Sintering - Volume Diffusion

vacancy and atomic interstitial diffusion image
Sintering process of tungsten carbide is accompanied by material migration, of which the transfer of material by atom diffusion also plays an important role. Material diffusion is caused by the difference in the degree of the degree caused by the concentration gradient of the vacancy.

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Why Spherical Tungsten Powder is The First Choice for Thermal Spraying Materials

thermal spraying image

Tungsten is an important thermal spraying material. Thermal spraying technology uses heat source to heat the spray material to melt or semi dissolve state, and spray at certain speed to deposit the coating on the pretreated substrate surface. The thermal spraying technology makes a special working surface on the surface of the ordinary material. 

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Determination of Tungsten Carbide with Inductively Coupled Plasma

inductively coupled plasma image

Hard alloy with high hardness hard tungsten carbide micron metal powder as the main ingredient, with cobalt (Co), nickel (Ni), molybdenum (Mo) as the binder, powder metallurgy products in vacuum furnace or hydrogen reduction furnace in sintering, different tungsten content plays a key role in the performance of the alloy. The detection requirements must be accurate and reliable, the test for the tungsten content of hard alloy mainly has the gravimetric method, colorimetry and atomic absorption spectrometry.

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Determination of impurities in Tungstate by Atomic Fluorescence Spectrometry

determination of atomic fluorescence spectrometer image

Tungstic acid is acidic substances a yellow powder, tungsten trioxide containing about 90%, also contains trace tin, molybdenum, silicon, calcium, iron, manganese, potassium, sodium, chlorine, phosphorus, sulfur, arsenic, antimony, magnesium and other elements, is the raw material for the production of ammonium paratungstate.

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How to Effectively Remove Sodium and Chlorine from Ammonium Paratungstate

ion exchange method method

With the development of the subsequent product process of tungsten, tungsten wire, tungsten powder, tungsten bars and other high-end hard alloy material of ammonium paratungstate rising, ammonium paratungstate zero grade existing national standard has been unable to meet the requirements of high-end hard alloy, not only the impurity and physical of ammonium paratungstate can put forward certain requirements, and part of the production of high-end products enterprises to individual impurity elements proposed particularly stringent requirements.

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Preparation of Tungsten Coating Strengthened Molybdenum Crucible

tungsten molybdenum crucible image

In the industry, the melting of rare earth, vacuum evaporation and sapphire growth in the field of crucibles, mostly made of tungsten and molybdenum materials. This is due to the fact that tungsten has the characteristics of high melting point and high density. Currently, tungsten, molybdenum and molybdenum alloy crucibles are mostly obtained by powder metallurgy and press working.

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Optimization of Ammonium Tungstate Solution by Ion Exchange Method

optimization of ammonium tungstate solution by ion exchange method image

Ion exchange method is currently China's tungsten smelting main purification process. At present, strong alkali anion resin 201 x 7 and weak alkaline anion resin are mainly used in the ion exchange process of removing impurity and transforming the tungsten solution.

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Extract Alkali from Crude Sodium Tungstate Solution

extract alkali from crude sodium tungstate solution image

Scheelite is hard mining and smelting tungsten smelting raw material in the last century, when alkali pressure leaching and scouring process of popularity, production capacity and size of scheelite smelting technology has been greatly enhance, and also further mature. Due to the excessive alkali process, although the leaching process consumes a large part of the base, but after the reaction, residual alkali from crude sodium tungstate solution is very high.

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Sintering Mechanisms of Tungsten Carbide

tungsten carbide image
The sintering of tungsten carbide is a complex process, where exists two or more than two mechanisms at the same time. Under certain conditions, a mechanism dominates and restricts the speed of the whole sintering process. Its kinetic equation can be used as an approximate description of the actual sintering process. But this approximation is still very rough, which requires a systematic and comprehensive theoretical description of the sintering process.

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Wettability of Sintered Liquid Phase

wetting condition image
Tungsten carbide is a typical multicomponent liquid phase sintering. It is sintered at a temperature below the melting point of the main component of the alloy (WC), of which the low melting point component (Co) melts and forms a low melting eutectic phase with WC. 

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