Method for forming big-size complicated shape tungsten product
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A technology with complex shape and large size, which is applied in the field of gel injection molding of large-size and complex-shaped tungsten parts in near-net shape. Restricted properties and energy consumption, reduced production costs, and improved forming conditions
Inactive Publication Date: 2011-08-10
UNIV OF SCI & TECH BEIJING
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Abstract
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Problems solved by technology
For tungsten products with large size and complex shape, compression molding is difficult to achieve
Moreover, the density of each part of the compact is uneven, and the shape is difficult to control, which makes the weight and size of the product highly dispersed, and the productivity is low.
Although the injection molding process solves some problems, due to the influence of binder and degreasing, only parts with relatively complex shapes and small thickness (or diameter) (10mm) can be formed.
The development of parts with large thickness or more complex shapes with large size and cross-section changes is limited
For parts with large cross-section changes and large diameters (>70mm) and complex-shaped tungsten alloy parts, it is very difficult to prepare them using the current powder injection molding technology.
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Embodiment 1
[0018] Embodiment 1: the gel injection molding of semi-ring shielding material tungsten product (diameter 95mm, wall thickness 20mm, height 100mm)
[0019] 1. Weigh 8.1kg of 325-mesh tungsten powder, add 236ml of hydroxyethyl methacrylate and 236ml of toluene into the organic solution, mix and stir;
[0020] 2. Weigh 20g of Solsperse-6000 hyperdispersant and add it to the slurry in the first step, and ball mill for 8 hours to mix evenly to make a high-concentration suspension slurry;
[0021] 3. Measure 1.8g of catalyst benzoyl peroxide and 20ml of initiator dimethylaniline into the high-concentration suspension slurry in step 2, stir evenly and degas under vacuum for 3 minutes;
[0022] 4. Inject the vacuum-degassed step 3 slurry into the pre-designed mold, slowly inject it and solidify it under a protective atmosphere at 60°C to obtain a ring-shaped green body;
[0023] 5. Put the green body in step 4 lightly on the pre-designed backing board for shaping, and put it into a ...
Embodiment 2
[0025] Embodiment 2: Gel injection molding of tapered tungsten product parts (maximum diameter is 85mm, height is 210mm) with large cross-section variation
[0026] 1. Weigh 6.8kg of 500-mesh tungsten powder for use.
[0027] 2. Dissolve 295g of monomeric acrylamide and 2.5g of cross-linking agent N,N'-methylenebisacrylamide in 995ml of deionized water, add the tungsten powder in step 1, and stir evenly;
[0028] 3. Measure 5.6ml of dispersant oleic acid and add it to the solution in the second step, stir evenly, and make a slurry with moderate fluidity after ball milling for 6 hours, and degas the slurry for 15 minutes under vacuum;
[0029] 4. Measure 5ml of catalyst N,N,N',N'-tetramethylethylenediamine and 6.5ml of initiator ammonium persulfate (to ensure sufficient injection molding time), add them to the slurry in step 3, and stir evenly.
[0030] 5. Slowly inject the slurry into a conical mold with a complex shape to solidify and form a conical tungsten part blank;
[...
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Abstract
The invention relates to a method for forming a big-size complicated shape tungsten product, belonging to the technical field of powder metallurgy. The invention is characterized by comprising the following steps: adding a monomer and a cross-linking agent with the volume ratio of 1-300:1 into an organic solvent or a deionized water to prepare a premixing solution with the volume ratio of 1-120:1and concentration of 5-50wt%; mixing tungsten powder and the prepared stable gel system premixing solution, adding a dispersing agent which accounts for 0.05-5wt% of the mass of the tungsten powder, adjusting the pH value, and carrying out stirring or ball-milling for 2-10h to obtain suspended size with good mobility; adding a catalyst with the concentration of 0.1-3.5 wt% and an initiator and stirring uniformly, injecting into a big-size complicated shape mould after vacuum degassing, solidifying at the temperature of 40-90 DEG C for 50s-30min, and demoulding; and drying a green body in vacuum or under protective atmosphere, and sintering to obtain the tungsten product. The big-size complicated shape tungsten product can be produced by the method in the invention, thereby avoiding complicated shape and property limitation and big energy consumption caused by super high pressure required in forming process and removing special degreasing technology. The invention has the advantages ofsimple technology and low production cost.
Description
technical field [0001] The invention relates to a forming technology of tungsten products, which belongs to the field of metal parts preparation in the powder metallurgy production process, and in particular provides a gel injection molding technology for nearly net-shaped large-sized and complex-shaped tungsten product parts. technical background [0002] Tungsten has the advantages of high density, good impact toughness, high plasticity and low yield strength, stronger absorption of X-rays and γ-rays than lead, high resistance to corrosion and oxidation, good electrical conductivity, and low thermal expansion coefficient. It is an ideal nuclear fuel storage and radiation shielding material, a contact material in the electronics industry and an armor-piercing projectile material in the weapon industry, so it is widely used in aerospace, energy, military, machinery and metallurgy and other fields. [0003] Tungsten products are usually prepared by traditional powder metallur...
Claims
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Application Information
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