Binary anorthite‐cordierite ceramic composite from kaolin and dolomite rock with improved characteristics

Abstract

Binary CaO‐MgO‐Al2O3‐SiO2 (CMAS) ceramics composites of anorthite‐cordierite composition were synthesized from natural raw materials (kaolin and dolomite rock). The change of SiO2/Al2O3 ratio in kaolin/dolomite mixtures (12, 24, and 36 wt.%) and synthesized composites along with analysis of their phase composition transformations (X‐ray diffraction) during heat treatment (thermogravimetric and differential thermal analysis) give the controlled design of aluminosilicate matrices. The obtained ceramic composites are represented by anorthite, a cordierite‐like phase whose ratio varies from 1.3:1 to 2.8:1. Mullite crystals, also included in the composition, reinforce the anorthite‐cordierite matrix. The morphostructural features of the samples were studied using optical and scanning electron microscopy. The porosity ranges from 7.8% to 24.2% depending on dolomite content. The impurities of iron and titanium interfering with obtaining a qualitative product are leveled by the presented technique including the heat treatment scheme justified by thermogravimetric analysis. Obtained CMAS‐ceramics of anorthite‐cordierite composition correspond to industrial international standards by their technical characteristics and exceed the requirements for heat‐insulating and chemically resistant materials by compressive strength.