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Causes And Solutions Of Tempered Glass Door
Jul 24, 2017

Causes and Solutions of Tempered Glass Door
  Tempered Glass Door blew can be expressed as a phenomenon that the Tempered Glass Door is automatically broken in the absence of an external direct effect. In the steel processing, storage, transportation, installation, use and other processes can occur during the glass door blew. (Such as stones, sand, bubbles, inclusions, gaps, scratches, bursts, etc .; the second is from the glass of nickel sulfide (NiS), the other is caused by the glass can be divided into two kinds of defects: Impurities caused by the expansion of blew.

        This is two different types of blew, should be clearly classified, different treatment, using different methods to deal with and deal with. The former is generally visible, detection is relatively easy, so the production control. The latter is mainly caused by the volume expansion of tiny nickel sulfide particles in the glass, which can not be visually inspected and therefore uncontrollable. In the actual operation and treatment, the former can generally be removed before installation, which can not be tested and continue to exist, become the use of the glass door blew the main factors. Nickel sulfide after the explosion is difficult to replace, high processing costs, and will be accompanied by greater quality complaints and economic losses, resulting in the owners of the dissatisfaction or even more serious other consequences. Therefore, the explosion caused by nickel sulfide is the focus of our discussion.

        Toughening mechanism of Tempered Glass Door

        The expansion of nickel sulfide inside the Tempered Glass Door is the main cause of the glass door blew. After the glass has been tempered, the surface layer forms compressive stress. The inner core layer has tensile stress, compressive stress and tensile stress together constitute a balance body. The glass itself is a brittle material, resistant to pressure but not pull, so most of the broken glass is caused by tensile stress.

        During the phase change of the nickel sulfide crystal in the tempered glass gate, the volume expansion of the nickel nitride crystal in the glass plate core creates a greater tensile stress inside the Tempered Glass Door. When the tensile stress exceeds the limit that the glass itself can bear , It will lead to Tempered Glass Door blew. Foreign studies have shown that: the main glass quartz sand or sandstone into the nickel, fuel and accessories into the sulfur, 1400 ℃ ~ 1500 ℃ high temperature melting furnace melting and melting to form nickel sulfide. When the temperature exceeds 1000 ° C, the nickel sulfide is randomly distributed in the molten glass liquid in the form of droplets. When the temperature dropped to 797 ℃, these small droplets crystallized and the nickel sulfide was in the high temperature α-NiS crystal phase (hexagonal crystal). When the temperature continues to drop to 379 ℃, the crystal phase transition to low temperature state of β-NiS (triplicate), accompanied by 2.38% of the volume expansion. The speed of this transition process depends both on the percentage of the different compositions (including Ni7S6, NiS, NiS1.01) in the nickel sulfide particles and also on the ambient temperature. If the conversion of nickel sulfide is not complete, the process continues even at the temperature of natural storage and normal use, but at a very low speed.

        When the glass is heated, the inner core temperature of the glass is about 620 ° C, and all the nickel sulfide is in the high temperature α-NiS phase. Subsequently, the glass enters the wind gate and quenches, and the nickel sulfide in the glass undergoes a phase change at 379 ° C. Unlike the float annealed kiln, the quenching time is very short, too late to convert to low temperature β-NiS and the high temperature nickel sulfide phase is "frozen" in the glass. Rapid quenching to the glass to be tempered, the formation of external pressure inside the stress balance of the body. In the steel has been tempered in the nickel sulfide phase change at low speed continued, the volume of expansion and expansion, the surrounding glass of the force increases. Tempered Glass Door core itself is the tensile stress layer, located in the Zhang stress layer of nickel sulfide phase change occurs when the volume expansion also forms a tensile stress, the two sheets of stress superimposed together, enough to cause the rupture of the glass door is blew.