The influence of crystallization on the flexural strength of MgO–CaO–Al 2O 3–SiO 2 composite glass

Abstract

Glass with the composition of MgO–CaO–Al 2O 3–SiO 2 (MCAS) is prepared by sol–gel method. X-ray diffraction studies on specimens with a sintering temperature higher than 940°C show that cordierite and anorthite exist as two different phases. For sintered MCAS glass ceramics, both the average flexural strengths and the crystallization rates of anorthite and cordierite increase with sintering time (sintered at 940°C) and sintering temperature (sintered for 40 min). The average flexural strengths of porous MCAS glass ceramics is decreased in a way that is exponential with porosity: δ= δ o exp(− np) Because of the crystallization of cordierite and anorthite, the dependence of flexural strength on both the pores fraction and the crystallization rates of cordierite can be expressed by the modified equation as follows: δ= δ o exp(−np)×[1+ ax i + b( x i ) 2] ( a and b are constants, x i is the crystallization rates for cordierite).