Enhancing semi‐insulating refractory performance with polymeric microspheres and distinct calcium aluminate cements

• Published in: International journal of applied ceramic technology Vol. 21; no. 3; pp. 1668 - 1677
• Main Authors: Farias, Thiago Wisley Barbosa, da Luz, Ana Paula
• Format: Journal Article
• Language: English
• Published: Malden Wiley Subscription Services, Inc 01.05.2024
• Subjects: Additives; Aluminous cements; binder; Calcium aluminate; Density; Formulations; Heat conductivity; Heat transfer; insulating refractory; Insulators; Mechanical properties; mechanical strength; Microspheres; Modulus of rupture; polymeric microspheres; Porosity; Production costs; Refractories; Shock resistance; Thermal conductivity; Thermal resistance; Thermal shock
• ISSN: 1546-542X; 1744-7402
• DOI: 10.1111/ijac.14650

Energy‐related expenses represent a significant concern for industries engaged in high‐temperature processes. In this context, macroporous refractories have garnered notable attention for their potential use as thermal insulators, offering the prospect of energy‐savings and decreased production costs across various industrial sectors. This study investigated the physico–thermo–mechanical performance of semi‐insulating refractory compositions containing pre‐expanded polymeric microspheres as pore‐forming additives and different types of calcium aluminate cements (CACs) as binders. Various experimental tests were employed to characterize the prepared samples, including flowability, modulus of rupture, apparent porosity and density, thermal shock resistance, and thermal conductivity measurements, among others. The incorporation of .6 wt.% of polymeric microspheres into the silica‐based refractory resulted in specimens with relatively moderate porosity values (34.70%), decreased density (1.51 g/cm3) and limited modulus of rupture (3.04 MPa) after firing at 815°C. The alumina‐rich CAC (Secar 71) emerged as the most advantageous binder choice, as the resultant specimens presented mechanical strengths of 9.21 and 4.3 MPa after drying (110°C) and firing (815°C), respectively, enhanced thermal shock resistance and reduced thermal conductivity (.66 W/m K at 800°C). Hence, the designed formulations resulted in semi‐insulating ceramic samples with a porous microstructure and favorable attributes for the fabrication of pre‐molded components.