Hardening phase is the periodic table of transition metal carbides, such as tungsten carbide, titanium carbide, tantalum carbide, their high hardness, melting point 2000 ℃ or more, some even more than 4000 ℃.In addition, the nitride, boride and silicide of transition metals have similar properties and can be used as hardening phases in hard alloys.The existence of hardening phase determines the extremely high hardness and wear resistance of the alloy.

The bond metal is usually iron metal, commonly used in cobalt and nickel.

When making hard alloy, the powder particle size is between 1 ~ 2 micron, and the purity is very high.The proportion of raw materials in accordance with the provisions of the ingredients, addition of alcohol or other medium wet in wet ball mill grinding, make them fully mixing, crushing, after drying, sieving join such kind of wax or gel forming agent, after drying, sieving mixture system.Then, put the mixture granulating, pressed, heated to close to bond metal melting point (1300 ~ 1500 ℃), the hardening phase bonding metal form a eutectic alloy.After cooling, the hardened phase is distributed in a grid of bonded metals, which are closely linked together to form a solid whole.The hardness of hard alloy depends on the content of hardening phase and grain size, that is, the higher the hardening phase content, the finer grain size, and the greater the hardness.The toughness of the hard alloy is determined by the bond metal, the higher the bond metal content, the greater the bending strength.

In 1923, Germany le shi into tungsten carbide powder, adding 10% ~ 20% of the cobalt adhesive, invented new tungsten carbide and cobalt alloy, hardness is second only to diamond, it is made of artificial a carbide in the world.When the tool is made of this alloy, the blade will wear out quickly and even crack.In 1929, schwarzkov in the United States added a certain amount of carbon tungsten carbide and titanium carbide compound carbide to the original composition, which improved the performance of cutter cutting steel.This is another achievement in the history of cemented carbide.

Cemented carbide with high hardness, wear resistance, good strength and toughness, heat resistance, corrosion resistance and a series of excellent properties, especially its high hardness and wear resistance, even at 500 ℃ temperature basic remains the same, there are still very high hardness at 1000 ℃.Hard alloy are widely used as a cutting tool material, such as turning, milling, planing tool, drilling, boring cutter, finger joint cutter, etc., used for cutting cast iron, non-ferrous metal, plastic, chemical fiber, graphite, glass, stone and ordinary steel, can also be used for cutting heat resistant steel, stainless steel, high manganese steel, tool steel and other hard processing material.Now the cutting speed of new carbide tool is several hundred times that of carbon steel.

Hard alloy can also be used to make drilling tools, mining tools, drilling tools, measuring tools, wear parts, metal abrasives, cylinder liner, precision bearings, nozzles and so on.

In the last twenty years, the coating cemented carbide has also appeared.Sweden in 1969 successfully developed the titanium carbide cutting tools, xu is cobalt tungsten titanium carbide tool matrix or cobalt tungsten carbide, titanium carbide coating on the surface of the thickness of just a few microns, but compared with the same brand of alloy cutting tools, 3 times longer service life, cutting speed increased by 25% ~ 50%.In the 1970s, the fourth generation of coating tools could be used to cut materials that were difficult to process.