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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Dear Friends<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I just located this old file from ProBEC showing a test of the Baldosa tile sample picked up at ETHOD ins 2008 (thanks to Dean S).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>It shows that after firing ‘properly’ to over 800 C there is a grate change in the thermal expansion characteristics. While the expansion coefficient is not particularly low, there is a dramatic suppression of the S curve typical of the silicon transformation at 573 degrees that is the main cause of most ceramic/clay stove fracturing.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The main discovery from the XRF and XRD analysis was that there is no free silica in the Baldosa tile (once fired well).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This may be of interest to stove producers in Central and South America who have access to traditional Baldosa tile production knowledge. The absence of a 573œ silicon phase change from A to B condition implies there is virtually no free silica in the final fired product.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The results are plotted against a lower expansion product containing a medium-level lithium content (≈4%) additive from Bikita Mina in Zimbabwe that (very unusually) contains no iron.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The expansion measurement/trace was made with a Dilatometer but you can do it as well with any sample, an oven and a digital caliper.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Regards<o:p></o:p></p><p class=MsoNormal>Crispin<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>