Sapphire Grinding Study

Abstract

Sapphire missile domes and plane parallel optical windows have had important military applications for many years, yet have been plagued by high manufacturing costs, primarily due to the material’s extreme fracture toughness, microhardness, abrasion resistance and critical load. Simply put, the attributes that make sapphire an attractive window material, also make it quite difficult to grind. In addition to its useful mechanical properties, sapphire has excellent thermal shock resistance, chemical stability at high temperature, a melting point in excess of 2000 degrees C, and good transmission from the UV through 3-5 microns. Studies to optimize precision microgrinding of sapphire will not only lead to more affordable tough durable multi-spectral military windows, but also will aid in an improved understanding of the grinding process for all optical materials.