There are plenty of ceramics that can be used in air over 1,500C - including sintered silicon carbide (up to 1,900C in air). SiC is the material I recommend for your application from both a thermal and strength perspective. We've produced very similar parts like this for pumps, but not quite...
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...
From what I've seen out there, WC is available only in thermal spray form (0.008" to 0.01" thickness), whereas SiC can be made to suit (up to 1" thick or more). Therefore the best option would be to epoxy sintered SiC tiles onto the wear area rather than thermally-spraying WC...
Try a fully-ceramic valve, like Fujikin's Cosmix valve. They're made of 99.5% alumina and are extremely wear resistant. They warranty the valves as well for up to two years.
http://www.fujikin.com/Products/valves/ceramic/cosmixballvalve.html
Check out this link - http://www.ceresist.com/products/fittings/reducers.htm. This company makes ceramic reducers (and other ceramic-lined components) out of solid ceramic. A good alternative to thermal sprays, and definitely better than tiling reducers.
