喷雾干燥法金刚石-陶瓷结合剂复合烧结体的制备及表征

以金刚石和无机溶胶为原料,采用喷雾干燥法制备金刚石-陶瓷结合剂复合粉体,将粉体压制、烧结,获得金刚石-陶瓷结合剂烧结体。采用扫描电镜和激光粒度分析仪对复合粉体的形貌和粒径分布进行表征,借助综合热分析仪选取复合体的烧结温度,利用抗折试验机、扫描电镜和X射线衍射分别对喷雾干燥法和熔融法所制烧结试样的抗弯强度、断面形貌及物相进行分析。结果表明:经喷雾干燥的复合粉体为球形,易于成型,且复合粉体尺寸分布范围较宽,利于提高坯体致密度;选取金刚石-陶瓷结合剂复合体的烧结温度为820℃,在此温度下结合剂可实现对金刚石的黏结和包裹;烧结后,随陶瓷结合剂含量增加,两种工艺所制试样的抗弯强度均有提高,气孔率都相应降低;当结合剂含量为32%(质量分数)时,喷雾干燥法所制烧结试样的微观结构均匀,易析晶,抗弯强度和气孔率分别为99.46MPa和38.55%;熔融法所制试样的抗弯强度和气孔率分别为72.42MPa和39.89%。

Synthesis and Characterization of Diamond-vitrified Bond Sintered Composite By Spray-drying M ethod

Based on the diamond and inorganic sol ,spray‐drying method w as used to prepare diamond‐vitrified bond composite powders and then the bulk samples were obtained after pressing and sintering the powders .The surface morphology and particle size distribution of the composite powders were ex‐amined by scanning electron microscope and laser particle size analyzer ,the sintering temperature of the composites was selected with the aid of the comprehensive thermal analysis instrument ,the ben‐ding strength ,fracture morphology and crystal phases of sintered samples prepared by spray‐drying method and melting method were characterized by motorized bending tester ,scanning electron micro‐scope and X‐ray diffraction ,respectively .The results show that the composite powders prepared by spray‐drying are spherical ,which is beneficial to mould forming .Their wide size distribution helps to improve the density of diamond‐vitrified bond green body .The sintering temperature of the compos‐ites is 820℃ .T he bonding and w rapping of diamond can be realized at this temperature .With the in‐crease of bond content ,the bending strength of sintered samples prepared by two methods increases and porosity decreases .When the vitrified bond content is 32% (mass fraction) ,the microstructure of samples prepared by spray‐drying is uniform and is easy to be crystallized ,and the bending strength and porosity are 99 .46M Pa and 38 .55% ;w hile for samples obtained from melting method ,the corre‐sponding figures are 72 .42M Pa and 39 .89% .