Tempered Glass (Reinforced Glass or Toughened glass)
Tempered glass, also known as reinforced glass, is a type of glass with surface compressive stress. The process of tempering, which enhances glass, began in France in 1874.
Tempered glass is a type of safety glass that is pre-stressed to increase its strength. Typically, chemical or physical methods are used to create surface compressive stress on the glass. When subjected to external forces, tempered glass first offsets surface stress, thereby improving its load-bearing capacity and enhancing resistance to wind pressure, temperature variations, and impact, among other factors.
Characteristics:
Safety: When tempered glass is broken by external forces, it shatters into small, blunt, honeycomb-shaped pieces, reducing the risk of severe injury to people.
High Strength: Tempered glass has 3-5 times the impact resistance and flexural strength of ordinary glass of the same thickness.
Heat Stability: It can withstand temperature differentials up to three times greater than regular glass, with the ability to handle variations of up to 300°C.
Advantages:
Enhanced strength compared to ordinary glass, reducing fragility.
Improved safety, even when broken, as tempered glass shatters into small, non-sharp fragments, significantly reducing the risk of harm to humans.
Excellent resistance to sudden temperature changes, with a 3-5 times higher capability than regular glass, which helps prevent thermal cracks. This makes it a preferred choice for high-rise buildings to ensure material safety.
Disadvantages:
Tempered glass cannot be cut or further processed after the tempering process. It must be shaped and processed to the desired form before tempering.
Although tempered glass has higher strength, it is still susceptible to spontaneous breakage (self-explosion), which is not a concern with regular glass.
Slight surface imperfections (wind streaks) and thinning of the glass may occur, especially due to rapid cooling during the tempering process. The degree of thinning varies depending on the equipment used. These factors limit its use for mirrors.
Architectural flat tempered glass, tempered by physical tempering, may have slight deformation, which affects the decorative effect to some extent (except for special requirements).
Manufacturing Process:
Tempered glass is produced by first cutting ordinary annealed glass to the desired dimensions. The glass is then heated to around 700°C, followed by rapid, uniform cooling (approximately 240 seconds heating and 150 seconds cooling for 5-6mm glass). The tempering process creates uniform surface compressive stress and internal tensile stress, greatly enhancing the glass's flexural and impact resistance. The strength of tempered glass is over four times that of regular annealed glass. Once tempered, the glass cannot be cut, ground, or otherwise processed without destroying the uniform surface compressive stress balance.
Classification:
By Shape:
Flat Tempered Glass
Curved Tempered Glass (bent glass)
By Process:Physical Tempered Glass (also called quenching)
Chemical Tempered Glass (produced using ion-exchange methods)
By Tempering Degree:Tempered Glass (Stress level: 2-4N/cm, Surface Stress α ≥ 95Mpa)
Semi-Tempered Glass (Stress level: 2N/cm, 24Mpa ≤ Surface Stress α ≤ 69Mpa)
Super Toughened Glass (Stress level: >4N/cm)
Applications:
Tempered glass, both flat and curved, is considered safety glass and is widely used in various industries:
Building and construction, including doors, windows, and interior decorations.
Furniture manufacturing, such as glass coffee tables and furniture components.
Home appliances like televisions, ovens, air conditioners, and refrigerators.
Electronics and instrumentation, including mobile phones, MP3 players, and watches.
Automotive industry, for car windows, and other glass components.
Everyday products such as glass cutting boards.
Specialized applications, including military-grade glass.
Because tempered glass shatters into uniform, small particles with no sharp edges, it is referred to as safety glass and is commonly used in cars, interior decor, and high-rise buildings with outward-opening windows.