adhdchemist: materialsscienceandengineering: e8u: materialsscienceandengineering: Cold sinterin
materialsscienceandengineering:
e8u:
materialsscienceandengineering:
Cold sintering of ceramics instead of high-temperature firing
Both hobbyists’ pottery and engineered high-performance ceramics are only useable after they are fired for hours at high temperatures, usually above 1000 °C. The sintering process that takes place causes the individual particles to “bake” together, making the material more compact and giving it the required properties, like mechanical strength.
In the journal Angewandte Chemie, American researchers have now demonstrated that sintering can also take place at significantly lower temperatures. This cold sintering process is based on the addition of small amounts of water to aid the key transport processes that densify the material.
“Since the stone age, ceramics have been fabricated by sintering at high temperatures,” reports Clive A. Randall from Pennsylvania State University (USA). “This includes the Venus of Doli Vestonice, one of the oldest ceramic objects.” The traditional firing process may now become unnecessary for many ceramic materials, because a broad spectrum of inorganic materials and composites can also be sintered between room temperature and 200 °C.
Unfortunately, I don’t see the part where they talk about oxides. Abstract says it’s in the supporting information, but idk.
They used a die press to compact their samples to very high pressure, in the range of 80-570 MPa (11.6k - 86k psi). Cold isostatic pressing could make this work for more complex shapes. I wonder if the mechanical compaction of the particles is important, or if perhaps this could be done in an autoclave?
Thanks for the links! As far as I can tell, they don’t actually talk much about oxides. I think they just meant that to inform the reader that they had tried the process on several oxides (such as the ones listed in table 1 of the supporting information like ZnO2, ZrO, WO3, and MgO) and that it worked.
As for cold isostatic pressing vs. autoclaving? I don’t know. I am far from an expert, but autoclaves are typically used at higher temperatures and use steam to sterilize the samples. I’m not sure if that would work for samples like these, though, like I said, I don’t know much about the topic.
Anyone else have any thoughts?
My only concern I have would be the amount of material you could synthesize at one time since mega pascal pressures were used. I also feel you could use PXRD for phase ID, but the technique could limit use of other XRD methods, such as single crystal growth if you wanted to do that or even in situ maybe. Definitely an interesting paper though.
