Glass Fiber Optics
A glass is an non-crystalline solid material. Glass plays an essential role in science and industry. The optical and physical properties of glass make it suitable for applications such as flat glass, container glass, optics and optoelectronics material, laboratory equipment, thermal insulator (glass wool), reinforcement fiber (glass-reinforced plastic, glass fiber reinforced concrete), and art. Glasses are typically brittle, and often optically transparent. Glass is commonly used for windows, bottles, or eyewear and examples of glassy materials include soda-lime glass, borosilicate glass, acrylic glass, sugar glass, Muscovy-glass, or aluminium oxynitride.
Strictly speaking, a glass is defined as an inorganic product of fusion which has been cooled through its glass transition to the solid state without crystallizing. Many glasses contain silica as their main component and glass former. Commonly, glass science and physics deal only with inorganic amorphous solids, while plastics and similar organics are covered by polymer science, biology and further scientific disciplines.
Glass fibre : glass fibres thread made from glass. It is made by forcing molten glass through a kind of sieve, thereby spinning it into threads. Glass fibres is strong, durable, and impervious to many caustics and to extreme temperatures. For those qualities, fabrics woven from the glass threads are widely used for industrial purposes. Glass fibres fabrics can also be made to resemble silks and cotton and are used for curtains and drapery. A wide variety of materials are made by combining glass fibres with plastic.
Pure silica (SiO2) has a “glass melting point” at a viscosity of 10 Pascal Second (100 P) of over 2300 C(4200 F). While pure silica can be made into glass for special applications (see fused quartz), other substances are added to common glass to simplify processing. One is sodium carbonate (Na2CO3), which lowers the melting point to about 1500 C (2700 F) in soda-lime glass; “soda” refers to the original source of sodium carbonate in the soda ash obtained from certain plants. However, the soda makes the glass water soluble, which is usually undesirable, so lime (calcium oxide (CaO), generally obtained from limestone), some magnesium oxide (MgO) and aluminium oxide (Al2O3) are added to provide for a better chemical durability. The resulting glass contains about 70 to 74% silica by weight and is called a soda-lime glass. Soda-lime glasses account for about 90% of manufactured glass.
Two other common glass ingredients are calumite (an iron industry by-product) and “cullet” (recycled glass). The recycled glass saves on raw materials and energy. However, impurities in the cullet can lead to product and equipment failure.
Glassmaking in the laboratory
New chemical glass compositions or new treatment techniques can be initially investigated in small-scale laboratory experiments. The raw materials for laboratory-scale glass melts are often different from those used in mass production because the cost factor has a low priority. In the laboratory mostly pure chemicals are used. Care must be taken that the raw materials have not reacted with moisture or other chemicals in the environment.