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isostatic compaction
Isostatic pressure molding is the main way of producing alumina ceramic ball.
The thermal isostatic pressure process applies high pressure (50-200MPa) and high temperature (400-2000℃) to the outer surface of the machining part by an inert gas (e. g., argon or nitrogen), and the increased temperature and pressure causes the material to eliminate the gap under the surface through plastic flow and diffusion. The thermal isostatic pressure process can achieve a uniform and fast cooling process through the thin-wall prestressed winding unit, which improves the production efficiency by 70% compared with the natural cooling process.
A cold isostatic pressure process can apply higher pressure on ceramic or metal powder, up to 100-600MPa at room temperature or slightly higher temperature (<93℃) to obtain "raw" components for processing and processing and sintering to final strength. Thermal and cold isostatic pressure technologies allow ceramic manufacturers to improve productivity while controlling material properties.
Introduction to thermal isostatic pressure technology
Thermoisostatic pressure technology emerged in the early 1950s, and it has been favored in many applications ever since then. Thermal isostatic pressure technology is a production process of compact casting, from the consolidation of metal powder (such as metal injection molding, tool steel, high-speed steel), to the ceramic compaction link, to additive manufacturing (3D printing technology) and more application fields, can see the thermal isostatic pressure technology.
Currently, about 50% of thermal isostatic units are used for consolidation and heat treatment of castings. Typical alloys include the Ti-6Al-4V, TiAl, aluminum, stainless steel, nickel super alloy, precious metals (e. g., gold and platinum), and heavy metals and refractories (e. g., molybdenum and tungsten). Due to the increasing interest in ceramic additive manufacturing in the aerospace and automotive fields in recent years, thermal isostatic pressure may rapidly expand to more applications in the future.
First of all, the thermal isostatic pressure components need to be heated in an elevated pressure or vacuum, and the gas is introduced in advance to expand and effectively establish the pressure atmosphere in the thermal static furnace, and this starting procedure depends on the material composition and the thermal isostatic pressure cycle.
The pressure applied using pure argon in thermal isopressure is generally between 100 and 200MPa. But sometimes other gases, such as nitrogen and helium, are also used, while hydrogen and carbon dioxide are rarely used. Sometimes different combinations of gases are also used. Both lower and higher pressures can be used in some special areas, and ultimately, the application fields are used to determine which gases should be used for what purposes. Because helium, argon and nitrogen are relatively expensive, and hydrogen is easily explosive at the wrong concentrations, special attention should be paid when used.
The main advantages of thermal isostatic pressure technology are: increasing the density of products, improving the mechanical performance of products, improving the production efficiency, reducing the waste rate and loss. After thermal isostatic pressure treatment of the casting, the internal pore defects can be repaired, the design is lighter, the product has better ductility and toughness, reduced performance fluctuations, longer service life (relying on the alloy system, parts fatigue life increased nearly 10 times), and can form a metallurgical combination between different materials (diffusion combination).