纳米金刚石-陶瓷结合剂复合粉体的高分子网络凝胶法制备与烧结

Preparation and sintering of nanodiamond-vitrified bond composite powders by polyacrylamide gel method

采用高分子网络凝胶(P-G)法制备了纳米金刚石-陶瓷结合剂的复合粉体,通过压制成型,低温烧结,获得了纳米金刚石-陶瓷结合剂的复合烧结块体试样;同时与采用高温熔融法制备的陶瓷结合剂,再加入纳米金刚石机械混合后烧结制备的复合烧结块体试样进行对比。通过X射线衍射分析了试样的物相构成,借助场发射扫描电镜对试样断口进行了显微形貌观察,采用三点弯曲法测试了试样的抗折强度,利用阿基米德原理测试了试样的密度和气孔率。结果表明,采用高分子网络凝胶法可以获得纳米金刚石均匀分散的纳米金刚石-陶瓷复合粉体,经过800℃/2h烧结后试样的抗折强度为60.41MPa,密度为1.81g/cm3,气孔率为15.67%;而采用高温熔融法+纳米金刚石的工艺获得的纳米金刚石-陶瓷结合剂烧结后试样,其抗折强度、密度和气孔率分别为46.48MPa、2.23g/cm3和11.75%,其显微结构中可见明显的纳米金刚石团聚体。高分子网络凝胶法可以成为超精磨削用纳米金刚石-陶瓷磨具制备的新方法。

Nanodiamond vitrified bond composite powder was prepared by polyacrylamide gel（P-G）method. The powder was pressed and sintered at low temperature, and the nanodiamond-vitrified bond composite sample was obtained. Contrast with this method, vitrified bond was also prepared by melting method, then mixed with nanodiamond and sintered at a proper temperature. The phase constitution and microstructure of sintered samples were characterized by X - ray diffraction and field emission scanning electron microscopy. The flexural strength was measured by three point bending method. The volume density and porosity were tested according to Archimedes＇ principle. The results show that nanodiamond-vitrified bond composite powder can be obtained by P - G method, and the flexural strength, volume density and porosity of samples sintered at 800 ℃/2 h are 60.41 MPa, 1.81 g/cm3 and 15.67%, respectively. When nanodiamond powder is mixed with vitrified bond matrix mechanically, the flexural strength, volume density and porosity of sintered samples are 46.48 MPa, 2.23 g/cma and 11.75%, respectively, and the agglomerate of nanodiamond is clearly observed. P -G method can be used as a new technology for preparing nanodiamond-vitrified composite as ultrafine grinding tools.