How to solve the tempered glass self-explosion?
SHENZHEN JIMY GLASS CO., LTD. Original 2017-07-10 15:53:38
Tempered glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. In order to improve the strength of the glass, We usually using chemical or physical methods to form the compressive stress on the glass surface. When the glass is subjected to external forces, the surface stress is first offsetand keep increasing the carrying capacity. Tempered glass as one of the most important building material in building industry. When we are thinking of the advantage of it, but we also worried about the self-explosion of the tempered glass.
Why tempered glass self-explosion happen?
- Impact of glass quality defects, There are stones in the glass, impurities, bubbles: glass impurities are tempered glass is weak, but also stress concentration. In particular, if the stone in the tempered glass tensile area is an important factor leading to burst.
- The stress distribution in the tempered glass is not uniform and offset. The temperature gradient of the glass in the direction of the thickness of the glass during heating or cooling is not uniform and asymmetrical. So that the trend of blooming products, and some in the cold when the "wind burst." If the tensile area is shifted to one side of the article or offset to the surface, the tempered glass is blew.
- The degree of steel, the experiment proved that when the degree of steel to 1 / cm when the number of self-explosion up to 20% to 25%. This shows that the greater the stress the greater the degree of taper, the greater the amount of self-explosion.
How to solve the slef-explosion of tempered glass?
Both reducing the stress value and stress evenly can solve the tempered glass self-exlosion,but the best way is heat soak. Heat soak treatment, also known as homogeneous treatment. The heat soak treatment is to heat the tempered glass to 290 ° C ± 10 ° C. And insulation for a certain time. So that nickel sulfide in the tempered glass in the rapid completion of crystal phase transition. Reducing the use of tempered glass after installation. The method generally uses hot air as a heated medium. We called "Heat Soak Test", referred to as HST, literal translation for the heat soak treatment. From the principle point of view, heat soak treatment is neither complicated nor difficult. But in fact to achieve this process is very difficult. Studies have shown that there are many chemical formulas of nickel sulfide in glass. Such as Ni7S6, NiS, NiS1.01 and so on. Not only the proportion of various components, and also may be doped with other elements. The phase change is highly dependent on the temperature level. Studies have shown that the rate of phase change at 280 ° C is 100 times that at 250 ° C, so it is necessary to ensure that the glass in the furnace experiences the same temperature regime. Otherwise the low temperature of the glass on the one hand due to insufficient insulation time, nickel sulfide can not completely phase change, weakening the effectiveness of heat soak. On the other hand, when the glass temperature is too high, it may even cause reverse phase transformation of nickel sulfide, resulting in greater hidden dangers. Both of these conditions can lead to heat soak treatment and reactive and even counterproductive. The temperature uniformity of the heat soak furnace is so important. In fact, heat soak technology and equipment has been constantly improving. German standard DIN18516 in the 90 version of the provisions of the holding time of 8 hours, while the prEN14179-1: 2001 (E) standard will keep the insulation time down to 2 hours. The effect of the heat soak process under the new standard is very significant, and there is a clear statistical technical indicators. Heat soak can be reduced to 400 tons of glass per case blew. On the other hand, the heat soak furnace is also constantly improving the design and structure, heating uniformity has also been significantly improved, the basic can meet the requirements of heat soak process. Although the heat soak treatment can not guarantee that no blew does not occur, but reduce the occurrence of blew, real solution to the troubled works of the parties self-explosion the problem. So heat soak is the world's unanimous endorsement of the most effective way to solve the problem of self-explosion.