Environment-Sensitive Hardness and Machinability of Alumina

摘要

The influences of water, toluene and the n-alcohols on the pendulum hardness of alumina monocrystals, and on the ease of drilling mono- and polycrystalline alumina, have been studied. It has been found that the adsorption-induced increases in pendulum hardness produced by certain alcohol environments can result in rates of drilling with diamond-studded core bits which are up to ten times greater than those measured in tests under water. A correlation between pendulum hardness, machinability and surface charge (the latter as indicated by zeta-potential measurements) has been established. This is that alumina is hardest and most effectively drilled with a diamond core bit at its zero point of charge. The possibility of making use of this correlation to develop more cost effective and ecologically viable cutting fluids for the machining of aluminia is discussed. (Author)