Prepared by swaging nanocomposite W-2% ThO2 electrode material of this test tungsten alloy plant in Taebaek, the specific process is as follows:

(1) Mixing: The After dispersing, mixing a good first composite powder sieved through a 100 mesh sieve manually three times and allowed to stand 30min. In sifted before adding binder, adhesive formulations as follows: ethanol + glycerol (volume ratio of 1: (1.5-2)). The proportion of binder added: Every 1000g sifted powder was added 3mL binder.

(2) Compression: W powder particle size of 0.6μm, very fine-grained, leading to increased friction, resulting in the actual sample pressure is still small. After the suppression of the larger specimens resilience, resulting in greater stress. Also causing uneven density inside the sample, the surface density, the center is less dense, prone to early stratification and micro-cracks, sintering is easy to burst. If the binder added more, since the surface density, gas difficult to discharge, it could easily lead to burst. If the mixed powder is uneven, the compacts are likely to cause an early break. Considering these factors, the pressing process point is: bonding agent added in moderation; powder mixed carefully controlled process to ensure uniform mixing powder; increase the pressure; increased dwell time. Specific process parameters: each billet quality powder 580g (normal 640g), pressure 70T (50T normal production pressure), a pressure of about 60MPa, dwell time 5min.

(3) Pre-Sintering: In the protection of hydrogen, at a temperature of 1150-1200 ℃ sintering 1h, aims to improve the density and strength of the green body in order to facilitate the subsequent sintering electrically heated melt down. Pre-sintered body size is about 400mm x 12mm X 12mm.

(4) Vertical melt sintering: current heating current is 90% of the fusing current, the temperature does not exceed 3000 ℃, time of l0min.

(5) The Swaging: the vertical melt sintered billet at a temperature of 1350-1450 ℃ swaging.

(6) Drawing: caustic deburring and oil after drawing wire.

(7) Straightening Polished.


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Milling Mixing Method

Generally the production of high-density tungsten alloy, mixture preparation materials are used mostly dry powder mixing method, namely mechanical mixing. This method is characterized by simple preparation process. Form a V-shaped or cone blenders. Since W, Ni, Cu metal powders of different densities, in order to achieve uniformity of mixture will generally be Ni, Cu, W powder, mixed 8-12h.

Secondary Pyrolysis Reduction Method

To obtain W-Ni-Cu highly uniform mixing of the components, and to mix with a high sintering activity, it developed a named "secondary pyrolysis Reduction" of new technology. The resulting coating has a certain performance W - Ni-Cu sintered mixture of different ingredients than normal milling mixture reduces 100-130 ℃, and the resulting aggregate is more excellent.

Secondary pyrolysis method is to first reduction of nickel nitrate dissolved in distilled water, then W powder and uniformly mixed solution of nickel nitrate, roasted solution and reduction, and the obtained composite powder of nickel tungsten package. Then the composite powder was mixed with copper chloride, drying, reducing, and finally obtain W, Ni, Cu composite powder.

Mechanical Alloying

Mechanical alloying process is the 1970s after the development of a special alloy materials Preparation mature technology. Mechanical alloying metallic raw material powder in proportion to the drum into a ball mill, adding the ball, in order to prevent dirty, the product of the same composition can also be a W alloy ball. Mechanical alloying time to reach the mixed powders reached after 60h alloying and composition distribution, then press forming and sintering processes. The sintering temperature can be considerably lower.

In addition, since the 1990s, foreign research developed yet another new job - RSU reactive spray deposition method, using this method time is short, quick, the production of tungsten alloy powder and mechanically mixed powder compared to greatly improve reactive sintering the alloy microstructure uniformity and mechanical properties of the alloy.




Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-alloy.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn