| 摘要 |
PURPOSE: A glass plate and a method for tempering a glass plate are provided, to obtain the glass plate for the window of a car, which is reinforced by rapid cooling and whose thickness is thinner. CONSTITUTION: The glass plate comprises 66.0-74.0 wt% of SiO2; 2.0-4.0 wt% of Al2O3; 7.0-10.0 wt% of CaO; 3.8-6.0 wt% of MgO; 12.6-14.6 wt% of Na2O; and 0.4-2.0 wt% of K2O, wherein the content of the components is 96 wt% or more; SiO2 + Al2O3 is 70.0-74.0 wt%; CaO + MgO is 12.5-14.5 wt%; Na2O + K2O is 13.5-15.5 wt%; and the mass ratio of CaO to MgO is 1.7 to 2.2. The method tempering the glass plate which has a thickness of 2-3 mm, an average linear heat transfer coefficient is 88 x 10¬-7/deg.C at 50-300 deg.C and a softening point of 715-740 deg.C, comprises the step of cooling the glass plate rapidly from the glass cooling initiation temperature where viscosity is 10¬9 to 10¬10 poise to the temperature where viscosity is 10¬12 poise, to allowing a heat transfer coefficient (h, W/m2 K) to satisfy the relation represented by h >4970.5 - 3149.9 t + 550.3 t¬2, wherein t is the thickness of a glass plate (mm).
|
