(Image source: ceramics.org)
A paper published as an "Early View" article by the Journal of the American Society shows that yttrium-stablized zirconia can be sintered to full density in a matter of seconds at 850 degrees Celsius. The key is subjecting the process to a dc electrical field above the critical threshold. Traditional YSZ sintering would require hours at 1450 degrees Celsius. The paper was written by Marco Cologna, Rishi Raj and Boriana Rashkova, who are in the process of testing other materials that they hope to be able to report on to the ceramic manufacturing community soon. An article from ceramics.org covers the story. Here's an excerpt:
"The trio's technique was fairly straightforward. They made dog-biscuit shaped samples from 3 mol% nanograin YSZ. They then sintered samples in a vertical tubular furnace, applying a constant dc voltage, varying temperature and voltage. In the stages of their tests, they encountered a phenomenon I have written about before: accelerated sintering speeds at lower temperatures, dubbed field-assisted sintering or "FAST". In fact Raj, Di Yang and Hans Conrad had recently published another paper about how low (20 V/cm) dc electric dields could speed sintering and slow grain growth."
With many radical advances taking place in the field of ceramics engineering since the end of the century, it should come as no surprise that a leap-forward in sintering technology is nigh on the horizon. While the process has not been perfected yet, and the reports are only preliminary at this point, those in our industry would do well to look forward to a more detailed report coming from this team in the coming months.
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