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Preparation method of tungsten billet for rolled plate

A technology of plate and tungsten powder, which is applied in the field of preparation of tungsten billet for rolling plate, can solve the problems affecting the quality of rolled tungsten plate for anti-ray, too fine grain of tungsten billet, low sintering cost, etc., and achieve moderate grain size , basic grain size, and uniform grain size

Active Publication Date: 2009-02-11
WESTERN METAL MATERIAL
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

The conventional production method uses tungsten powder with a single average particle size to directly charge the powder and press the billet for sintering. After sintering, the structure of the tungsten billet is better, but the density fluctuates in the range of 90% to 95% of the theoretical density, and cracks often occur in subsequent rolling. , which seriously affects the quality of rolled tungsten plates for radiation resistance
On the other hand, due to the simple equipment and low sintering cost, the hydrogen-protected intermediate frequency induction (fixed frequency) sintering method has been widely used in the sintering of tungsten blanks for rolling plates, but due to the low actual sintering temperature, the tungsten blanks crystallize after sintering. If the grain is too fine, there is a certain degree of underburning, which brings difficulties to the subsequent rolling

Method used

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  • Preparation method of tungsten billet for rolled plate
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preparation example Construction

[0013] A method for preparing high-quality tungsten blanks for rolling plates, the process comprising:

[0014] a. Select tungsten powder whose chemical composition meets the requirements of GB / T3458-2006FW-1 and whose particle size is 1.8μm, 2.0μm, and 2.2μm respectively for blending. The weight percentages of the above three particle sizes of tungsten powder in each mixed tungsten powder are as follows: 20%, 60%, and 20%, use a V-type or conical mixer to mix evenly, and the mixing time is 6h to 12h. The mixed powder is all passed through a 120 mesh sieve.

[0015] b. Using the method of isostatic pressing, under the condition of pressure of 230MPa-250MPa, hold the pressure for 1min-2min to press into a green body.

[0016] c. Use hydrogen protection medium frequency (variable frequency) induction sintering method for billet sintering, that is, use 2500Hz frequency for sintering below 2000°C, reduce the frequency to 1000Hz~1500Hz above 2000°C, and keep warm for 6h~8h at 2280...

Embodiment 1

[0018] Put 200Kg of tungsten powder whose chemical composition meets the requirements of GB / T3458-2006FW-1, including 40Kg of tungsten powder with an average particle size of 1.8μm, 120Kg of tungsten powder with an average particle size of 2.0μm, and 40Kg of tungsten powder with an average particle size of 2.2μm, and put them into the V-shaped mixer. The feeder is mixed for 12 hours. After the mixing is completed, all the tungsten powder is passed through a 120-mesh sieve; a rubber sleeve with a thickness of 35mm is selected, and the material is loaded and pressed by oil isostatic pressure with a pressure of 250MPa and a holding time of 2 minutes. The billet is sintered in a frequency-variable hydrogen intermediate frequency induction furnace sintering furnace. The sintering is carried out at a frequency of 2500Hz below 2000°C, and the frequency is reduced to 1000Hz above 2000°C, and the temperature is kept at 2300°C for 6 hours. The chemical composition of the sintered blank m...

Embodiment 2

[0020] Put 100Kg of tungsten powder whose chemical composition meets the requirements of GB / T3458-2006FW-1, including 20Kg of tungsten powder with an average particle size of 1.8μm, 60Kg of tungsten powder with an average particle size of 2.0μm, and 20Kg of tungsten powder with an average particle size of 2.2μm, and put them into the cone mixer The feeder is mixed for 6 hours. After the mixing is completed, all the tungsten powder is passed through a 120-mesh sieve; a rubber sleeve with a thickness of 30mm is selected, and the material is loaded and pressed by oil isostatic pressure with a pressure of 230MPa and a holding time of 1 minute. Blank sintering is carried out in a frequency-variable hydrogen intermediate frequency induction furnace sintering furnace, sintering at a frequency of 2500Hz below 2000°C, and reducing the frequency to 1500Hz above 2000°C, and holding at 2280°C for 8 hours. The chemical composition of the sintered blank meets the requirements of GB / T3875-200...

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Abstract

The invention discloses a method for preparing tungsten bar used for rolled plates, which relates to a method for preparing indissolvable metal by means of a powder metallurgy process, and is characterized in that tungsten powder with chemical composition in accordance with requirements of GB / T3458-2006 FW-1 and with the granularity of respectively 1.8 Mum, 2.0 Mum and 2.2 Mum is adopted to be doped; in each part of the mixed tungsten powder, the weight percentage of the tungsten powder with the three different granularities is 20 percent, 60 percent and 20 percent in sequence. Excellent grain filling is realized; extremely high sintering density can be obtained; simultaneously, the uniformity of crystal grain structure is guaranteed. A method of medium frequency induction sintering with variable frequency hydrogen is adopted to sinter the blank, namely, the sintering is carried out under 2000 DEG C with the frequency of 2500Hz; frequency is lowered to 1000Hz-1500Hz when temperature is higher than 2000 DEC C; eddy skin depth can be improved by 4-5 times; actual sintering temperature is higher than the medium frequency induction sintering with the hydrogen with relatively fixed frequency; the size of sintered blank grain is moderate and is suitable for following rolling.

Description

technical field [0001] The invention discloses a method for preparing a tungsten billet for rolling plates, and relates to a method for preparing a refractory metal billet by adopting a powder metallurgy process. Background technique [0002] Rolled tungsten plate has good radiation resistance and is widely used in medical CT and semiconductor ion implantation. There are strict requirements for this type of tungsten plate in terms of purity, dimensional accuracy, surface quality, and organizational properties. Therefore, high requirements are put forward for the tungsten blanks used for this type of rolled tungsten plates, especially in terms of density and structure. The usual process for preparing tungsten blanks by powder metallurgy is: tungsten powder → pressing green blanks → sintering. The particle size of tungsten powder has a great influence on the density and structure of the sintered tungsten billet. The conventional production method uses tungsten powder with a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F3/16
Inventor 邓自南郭让民淡新国雷铁柱黄先明李斌杨明杰
Owner WESTERN METAL MATERIAL
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