A route to highly porous grinding wheels by selective extraction of pore inducers with dense carbon dioxide

A novel route for the production of highly porous vitrified grinding wheels was developed via selective extraction of pore inducers with dense CO2. The extraction was performed with liquid and supercritical CO2 (scCO2) at temperatures ranging from 295 to 338 K, pressures from 8.8 to 27.6 MPa and flow rates of 3.4×10−5 and 7.5×10−5 kg s−1 CO2. The extraction rate was a strong function of temperature, flow rate, and flow direction, while unaffected by particle size of the pore inducer and pressure. The extraction had no detrimental effect on the green wheel’s microstructure. Grinding tests were performed on the CO2 extracted pore induced wheels and results were compared to those from a conventionally manufactured pore induced grinding wheel. The extracted grinding wheels performed similarly to the conventional wheels. At high metal removal rates, the extracted wheels with large pore sizes outperformed the wheels with smaller particle sizes as well as the conventional wheel. This may be due to the larger pore sizes increasing lubrication at the surface and increasing the wheel strength.