Laser cladding in-situ carbide particle reinforced Fe-based composite coatings with rare earth oxide addition
来源期刊：JOURNAL OF RARE EARTHS2009年第6期
论文作者：WU Chaofeng ZHANG Weiming LIU Wenjin ZHANG hongjun ZHONG Minlin MA Mingxing
Key words：laser cladding; particle reinforced; rare earth oxide; nucleation; rare earth carbide;
Abstract: Particulate reinforced metal matrix composite (PR-MMC) has excellent properties such as good wear resistance, corrosion resis-tance and high temperature properties. Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles. Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements, was fa-vorable for the formation of in-situ synthesized carbide particles. In this paper, rare earth oxide (RE_2O_3) was added into the clad powder mix-ture to investigate the effects of RE_2O_3 on the in-situ carbide particle formation in Fe-based composite coatings. Through the analysis using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS) and transmission electron microscope (TEM), it was revealed that: (1) Adding RE_2O_3 to the Fe-based powder mixture could effectively reduce cracks and porosities and the coating surface was more smooth; (2) The solubility of carbon could be improved which increased the eutectic degree of the microstructure; (3) RE_2O_3 could promote the nucleation of the reinforcement particles as heterogeneous nuclei. During the precipitating process of the carbide particles, some RE_2O_3 powders still existed while others react with carbon in the melt to form rare earth carbides. Both of them acted as heterogeneous nuclei for the formation of particles.
WU Chaofeng1，ZHANG Weiming1，LIU Wenjin1，ZHANG hongjun1，ZHONG Minlin1，MA Mingxing1
(1.Key Laboratory for Advanced Materials Processing Technology Ministry of Education Department of Mechanical Engineering,Tsinghua University,Beijing 100084,China)
Abstract:Particulate reinforced metal matrix composite (PR-MMC) has excellent properties such as good wear resistance, corrosion resis-tance and high temperature properties. Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles. Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements, was fa-vorable for the formation of in-situ synthesized carbide particles. In this paper, rare earth oxide (RE_2O_3) was added into the clad powder mix-ture to investigate the effects of RE_2O_3 on the in-situ carbide particle formation in Fe-based composite coatings. Through the analysis using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS) and transmission electron microscope (TEM), it was revealed that: (1) Adding RE_2O_3 to the Fe-based powder mixture could effectively reduce cracks and porosities and the coating surface was more smooth; (2) The solubility of carbon could be improved which increased the eutectic degree of the microstructure; (3) RE_2O_3 could promote the nucleation of the reinforcement particles as heterogeneous nuclei. During the precipitating process of the carbide particles, some RE_2O_3 powders still existed while others react with carbon in the melt to form rare earth carbides. Both of them acted as heterogeneous nuclei for the formation of particles.
Key words:laser cladding; particle reinforced; rare earth oxide; nucleation; rare earth carbide;
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