V-EPC铸渗法制备铁基表面复合材料的铸渗机理研究

【作者】 叶小梅；

【导师】 蒋业华；

【作者基本信息】 昆明理工大学 ， 材料加工工程， 2007， 硕士

【摘要】 论文对V-EPC铸渗法制备碳化钨／铁基表面复合材料的铸渗机理进行了研究，主要包括铸渗工艺参数对铸渗深度的影响规律和有关界面的研究等。首先，为模拟铸渗过程，考察浇注温度和真空度这两个工艺因素对铸渗深度的影响，论文设计了一个简易的铸渗动力学装置，选取同一真空度下（-0.06MPa）不同浇注温度（1400℃、1450℃、1500℃、1550℃和1600℃）以及同一浇注温度下（1500℃）不同的真空度（0、-0.02MPa、-0.04MPa和-0.06MPa）进行实验，结果表明：铸渗深度分别随着浇注温度的升高和真空度的增大而增加，相关的铸渗深度的公式也证实了实验所得的结论。论文还针对可能发生的界面反应进行热力学计算，结果表明：首先发生反应W₂C=WC+W，然后析出的W或与C结合重新生成WC或W₂C析出，或与WC结合生成W₂C，后者发生的可能性较大。论文中复合材料的界面为第3类界面，即铸渗过程中界面处碳化钨、高碳铬铁和灰铸铁这三种物质之间相互作用并生成界面反应物。论文设计了一组有关这三种物质的差热分析实验，并对该实验得到的试样进行XRD和SEM等一系列实验，为研究该界面提供指导。结果表明：铸渗过程中，高碳铬铁熔化，碳化钨颗粒产生局部溶解，界面产物主要有重新析出的WC和W₂C、M₆C型碳化物和M₇C₃型碳化物（M为Fe、Cr、W）；WC的溶解和析出，改变了碳化钨颗粒和基体的原始成分和形态，且适当的界面反应，有利于基体合金化、减小界面处的应力集中，提高界面结合强度，进而提高材料的耐磨性；只将碳化钨看作增强相时，灰铸铁加高碳铬铁基体中碳化钨的溶解程度最大，析出产物最为复杂。复合层形成的条件是能量流和物质流必须同时存在；高碳铬铁未能与碳化钨颗粒形成良好的冶金结合正说明了只有能量流存在时，不能形成复合层。更多还原

【Abstract】 In the paper, the cast-infiltration mechanism of WC reinforced HT300 matrix surface-layer composite fabricated by V-EPC and cast-infiltration process was studied, including the influence of cast-infiltraton parameter on infiltration depth, and the study on the interface in the composite material.First of all, for simulating the cast-infiltration process, a simple infiltration apparatus was designed to study the influence of the melting temperature and vacuum degree on infiltration depth, and melting temperature and vacuum degree varied in series experiments. The results show that the infiltration depth increases as the melting temperature and vacuum degree increases. The relating infiltration depth formula confirms to it.In addition, the possible interface reactions were calculated on thermodynamics. The resulte shows as is followed: there is the reaction W₂C = WC+W, then the formedW synthesizes with C to form WC or W₂C, or synthesizes with WC to form W₂C. The tendency of the latter is bigger than the former.The interface in the composite material in this paper is the third interface, on which tungsten carbide, high carbon chrominum iron and grey iron interact, forming interface reaction formation. The three matters were analyzed by Differential Thermal Analysis （DTA） to study the interface reactions. The samples gained by DTA were analyzed by Scanning Electron microscope （SEM） and X-Ray Diffraction （XRD）. The results show that in the cast-infiltration process high carbon chrominum iron melted, tungsten carbide particle partly dissolved and the interface reaction formations were reformed WC and W₂C, M₆C and M₇C₃ carbide while M contained Fe,Cr and W; The dissolution and formation of tungsten carbide particles changed the original contain and shape of the tungsten carbide particles and the matrix, and the appropriate interface reactions were good for the matrix alloying, reducing stress concentration on the interface, increasing the interface bond strength and improving the abration resistance of the material. During the different matrice, tungsten carbide in the grey iron and high carbon chrominum iron matrix dissolved the most and the formations were the most. The composite layer formed when the energy flow and matter flowegsisted simultaneously. When there was only energy flow the composite layer didn’t form. It was showed by that high carbon chrominum iron and tungsten carbide didn’t form the metallurgical bond.更多还原