Isostatic Pressing and Powder Metallurgy
One of the basic processes in powder metallurgy, the purpose of which is to turn loose powder into semi-finished or finished products with a predetermined geometry, size, density, and strength. Die forming is the most widely used forming method in powder metallurgy production. Similar powder metallurgy processes were used in the second half of the 18th century and the first half of the 19th century in Spain, Russia and England to make platinum products. At that time, Russian Sobolevsky (P., C, breakwebs daredaredobech) used steel die and screw press. W.h. Wollaston in Britain used a pull-rod press with greater pressure and a higher purity of platinum powder to produce a compact platinum material with few remaining pores. Later, the die forming method was gradually perfected and used to manufacture various shapes of copper base oil bearing and other products.
Isostatic pressure
The method of densifying the powder body by transferring pressure through liquid or gas is called isostatic pressing, or isostatic pressing (see isostatic pressure processing). Isostatic pressure can be divided into cold isostatic pressure and hot isostatic pressure.
Cold isostatic pressure
Usually, the powder is sealed in a soft envelope, and then placed in the liquid medium in a high-pressure vessel. By applying pressure to the liquid, the powder body is under uniform pressure in all directions, so as to obtain the required billet. The liquid medium may be oil, water, or glycerin. The casing material is elastoplastic material such as rubber. The metal powder can be installed directly or after molding. Because the powder is under uniform pressure in all directions in the envelope, the compact with uniform density can be obtained, so it is not easy to deform and crack during sintering. Its disadvantage is the dimensional precision of the compact is poor, but also mechanical processing. Cold isostatic pressing has been widely used in forming hard alloy refractory metal and other powder materials.
Hot isostatic pressure
This is a new technology from the '50s. The metal powder is packed into a jacket that is easy to deform at high temperature, and then placed in an airtight cylinder block (a high-pressure vessel with a heater on the inner wall). After the cylinder block is shut down, the gas is driven in by a compressor and heated by electricity. As the temperature rises, the gas pressure in the cylinder increases. The powder becomes a product with a certain shape under the action of uniform pressure and temperature in all directions. Argon gas is generally used as the pressurized medium. Commonly used cladding materials for metal (low carbon steel, stainless steel, titanium), but also available glass and ceramic. Due to the simultaneous action of temperature and isostatic pressure, many kinds of hard to form materials can reach or close to the theoretical density, and fine grain, uniform structure, isotropy and excellent performance. Hot isostatic pressing is most suitable for the production of cemented carbide, powder superalloy, powder high speed steel, beryllium and other materials and products. It can also be used for secondary treatment to eliminate pores and microcracks. It can also be used to manufacture multiple layers or composite materials and products which are closely bonded with different materials.
Jiangsu High Industry focuses on the research and production of isostatic pressing moulds, customizes various dry bag and cold isostatic pressing moulds, adapts to different models of various manufacturers at home and abroad, and deeply understands the needs of various industries. Alloy, graphite and other industries provide high-performance isostatic pressing mold rubber sleeves.
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