Extra coarse grain WC-Co hard alloy and preparation process thereof

Abstract

The invention relates to an extra coarse grain WC-Co hard alloy. The hard alloy comprises 5 to 15 weight percent of Co and the balance of WC, wherein the average grain size of the WC is 6 to 10mu m. A preparation process for the hard alloy comprises the following steps of: pre-ball-milling coarse and fine tungsten carbide to prepare mixed tungsten carbide powder, preparing mixed tungsten carbide powder-cobalt-former mixed powder, pressing, and sintering, wherein the sintering step is divided into a former removing part and a high-temperature sintering part. The average grain size of a metallographic structure of the WC-Co hard alloy prepared by the process is 6mu m or more than 6mu m, the process method is simple and convenient to operate, the prepared hard alloy has a large average grainsize, a narrow grain distribution range, a low thermal expansion coefficient and high heat conductivity, high-temperature wear resistance, transverse rupture strength and rupture toughness, and is suitable for a mining tool and an excavating tool, and the thermal fatigue crack resistance of the alloy is effectively improved.

Description

technical field [0001] The invention relates to a production method of cemented carbide, in particular to an ultra-coarse-grained WC-Co cemented carbide and a preparation process thereof. technical background [0002] During the use of mining tools and excavating tools, cemented carbide parts are subjected to cyclic loads and frictional forces, resulting in instantaneous high temperatures, which cause the alloy to withstand thermal fatigue stress and mechanical stress, resulting in microscopic spalling and microscopic fracture of the alloy surface, as well as high-temperature wear. grain wear. At the instant of 1 / 10 second when the alloy teeth interact with rock and cement, when the pressure increases from 0 to 10 tons, the surface temperature of the alloy teeth can increase from room temperature to 800°C to 1000°C, and thermal fatigue cracks (snake skin) are prone to occur during the use of the alloy. crack). [0003] In recent years, due to the continuous development of ...

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Problems solved by technology

[0004] Although my country's total output of cemented carbide ranks first in the world, accounting for more than 40% of the world's total output, the market share of high-performance cemented carbide for shearer and shield machine cutter heads is still less than 2%. The quality of cemented carbide products for coal mining and shield machine cutter heads is still more or less problematic, and it is difficult to be generally recognized by the industry. There is no cemented carbide company that can stably produce and supply coal shearers and shield machines. High performance cemented carbide for cutter heads

[0015] Although the above two U.S. patents can prepare ultra-coarse WC powder with uniform crystal grains, triethylamine is highly toxic and is not suitable for safe production. Water spray has just started in China and requires high-purity deionized water. suitable for recycling

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