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ALUMINA CRUCIBLE INSTRUCTIONS
At Ceramxpert we want you to get the absolute best results possible from every crucible we provide. It is often the case that the difference between a crucible that performs consistently and a crucible that fails to perform at the expected level, is a matter of how the crucible is handled, operated and maintained at the customers end. That’s why we’ve produced these alumina crucible instructions.
Herein you will find a list of tips for how you can expect to get the very best out of your crucible – and increase its lifespan.
1) CHECK YOUR CRUCIBLE FOR CRACKS, DAMAGE OR ABNORMALITIES WHEN RECEIVED.
Our extensive quality control and packaging process helps to eliminate most cases of damage, however very occasionally damage can result in transit. When a crucible arrives at your location we ask you to inspect it carefully and never put a damaged crucible into service. If any are damaged get in contact and we will replace them.
2) HANDLE AND STORE YOUR CRUCIBLES WITH DUE CARE
We tell our customers never to stack crucibles inside one another, as this can lead to cracking.
3) TAKE CARE WHEN INSTALLING YOUR CRUCIBLE
If you do not have adequate clearances between your crucible and top and sides of your furnace this may cause cracking when the heated crucible expands. We recommend positioning your crucibles at least 25mm away from the heating elements (minimum), preferably at least 50mm. Do not overfill or over compact the materials within the crucible – be aware of differences in thermal expansion between the crucible and your material.
4) PREVENT THERMAL SHOCK
Larger crucibles may require some preheating to eradicate the possibility of thermal shock causing cracking, we recommend you place your crucibles on top of a substrate plate of the same material to reduce the risk of thermal shock. For smaller crucibles it is possible to increase the ramp rate without issue, for the larger crucibles we recommend a ramp of rate of around 250°C. For larger crucibles we recommend a maximum heating and cooling rate of 5°C per minute. For smaller crucibles faster heating & cooling rates can usually be used without issues but we recommend carefully increasing rates to confirm what your particular process can withstand.
5) NEVER EXCEED THE MAXIMUM TEMPERATURE LIMIT FOR EACH CRUCIBLE
Every crucible has a maximum temperature limit, these differ by material. If you exceed the maximum temperature for your crucible it will likely become damaged and fail. It is important to maintain careful control of your crucible temperatures.
The bottom of the large crucibles should not be in direct contact with the bottom of the furnace. It is recommended to use alumina footpads or other temperature-resistant materials to raise the crucibles (as shown in the figure below) for air convection.
6) INSPECT YOUR CRUCIBLE REGULARLY, REPLACE IT WHEN IT BECOMES WORN OR DAMAGED
In the same way you would care for a car, you can maintain a log of your crucibles’ use. This will allow you over time to build a service history that can be used to anticipate the normal service life of future crucibles used in the same operations. You can then plan replacement orders around this that will minimize downtime.
At Ceramxpert it is our promise to supply every customer with the exact crucible they need. If you know the exact type of crucible you need and it is not among the products on this site, contact us, as we are able to make crucibles bespoke to your requirements.
We hope you get the most out of these alumina crucible instructions, please note many of the points raised apply to any material crucible or refractory product we supply.
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