil and natural gas industry, New Energy, Military industry, Aerospace, Auto parts industry, Steel smelting, Coal mining, Chemical industry. More detail: www.ls-carbide.com