Pressing, hot isostatic

Ewsuk K G 1986 Finai stage densification of aiumina during hot isostatic pressing PhD Thesis The Pennsyivania State University... 

Ewsuk K G and Messing G L 1986 A theoreticai and experimentai anaiysis of finai-stage densification of aiumina during hot isostatic pressing Hot IsostatIc Pressing Theories and Applications ed R J Schaefer and M Linzer (Materiais Park, OH ASM internationai) pp 23-33... 

P/MForging. Even after conventional repressing of a P/M component, it is stiU difficult to increase density above 95%. However, hiU density in a P/M part improves its properties. Hot isostatic pressing in autoclaves works weU, especiaUy for titanium and superaUoy components, but the capital equipment is expensive and production rates are slow. 

Metal-Matrix Composites. A metal-matrix composite (MMC) is comprised of a metal ahoy, less than 50% by volume that is reinforced by one or more constituents with a significantly higher elastic modulus. Reinforcement materials include carbides, oxides, graphite, borides, intermetahics or even polymeric products. These materials can be used in the form of whiskers, continuous or discontinuous fibers, or particles. Matrices can be made from metal ahoys of Mg, Al, Ti, Cu, Ni or Fe. In addition, intermetahic compounds such as titanium and nickel aluminides, Ti Al and Ni Al, respectively, are also used as a matrix material (58,59). P/M MMC can be formed by a variety of full-density hot consolidation processes, including hot pressing, hot isostatic pressing, extmsion, or forging. 

H. T. Larker, in T. Garvare, ed.. Hot Isostatic Pressing Theories and Applications, Centek Pubbshers, Lulea, Sweden, 1988. 

Fig. 19.4. Hot-isostatic pressing ("HIPing") the powder, in a thin steel preform, is heated and compressed by high-pressure argon.

Normal reheat treatment can partially restore blade properties however, it does not appear to be capable of full property recovery, although the miscrostructures are comparable to new blades. This shortcoming implies that cavitation may be present and was not removed by conventional reheat treatment. Hot isostatic press (HIP) processing is an alternative that ensures void removal. It has demonstrated its ability to remove even gross internal shrinkage porosity in investment castings. The results of HIP treatment... 

Steel alloyed with 1% A1 is more resistant to oxidation at high temperatures. The macro- and microscopic homogeneity of the distribution of all elements is better for powder metallurgical, hot isostatically pressed steels. Combining these advantages should result in better performance of high-speed steels. 

The steel particles are covered with an AI2O3 layer before hot isostatic pressing [3.58]. 

Significant advances have also been made by forging titanium alloy (T1-6A1-4V) and cobalt chromium alloys cold working multiphase cobalt based alloys and by hot isostatically pressing cobalt chromium alloy powders. The property values claimed by the manufacturers are far in excess of the minimum values specified in the British, American and International Standards... 

Production of submicron powder for hot pressing or hot isostatic pressing of high-precision tooling (see Ch. 19). 

Conventional ceramics initially take shape on a potter s wheel or by slip casting and are fired (sintered) in kilns advanced ceramics are formed and sintered in more complex processes such as hot isostatic pressing. 

Hot isostatic pressing (HIP), 16 169 cemented carbides, 4 657 ceramics processing, 5 662 Hot isostatic pressure impregnation carbonization (HIPIC), 26 767 Hot-melt adhesives, 1 530-532... 

Sinter-hot isostatic pressing (sinter-HIP) cemented carbides, 4 657 Sintering, 11 99, 14 497, 734-735, 26 265 catalysts, 5 270-274 catalyst regeneration after deactivation, 5 310-311 ceramics... 

The EBRD process has been demonstrated applicable to the atomization of a variety of reactive and refractory metals and alloys in addition to Ti alloys. The process is being further developed to utilize highly contaminated raw materials and to produce high quality powders for hot isostatic pressing application without additional treatment. 

Siemer, D. D., Roy, D. M., Grutzeck, M. W., Cougar, M. L. D. Sheetz, B. E. 1997. PCT leach tests of hot isostatically pressed (HIPed) zeolitic concretes. Materials Research Society Symposium Proceedings, 465, 303-310. 

When the powder is isostatically compacted at elevated temperatnres, the process is called hot isostatic pressing (HIP). In this case, the flexible dies are often made of thin metals, and high-pressnre gases snch as argon are nsed to heat the part rapidly and rednce thermal losses. Pressnre np to 100 MPa and temperatnres in excess of 2000°C are possible nsing HIP, and parts up to 600 kg can be fabricated. A schematic diagram of a typical HIP apparatus is shown in Figure 7.18. Metals that are processed commercially by HIP include various specialty steels, superalloys, hard metals, refractory alloys, and beryllium. We will see in Section 7.2 that HIP is also particularly useful for the densification of ceramic components. 

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