 Good morning. With today's session, we are going to learn about metals, alloys and ceramics and that types of glass and manufacturing of glass. Learning outcome. At the end of this session, students will be able to explain the different types of glasses and manufacturing of the glass. Content of today's session, that is, we are going to learn about the types of glasses like soft glasses, hard glasses, borosilicate glass, optical glass, laminated glass and manufacturing of glass. Introduction. Glass is an amorphous, hard, brittle, transparent and supercooled liquid of infinite viscosity. It is obtained by fusing a mixture of a number of metallic silicates, such as of sodium, potassium, calcium and lead, etc. Generally, it may be represented as X, R2, Y, Mo and 6 SiO2, where R stands for atom of monovalent alkali metal like sodium, potassium, etc. X and Y, these are the whole numbers. Types of glasses. First, soft or sodaline glass. The raw materials that are used in this particular manufacturing of soft or sodaline glass are silica, calcium carbonate and sodium carbonate. Its approximate composition is Na2O CaO 6 SiO2. The cost is low and are resistant to water. They melt easily and hence can be hot worked easily. These are affected by acids. Uses of this glass. It is used as a window glasses, used as electric bulbs, plate glasses, bottles, jars, etc. It is also used for making building and cheaper tableware, second type of glass that is hard glass or potash lime glass. The raw materials used for manufacture of hard glass is sand, calcium, carbonate and potassium carbonate. The approximate composition is K2O CaO 6 SiO2. They possess high melting point and it is less affected by acids, alkali and other solvents. Uses of hard glass. It is used for making chemical apparatus. It is also used for making combustion tubes, etc. Third type of glass it is borosilicate glass also known as a Pyrex glass. The raw materials used for this manufacturing is silica and boron with a small amount of alumina and some alkali oxides. Composition of such glass is SiO2 almost 80.5% B2O3 13% aluminum oxide 31% K2O 3% Na2O 0.5%. These glasses have very high softening points and excellent resistivity. Uses of borosilicate glass. It is used in industry for making pipelines, glass glasses, superior laboratory apparatus. It is also used in making electrical insulators, kitchen wares, chemical plants, television tubes, etc. Fourth type of glass that is optical glass. This contains phosphorus and late silicate with little cerium oxide. Cerium oxide is capable of absorbing ultra valid radiations. In general, optical glasses have low melting point and are relatively soft. Their chemical resistance and durability are lower than those of ordinary glasses. Uses are used in making the lenses. Fifth type of glass it is laminated glass. It is made by pressing together two or more sheets of glass with one or more alternating layers of bonding material like plastic resin, synthetic rubber, etc. These are shatter proof. A bullet resistant laminated glass is obtained by pressing together several layers of glass with vinyl resin in alternate layers. Thickness of such glass varies from 12.7 millimeters to 76.5 millimeters. Uses of laminated glass. It is used in making safety glasses useful in airplanes, automobile industry, helicopters and submarines, etc. Safety glasses. It is made by taking two or three flat sheets of glass and in between the alternate thin layer of vinyl plastic is introduced. The whole of the content is subjected to slight pressure. It is then heated till the glass layer and plastic layers merge into one another which on cooling the glass becomes quite tough. When such glass breaks does not cut into pieces since the inner plastic layer tends to back the broken pieces of the glass. Now pause the video and answer this question. Question is in manufacture of optical glass the cerium oxide is used as A. It decreases the melting point B. It absorbs ultraviolet radiations C. It increases hardness and D all of the above. Well the answer for the question that is in manufacture of optical glass the cerium oxide is used as the answer is B. It absorbs ultraviolet radiations. Manufacturing of glass. Steps that are involved in manufacturing process. The first step is melting. In case of the melting raw materials in proper proportion are finely powdered and the mixture is fused in furnace in which heating is done by burning producer gas and air at 1800 degrees Celsius temperature the charge melts and fuses. So what are the reactions that are involved? So calcium carbonate react with this silica and that forms a calcium silicate that is Ca SiO3 but along with this carbon dioxide is also released. Same is the case with this sodium carbonate. Sodium carbonate react with this silica and that forms a sodium silicate that is Na2 SiO3 also a carbon dioxide gas is released out. When all the carbon dioxide gas is escaped decal rises are added to react with ferrous compounds and carbon if present in such a melting mixture. If colored glass is desired the coloring salts are added at this particular stage. Heating is continued till the molten mass is free from bubbles and then cooled to 800 degrees Celsius. Well this is a diagram for manufacturing of glass this is tank furnace. This consists of a tank where we are melting the raw material. This is an inlet for air fuel gases are also introduced from this particular inlet. Here the burning of gases takes place because of which the mass gets melted and whatever the fuel gases are produced these are taken out from this particular outlet. Second step after melting forming and shaping. Molten glass is then worked into articles of desired shapes by either blowing or molding or pressing between the rollers. Third step that is annealing. Glass articles are then allowed to cool to room temperature. If allowed to cool rapidly the superficial layer cools down first leaving the interior portion in a state of strain owing to this unequal expansion of the glass shows cracking. Last step that is finishing. All glass articles after annealing are subjected to finishing process. References for this session I have used a textbook of engineering chemistry by Jane and Jane. Thank you.