Fracture strength of zero-thermal-expansion glass-ceramics for ultra-precision components

Zero-thermal-expansion glass-ceramic is a key material in ultra-precision e ngineering. However, applications of this material have been limited in sta tic components, because of a lack of data on the fracture strength of this material. We examine the fracture strength of the material by means of a 4- point bending test on samples machined using various methods. Etching techn ology is useful in increasing the strength, which strongly depends upon the surface roughness after etching. The float-polished sample has a fracture strength of 546MPa, which is more than 4 times higher than that of normally machined surfaces, and also much higher than that of alumina.