English

Etymology

Spear sense from Old Norse grein meaning division. (Reference: Ray Parkin, H. M. Bark Endeavour, Miegunyah Press, second edition 2003, ISBN 0-522-85093-6, page 196.)

Noun

grains

1. Plural of grain
2. An iron fish spear with a number of points half-barbed inwardly.

   1770: Served 5 lb of fish per man which was caught by striking with grains — journal of Stephen Forwood (gunner on H.M. Bark Endeavour), 4 May 1770, quoted by Parkin (page 195).

For grains in the sense of cereal crops, see cereal.

Explanation

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.

Method

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.