Do You Know What Borosilicate Glass Is ?

In the previous article, we discussed Aluminum-silica Glass. When we think of Aluminum-Silica Glass, the first thing that comes to our mind is its excellent transmittance, high clarity, and high color reproduction. For example, Corning's Gorilla is a very famous Aluminum-Silica Glass brand.

Then Borosilicate Glass, what do we first emphasize? Of course, it has an ultra-low coefficient of thermal expansion (one-third of ordinary glass), which means that borosilicate glass has excellent resistance to high temperature and thermal shock.

I. What is borosilicate glass? What is its composition?

Glass Containing boron trioxide (B-2O-3) 5 to 13 % (m/ m) is called borosilicate glass, of which high silica-boron glass is used when SiO2 > 78% and B2O3 > 10% in the components, which has very obvious advantages in its performance.

It has the following four kinds:

1, low alkali borosilicate glass: refers to the SiO2-B2O3-R2O composition, containing low R2O, high SiO2 glass, small coefficient of linear expansion, small dispersion, good chemical stability, high thermal stability, good electrical insulation, used as a former glass (such as Pyrex), heat-resistant cooking utensils, ampoule glass, neutral glass, electro-vacuum glass, optical glass, LCD substrate, solar panels and collectors.

2, alkaline earth borosilicate glass: SiO2-B2O3-RO composition, such as SiO2-B2O3-PbO composition, the use of the preparation of optical glass, low-temperature glaze; SiO2-B2O3-PbO/ZnO composition used for crystalline powder solder, for cathode ray tube (CRT) sealing; SiO2-B2O3-ZnO composition for rectifiers, passivation of electronic devices. .

3, lanthanum borosilicate glass: refers to the SiO2-B2O3-La2O3-RmOn composition, such as SiO2-B2O3-La2O3-CaO-ZnO-ZrO2 composition has a high refractive index, low dispersion, better chemical temperature, lower transmittance loss, used as optical glass.

4, rare earth doped borosilicate glass: SiO2-B2O3-RmOn as the base composition, doped Pr, Nd laser glass, doped Au, Ag, Cu, non-linear optical glass, light-emitting glass with reference to CdS, ZnS: Mn nanocrystals.

Therefore, borosilicate glass has a very low coefficient of thermal expansion, good thermal and chemical stability and mechanical properties, as well as the advantages of adaptability and low cost.

Seeing this, maybe you don't understand what coefficient of thermal expansion means?

What does a high or low coefficient of thermal expansion mean for glass?

First, let's look at the concept of coefficient of thermal expansion:

"The coefficient of thermal expansion refers to the phenomenon of expansion and contraction of an object due to a change in temperature. Its ability to change is expressed in terms of the change in the amount of length due to a unit change in temperature at equal pressure (p certain)."

What does this statement mean?

Simply put, glass expands at high temperatures!

So, can it expand indefinitely? It can't! Because when glass expands to a certain point, it bursts.

Therefore, we know that the higher the temperature, the smaller the glass expands, the more subtle, or almost no expansion, then the glass is more stable. The lower its coefficient of thermal expansion.

Let's look at the physical and chemical properties of borosilicate glass as an example: 

Borosilicate glass is precisely due to the many excellent properties: such as good thermal stability, resistance to thermal and cold shock, the chemical stability mechanical, technological and optical properties, it is now widely used in optical batteries, pharmaceutical glass, utensils, optoelectronics and other fields.