Flexural strength and crack propagation of porous clay-precipitated calcium carbonate

Abstract

Porous clay-precipitated calcium carbonate were prepared via polymeric sponge replication method using precipitated calcium carbonate (PCC) and red clay as raw materials. Different compositions of precipitated calcium carbonate (PCC) which is 10 wt.% and 15 wt.% with 24 hours and 48 hours milling time were sintered at 1250°C for 2 hours respectively which influenced the flexural strength and morphology of the porous ceramic. The highest flexural strength (1.843 MPa) were obtained by 10 wt.% [CaCO₃]PCC milled at 24 hours related to the lowest percentage of porosity (81%). Mineralogical characterization of porous ceramic were determined via X-ray diffraction (XRD) shows the presence of crystalline phases such as anorthite (2CaAl₂Si₂O₈), gehlenite (Ca₂Al₂SiO₇) and esseneite (CaFeAlSiO₆) after sintering process. The morphological analysis via stereomicroscope shows that the porosity and struts were found due to presence of precipitated calcium carbonate that act as pore forming agent. The colour of porous ceramic between 10 wt.% [CaCO₃]PCC and 15 wt.% [CaCO₃]PCC shows significant difference due to iron oxide contained in the red clay which contributes to the colour of the samples. Crack propagates in the inter granular type of fracture mode due to resulted porous ceramic is a brittle material.