The isostatic pressing graphite technology is a kind of super high pressure hydraulic equipment,and its working principle is that products formed under the condition of equal pressure and high pressure in all directions and closed high-pressure container . The working principle of the isostatic pressure is Pascal's Law: "the pressure of the medium (liquid or gas) in the closed vessel can be transferred to all directions equally." Isostatic pressing technology has had 70 years of history, was used in the powder molding of powder metallurgy initially . In the past 20 years, the isostatic pressure technology has been widely used in many fields such as ceramic casting, atomic energy, tool manufacturing, plastics, super high-pressure sterilization of food and graphite, ceramics, permanent magnet, high voltage electricity magnetic insulator, preparation of biological medicine, food preservation, high performance material, military and other fields.
The isostatic pressing technology is divided into three kinds of different types such as cold isostatic pressing, temperature isostatic pressing and hot isostatic pressing according to the temperature of the forming and solidification .
The cold Isostatic Pressing, CIP for short,it is at room temperature, rubber or plastic are used for package sets of mould material, and a liquid is used for pressure medium,the technology is mainly used in powder material compaction, it provide green body for further sintering, forging or hot isostatic pressing process usually. General application pressure is 100~ 630MPa.
The temperature isostatic pressure technology, the pressing temperature is generally in the 80 ~ 120 ℃ ,some are also in 250~450 ℃, it transfer the pressure by special liquid or gas , the application pressure is 300MPa. It’s mainly used in graphite,polyamide rubber and other powder materials which can not be molded in room temperature so that we can obtain a solid body at an elevated temperature.
The hot isostatic pressing，HIP for short, it is a technology which make material to go through isostatic pressing under the high temperature and high pressure at the same time, It is not only used for powder consolidation and two step work of traditional powder metallurgy forming and sintering are completed together,but also for diffusion bonding of the workpiece, the elimination of casting defects, and complex shape parts production. In hot isostatic pressure, it generally use argon, ammonia and other inert gas as the pressure transfer medium, the package of materials are usually used in metal or glass. Operating temperature is generally 1000~2200℃, the working pressure is often 100~200MPa.
