Powder metallurgical methods

Powder metallurgical methods These include reaction of the elements and car-bothermal reduction methods. Fine powders of the metal (Hf, V, Nb, Mo, W, etc.) and carbon (graphite, lampblack) may be mixed, possibly in wet conditions with an organic solvent to be removed later, then pressed and compacted into pellets or bricks to be heated at high temperature (1800-2000°C). To perform the carbother-mal reduction, mixtures of carbon with an oxide (of Ti, V, Cr, etc.) are compacted and heated. An additional heat treatment in a high vacuum may be useful to remove O, N, etc. below a low level. 

Complex carbides containing boron, occurring frequently in boron-alloyed steels and superalloys, are also named carboborides. Metal borocarbides (see Table 1) are synthesized by powder metallurgical methods or are extracted from a metal matrix. There are pseudoternary or -quaternary borocarbides, such as Mn23(B, C) or (Cr, Mn, Fe)23 (B, C)g (t phases) although boron-carbon substitution in borocarbides is less pronounced than nitrogen-carbon substitution in metal carbonitrides. 

As FGM interlayer, eleven kinds of sintered compacts in which the mixing ratio of beryllium powder and oxygen free copper powder was different, were manufactured by powder metallurgical method, that is, HP and HIP. In this study, to estimate thermal stress at joining interface, thermal conductivity and thermal expansion coefficient of Be/Cu sintered compacts were measured by laser flash method and laser interferometry method, respectively. The characterization on these compacts was performed by using SEM (Scanning Electron Microscope) to investigate distribution of intermetallic phases on these compacts. 

Ce-TZP can be sintered easily and compounded simply without performing gas-pressured sintering. It is understood that the material is suitable for compounding by powder-metallurgical methods. In this study, Ce-TZP and AI2O3 were compounded using the ratios of both materials obtained in previously reported studies ... 

Ahm] Ahmed, M., Thuemmler, F., Zapf, G., Metallographic Investigations ofthe Fe-Cr-Cu Alloys Prepared by Powder Metallurgical Methods , Arch. Eisenhuettenwes., 41, 797-803 (1970) (Phase Diagram, Meehan. Prop., Experimental, 25)... 

The metals chapter has been re-organized for clarity, and continues to treat the full spectrum of powder metallurgical methods, complex phase behaviors of the... 

The fabrication of interconnect plates of Cr 5Fe IY2O3 is done by powder metallurgical methods and starts with the alloying of Cr flakes with Fe and Y2O3 by... 

Beryl ores are processes in one of two ways. They may be finely ground, sintered with sodium fluorosilicate, and the resulting beryllium fluoride leached with water or the lump ore can be fused, quenched, annealed, and the beryllium sulfate leached with sulfuric acid. In either case, the resulting solutions are purified, and beryllium hydroxide is precipitated. This may be converted to other beryllium compounds, or reduced to the metal. Beryllium metal is then generally broken into small particles that are pressed into masses with various desired shapes through powder-metallurgical methods. Alloys, beryllium metals, and BeO account for all but a small amount of beryllium used [15]. 

The Direct Current Potential Drop Method for Testing of Powder Metallurgical Parts. 

The Direct Current Potential Drop method (DCPD) has been evaluated for non destructive testing of uniaxially produced Powder Metallurgical (P/M) parts. The aim is to adapt DCPD to be functional as an ndt tool during production of parts. Defects can occur at different stages in the production cycle which means that DCPD has to be performed on components in different states and searching for different defects. 

Metal fibers can be produced by metal-cutting processes, by foil cutting processes, powder metallurgically by the sintering of metal powders which can be extruded with the help of organic binders to fibers, by metallization of non-metalic fibers and also by the controlled chemical dissolution of wires to the required fiber thickness. Thin metal wires and thick metal fibers can in principle be produced by the same methods. 

This chapter will follow the different stages of powder metallurgical manufacture. More emphasis will be put on the description of WC powder production methods and qualities, and the preparation of graded powders. Less emphasis will be put on sintering, hardmetal qualities, and applications. In this context, we refer to several excellent books and review articles dealing particularly with hardmetal technology, properties, and applications [9.1, 9.2, 9.4, 9.7-9.9]. 

Powder metallurgical production methods for high-tech materials are very clean operations and do not generate any waste or emissions. Internal and external scrap recycling is excellently organized worldwide. 

Les] Stationary-drop method tests of wettabiUty, optical microscopy, electron microscopy, EPMA Adhesive characteristics and formation of phase boundaries in Cu rich composite materials manufactured by powder metallurgical process at 1100-1300°C... 

The application of powder metallurgical techniques using mixtures of the elements or the metal hydride and graphite have resulted in relatively pure carbides of various compositions. This is a particularly useful method when defective compounds in Groups 5 and 6 are needed. The powdered metals or hydrides in Group 4 and the actinide series are sufficiently reactive to air that the introduction of oxygen is hard to avoid. 

Gd2lr3Ges was found to crystallize with the U2Co3Si5 type (a= 1.0127, b= 1.178, c = 0.5980, X-ray powder diffraction method) by Venturini et al. (1986b) from a sample prepared by a powder metallurgical reaction at 1173 K. The purity of the starting materials was greater than 99.9mass%. 

In the 1960s the A. O. Smith Company in the United States introduced a new method for the development of powdered metal, called water atomization. In this method, the pure metal is melted and a small stream of the liquid is allowed to flow from the bottom of the container of molten metal. A high-pressure blast of cold water hits the stream of metal, breaking it into small droplets that quickly solidify. Powdered metal particles made in this way are more smooth and dense than the sponge powder particles from oxide scrap. In addition to powdered iron metal, many copper, bronze, carbide, and brass parts are made through powder metallurgical processes. 

---