- For grains in the sense of cereal crops, see cereal.
Grains is the giant structure of a metal is not usually the same all through the metal. if you look closely at a metal surface that has been spacially prepared, you can see that the metal is made up of a number of small crystals. These are called grains, and the places where they join are the grain boundaries.
A method of preparing preferred abrasive grain material is provided. The method involves steps of coating a non-sintered aluminum base particles with a metal alkoxide containing coating; heating to convert the coating to a metal oxide coating; and then sinter the base particles to provide sintered particles having an alpha-alumina-based core with an autogenously bonded metal oxide coating. The invention also concerns improved abrasive grain materials and abrasive products including the improved abrasive grain materials therein.