Annealing of high-alumina & SiC. Is it really worth it?

[tsapa]

Greetings,

I've heard through numerous ceramic manufacturers that annealing "technical ceramics" such as >99% alumina, sintered silcon carbide, etc., is sometimes worth the extra step, sometimes not. It makes sense to anneal the finished part after it has undergone extensive post-firing grinding to relieve stresses, but is this actually true and is it common practice? Does anyone have experience in doing so, and if yes - would it be for stress relief of other reason(s)? The parts we would be annealing would be for use in valves and pumps.

Thanks!
Tsapa

 

[corrosionman]

We make extensive use of the two materials you mention for wear resistant plates on scroll conveyors off centrifuges whee they protect against incredibly dense abrasive materials. We never heard of annealing the material in 12 years of use. Tomorrow I will enquire of my suppllier if he does this. Watch out that SiC is electrically conductive and therefore will act exactly as a dissimilar metal and can cause corrosio problems. Cheers David Whitlock.