Doug, I've only ever called it refractory cement. I would imagine there are different types. and suppliers with brand names. I'd check out a group called castinghobby. They are a yahoo group. A good many of them build their own speciality furnaces. They will know about casting over your heating element also. The element in my oven sits in a grove and when the element breaks it can be easily replaced. Just a thought. Brad

I just paint my resistance elements with ITC-213, a product made by International Technical Coatings for that purpose. It seals the elements against oxidation, prolonging their life. For small quantities, try the Anvilfire Store.

You might also check with Omega.  They sell lots of resistance heating components and materials.

Pryor Giggey makes a whole line of these castable refractory cements. I have made cast forges with some of them, and it works very well.
They have distributors all around the country.

http://www.pryorgiggey.com/