Research on Properties of Fe-Based Powder Metallurgy Material Strengthened by Boriding
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RESEARCH ON PROPERTIES OF Fe-BASED POWDER METALLURGY MATERIAL STRENGTHENED BY BORIDING H. M. Fanga,b,1 and F. Xua
UDC 539.4
The pack boriding process of Fe-based powder compact was carried out at 850 to 1050°C for 3 to 10 h. The microstructure and the thickness of the boride layer were observed by VHX-6000 ultra-depth microscopic three-dimensional microscope. The surface hardness of the boride layer was measured by a Rockwell hardness tester, the phase composition of the boride layer was analyzed by X-ray diffractometer and the friction and wear properties of the sample were tested on the MMW-2 friction and wear tester. The worn surfaces of boride layer was observed by scanning electron microscope. The results show that the boride layer was mainly composed of Fe2B single phase, and its thickness was uniform and firmly bonded to the substrate. The thickness and hardness of the layer gradually increased with time and temperature. The binding force between the layer and the substrate would be decreased while the thickness of the layer was too thin or too thick. Boriding at 850, 900, and 950°C resulted with formation of Fe2B phase while FeB and Fe2B phases occurred at 1050°C. The thickness of the layer in a suitable range could improve the wear properties of the material. Keywords: pack boride, Fe-based powder metallurgy material, abrasion loss, friction and wear, surface hardness. Introduction. Fe-based powder metallurgy materials have great application potential. They are rapidly developed and widely used in machinery, aerospace, agricultural machinery, especially in the automotive industry. With the development of modern industry and technology. The problem like improve the hardness the wear resistance of the surface of powder metallurgy materials was urgently needed to be solved in the use of powder metallurgy materials [1]. Surface modification of powder metallurgy materials has gradually become an important field of material science research. At present, the surface modification technologies include surface mechanical strengthening technology, laser surface strengthening technology and surface chemical heat treatment technology, etc. The mainly researches of the latter were to improve the surface hardness and wear resistance of the material by nitriding, carburizing, and carbonitriding and to improve the corrosion resistance and high temperature oxidation resistance by infiltrating silicon, chromizing, aluminizing on the surface of the material [2]. Through analysis and comparison, the solid powder boride is an ideal method that can meet the process and economy, which is included in the chemical heat treatment method on the surface of powder metallurgy materials [3–6]. In this paper, the surface of Fe-based powder metallurgy materials is chemically strengthened by solid powder method. The thickness and surface hardness, phase composition and friction and wear properties of the layer were studied to expand the use of Fe-based powder metallurgy materials. 1. Experiment. 1.1. Materials and Methods of Experiment. T
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