Although the tortoise is alive, there is still time; the python is foggy and ends up being ash. Everything in the world has a process from production to extinction. Nothing is immortal. Even the universe we exist, according to speculation by cosmologists at the University of North Carolina, will be annihilated after 22 billion years.
The ancient beasts and the annihilation of the universe are far away from us, but as a hard-working glass man, what is the life of the glass we deal with every day? Let's talk about it today. . .
The life of glass ordinary glass (soda lime glass) does not have "aging" problems in the natural environment. The chemical composition of the glass is very stable. In the natural state, the glass will not be affected by the sunlight and rain, and the performance will be attenuated; ordinary acid and alkali will not damage the glass, so we think that the chemical experiment utensils at the time of reading are clear. It is.
Usually only two conditions affect the life of the glass, humid air and high temperature. Persistent moist air can cause mildew in the glass, but at room temperature, the mildew of the glass is very slow, usually takes several months, and there are few humid air that lasts for several months under normal use. Therefore, the glass will not be mildewed when exposed to the air. Generally, the mildew of the glass occurs in the overlapping storage process of the glass, and the glass is more prone to mildew in the wet warehouse or in the open air. In general, raw glass without tempering is more susceptible to mildew than tempered glass.
Regardless of the thermal cracking factor, temperatures below 300 °C have no effect on glass life and chemical stability. However, as the temperature rises above 300 °C, the physicochemical properties of the glass change with increasing temperature. Physically, the general glass begins to soften at around 600 degrees. Chemically speaking, an increase in temperature causes crystallization in the interior of the glass, causing the glass to gradually change from transparent to fuzzy. The process of devitrification of the glass at 700 ° C takes several days, and in the case of 300 ° C it may take months or even years. In the case of normal temperature, the crystallization of the glass may become ambiguous for tens of thousands of years, so it may not be considered.
The life of tempered glass is physical tempering, which is to heat and quench the glass, which changes the structure between the molecules and molecules in the glass. Chemical tempering is used to ion exchange the molecular structure of the glass surface at high temperature; both methods are longer. Changed the microstructure of the glass material. Therefore, unless there is high temperature and strong chemical action, the characteristics of the tempering will not attenuate or change with time under normal use.
Life of Insulating Glass Insulating glass is a combination of a glass substrate, a spacer frame (aluminum strip), a desiccant (molecular sieve), a sealing material (butyl rubber, polysulfide rubber or structural adhesive). In the construction of insulating glass, glass and aluminum frames are usually very stable, and the life of insulating glass depends on the life of molecular sieves and sealing materials.
In the construction of the insulating glass system, the glass is very stable. In the case of the glass substrate, we have mentioned that the problem of aging is not considered in the case of substantially normal use; the aluminum strips recommended by the standard hollow are surface anodized. The physicochemical properties of the surface anodized aluminum strip are very stable under normal conditions. Even if the aluminum strip without surface anodization is almost inferior, the oxidation will occur during use to tarnish the aluminum strip, but this has no significant effect on the properties of the aluminum strip itself.
For the insulating glass, we should see that the value of the hollow system construction is that the hollow glass with closed and dry cavity can play the role of heat insulation and sound insulation. Due to changes in ambient temperature, the gas in the hollow cavity is always in an expanded or compressed state, so that the insulating glass sealing system is always under stress, and the ultraviolet, water and moisture in the environment will accelerate the aging of the sealing system, resulting in The water vapor accelerates into the hollow cavity. When a large amount of water vapor appears in the hollow glass cavity, the insulating glass fails, and the failure of the insulating glass means that the service life of the insulating glass is terminated. The key to ensuring that the insulating glass does not fail is the desiccant and sealing material.
Regarding the life of insulating glass, the concept of 10-year warranty period was given by Chinese glass enterprises with reference to American standards. In the insulating glass national standard GB/T11944-2012, the reference convention for the life of insulating glass was proposed for the first time. The life expectancy of glass should be greater than 15 years. In fact, the life of the insulating glass has a close relationship with the selection and processing technology of the insulating glass material, and is also affected by many factors such as the composition of the insulating glass plate and the use environment, which is difficult to quantify. For insulating glass that has been installed on a wall, the simpler measure is actually measuring the dew point or spacer air humidity.
LOW-E Glass Life The life of LOW-E glass depends primarily on the life of the hollow sealing system in which it is located. We know that the main constituent materials of the LOW-E film layer are metals, alloys, metal oxides and metal nitrides. Metal nitrides are generally used as a protective layer in a film structure, and their properties are very stable. The metal oxide and alloy layers generally connect the silver layer and the protective layer as a dielectric layer in the film layer, and the properties thereof are also relatively stable. The silver layer in LOW-E is relatively active, but its oxidation is conditional and requires water vapor.
Therefore, as long as the insulating glass does not fail, it is basically unnecessary to separately consider the life of the LOW-E film layer.
The life of laminated glass is a composite glass product in which two or more organic polymer interlayer films are sandwiched between glass and processed to make the glass and the intermediate film adhere together for a long time. The laminated glass will be stuck to the film even if the glass is broken, which effectively prevents the occurrence of debris pitting and penetrating fall events, and ensures personal safety.
The life of laminated glass depends mainly on the material of the interlayer in the interlayer. Normally, wet laminated glass and EVA laminated glass are mainly used for indoor partitions, and are not suitable for building doors and windows or curtain walls. Wet laminated glass and EVA laminated glass will accelerate aging under sunlight, and yellowing will occur after 1-2 years. Degumming bubbles, ice and fog will appear in 2-3 years. In general, wet laminated glass ages much faster than EVA laminated glass. EVA laminated glass can be used indoors for more than 10 years without direct sunlight.
PVB and SGP laminated glass, which is commonly used as a door or window or curtain wall, has much better aging resistance. The typical failure of laminated glass PVB and SGP is the opening of the glue. Opening the glue means that the glass and the spacer layer are disengaged, losing the safety characteristics of the laminated glass. Regarding the life of PVB and SGP laminated glass, there are currently no relevant standards and specifications in China. At present, domestic glass processing enterprises generally give 5-7 years product warranty period with reference to foreign PVB and SGP supplier related materials.
In fact, the life of PVB and SGP laminated glass is greatly affected by the thickness of the intermediate spacer, the quality of the laminated glass substrate, and the process control of the laminated glass, in addition to the influence of the material of the intermediate layer.
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