TiC-TiWC2增强高铬铸铁基复合材料的组织与磨损性能研究

Investigation of Microstructures and Wear Properties of TiC-TiWC2 Reinforced High Chromium Cast Iron Matrix Composites

摘要:

高铬铸铁因优良的韧性和耐磨性，被广泛应用于各种工程领域。然而，在高负荷和极端磨损条件下，高铬铸铁的表面会出现凹坑、裂纹及断裂等失效现象，无法满足工况需求。硬质金属碳化物因具有较高的硬度，能够有效抵抗多种形式的磨料磨损，因此常被添加至金属基体中，以提升基体的硬度与耐磨性能。通过引入W、Ti、C的混合金属碳化物体系，采用粉末冶金与铸造相结合的方法制备了TiC-TiWC₂增强的高铬铸铁基复合材料。利用SEM、XRD、EDS法对复合材料的微观组织和物相进行分析，通过维氏硬度计测试复合材料的显微硬度，利用三体磨损试验机比较了复合材料与传统高铬铸铁材料在相同工艺条件下的耐磨性能。结果表明，在原位反应过程中，复合材料内部形成了TiC-TiWC₂增强相，该增强相以核壳结构的方式生长。复合区域的平均硬度值可达到1 300 HV左右，几乎是基体区域硬度的2倍。在三体磨损实验中，传统高铬铸铁材料中的M₇C₃型碳化物发生脆性断裂和疲劳剥落，因而磨损表面多呈现连续的划痕和面积较大的凹坑，而复合材料的磨损表面相对平整，仅部分基体区域表现出短而浅的划痕和犁沟，磨损截面整体连续且无明显纵向裂纹。通过对比分析发现，复合材料的耐磨性能相比高铬铸铁基体提升了2倍以上，表明TiC-TiWC₂增强相显著提高了高铬铸铁的硬度和耐磨性。

Abstract:

High chromium cast iron is extensively utilized in various engineering applications for its excellent toughness and wear resistance. However， its wear performance is limited under high load and extreme wear conditions ， which can lead to surface failures such as craters， cracks， and fractures. Hard metal carbides， known for their high hardness， offer effective resistance to various forms of abrasive wear， and are often incorporated into the metal matrix to improve hardness and wear resistance. This study investigates the preparation of a TiC-TiWC₂ reinforced high chromium cast iron matrix composite by introducing a mixed-metal carbide system of tungsten （W）， titanium （Ti）， and carbon （C） through powder metallurgy and casting techniques. The microstructure and phases of the composite were analyzed using scanning electron microscopy （SEM）， X-ray diffraction （XRD）， and energy dispersive spectroscopy （EDS）. Microhardness was evaluated with a Vickers hardness tester， while wear resistance was assessed via three-body wear tester， comparing the composite to high chromium cast iron under the same processing conditions. The results indicated that an in-situ reaction led to the formation of a TiC-TiWC₂ reinforced phase within the composite region， primarily in a core-shell structure. The average hardness of the composite region was approximately 1 300 HV， nearly twice that of the matrix. In wear tests， the high chromium cast iron matrix showed brittle fracture and fatigue spalling of M₇C₃-type carbides， with wear surfaces characterized by significant scratches and pits. In contrast， the wear surface of the composite appeared smoother， with only short and shallow scratches and furrows in localized areas. The composite’s wear cross-section was continuous and free of major longitudinal cracks. Overall， the wear resistance of the composite was more than twice that of high chromium cast iron， highlighting the effectiveness of the TiC-TiWC₂ reinforced phase in significantly improving both hardness and wear resistance of the high chromium cast iron.