GLASS

“As blowing and making bottles” Have you ever hear this expression? “As blowing and making bottles” WELCOME! Here we will found out if this sentence is really true!

Properties of galss History How they do it? Uses Different types What is the glass? Properties of galss History How they do it? Uses Different types Advantages Colouring Glass

Introduction The term glass was developed in the late Roman Empire. It was in the Roman glassmaking center at Trier, Germany, that the late-Latin term glesum was originated, probably from a Germanic word for a transparent, lustrous substance. Nowadays, Glass plays an essential role in various scientific fields and in industry.

What is the glass? Glass is a hard material, normally fragile and transparent that is obtained by melting at about 1500 Â ° C Salice sand (SiO2), sodium carbonate (Na2CO3) and limestone (CaCO3). The noun "glass" is used frequently as a synonym of crystal, but is incorrect because the glass is an amorphous solid and not a crystal itself.

Properties of galss The thermal, optical, electrical and chemical properties of glass vary with its composition.

Properties of galss Glass is a good thermal conductor. Glass is an electrically insulating material: it does not conduct electricity.

Properties of galss When light falls on glass, part of the light is reflected at the surface, part of the light is absorbed in the glass, and part of the light is transmitted. If most of the light is transmitted, the glass is transparent. By colouring the glass or changing its composition, it is possible to transmit selectively some wavelenghs of the spectrum.

Properties of galss Common glass does not transmit ultra-violet radiation (short wavelengths): you will not get a tan behind a window! However it does transmit infrared radiation (long wavelengths): this is why it is always hot behind a glass window.

History Its first use dates back to ancient times, was for items of jewelery. giving various minerals during the melt were obtained accounts of different colors. Blowing was invented in ancient Rome, a technique that allowed the production of containers, and even pictures to the windows. However, the technique was so primitive that the layers of good quality could only be small size. In the Middle Ages were widely used for the stained glass windows of cathedrals. The glass industry has experienced a dramatic change from the first quarter of the nineteenth century but it was not the end of the eighteenth century they started to manufacture high quality glass for optical instruments. With the years, the use of objects such as bottles, glasses, mirrors and other devices grew, with consequent improvement in quality of life.

The six basic types of glass considered here are: Diferents types The six basic types of glass considered here are: Soda-lime glass (also called lime glass) most common glass. It is made of oxides of silicon (SiO2), calcium (CaO) and sodium(Na2O). cheap to make and can be made into a wide variety of shapes; medium resistance to high temperatures and sudden changes of temperature, fair resistance to corrosive chemicals. used to make bottles and windows.

Diferents types Lead-alkali glass (also called lead glass) lead oxide (PbO) is used in place of calcium oxide. more expensive than soda-lime glass; excellent electrical insulating properties; poor resistance to high temperatures and sudden changes of temperature. used for electrical applications. Borosilicate glass appreciable resistance to high temperature or sudden changes in temperature; medium resistance to chemical attack. Moderate cost to make. used for light bulbs, photochromic glasses, sealed-beam headlights, laboratory ware, and some bake ware products.

Diferents types Alumino-silicate glass alumina (Al2O3) is added to the glass batch to improve the properties of the glass. good resistance to high temperature or sudden changes in temperature; difficult to make. used in electronics.

Diferents types Ninety-six percent silica glass special type of glass made by a proprietary method, at temperatures up to 900°C. used to furnace sight glasses, for outer windows on space vehicles. Fused silica glass only made of silicon dioxide (SiO2) in the noncrystalline state. expensive and difficult to make; maximum resistance to high temperature (900°C for extended periods, 1200°C for short periods). used in special applications such as optical waveguides, crucibles for growing crystals.

Advantages Strength of Glass Glass is a strong material. Like most materials, glass can be bent until a certain limit. Imagine bending a long rod of glass. If you release the tension before this limit, the rod returns to its original shape: the deformation is elastic. If you pass the limit, the glass breaks. Why does glass shatter? The strength of glass is only slightly affected by composition but is highly dependent on the surface condition. If stress is applied on the damaged surface, the stress at the damaged points will be increased and the glass will shatter. Glass does not age quickly: glass windows remain clear and undamaged after many years of exposure to the elements.

Colouring Glass Unless the raw materials are very pure, glass is normally green. In order to change the colour of glass, one can decolourise the glass by adding colorants which produce the complementary colour to green. The colour depends on the state of oxidation of the colorant, the composition of the glass and the thermal treatment.

Colouring Glass COLORANT GLASS COLOUR/S iron green and aqua iron and sulfur amber copper light blue cobalt dark blue manganese purple

Uses From a natural mineral created by the volcanic furnaces to a luxury material, glass has now become a commodity. We use glass every day of our lives; we are surrounded by glass...

Glass is also used to create objects of art

Uses Glass, in the form of optical fibre, has some important applications in medicine. An endoscope is a flexible tube with both a light source and a camera lens for viewing at its end. Tiny surgical tools can also be manipulated through the endoscope to perform non-invasive surgery. The endoscope provides a visual examination of the interior of the body through a natural body opening such as the throat or through a small incision into the body.