pelagic02 said:
We would want to produce fireclay assay crucible here in the Philippines.Can somebody advise me the material composite of this product?We have tested several fireclays available but they crack on a single trip.We use cordierite-mullite grog but they are expensive for mass production.Is it true that they are made mostly of Sillimanite?It seems they are easy to make at first glance but truth is on the contrary.
I don't know the exact answer to your question, but I would think the amount of alumina and silica, as well as other components would be the key. You may also need to check the particle size of the clay, and make sure you are getting a good mix. Then, the type of mold is going to be important- do not use a clamshell mold as this will lead to seams. You need a type of mold that will minimize any "folds" in the clay. And finally, you need to have the proper mold pressure and fire temperature. You may need to hire a ceramic engineer to nail all these issues down because, as you say, "it ain't easy"!