抄録
The changes in the crystal structure of powder produced by a rotating friction mill, devised to produce a submicron powder by the mutual friction grinding of two specimens composed of the identical brittle materials, were experimentally studied by electron microscopic observation, selected area electron diffraction and the X-ray diffraction method. The following results were obtained:
(1) From electron microscopic observation and from the electron diffraction patterns, it was known that the powder produced by friction grinding might form a fairly thick amorphous layer, and that the powder produced by agate mortar grinding might cause cleavage fracture.
(2) From the X-ray diffraction patterns of talc, it was found that growth of the lattice strain and the amorphous layer occurred. It is thought that the material of a layer structure, such as talc, first wore away to cause a slip occurring at the weak bond between layers, followed by two-dimensional structure grinding.
(3) From the X-ray diffraction patterns of limestone and marble, it was found that calcium carbonate was transformed from a crystal of calcite to aragonite by friction grinding. This transformation could be explained by considering the force exerted by friction grinding and the process of ship frequently observed in metal crystals.
