Glass Production and Properties PDF

Glass is made from liquid sand. More specifically, glass is made by heating ordinary sand (mostly composed of silicon dioxide SiO2) until it melts and turns into a liquid. The molten sand is allowed to cool, and it turns into a frozen liquid or an amorphous solid. An amorphous solid can be...

Glass is made from liquid sand. More specifically, glass is made by heating ordinary sand (mostly composed of silicon dioxide SiO2) until it melts and turns into a liquid. The molten sand is allowed to cool, and it turns into a frozen liquid or an amorphous solid. An amorphous solid can be considered to have a random arrangement of atoms. It lacks long-range order found in crystalline solids. Historically the most common and familiar form of glass is clear (optically transparent) silica glass (or silicate glass) which is composed largely of silicon dioxide (SiO2). In fact, theoretically, any crystalline solid that can be brought to a liquid state, can be forced into an amorphous solid state through rapid solidification via high cooling rates. This is easily observable by recognizing that quartz, a very common crystalline solid, has the same composition as silica glass (SiO2) but was cooled slowly enough to form long-range order.  The glass making process: In the past, glass was made by heating sand to 3090°F (approximately 1700 °C) turning it into a molten liquid that is then shaped into glass products. When the molten sand cools, there’s a significant transformation in the material’s molecular structure. The change is from the crystalline structure of sand to the amorphous structure of glass. https://www.youtube.com/watch?v=UOwk2QIfDqY&list=WL&index=74 Today, glass is made by mixing sand with sodium carbonate lowering the melting point of silica. However, this process also makes the soda-glass mixture water- soluble. Therefore, limestone or calcium carbonate is often added to the mix to prevent the glass from dissolving and to make it waterproof. The modern glass making process also involves using several additives with silica mixture to give different properties within the glass, such as strength, conductivity, color, etc. Depending upon composition, it can be made stronger than steel or soluble in water  All of the most important glasses are based on silica SiO2. Two glasses of special interest are soda-lime glass, used in windows and bottles, with composition 70SiO2.10CaO.15Na2O, and borosilicate glass, used in cooking and chemical glassware, with composition 80SiO2.15B2O3.5Na2O. Oxides that form glasses are known as network formers. Common examples are SiO2, B2O3, GeO2, and P2O5. Glass can have other additives such as Na, K, B, and others. This is done to modify the properties of the glass and make it more suitable for human use.  Bone Scaffolds Traditionally, bioactive glasses have been used to fill and restore bone defects. More recently, this category of biomaterials has become an emerging research field for bone tissue engineering applications. https://www.youtube.com/watch?v=_dM9uB0jgrM