Separate phases with little borosilicate having warmth expansion coefficient, high deformation temperature and good mechanical properties and a method for the production thereof

摘要

1338386 Opal and opaque glasses ANCHOR HOCKING CORP 25 Nov 1970 [26 Nov 1969] 56138/70 Heading ClM An opacified glass article comprises in weight percentages the opaqueness being produced by the presence in the article of at least two immiscible vitreous phases, the quantity of alkali metal oxide when present being less than 3%, the quantity of Na 2 O when present being less than 1% and the balance, if any, being compatible. When the Al 2 O 3 content is 18-23, CaO and ZnO may each be present in an amount 0-6%. Up to 6% of PbO, TiO 2 , ZrO 2 or SnO 2 may also be present. Many examples are given. The vitreous phases may be produced either by careful cooling of the article or by a reheating step below the temperature necessary to crystallize the glass. By controlling the cooling of window glass to avoid phase separation, a transparent glass may be produced which will then phase-separate on heating, as during a fire. The opaque glass can be used for insulators and table ware. Specification 1,162,015 is referred to.