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Unformatted text preview: Romanian Reports in Physics, Volume 56, No. 3, P. 505 - 516, 2004 NEW RESEARCH DIRECTIONS IN POWDER METALLURGY R.L. ORBAN TECHNICAL UNIVERSITY OF CLUJ-NAPOCA 103-105 MUNCII BLV.,400641 CLUJ-NAPOCA, ROMANIA E-mail: Radu.Orban@stm.utcluj.ro Abstract. An overview on the present research and development directions in Powder Metallurgy (PM) is realized. There are analysed investigations focused on the mechanical properties of sintered structural parts improving, for overcoming the PM limitations concerning the complex shape and large parts realization as well as for the advanced materials obtaining, like nanocrystalline materials, intermetallics and composites, the most recent methods for this purpose being considered. Keywords: Advanced Technologies, Powder Metallurgy, Advanced materials, Powders, Sintered structural parts, Powder Injection Molding, Mechanical Alloying, Reactive Processing. 1. INTRODUCTION Over the last years Powder Metallurgy (PM) has known an impressive development …. This is eloquently highlighted by the upgraded classification of its present applications given in Figure 1. The key factors of this development are its high potential in advanced material producing (some of them impossible to be produced by other technological methods), its known advantages in structural parts production , as well as the less influence of the PM companies’ activity than of the traditional, especially metallurgical, ones on the ecological system . As PM applications cover very diversified domains of the modern industry, their development continuously stimulate the research efforts for PM progress. The most important directions of these intensive researches will be analysed in this paper. 2. SINTERED PART TECHNOLOGY IMPROVING Sintered parts have applications both as structural parts and as parts realized from special materials (see Fig.1). For both, improving the processing technologies to overcome the known PM limitations concerning high mechanical properties, complex shape and large parts realization are well-defined research targets. 506 R. L. Orban 2.1. Researches for mechanical properties improving The largest PM application from the tonnage point of view is to the structural parts, especially for the automotive industry, production . They are commonly made of low- alloyed with C, Cu, Ni, Mo and, recently, also with Cr, Mn, Si steels. There are several research directions for their mechanical properties improving. 2.1.1. Increasing powder compressibility/homogeneity, dust and hazard reduction In the sintered structural parts production, water atomized iron powders are going to replace the sponge ones . Therefore, numerous researches are focussed on the atomization technology improvement for a better particle size distribution and a higher cleanliness obtaining. Beside those concerning the atomisation nozzle geometry and processing parameters of standard units optimisation , high-pressure water atomization (up to 150 MPa) is investigated to increase fine particle fraction, enhancing particle size...
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