Process for the preparation of alumina abrasives

摘要

The present disclosure is directed to a method of converting the preferred hydrated alumina oxide, boehmite, into a green particle which is then sintered to form an abrasive alumina particle. The process involves dispersing boehmite in water at a slightly elevated temperature with an acidic pH, then seeding it with alumina seed particles and drying it, then crushing to desired shapes and sizes, calcining the dried precipitate and sintering the calcined. This forms a high quality alumina abrasive grains. The apparatus used for sintering incorporates an elongate hollow tube, an insulative sleeve thereabout to define an elevated temperature zone, and a microwave generator coupled through a wave guide into a microwave cavity incorporated in the tube. The particles are moved through the tube at a controlled rate to assure adequate exposure to the microwave radiation.