Cold Sintering of Calcite: A Low‐Temperature Method for the Fabrication of Artificial Marble

This study presents a novel approach for the low‐temperature fabrication of dense calcite (CaCO 3 ) without the use of a carbon dioxide (CO 2 ) atmosphere. CaCO 3 powder was cold sintered (390 MPa, 150°C) using distilled water as a transient liquid, followed by heat treatment at 350°C (lower than the decomposition temperature of CaCO 3 ) for 5 hours. The resulting ceramics achieved a relative density of 95 ± 1%, compared to 76 ± 2% prior to heat treatment and 78 ± 2% for conventionally sintered samples. An optimum hardness (134 ± 24 MPa) equivalent to artificial marble was achieved after heat treatment at 350°C, indicating effective densification and strong interparticle bonding. X‐ray diffraction and Raman spectroscopy confirmed the retention of the calcite phase, with no evidence of aragonite or vaterite, demonstrating phase stability. Scanning electron microscopy micrographs revealed a dense microstructure with minimal porosity and well‐developed grain contacts, consistent with the improved mechanical performance. These results highlight the potential of cold sintering as a sustainable, low‐temperature, and binder‐free route for fabricating dense and mechanically robust CaCO 3 ceramics.