碳化硅基底改性硅表面的磁流变抛光

Manufacture of Silicon Modification Layer on Silicon Carbide Surface by Magnetorheological Finishing

为克服传统抛光方法在硅改性的碳化硅表面抛光存在的不足,采用磁流变抛光在精抛光阶段实现面形误差高效去除和快速收敛。基于实际应用中的对磁流变抛光液的需求,提出了磁流变液的性能要求,并配制了适合改性硅表面抛光的磁流变抛光液,检测所配制的抛光液体的流变特性和分散稳定性,证明了液体具有良好的性能。对口径为130 mm(有效口径为120 mm)的硅改性的同轴非球面碳化硅工件进行实际抛光。经过两个周期约3 h的抛光,面形误差均方根(RMS)从0.051λ(λ=632.8 nm)快速收敛至0.012λ,粗糙度Ra达0.618 nm。验证了所配制的磁流变抛光液满足碳化硅基底改性硅表面的抛光需求,证明了磁流变抛光技术在镜面硅改性后精抛光阶段具有独特的优势。

Magnetorheological finishing（MRF） process is adopted to overcome the drawback of traditional polishing method in final finishing of SiC after silicon modified and removing the debris of optical surface in final finishing with high efficiency and fast convergence. The requirements of magnetorheological（MR） polishing fluid are proposed according to the actual polishing situation. The rheological characteristic and dispersion stability are tested, which verify that the prepared MR polishing fluid possesses good performance. A silicon modified reactbonded coaxial asphere mirror with diameter of 130 mm（effective sub-aperture is 120 mm） is polished with two iteration in three hours approximately. The root-mean-square（RMS） of the surface accuracy is improved from0.051λ（λ=632.8 nm） to 0.012λ rapidly and the surface roughness Rareaches 0.618 nm. The results proves that the prepared MR polishing fluid can satisfy the polishing requirement of modification layer on silicon carbide and MRF possesses outstanding advantages in final finishing of silicon modified mirror.