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Primary applications are the reduction of microshrinkage, the consolidation of powder metals, ceramic composites and metal cladding. Hot isostatic pressing is thus also used as part of a sintering (powder metallurgy) process and for fabrication of metal matrix composites, [3] often being used for postprocessing in additive manufacturing. [4]
After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed. In hot isostatic pressing high temperature and pressure are used to consolidate powders to close to their maximum theoretical densities.
Powder forging: A "preform" made by the conventional "press and sinter" method is heated and then hot forged to full density, resulting in practically as-wrought properties. [citation needed] Hot isostatic pressing (HIP): Here the powder, normally gas atomized and spherical, is filled into a mould, usually a metallic "can". The can is vibrated ...
When isostatically pressed the powder takes the shape of a flexible membrane acting as the mould, forming the shape and size of the pressed powder. Isostatic presses can be either high speed, high output type of automatic presses for such parts as ceramic insulators for spark plugs or sand blast nozzles, or slower operating "wet bag" presses ...
Hot pressing is a high-pressure, low-strain-rate powder metallurgy process for forming of a powder or powder compact at a temperature high enough to induce sintering and creep processes. [1] This is achieved by the simultaneous application of heat and pressure. Hot pressing is mainly used to fabricate hard and brittle materials.
A variant used for 3D shapes is called hot isostatic pressing. To allow efficient stacking of product in the furnace during sintering and to prevent parts sticking together, many manufacturers separate ware using ceramic powder separator sheets. These sheets are available in various materials such as alumina, zirconia and magnesia.
Processes such as ECAE and HPT have also been used to consolidate metal powders and composites without the need for the high temperatures used in conventional consolidation processes such as hot isostatic pressing, allowing desirable characteristics such as nanocrystalline grain sizes or amorphous structures to be retained. [24] [25]
Compaction of ceramic powders is a forming technique for ceramics in which granular ceramic materials are made cohesive through mechanical densification, either by hot or cold pressing. The resulting green part must later be sintered in a kiln. The compaction process permits an efficient production of parts to close tolerances with low drying ...