Proper Use - Getting the most out of every crucible

December 17, 2015


At Almath 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.

With this in mind we have produced 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).



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.



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 following table shows our crucible material types alongside their respective maximum temperature:
 Material Type
Maximum Temperature Limit (°C)
(ALM) Alumina 

Al2O3

1750°C
(FSZ) Fully-Stabilised Zirconia 2250°C
(G) Graphite Carbon 3000°C
(BN) Boron Nitride 2000°C
(PBN) Pyrolytic Boron Nitride 2500°C



*DISCLAIMER: All of these temperatures are approximations to be used as guidelines. The actual maximum temperature for your crucible will depend on a number of factors related to your specific application and heating environment (e.g. vacuum).



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.



7) ENSURE YOU HAVE THE RIGHT CRUCIBLE FOR YOUR OPERATION

The most fundamental way you can maximise crucible service life is by selecting the right crucible for your chosen application. Consider our entire range of materials, shapes and sizes, noting that each will provide different results and if in doubt, ask us for a recommendation.

At Almath 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.