Just found one reference to 1000C. in a newsgroup post.
The Cornish patent seems to support this.
But I cant find any actual reference to a temperature
This article may be worth a look.
Modification of Al Particle Surfaces by -Al2O3 and Its Effect on the Corrosion Behavior of Al
Zhen-Yan Deng1, Yu-Fu Liu1, Yoshihisa Tanaka1, Jinhua Ye1, and Yoshio Sakka1*
Metal Al particle surfaces were modified by fine -Al2O3 grains using a mixture of Al and Al(OH)3 powders, which was pressureless sintered at a temperature of 600°C in vacuum. All the constituents on original Al particle surfaces were transformed into -Al2O3 phase after sintering. No dense passive oxide layers on Al particle surfaces were formed even after the modified Al particles were exposed to oxidation environment. The modified Al particles could continuously react with pure water and generate hydrogen at room temperature. The present finding implies that metal Al could become hydrogen-generation material by surface modification.
from here
http://www.blackwell-synergy.com/doi/ab ... 05.00154.x
I havent had a look at it cause it was going to cost me 40 bucks.
but maybe someone has an access with subscription.
Regards
johnh
JohnH