High-quality Finishing Process for Silicon Carbide Optical Components Using Conventional Equipment

Marcos Valentim Ribeiro Dos Santos ,Álvaro José Damião ,Antônio Jorge Abdalla

doi:10.1590/1980-5373-mr-2021-0422

Marcos Valentim Ribeiro Dos Santos , Álvaro José Damião + Show 1 more

Open Access

https://doi.org/10.1590/1980-5373-mr-2021-0422

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Abstract

The development of low-cost high quality surface finishing methods for silicon carbide (SiC) is an arduous task. Nowadays, the SiC mirrors manufacture involves extensive, complex, and costly finishing processes carried out on highly expensive ultra-precise machines. In this work, a cost-effective surface finishing method has been successfully developed, using conventional machines for the optical finishing of SiC. The results showed that the combination of ductile grinding and polishing in conventional low-cost machines allowed to obtain high-quality surface finish on SiC substrates with low roughness (4 - 10 nm Ra ) and optical figure in the range λ / 4 - λ / 8, at a reduced 32 hours total processing time.

Highlights

Compared to conventional glasses and metals, silicon carbide (SiC) is an excellent substrate for high-performance optical applications due to its high specific stiffness, high thermal conductivity, and superior dimensional stability[1,2]
Different techniques and technologies[1,3,5] have been used to produce SiC substrates close to the final dimension in order to reduce their post-processing, due to the complexity of the finishing process, generally carried out by diamond wheel grinding in expensive ultra-precise machines[6,7,8,9]
In the ductile grinding process, the mechanism of material removal occurs by plastic flow

Summary

Introduction

Compared to conventional glasses and metals, silicon carbide (SiC) is an excellent substrate for high-performance optical applications due to its high specific stiffness, high thermal conductivity, and superior dimensional stability[1,2]. It is considered the preferred material in manufacturing lightweight mirrors for aeronautical and aerospace uses[3]. The process of material removal by brittle fracture predominates[10]. The machined surface is characterized by parallel lines called ductility streaks, and the subsequent polishing process takes place in less time and with a better result for the surface finish[14]

Methods

Results

Conclusion