定向凝固Fe-B-C合金基体和硼化物协同抗磨料磨损行为基础研究

In the process of material crushing, ball mill grinding ball is an important consumable part. Currently, chrome cast iron grinding ball contains more chromium, molybdenum and other elements, which improve production costs. The cheap boron is selected as a hard phase forming element, based on obvious anisotropic mechanical properties of hard phase boride, the objective of this project is to elucidate the synergistic antiwear behavior of the matrix and boride with different orientation in the directional solidification Fe-B-C alloy. According to the matrix and boride composition in the alloy, the pure matrix and pure boride test pieces are prepared, and then the wear rates are measured, respectively. Thus, the wear rates of the matrix and the boride (with different orientation) are separated and characterized from the total wear rate of directional solidification Fe-B-C alloy. And then, the matrix and boride with different orientation synergistic anti-wear mechanism is explicited, and the damaged physical model of the phase in the alloy will be constructed. By changing the wear load, abrasive kind, etc., the relationship between the alloy wear rate and the wear condition is clarified, and the transformation law of the wear mechanism is revealed. Based on the above study, the boron content is used to adjust the boride volume fraction in directional solidification Fe-B-C alloy, and the effect of the boride volume fraction on abrasive wear properties of the alloy was explored. The research results of this project will provide a new design method and control method for strengthening abrasive wear resistance of anti-wear parts such as grinding ball.

球磨机磨球是物料破碎过程中的重要消耗备件，目前应用的铬系铸铁磨球含有较多铬、钼等元素，提高了生产成本。本项目以廉价硼作为硬质相形成元素，基于硬质相硼化物存在明显的力学性能各向异性，以阐明定向凝固Fe-B-C合金基体与不同位向硼化物协同抗磨料磨损行为为研究目标，依据合金基体及硼化物成分分别制备纯基体及定向凝固硼化物试块并测定二者的磨损率，由此将基体磨损率与不同位向硼化物磨损率从定向凝固Fe-B-C合金总磨损率中分离并表征，进而明确基体与不同位向硼化物的协同抗磨机制，构建合金组相损伤的物理模型；通过改变磨损载荷、磨料种类等参数来阐明合金磨损率与磨损条件之间的关联性，揭示磨损机制转变规律。基于上述研究，利用硼含量来调控定向凝固Fe-B-C合金中硼化物的体积分数，探索硼化物体积分数对合金磨料磨损性能的作用规律。本项目研究成果将为强化球磨机磨球等抗磨部件的磨料磨损抗力提供新的设计方法与控制途径。

在磨料磨损工况我国年消耗钢铁耐磨合金铸件350万吨以上，目前广泛应用的铸造钢铁耐磨合金往往存在低耐磨、高耗能的情况，研究严酷磨料磨损工况下材料的失效机理并开发高性能耐磨材料具有重要的意义。鉴于硼化物在不同位向存在性能差异的特点，本项目采用定向凝固工艺制备了定向低、高硼合金。定向低硼合金组织由铁素体、渗碳体和共晶硼化物构成，定向高硼合金由铁素体、渗碳体、初生硼化物和共晶硼化物组成。当硼化物的[002]生长方向垂直于金相面时，硼化物的高硬度(002)晶面与金相面平行，使定向低、高硼合金在此金相面的硬度分别达到最高值59.1HRC和67.3HRC。. 在两体或三体磨损试验条件下，粗磨料配合高磨损载荷能够加剧低、高硼合金中硼化物的破碎程度，降低基体与硼化物的协同失重占比，进而降低两合金的耐磨性。在任一两体、三体磨损试验条件下，当定向凝固低、高硼合金中硼化物的[002]位向垂直于磨损面排列时，两合金的基体与各自定向排列的硼化物的协同失重占比均最高，此时，基体的有效支撑配合高硬度硼化物使两合金均表现出最优的磨损性能。. 在碳化硅砂纸两体磨损试验条件下，相对于定向低硼合金，定向高硼合金中一次硼化物的硬度高，硼化物的体积分数高，基体与硼化物的协同失重占比高，因此耐磨性高；在石英砂和碳化硅磨料三体磨损试验条件下，相对于定向高硼合金，定向低硼合金中硼化物的体积分数低，基体能够有效支撑硼化物，使基体与硼化物具有高协同失重占比，因此耐磨性高。可见，对于两体磨损工况，硼化物数量的增加能够提升定向铁硼合金的耐磨性；对于三体磨损工况，硼化物数量的增多将减弱基体的支撑能力，导致硼化物破碎加剧，致使耐磨性下降。