"fiberglass" is also known as "glass wool" or "fiberglass". It is a new material that plays a reinforcing role. It is usually used as a reinforcing material in composite materials, electrical insulation materials and thermal insulation materials, circuit substrates and other fields of the national economy. The diameter of its single filament is a few microns to more than 20 microns, which is equivalent to 1/20-1/5 of a hair. Each bundle of fiber strands is composed of hundreds or even thousands of single filaments.

It is made of six kinds of minerals, including pyrophyllite, quartz sand, limestone, dolomite, colemanite, and magnesia stone, through high-temperature melting, wire drawing, yarn winding, and weaving. It is an inorganic non-metallic material with excellent performance and a wide variety of types. Its advantages are good insulation, strong heat resistance, good corrosion resistance, and high mechanical strength, but its disadvantages are brittleness and poor wear resistance.

The main components are silicon dioxide, aluminum oxide, calcium oxide, boron oxide, magnesium oxide, sodium oxide, etc. According to the alkali content in the glass, it can be divided into:

①, Alkali-free fiberglass (sodium oxide 0%~2%, aluminoborosilicate glass)

②, medium alkali fiberglass (sodium oxide 8% ~ 12%, boron-containing or non-boron-containing soda-lime silicate glass) and high alkali fiberglass (sodium oxide more than 13%, soda-lime silicate glass).