【Quality Inspection Classroom】Popular science of tempered glass

Tempered glass has quietly penetrated into all aspects of our lives. Whether it is the glass curtain wall of high-rise buildings, the coffee table and dining table at home, or the window of a car, or the screen of a smart phone, tempered glass has become an indispensable safety guardian in modern architecture, transportation, home and other fields with its excellent performance.

1. What is tempered glass?

Tempered glass, also known as tempered glass or safety glass, is a type of prestressed glass that has been treated by a special process. The production process is mainly divided into two steps: first, the ordinary float glass is cut to the desired size and heated to close to the softening point (about 700°C); It is then quickly and uniformly cooled (physically toughened) or the surface composition is changed by ion exchange (chemical toughening). This process causes compressive stress to form on the surface of the glass and tensile stress to the inside, which greatly enhances its mechanical strength and safety. To put it simply, tempered glass is like "putting on protective armor", which is both hard and safe.

2. The advantages of tempered glass

1. Safety: Broken does not hurt people

The most striking feature of tempered glass is its broken form. When destroyed by external force, it will instantly split into small honeycomb-shaped particles, and the edges are blunted, reducing the cutting injury to the human body. This characteristic of "self-explosion into pieces" makes it widely used in glass doors, guardrails, children's activity areas and other scenes in public places, and has become a representative of "safety glass".

2. High strength: compressive and impact resistant

The flexural strength of tempered glass is 3~5 times that of ordinary glass, and the impact strength is 5~10 times that of ordinary glass. This means that it can easily resist external forces such as strong winds, heavy impacts, etc., and even if it is broken, it requires more external forces. For example, the tempered glass on the exterior walls of buildings is effective against typhoons, and the front windshields of cars can withstand the impact of high-speed flying rocks.

3. Heat and cold resistance: "immunity" to temperature differences

Ordinary glass is very easy to burst when it is cold at high temperatures (such as hot soup spilled on cold glass), while tempered glass can withstand temperature changes of more than 200°C. Whether it's a hail shock in the cold of winter or a shower after a summer sun, tempered glass remains stable and avoids the risk of thermal bursts.

3. Disadvantages of tempered glass

Despite its many advantages, tempered glass has limitations:

1. Unable to reprocess: the tempered glass is like a "stereotyped warrior", which can no longer be cut, drilled or edging. All shapes must be machined before tempering.

2. Risk of self-explosion: when the temperature difference changes drastically or the internal stress is uneven, the tempered glass has a self-explosion rate of 0.3%~0.5% (ordinary glass does not have this problem). Although the probability is low, it is necessary to pay attention to the strain relief design during installation.

3. Micro-deformation of the surface: Rapid cooling may lead to slight concave and convex surfaces, and the thickness is slightly thinner (about 0.2~1.8mm), so tempered glass cannot make high-precision mirrors.
4.Ubiquitous application scenarios

1. Architectural field: curtain walls, lighting ceilings, sightseeing elevators, indoor partitions, etc. of high-rise buildings, tempered glass takes into account both beauty and safety.

2. Transportation: The front and rear windshields of automobiles, high-speed railways, and airplanes, and the observation windows of ships are all made of tempered or composite tempered glass to resist impact and temperature changes.

3. Household appliances: oven doors, microwave oven panels, refrigerator doors, coffee table countertops, shower room partitions, etc., heat resistance and safety performance are particularly important.

4. Electronic devices: smart phones, computer screens, touch screens, etc., use tempered glass to protect the screen with wear resistance and high strength.

5. Special scenes: the observation window of chemical high-pressure vessels, the protective glass of shadowless lamps for medical devices, etc., give full play to their heat and pressure resistance.
5. How to identify and use tempered glass?

1. Identification identification: regular tempered glass usually carries the "CCC" certification mark.

2. Installation attention: avoid sharp objects hitting the corners (stress concentration points), and reserve expansion space during installation to prevent thermal expansion and cold contraction.

3. Cleaning and maintenance: use neutral detergents to avoid acid and alkali corrosion of the surface stress layer.
6. Future prospects

With the progress of material science and technology, tempered glass is developing in the direction of lighter, thinner, higher transparency and multi-function. For example, low-emissivity tempered glass combined with coating technology can save energy and reduce consumption, and intelligent dimming tempered glass can dynamically adjust light transmittance, bringing more possibilities for architecture and technology.