One sintered material (with the application temp. of 1700C) could be sintered at around 1300C with the aid of some additions in order to lower down the sintering temp. May it change the application temp. into 1300C as well? Or the phase change made into the structure (as a result of sintering aid materials) could resist at the original application temp. of 1700C.
reversible or irreversible depends on the type of alloy additions and its volume phase too, if i am right which will alter the application temperature with respect to the duration
Yeah, calcium carbonate is used for this purpose. There are some other glass modifying reagents that can be used for similar purposes such as sodium oxide,
So, how should we measure that? I mean the change in application temperature without having any trial and error in this regard, which may be catastrophic!
Another word for a sintering aid is "flux". Basically one is forming low melting liquids around the aggregate and when it cools it is either a glass or low melting mineral phase(s). I agree with Amir - does depend on how you are measuring the use limit. Long term shrinkage is one way (min 24 hour reheats at 50F below the use limit), but also important is high temperature creep and/ or hot load deformation near the application temperature.
Thanks for your answers, the problem is that when you use the flux, it seems you're decreasing the maximum tolerable temperature of the product.
Is there any cases in which we can sinter a material in low temp. while it could still be used in very high temp. applications e.g. as a refractory?
or it should be in a temp. close enough to the one in which should be used in?
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