目的 针对传统粉末热压成形细粒度金刚石磨具存在颗粒团聚、磨削碳化硅陶瓷容易在表面产生较深划痕的问题，提出一种基于冷冻-解冻凝胶成形的细粒度金刚石磨具，用于精密磨削碳化硅陶瓷，并研究其加工工艺。方法 制备聚乙烯醇-酚醛树脂复合凝胶胶水，将金刚石和填料在凝胶胶水中剪切分散，得到的浆料浇筑在模具中，在–20 ℃低温条件下反复冷冻，形成胶体，再经干燥、烧结，得到粒度为2.5 μm的细粒度金刚石磨削磨具。采用制备的金刚石凝胶磨具磨削碳化硅平面反射镜，对比不同磨具转速、进给速度、磨削深度工艺条件下的表面磨削质量。结果 在低温条件下，聚乙烯醇-酚醛树脂分子链发生了物理交联，形成凝胶体，凝胶结合剂结合强度高，且分布均匀，所制备的凝胶磨具强度高于热压磨具，该方法可以解决传统粉料压制成形方法容易出现物相团聚、微观结构不一致的问题。磨削结果显示，当磨削进给速度为0.008 mm/min、磨具转速为1450 r/min、磨削深度为0.016 mm、转台转速为60 r/min时，获得了表面粗糙度Ra低于3.5 nm的镜面磨削效果，表面质量好于热压磨具磨削效果，3个?100 mm区域平面度PV值均小于0.5 μm。结论 采用聚乙烯醇-酚醛树脂复合凝胶成功制备了细粒度金刚石磨削磨具，通过优化磨削工艺参数，为碳化硅平面反射镜镜面加工提供了一种新的加工工艺。

Aiming at the problem of particle agglomeration in traditional powder hot pressing fine-grained diamond grinding tools, which is easy to produce deep scratches on the surface of grinding SiC ceramics, a sol-gel forming fine-grained diamond abrasive tool for precision grinding of SiC ceramics is proposed, and grinding process is studied. Diamonds and fillers are sheared and dispersed to prepare polyvinyl alcohol-phenolic resin composite gel glue in the gel glue, and the obtained slurry is poured into a mold, repeatedly frozen at a low temperature of –20 ℃ to gel, then dried and sintered to obtain 2.5 μm diamond sol-gel abrasive tools. Grinding SiC plane mirror with the prepared diamond sol-gel grinding tool, the surface grinding quality under different grinding speed, feed speed and grinding depth was compared. The molecular chain of polyvinyl alcohol phenol-formaldehyde resin has formed physical gel at a low temperature. The strength of the gel binder with uniform distribution is high. The strength of the gel grinder is higher than that of the hot pressing abrasive tool. This method can solve the problem of phase agglomeration and microstructure inconsistency in the traditional powder compaction process. The grinding results show that when the grinding feed speed is 0.008 mm/min, the grinding speed of the tool is 1450 r/min, the grinding depth is 0.016 mm, and the rotation speed of the rotary table is 60 r/min, the surface roughness is lower than Ra 3.5 nm, and the surface quality is better than that of the hot press grinding tool. The Flatness PV values of three areas with a diameter of 100 mm are all less than 0.5 μm. Fine-grained diamond grinding tools are successfully prepared by using polyvinyl alcohol phenolic resin composite gel. By optimizing the grinding parameters, new processing technology is provided for the surface processing of the SiC flat mirrors.