Reliability studies of gelcast fused silica between organic and inorganic binder systems

Abstract

Fused silica ceramics was prepared by using conventional organic binder, mathacrylamide‐N,N′‐methylenebisacrylamide (MAM‐MBAM) system by gelcasting process. Mechanical properties of green bodies were studied as a function of solid loading varying from 60 to 72 vol%. After evaluating the green body mechanical properties, the samples were densified at different sintering temperature from 1200 to 1450°C with definite intervals of 50°C and subjected to flexural strength analysis. Variation in flexural strength with sintering temperature was observed and correlated with the quantity of devitrification of fused silica during sintering. Quantification of devitrified cristobalite was carried out by using 20 wt% rutile (TiO2) as an internal standard by X‐ray diffraction. It was found that, as the cristobalite content increased, flexural strength decreased. Reliability studies were carried out for the samples having maximum flexural strength with and without crystalline content. Reliability studies have shown that for this organic binder system the sample sintered at 1300°C is crystalline free and most reliable product. The mechanical properties and reliability of this product processed with organic binder are compared with inorganic binder system. Results indicate that the sample fabricated using inorganic binder system is exhibiting high Weibull modulus and thus better reliability.

Description of the statistical variations of the measured strength for brittle ceramics: A comparison between two-parameter Weibull distribution and normal distribution

“…Extensive studies have been conducted to explore the applicability of Eq. 2 in describing the strength variations in the measured strength of real materials [9][10][11][12]. Weibull function was also used to describe the statis-tical characteristics of other properties, such as hardness [13], fracture toughness [13][14][15], dielectric breakdown strength [16,17], subcritical crack growth [18], etc.…”