Schott Brazil replied my e-mail with some informations. Comparision of coefficient of expansion: Tempered: 6.0x10^-6 Borosilicate: 3,3x10^-6 Neoceram: 0.6x10^-6 (close to zero) Thermal shock: Tempered: 270°C Borosilicate: 360°C Neoceram: 760°C edit: The color variation in Robax and Nextrema are related to the transmission of UV and IR radiation, due to the oxides that compose the glass ceramic, but this does not interfere in the performance of the product nor in the heat transfer They
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