What’s heat-soaked glass?
Heat-soaked glass is a type of tempered glass treated under specific conditions. Unlike ordinary single-pane tempered glass, heat-soaked glass forms compressive stress on the surface of the glass after being subjected to external forces rather than tensile stress. This makes the glass highly resistant to impact even after being struck.
Why is heat soaking?
Tempered glass is commonly used as safety glass in the construction industry, particularly in tall buildings. However, tempered glass tends to self-explode, with an industry-wide allowance of 0.3%. This spontaneous shattering can cause issues during use, and to address this risk, one solution is heat soaking. Heat soaking is a process that involves treating tempered glass to reduce the likelihood of self-explosion before it leaves the factory, significantly decreasing the risk of self-explosion during use.
How to make heat-soaked glass?
Heat-soaking tempered glass involves placing it in a heat-soaked furnace and gradually increasing the temperature to around 298°C while maintaining a heating rate of no more than 1.5°C/min. This temperature is held for several hours, causing any nickel sulfide phase or hard impurities within the tempered glass to expand and potentially shatter the glass. After cooling, intact glass can be removed from the furnace. This process is also referred to as explosive treatment.
Special quality requirements for heat-soaked glass
The heat-soaked glass must meet all standard quality requirements, including specific regulations for bending strength. The bending strength is determined by a 95% confidence interval and a 5% probability of breakage. The bending strength of heat-soaked glass must meet the following requirements: heat-soaked glass made from float glass must have a flexural strength of 120MPa, coated heat-soaked glass must have a flexural strength of 120MPa, ceramic fritted heat-soaked glass must have a bending strength of 75MPa, and textured heat-soaked glass must have a bending strength of 90MPa.
Why is heat-soaking not widely used?
Heat soaking is not commonly used due to several reasons. Firstly, there is no reliable method to determine whether tempered glass has undergone heat soaking. Second, heat soaking involves placing tempered glass in a furnace for several hours, causing any nickel sulfide within the glass to expand and potentially shatter the glass. However, it is impossible to accurately predict how much the glass will break during this process, making it difficult to control and ensure consistent quality. Finally, there is insufficient data to accurately see the self-explosion rate of tempered glass after heat soaked.