Tempered glass homogenization treatment, also known as hot dip treatment, is the process of reheating tempered glass to around 300 ℃, then holding it for two to four hours, allowing defective glass to burst during this process. This is called homogenization treatment. So why does tempered glass need to be homogenized? Is this necessary for all tempered glass?

What is homogeneous tempered glass?

What are its advantages?

Homogeneous tempered glass is a product obtained by homogenizing tempered glass,and there is currently a national standard for this product.The homogenization treatment process is to place tempered glass in a homogenization furnace,maintain a heating rate of no more than 1.5℃/min,and continue to heat up to about 298℃for several hours,promoting the NiS transformation or hard impurities inside the tempered glass to expand and cause glass breakage.After gradually cooling,the intact glass is taken out.This process is also vividly referred to as detonation treatment.

Why does tempered glass need to undergo homogenization treatment

The process of homogenization treatment

The main purpose of homogenizing tempered glass is to reduce its self explosion rate.In the national standard for tempered glass GB15763.2-2005,the phenomenon of self explosion of tempered glass is explained.Nickel sulfide crystals appear in the tensile stress zone of tempered glass,and self explosion occurs when the crystals transform.So generally,a glass tempering furnace is used to homogenize the glass and improve its safety during use.

The probability of self explosion of tempered glass allowed by the industry is 0.1%to 0.3%,which is determined by the inherent characteristics of the glass and cannot be avoided.The main way to solve this phenomenon is to control the quality of glass raw materials and control the stress of tempered glass within an appropriate range.Homogenization treatment is widely recognized as an effective method to solve the problem of self explosion.

The reasons for self explosion of tempered glass

The reason for the self explosion of tempered glass is the mixing of sulfur and nickel impurities during the glass manufacturing process,which generates nickel sulfide at high temperatures.Nickel sulfide has two types of crystallization,which occur at high temperatures(t>380℃)αAt low temperaturesβXiang.Due to rapid cooling during tempering,αWithout enough time to transform intoβXiang.During use,it is metastable at room temperatureαGradually transforming into a stable phaseβThe self explosion of tempered glass is caused by approximately 4%volume expansion.

The benefits of homogenizing tempered glass

The function of a homogenizing furnace is to make nickel sulfideαCompletely transformed into low-temperature stable phaseβSimilarly,the glass produced from the furnace is unlikely to self explode,effectively ensuring that tempered glass has no possibility of self explosion.

The process of homogenization treatment

The process of homogenizing tempered glass includes three stages:heating,insulation,and cooling,which is similar to the process of tempering the original sheet.

1.Heating stage:The heating starts from the ambient temperature of the glass and stops after all the glass reaches 280℃.The surface temperature of the glass should not exceed 320℃,and the time for the glass surface to exceed 300℃should be shortened as much as possible,which requires us to heat up more evenly.

2.Insulation stage:After all glass reaches 280 degrees Celsius,turn on the insulation and maintain the surface temperature of the glass within the range of 10℃above and below 290℃for at least two hours.

3.Cooling stage:After the insulation is completed,the glass enters the cooling stage,allowing it to drop to room temperature.When the temperature inside the furnace drops to 70℃,the furnace door can be opened to terminate the cooling output.

Homogenization process inspection

Generally,inspections are conducted by qualified third-party supervisory agencies,including on-site inspections of the homogenization process and inspections of homogenized glass products.The inspection includes parameters such as spacing,position,type,material,temperature,etc.during the operation process,as well as inspections of the related properties of the finished tempered glass.The validity period of the report issued by the inspection is one year.

This inspection can standardize the homogenization process of enterprises,further standardize their production behavior,ensure the quality of homogenized tempered glass,and improve the safety of product use.

The above is why tempered glass needs to be homogenized?And an introduction to the process and inspection methods of homogenization treatment,hoping to help everyone better understand the significance of homogenization treatment for tempered glass.

(The article comes from the internet)