Some solutions to the nickel sulphide problem in toughened glass

Tempered glass in high rise buildings is still failing because of the presence of nickel sulphide inclusions albeit at less frequent intervals. When glazed panels are found to contain nickel sulphide inclusions there are several options available ranging from simple replacement on failure to reglazing the entire building. The chosen option depends on the economics associated with each outbreak. Although heat soaking can almost completely eliminate the possibility of nickel sulphide failures it is not always used because of commercial considerations. A better approach is to ensure that there are no inclusions in the glass in the first place. Initial results indicate that nickel sulphide free glass can be produced by melting under oxidised conditions (P O2 ≥10 -3 atm at 1300°C)