Highly Porous Vitrified Bonded Abrasives by the Selective Extraction of Butyl Carbamate from Green Grinding Wheels with Supercritical CO2

Abstract

Highly porous vitrified bonded grinding wheels were produced by selective extraction of butyl carbamate pore inducer using supercritical (sc) CO2. Butyl carbamate was found to be an excellent pore inducer, as the extraction was fast and the desired pore structure was obtained. The investigation revealed that the extraction was controlled by the solubility of butyl carbamate in scCO2 and the flow direction had a large effect on extraction times. The solubility of butyl carbamate determined from cloud point measurements was found to be high at moderate conditions. Grinding tests demonstrated that scCO2 pore‐induced wheels performed slightly better then conventionally produced wheels at the conditions investigated. The power required for grinding, wheel wear, and part quality were comparable with those of conventionally produced wheels at low metal removal rates. However, the extracted wheels outperformed the conventional wheel at high metal removal rates, indicating the scCO2 processing produces a slightly superior product than that made by conventional means. Liquefaction of the pore inducer during extraction had a minor effect on the final properties of the wheel.