Isostatic press

Cold-isostatic-pressing followed by vacuum sintering or HIP is also used to manufacture smaller intricate shapes. In this instance beryllium powder is loaded into shaped rubber bags and pressed isostatically in a pressure chamber up to 410 MPa (60,000 psi). After the pressing operation the rubber bag is stripped from the part which is then vacuum sintered to about 99% of theoretical density at about 1200°C. If full theoretical density is required, the sintered part may be simply given a HIP cycle because there is no open porosity after vacuum sintering. In a similar manner, conventional axial cold-pressing... 

Property Reaction-bonded3 Sintered Hot-pressed isostatically Hot-pressed... 

Due to the friction between the powder and the die wall and the nature of the load distribution inside the die, the pressing density is not the same all over the compact. This is more pronounced for large parts and large part heights and can lead to crack formation and/or distortion of the pressed compact during sintering. Large and critical parts are therefore commonly pressed isostatically. 

Property Reaction-bonded3 Sinteredb Hot-pressed isostatically Hot-pressedd... 

W. Pietsch, Roll pressing, isostatic pressing and extrusion. Section 7.4 in M.E. Fayed and L. Often (eds.) Handbook of Powder Science and Technology , Van Nostrand Reinhold Co., Inc., New York (1984), 269-285. 

Metal powder Press aggl. Punch-and-die or roller presses, isostatic presses, sintering... 

Isostatic pressing involves the application of hydrostatic pressure to a powder in a flexible container. The advantage of applying pressure in all directions is that there is more uniform compaction of the powder and more complex shapes can be produced than with uniaxial pressing. Isostatic pressing can be performed either with or without applied heat. 

Howmet SN-4 Cold formed (die pressing/isostatic pressing) sintered and HIP ed Si3N4 with 10% oxide sintering aids (Al O and Y2O2). 

Tape casting is the only process that requires the binder, and the body as a whole, to remain very flexible even after drying. To some extent, spray drying needs to generate a powder that has a "soft" binder to facilitate pressing (isostatic, dry, ram or extrusion), but the final shape needs to be fairly stiff to withstand handling or machining. 

Zinc oxide and nickel oxide powders were pressed isostatically. Zinc oxide pellets were sintered in air at 900°C for 100 hr, resulting in compacts 85.5% theoretical density. Nickel oxide specimens were sintered in air at 1000°C for 120 hr, yielding compacts of only 78% theoretical density. The spheres of these oxides were obtained by crushing the pellets and then grinding them in a modified Jordan air-grinder ( ). The spheres thus obtained had diameters varying from 0.5 to 0.8 mm. In addition MgO single-crystal spheres of uniform diameter of 1 mm were employed. 

Gas pressure, hydrostatic pressing, hot pressing, isostatic pressing, shock wave synthesis Ultra-vacuum technology... 

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