Steel powder

The adsorption of stearic acid from n-hexane solution on a sample of steel powder is measured with the following results ... 

The United States has the largest metal powder producing and consuming industry of any country. The value of U.S. metal powder shipments, including paste and flake, was 1,243 bHHon in 1992. Approximately 307,000 t of Hon and steel powder and 21,000 t of copper and copper-base powders were shipped in North America in 1994. Estimated annual world metal powder production exceeds 950,000 t. 

P/M Tool Steels. In conventionally produced high alloy tool steels (slowly cooled cast ingots), carbide tends to segregate (48). Segregated clusters of carbide persist even after hot working, and cause undesirable effects on tool fabrication and tool performance. P/M tool steels, on the other hand, provide very fine and uniform carbides in the compact, the final bar stock, and the tools. Several tool steel suppHers consoHdate gas-atomized tool steel powder by HIP to intermediate shapes, which are then hot-worked to final mill shapes. Water-atomized tool steel powder is also available (see also T OOL materials). ... 

The membrane is usually made from one of several materials. Woven polyester or cotton, the most commonly used and least expensive material, is adequate for temperatures up to 150°C. Siatered plastic is used where a low cost, washable surface is desired. This material is temperature limited by the polymer material to about 60°C and the flow of some powders may cause a static charge build-up on the membrane that could be hazardous ia some operatioas. Wovea fiberglass fabric or porous ceramic block is used for temperatures up to about 425°C. Siatered stainless steel powder or bonded stainless mesh is used for corrosion resistance, and for temperatures up to 530 to 650°C. Additional information can be found ia the Hterature (38,39). 

A PM preform could be made using recently developed prealloyed steel powders, and full densification could be achieved by hot precision forging to final configurations after the sintering operation... 

A Military Specification (MIL-F-45961), the first of its kind,for prealloyed steel powder forgings was then drafted and has been accepted as a standard by Department of Defense and commercial organizations. The significance of this work is that the improved PM manufacturing technology is applicable to all weapon systems which require complex-shaped steel forgings... 

A more comprehensive purification procedure uses a sequence of steps as follows filtration at 200°C through a stainless steel powder compact filter of 10-jum pore size reduces the oxygen content and removes any solid impurities. Gettering with Zr foil for 46 h at 760°C reduces the oxygen concentration to 200 ppm. The weight ratio of K to Zr is 13 1 with a surface area to volume ratio of Zr to K 4 1. A second gettering with zirconium foil for 72 h at 800°C reduces the oxygen content 50 ppm. 

IPS Steel Powder AB in Sweden, probably the only operating plant using oil atomization, routinely produces steel powders using oil atomization. The oil pressure used in atomization is low (0.5 MPa) and thus the resultant powder size is coarse (-500 pm). The oxygen content is, however, very low (<0.01 w/o O). High-pressure oil atomization (up to 10 MPa) is currently under evaluation by this company in an attempt to produce finer powders. 

Stainless steel powder with a mean particle diameter of 50 mm has been compacted to a green density of 58% and sintered in pure H2. The resulting shrinkage measurements are given below. Published diffusion data for this stainless steel show that the activation energies are 225 kJ/mol for surface diffusion, 200 kJ/mol for grain boundary diffusion, and 290 kJ/mol for volume diffusion. Use the data below to determine the mechanism. 

Kielemoes J, DeBoever P. Influence of denitrification on the corrosion of iron and stainless steel powder. Environ Sci Technol 2000 34 663. 

Molybdenum High Speed Steel Powder Metallurgical Molybdenum High Speed Steel M2 "ASP23 PM" -M3PM T11302 HS 6-5-2 HS 6-5-3 PM 1.3343... 

Ref J. DiBenedetto, Machine Gun Parts from Steel Powder , NatlDefense LXI, No 340 (Jan-Feb 1977), 264-66... 

The mixed powders with prescribed ratio were tapped into the powder container as illustrated in the right hand side of Figure 1. Hard steel powder in the top side was used to prevent the scattering of FGM powders from the powder container and SUS304 powder in the bottom side was used for momentum trap. 

During our initial screen, we also check the thermal stability of the sample in the presence of stainless steel. Accidents have occurred when processes that were no problem in glass equipment were either scaled-up in, or switched to stainless steel equipment. We perform this check during our isothermal DTA test by running duplicate samples and adding stainless steel powder to one of them. We use the isothermal test because it allows longer contact time between the sample and the stainless steel. 

TABLE 11-5. REACTION OF ORGANIC SULFIDES WITH ACTIVATED STEEL POWDER... 

In practice, the variance in aH°, AS° and i )/( 1 - (()) that can be tolerated is determined by the limits of experimental precision. However, the real adsorption of boundary additives on metal surfaces frequently departs from the simple behavior to which Eqn 15-46 applies. For example. Spikes and Cameron [52] found that the adsorption of n-octadeylamine from cetane onto stainless steel powder was not completely reversible, and they were therefore force to settle for the isosteric heat of adsorption, from the equation... 

Bronze is the most popular metallic filler, although steel powder is occasionally used. Laige quantities (40%-60% by weight) of bronze reduce deformation under load and raise thermal and electrical conductivity of PTFE compounds. These two characteristics are beneficial to applications where a part is subjected to load at extreme temperatures. Transmission and air-conditioner compressor seals are two examples of such parts. Bronze is an alloy of copper... 

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