Al2O3/WC powder was synthesized by means of aluminothermic reduction-carbonization with metallic Al powder, yellow tungsten oxide and carbon black or graphite as raw materials under the protection of coke granules. Th...Al2O3/WC powder was synthesized by means of aluminothermic reduction-carbonization with metallic Al powder, yellow tungsten oxide and carbon black or graphite as raw materials under the protection of coke granules. The effects of Al2O3 content, temperature, C/WO3 molar ratio, and atmosphere on the synthesis of Al2O3/WC powder were studied. The results show that the relative content of WC and W2C is strongly influenced by the factors mentioned-above. Carbon black has higher reactivity than graphite. Al2O3-WC composite is easier to obtain under the protection of coke granules than under argon atmosphere. The CO in the coke layer can easily react with tungsten to form WC and to transfer from W2C to WC.展开更多
A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer...A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer were investigated. The composite layer has graded microstructures and compositions, due to the fast melting followed by rapid solidification and cooling during laser cladding. The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified. The size of TiC dendrites decreases with increasing depth. Y2O3 fine particles distribute in the whole clad layer. The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380, which is 4 times higher than the initial hardness. The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.展开更多
采用电极感应气雾化法(electrode induced gas atomization,EIGA)制备Y2O3增强Ti-6Al-4V(TC4合金)复合粉末。测定粉末的流动性和松装密度,并通过光学显微镜和扫描电镜观察Y2O3的形态与分布,利用X射线衍射仪和等离子体发射光谱仪分析Y2O3...采用电极感应气雾化法(electrode induced gas atomization,EIGA)制备Y2O3增强Ti-6Al-4V(TC4合金)复合粉末。测定粉末的流动性和松装密度,并通过光学显微镜和扫描电镜观察Y2O3的形态与分布,利用X射线衍射仪和等离子体发射光谱仪分析Y2O3/TC4复合粉末的物相及元素组成。结果表明,采用EIGA法制备的Y2O3/TC4复合粉末球形度良好,存在少量非球形粉,表面黏附有卫星粉和Y2O3颗粒。复合粉末的流动性较差,为33.9~45.6 s/50 g,受Y2O3的原始粒度影响较大;粉末的松装密度主要受Y2O3含量(w(Y2O3),下同)影响,随Y2O3含量增加而增大。Y2O3均匀分布于TC4基体中,与基体的结合界面光滑、平整,基本保持原有形态和尺寸。Y2O3易团聚,其微观形态主要受原始粒度影响。大尺寸的Y2O3/TC4复合粉末中Y2O3呈环状分布,小尺寸粉末中Y2O3颗粒较少,分布均匀。展开更多
文摘Al2O3/WC powder was synthesized by means of aluminothermic reduction-carbonization with metallic Al powder, yellow tungsten oxide and carbon black or graphite as raw materials under the protection of coke granules. The effects of Al2O3 content, temperature, C/WO3 molar ratio, and atmosphere on the synthesis of Al2O3/WC powder were studied. The results show that the relative content of WC and W2C is strongly influenced by the factors mentioned-above. Carbon black has higher reactivity than graphite. Al2O3-WC composite is easier to obtain under the protection of coke granules than under argon atmosphere. The CO in the coke layer can easily react with tungsten to form WC and to transfer from W2C to WC.
基金Projects (51101096, 51002093) supported by the National Natural Science Foundation of ChinaProject (1052nm05000) supported by Special Foundation of the Shanghai Science and Technology Commission for Nano-Materials ResearchProject (J51042) supported by Leading Academic Discipline Project of the Shanghai Education Commission, China
文摘A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer were investigated. The composite layer has graded microstructures and compositions, due to the fast melting followed by rapid solidification and cooling during laser cladding. The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified. The size of TiC dendrites decreases with increasing depth. Y2O3 fine particles distribute in the whole clad layer. The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380, which is 4 times higher than the initial hardness. The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.
