Glass internal expansion is the main cause of nickel sulfide glass blew . After the glass was tempered manager, the surface layer stress. Internal board core tensile stress was compressive stress and tensile stress together constitute a balanced body . Glass is a brittle material itself , but the impatience pull pressure , so most of the broken glass tensile stress is triggered . When heated glass and steel , glass plate core internal temperature of about 620 ℃, all nickel sulfide phases are in α-NiS high temperature state . Subsequently, the glass into the wind gate quench , nickel sulfide glass phase transition occurs at 379 ℃ . And float Lehr is different, steel quench time is very short , too late into a cold state β-NiS and high temperature nickel sulfide α -phase state is "frozen " in the glass. Rapid quenching the glass to steel, to form the unified external pressure balance sheets of stress the body . Already toughened glass in the nickel sulfide phase change continuously engaged in low- volume expansion continues to expand its forces around the glass increases. Tempered glass plate core itself is tensile stress layer , phase change volume expansion also formed when tensile stress within the nickel sulfide layer tensile stress occurs , both the tensile stress superimposed together , enough to trigger a burst that blew glass .
Simply put, nickel at high temperature is very small , but at room temperature, they become large. Glass nickel element in the heating process becomes small, but not in the rapid cooling to room temperature, and the state changes back to the body , the glass blew . State regulations, blew glass was 3 ‰.