Irradiation effects on RB-SiC ceramic with heterogeneous grain boundary segregation interfaces induced by oxygen (O2) plasma surface modification

Abstract

For RB-SiC space optical hard-brittle ceramic materials, it’s easy to introduce subsurface damage defects during precision grinding. Subsurface damage (SSD) defects affect the imaging quality, stability, service life and other key technical parameters of space optical hard-brittle ceramic materials. In order to adapt optical components to deep space exploration environment and extreme environment conditions, it’s necessary to further highlight the efficient, low damage and high quality to reduce the subsurface defects of optical components, so as to improve the optical performance of optical components. With oxygen (O₂) plasma torches surface modification at room temperature environment (25 ± 5℃) via plasma irradiation, the optical parameters after precision grinding process was improved and SSD was reduced. Via the oxygen plasma surface modification process, the SSD depth will be reduced with [12.6, 28.5] μm. Compared with the process of plasma surface modification and without plasma surface modification, the results show that the subsurface damage (SSD) depth of the grinding zone without plasma surface modification was larger via the value reaches as [21.2, 29.8] μm. In addition, the melting point of Si phase (1410℃) and SiC phase (2700℃) via the oxygen (O₂) plasma surface modification process with the SiO₂ (hardness = 7) layer with hardness less than SiC (Mohs hardness = 9.2 ~ 9.5) layer was generated. Established a hierarchical precision grinding RB-SiC ceramic the shape precision and surface quality comparison model and analysis fabrication of highly shape accuracy mechanism of subsurface damage (SSD) parameters. As the Normal Temperature Oxygen Plasma Surface Modification Precision Grinding (NT-OPSMPG) process via the oxygen plasma torch (100 °C), the crack, fold, tiny particle defects at the Si phase and SiC phase boundary of the two phases are obviously reduced (↓).

Graphical abstract

Subsurface Damage (SSD) forming mechanism: (a) Effect of indentation interaction on middle diameter / radial crack propagation; (b) Mechanism of subsurface damage (SSD)