Alumina and Zirconia crucibles
The link between metals and ceramics is a long one. Archaeologists have found evidence linking the use of ceramics to contain molten metal as far back as 6000BC. Ceramic containers (Crucibles) continue to be used to this day.
Whereas the basic principals of casting have remained the same over the years, the technology has changed significantly. Methods of melting have changed with the advent of mains power although believe it or not there are still a small number of foundries in the UK melting on an open fire. The ceramics used are also much more technically advanced.
As more stringent requirements for castings such as jet engine components and other high-tec applications have developed then the ceramics used for these materials and the methods to produce the ceramics have continued to evolve.
Alumina and Zirconia are the materials of choice for these high end applications. Crucibles made from these materials can be formed in a variety of ways giving differing performance characteristics. It is often the case that high end zirconia crucibles are used as a matter of course as this is the safest option to prevent contamination. The problem with this is that in a lot of cases this results in a crucible spend considerably higher than necessary.
As with all applications involving ceramics, the selection process for the material and production method is critical if you are to achieve the most cost effective solution.