Nickel sulphide: new results to optimise the heat soak test for thermally toughened building glasses

Abstract

The spontaneous failure of tempered facade glazings has been known as a security and reputation problem of these beautiful parts of the surface of modern buildings since the late fifties. By kinetic investigations on synthetic nickel sulphides and by statistical analysis of the breakage of heat soak test ovens it is shown that this problem can be solved. If the test is done in a right and careful way, at temperatures of (290 ± 10) °C, holding time need not be longer than 2 to 3 h to fulfil the implicit requirements of the German Standard (DIN 18516). On the other hand, literature data show that it should be possible to further shorten this holding time if it were possible to heat up faster and more homogeneously the glass to be tested.