【作者】 宋延沛；

【导师】 毛协民； 董企铭；

【作者基本信息】 上海大学 ， 材料学， 2006， 博士

【摘要】 金属基复合材料由于综合发挥了基体材料和添加材料的特性，使其表现出优异的综合性能，从而引起航空航天和汽车应用领域的高度重视。铝基和镁基复合材料已在这些领域得到广泛的研究和应用，而Fe-C合金基复合材料由于其熔点高，比重大，制造工艺极其复杂而研究甚少。高速线、棒材热轧生产线的预精轧段和精轧段用轧辊的工作条件十分恶劣。它不仅要求在高温高速旋转下具有足够的强度，而且要求其表面在高温、高载荷、高速滑动磨擦下具有极高的耐磨性能。再加上，在高速线、棒材热轧线上更换轧辊的昂贵的成本，探索一种低成本、在高温、高载荷、高速滑动磨擦下具有高寿命、优异综合性能的轧辊环材料替代目前生产线上使用的WC钴镍烧结硬质合金和高速钢轧辊成为人们追求的目标。 本文利用比重差，采用离心铸造技术，在自制的卧式离心铸造机上，制备了由WC_p增强的铁基梯度复合材料外部工作层和Fe-C合金芯部基体组成的复合结构辊环，并对其进行了系统全面的分析研究，取得了规律性的认识和生产线上有实用价值的成果。 论文在分析了离心力场下外加增强粒子在金属熔体中的迁移和分布规律的基础上，以碳化钨颗粒(WC_p)为增强粒子，以Fe-C合金为基体，建立了离心力场条件下，外加WC粒子在Fe-C合金熔体内运动和分布的理论模型。从理论上考察研究了外加WC_p颗粒在Fe-C合金熔体内的运动和分布。并利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、X-ray衍射仪等多种现代化微观分析手段和万能电子拉伸试验机、高速滑动磨损试验机等先进性能试验设备，研究了梯度复合材料的组织、性能、界面结构、断裂和磨损行为及其机制。 采用离心铸造法成功地在转速600rpm～1200rpm下制备了外径164mm～292mm，内径78mm～140mm，高67mm～100mm的由WC_p／Fe-C梯度复合材料外层和Fe-C合金芯部基体组成的复合结构厚壁环试样，厚壁环试样的WC_p／Fe-C梯度复合材料外层厚度达到了20～30mm。对试样的分析研究表明，在该试验条件下，建立的外加WC_p在Fe-C合金熔体内运动和分布的理论模型与试验结果基更多还原

【Abstract】 Metal matrix composites exhibit excellent comprehensive properties because of bringing the comprehensive character of matrix material and reinforcement particle into play. It is, therefore, of interest to research the excellent comprehensive properties and application of metal matrix composites for aerospace and automotive. Composites with aluminum and magnesium matrices have been investigated and applied extensively in these fields, while less work has been carried out on iron matrix composites because of their high melting point, large density, small specific strength and very complex processing. Working condition of roller rings used in finishing roll sector or pre-finishing roll sector of high speed line or rod rolling mill production line is extremely vile. The roller rings require not only high strength, but high wear resistance for working layer of the roller rings under high temperature, high load and high speed sliding friction besides the expensive cost of changing the roller rings. Therefore, probing a low-cost roller ring with high life and excellent comprehensive properties under high temperature, high load and high speed sliding friction to replace WC Co-Ni sintered hard alloy and/or WC steel sintered hard alloy and high speed steel roller rings used in high speed line and rod rolling mill production line at present, have become a target of people seeking all along.Utilizing the different centrifugal force resulted from difference of density between Fe-C alloy melt and WC_P, a composite structure roller ring, consisting of WCp/Fe-C gradient composites outer working layer and Fe-C alloy core, was fabricated from a mixture of Fe-C alloy melt and WC_P with centrifugal casting technology in this paper, and a regularity knowledge and the valued achievement were acquired by overall systematic analysis and investigation on the composite structure roller rings.On the basis of analyzing the law of movement and distribution of foreign adding particle in metal melt, the theoretic model of movement and distribution of foreign adding WC_P in Fe-C alloy melt were established under centrifugal field. The movement and distribution of foreign adding WC_P in Fe-C alloy melt are investigated on theory. Therewithal, the microstructure, properties, interface structure, fracture and wear behavior of the gradient composites were investigated by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer, AG-1 250kN universal tensile test machine and MMS-1G high velocity wear testing machine.A composite structure thick-walled rings, consisting of a WC_P/Fe-C gradient composites outer layer of 20-30 mm heavy-section and Fe-C matrix alloy core, was successfully obtained by centrifugal casting method at 600-1400rpm, dimensioned by outer diameter 164-292mm, inner 78-140mm, highness 74-100mm. Analysis and investigations on the thick-walled ring specimen showed that the results of computer simulation, in term of the movement and distribution model of WC_P in Fe-C alloy更多还原