Ceramic microspheres.

摘要

A calcined microsphere of ultrafine bauxite particles having a mean particle size in the range 0.01 to 0.3 micrometers, said microspher having a particle size less than 30 micrometers and being characterised by a substantially solid form having a pycnometric density substantially falling in the range 3.2 - 3.9 g/cm<3>, a BET surface area substantially falling in the range 0.05 to 0.5 m<2>/g and a crystal grain size less than 4 micrometers, the surface chemistry of the microsphere being modified to enhance the wettability to the microsphere and to improve its ability to bond strongly with matrix materials in use.