Preparation of Sound‐Insulating Lightweight Ceramics from Aluminosilicate Rocks with High CaCO₃ Content

Abstract

A sound‐insulating lightweight ceramics with “pseudo‐open” porosity was obtained from calcite‐zeolite rock using energy‐saving procedure. A thorough analysis of chemical processes occurring during material preparation revealed that decomposition of CaCO3 with extensive gas release destroys cellular structure of thermally softened material. The latter, however, can be overpassed by proper alkali activation, which leads to transformation of CaCO3 into sodium carbonates (like trona and thermonatrite) with lower decomposition temperature. The reported results suggest that quality lightweight ceramics with sound‐insulating properties can be obtained even from poorly zeolitized rocks with high CaCO3 content previously treated as unsuitable for such application.

Biocompatible, Ultralight, Strong Hydroxyapatite Networks Based on Hydroxyapatite Microtubes with Excellent Permeability and Ultralow Thermal Conductivity

“…In the past decade, ultralight materials such as aerogels and microlattices have been of great interest owing to their superior properties including high porosity, low density, and low thermal conductivity; thus, they are promising for applications in many advanced technologies from catalysis to thermal/acoustic insulation to environmental protection, etc. − Up to now, different kinds of ultralight materials have been successfully prepared including Au aerogel, Cu aerogel, graphene aerogel, carbon nanotube aerogel, silica aerogel, alumina aerogel, lightweight ceramics, nanolattices/microlattices, etc. − Although some progress has been made, the dimension, porosity, density, and mechanical properties of those materials usually cannot meet the requirements for practical applications. For example, aerogels exhibit high porosity but tend to be low in mechanical strength. , Nanolattices and microlattices possess both high porosity and outstanding mechanical properties, but their dimensions are usually small. , Recently, ultralight, strong, three-dimensional SiC structures with high porosity and ultralow density (300 mg/cm 3 ) were fabricated using SiC microfibers, which exhibited advantages such as low thermal conductivity and acoustic impedance; however, the sintering temperature was very high nearly up to 2000 °C, and sintering aids and a special atmosphere were needed for the synthesis.…”