Production of cordierite ceramic by aqueous tape casting process

Thermal expansion coefficient and dielectric properties of non-stoichiometric cordierite compositions with excess MgO mole ratio synthesized from mainly kaolin and talc by the glass crystallization method

“…Although samples A5, A6 and A7 contain forsterite which has a higher CTE compared to ␣-cordierite, they possess lower CTEs. This can be explained by the fact that particles of larger thermal expansion coefficients in a matrix of lower CTE generate micro-cracks in the matrix around the structure [14]. When this occurred in the present samples, hysteresis of the thermal expansion curve was observed, which also resulted in the decrease of thermal expansion [31].…”

“…Even though, there are many studies on the synthesize of ␣-cordierite using talc and kaolin as the starting raw materials together with other minerals [4][5][6][7][8][9][10][11][12][13][14], however, most of them following solid state reaction route, except two [15,16] used glass crystallization method but with exact stoichiometric cordierite compositions.…”

“…Although it is now known that higher MgO mole ratios can decrease crystallization temperature, its significant effect to dielectric and coefficient of thermal expansion (CTE) should also be examined. Although the axial thermal expansion and dielectric properties data on ␣-cordierite synthesize from minerals talc and kaolin, have been studied, but the results are obtained from solid state method with high sintering temperature [4][5][6][7][9][10][11][12]14,[27][28][29]. Only a few data following glass method [16,30].…”

Crystal structure of single phase and low sintering temperature of α-cordierite synthesized from talc and kaolin

“…The cystallization phase has been identified as ␣-cordierite (ICDD 048-1600). However, other researchers [44][45][46] found that at this temperature the amorphous phase is still present together with ␣-cordierite. Studies by Amista et al [23] found that at this temperature the amount of amorphous phase can be reduced by the addition of excess MgO in the composition.…”

“…Therefore, further research was carried out to synthesized ␣-cordierite using mainly talc and kaolin by crystallization glass methods in order to decrease the melting temperature of glass and crystallization temperature of ␣-cordierite without the addition of flux, which would increase the CTE values. Even though, there are many studies on the synthesize of ␣-cordierite using talc and kaolin as the starting raw materials together with other minerals such as magnesium compounds [39], silica, alumina [40], gibbsite [31,41], calcined alumina and fly ash [32], magnesium oxide [42], diatomite and alumina [36], silica, sepiolite and felspar [43], fly ash, fused silica and alumina mixture [33], alumina [44,45]; however, most of them following solid state reaction route, except two [1,10] used glass crystallization method.…”