One of the most attractive features of quartz glass is its very low thermal coefficient of expansion (TCE). The average TCE value for quartz glass at about 5.0 × 10 –7/ °C is many times lower than that of other common materials. To put this in perspective, imagine if 1 m3 blocks of stainless steel, borosilicate glass and quartz ware were placed in a furnace and heated by 500 °C. The volume of the stainless steel block would increase by more than 28 liters and that of the borosilicate block by 5 liters. The quartz block would expand by less than one liter. Such low expansion makes it possible for the material to withstand very severe thermal shock.
It is possible to rapidly quench thin articles of quartz glass from over 1000 °C by plunging them into cold water without breakage. However, it is important to realize that the thermal shock resistance depends on factors other than TCE such as surface condition (which defines strength) and geometry. The various types of fused silica and fused quartz have nearly identical TCE’s and thus can be joined together with no added risk of thermally induced breakage.
