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以高纯铬板为原料,采用原位合成-热处理工艺在HT300表面制备出Cr_7C_3增强表面梯度复合材料。用扫描电镜、X射线衍射仪、纳米压痕仪和划痕仪对该复合材料的微观形貌、物相组成及磨损性能进行表征。结果表明:在900℃下保温4 h后所得Cr_7C_3致密层的厚度约为30μm,颗粒体积分数接近100%,无明显晶界存在,与基体之间呈现良好的冶金结合。Cr_7C_3陶瓷层的显微硬度和弹性模量分别为12.711、256.04 GPa。在划痕试验中,划痕底部裂纹主要经过微裂纹、细小密集裂纹、中小型混合裂纹和贯穿裂纹等过程,可将其磨损形式归结为挤压-撕裂式磨损。
Cr_7C_3 reinforced surface gradient composite was prepared on the surface of HT300 by high-purity chrome plate as raw material. The microstructure, phase composition and wear properties of the composites were characterized by scanning electron microscopy, X-ray diffraction, nano indenter and scratch tester. The results show that the Cr_7C_3 dense layer has a thickness of about 30μm and a particle volume fraction of nearly 100% after being kept at 900 ℃ for 4 h. There is no obvious grain boundary, showing a good metallurgical bond with the matrix. The microhardness and elastic modulus of Cr_7C_3 ceramics were 12.711 and 256.04 GPa, respectively. In the scratch test, the crack at the bottom of the scratches is mainly subjected to microcracks, small and dense cracks, small and medium-sized mixed cracks and through cracks. The wear pattern can be attributed to extrusion-tearing wear.