Hot Isostatic Pressure HIP Sintering

Hot isostatic pressure (HIP) (sintering) Pressing of an object uniformly from all direchons, usually in a hydrostahc media, at a high temperature. Used to form dense structures from powders. 

High-pressure treatments were carried out in two units a hot isostatic press (HIP) and a multiple anvil-type high-pressure generator. The powder sample for HIP treatment were pelletized and sealed in Ag tubes in vacuo, and was then sintered at 0.15 GPa and 823 K for 2 h in N2. High pressures up to 5 GPa were applied to the powder sample in the cubic/ octahedral anvil apparatus according to a technique described elsewhere.34 Briefly, the raw powder sample was packed into a BN capsule and placed at a center of the inner octahedral anvils with pyrophyllite pieces as... 

Densification method Low gas pressure sintering Gas pressure sintering Hot pressing Hot isostatic pressing (HIP) Reaction bonding Reaction bonding and postsintering... 

Hot isostatic pressing (HIP) is often applied to densify sintered materials and to correct casting defects. Recently a new HIP process for the production of porous materials was developed. Partially densified compacts are sintered in a high pressure atmosphere. The pressurized gas in the open pores delays densification and porosity remains largely intact. 

Not unlike the case of superplastic ceramics, ductility and strength relations are influenced by strain rate. The conditions of the experiment must be above the DBT to observe plastic flow, which is different for various ceramics. An illustration of the effect of strain rate and temperature on the strain (ductility) at some stress level can be seen in monolithic Si-C-N. Silicon-nitride-based ceramics are quite promising candidates for mechanical applications at elevated temperatures. Specimens were prepared by hot isostatic pressure (henceforth HIP) of pyrolyzed powder compact at 1500 °C and 950 MPa, without any sintering additives. These compression tests were conducted at temperatures from 1400 to 1700 °C in a nitrogen atmosphere with a servo-hydraulic-type testing machine at constant crosshead speed in an induction heating furnace. In Fig. 2.5, stress-strain curves... 

Pressure Sintering. Densification of refractory carbides and nitrides can be achieved by external pressure with techniques such as uniaxial hot pressing, hot-isostatic pressing (hipping), and gas-pressure sintering. 

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