Abstract
has been chosen as the coating material for cemented carbide cutting tool inserts. The coatings have been prepared by chemical vapor deposition via hydrolysis of 
. The hard, dense and adherent alumina layers consisted of 
when deposited at temperatures above 850°C. Depending on the choice of the deposition parameters, the layer growth rate varied between a few tenths to 20 μm/hr. Machining tests carried out with cast iron and steel have shown that the presence of the alumina coating considerably increases the lifetime of the tool insert, reduces the number and the size of "cutting microholes" on the work piece, and decreases the amount of heat generated.