When we talk about the most common and widely used material in daily life, the instant thought goes to glass. It has a wide array of uses and is a preferred material over others for various reasons.
Salient features of glass that make it the preferred choice to replace it with other materials
Unless a material is useful and versatile, we do not think about using it. This holds true for glass too. Here are the salient features of glass, due to which it gets the status of preferred material for multiple use.
⦁ Glass is transparent. It is resistant to both heat and chemicals.
⦁ It has a smooth surface and is crystal clear in appearance.
⦁ Glass has the ability to reflect, refract as well as transmit light without wasted dispersal. Hence, it is used in making prisms, optical lenses (spectacles, magnifying glass) and other optoelectronic materials.
⦁ Silicate glass has the property of being molten, poured and formed into many shapes including flat pressed sheets. It can be extruded and molded in optical fibers or unusual designs (vases, bowls, artifacts)
⦁ It has vast practical, decorative and technological usage like glass doors, window panes, utility items (bowls, glasses), intricately crafted show pieces and optical fibers for telecommunication.
⦁ Addition of metal salts enables the coloring of glass and renders it beautiful. Besides, plain transparent glass can be painted and printed with vitreous enamels that convert it into attractive stained glass, used for windows and art objects like lamp shades, vases.
⦁ Due to its thermal insulating property, glass wool is used as matting to trap air.
⦁ Glass can withstand pressure and therefore glass-fibers are used as reinforcement of plastic to form fiberglass.
⦁ Volcanic magma forms natural glass. High ⦁ silica content Obsidian is an example of volcanic glass, formed on rapid cooling of extruded lava. Obsidian has the property to fracture along extremely sharp edges and thus in Stone Age it was utilized to make weapons and cutting tools.
How rigid can a glass be to serve for long?
Float Process produces flat sheets of glass, which are in use for multiple purposes. In this process that was devised by Sir Alastair Pilkington in 1952, a continuous strip of glass heated to 1000 degrees Celsius and melted, is poured from the furnace into a shallow bath of molten metal, normally forming a tin sheet. The glass thus floats on the sheet and forms an even layer on cooling. As a result, a perfectly parallel and flat glass sheet is obtained. This process enables manufacture of flat glass on a large scale and the panels can stretch to a kilometer and have width up to 3 meters and a thickness of 0.4 mm to 25 mm.
The strength of glass depends upon its manufacturing process, especially the cooling rate. Thus, there are four categories of glass available
⦁ Annealed Glass: This is the most basic form of glass. The molten glass in the shallow bath is allowed to cool gradually in a controlled environment until it attains room temperature. Due to controlled cooling, there are no internal stresses that can make the glass crack at the slightest change in temperature or mechanical impact. Annealed glass is the foundation used in the manufacture of other advanced glass forms.
⦁ Laminated Glass: Any type of glass can be laminated, which is used to advantage in safety and security purposes. The most common laminated glass in use is two sheets of toughened glass with an interlining of 1.52 mm thick PVB (Polyvinyl Butyral). This type of glass is used in car windshields. The impact on glass that may shatter the pane does not destroy it completely as the second layer remains intact due to interlayer. Another interlayer material commonly used is SGP (Sentry Guard Plus manufactured by DuPont), as this laminated glass is five times stronger than PVB and 100 times more rigid than other laminated glasses. Different types of interlayer offer properties like fire resistance, soundproofing and high load tolerance. Colored interlinings are used for decorative purpose and privacy.
⦁ Heat Strengthened Glass: This is a semi-tempered or semi-toughened variety of glass. During this process, the annealed glass is reheated to 650 to 700 degrees Celsius and subjected to quick cooling. However, the cooling is not as rapid as in toughened glass. The process not only makes it twice as tough as annealed glass, but also increases its thermal and mechanical strength. On breaking, the pieces of heat treated glass have better chances of staying together than annealed glass.
⦁ Toughened or Tempered Glass: By sheer virtue of its toughness – Tempered glass is the preferred glass by architects for making structural balustrades. Tempered glass is formed on heating annealed glass to around 700 degrees Celsius by triple process of conduction, convection and radiation. A uniform and simultaneous blast of air on either side accelerates the cooling process. The difference in surface and internal cooling rates render different physical properties to the glass. The surface compressive stresses are balanced by the tensile stresses in the interior of glass. This facilitates the treated glass to be four to five times safer and sturdier than any other glass type. Tempered glass has better mechanical resistance to breakage due to these counterbalancing stresses.
Which glass is in high demand in the USA?
In USA, purchased glass, pressed or blown glass, flat glass and glass containers are in use. Nonetheless, the glass in high demand is bulletproof or toughened glass variety. This is due to the increased crime rate and want of security. There are multiple uses of this glass in construction, automotive, kitchenware, railings, partitions and others.
Another type in demand is energy efficient glass that is used for doors and windows coatings to retain the heat and offer thermal insulation, thus making the building or home energy efficient.
As we can see, glass is a versatile material and thus preferred over other materials.