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ENMAT101A Engineering Materials and Processes Associate Degree of Applied Engineering (Renewable Energy Technologies) L

ENMAT101A Engineering Materials and Processes Associate Degree of Applied Engineering (Renewable Energy Technologies) Lecture 22 – Glasses. Glasses. EMMAT101A Engineering Materials and Processes. Glasses (Higgins 22). High quality glass goes back to ancient times.

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ENMAT101A Engineering Materials and Processes Associate Degree of Applied Engineering (Renewable Energy Technologies) L

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  1. ENMAT101A Engineering Materials and ProcessesAssociate Degree of Applied Engineering (Renewable Energy Technologies)Lecture 22 – Glasses

  2. Glasses EMMAT101A Engineering Materials and Processes

  3. Glasses (Higgins22) High quality glass goes back to ancient times. The engineering definition of glass includes a whole range of substances that are not true crystalline solids. Hence terms like “glassy metals” means metal atoms in a glass-like structure. Moldavite, a natural glass formed by meteorite impact, from Besednice, Bohemia A modern greenhouse in Wisley Garden, England, made from float glass Roman Cage Cup from the 4th century CE EMMAT101A Engineering Materials and Processes

  4. 22.2 Composition and structure of glass (Higgins22.2) Higgins EMMAT101A Engineering Materials and Processes

  5. 22.3 Glass-transition temperature (Higgins22.3) Higgins EMMAT101A Engineering Materials and Processes

  6. 22.3 Glass-transition temperature (Higgins22.3) 22.3.1 Devitrification 22.3.2 Glass ceramics Higgins EMMAT101A Engineering Materials and Processes

  7. 22.4 Glass manufacture (Higgins22.4) 22.3.1 Devitrification 22.3.2 Glass ceramics Higgins EMMAT101A Engineering Materials and Processes

  8. 22.4 Glass manufacture (Higgins22.4) 22.4.1 Float process Higgins EMMAT101A Engineering Materials and Processes

  9. 22.4 Glass manufacture (Additional) Toughened or tempered glass is heat treated to created a surface compression. This increases the strength of the glass but makes it impossible to cut by any process (scoring, sawing, drilling, water jet cutting etc). The glass must be annealed before it can be processed and then re-tempered. When broken, the glass breaks into small granular chunks instead of splintering into jagged shards. Wikipedia Wikipedia EMMAT101A Engineering Materials and Processes

  10. 22.4 Glass manufacture (Higgins22.4) 22.4.2 Glass blowing Higgins EMMAT101A Engineering Materials and Processes

  11. 22.5 The properties of glass (Higgins22.5) However a 'glass' is, by definition, a substance existing below the glass transition temperature so that very little movement of molecules is possible. This means that a glass at ambient temperature is extremely brittle. Higgins EMMAT101A Engineering Materials and Processes

  12. 22.6 Glasses and their uses (Higgins22.6) 22.6.1 Pyrex 22.6.2 Glass ceramics Higgins EMMAT101A Engineering Materials and Processes

  13. 22.7 Metallic glasses (Higgins22.7) Higgins EMMAT101A Engineering Materials and Processes

  14. Glassy Metal 'Melt Spinning' or 'Splat quenching' to produce metallic glass ribbon. Molten tin alloy is fed through several nozzles onto a rotating metal drum, resulting in extremely high cooling rates (approx. 1 million Kelvin per second). High speed photography at 4000 fps. You Tube Offline From TLP: Casting, http://www.doitpoms.ac.uk/tlplib-dev2008/casting/casting_other.php DoITPoMS, The University of Cambridge. EMMAT101A Engineering Materials and Processes

  15. Resources. Wikipedia: Glass EMMAT101A Engineering Materials and Processes

  16. Glossary Amorphous Crystalline Toughened glass Annealed glass Laminated glass Tempered glass Safety glass Refractive index Transmittance Absorptance Reflectance Dispersion Glass transition temperature EMMAT101A Engineering Materials and Processes

  17. QUESTIONS Higgins Ch22, Newell, Timmings • Define all glossary terms • How do network modifiers affect the properties of glasses? • Compare and contrast the glass transition temperature of glasses with those of polymers. • Explain why molten SiO2 forms glass instead of cooling back into a crystalline form. • Compare and contrast the properties of silica glass and Portland cement. • (a) Select two types of glass and describe their composition, properties and typical applications. (b) Describe the heat-treatment processes available for making glass less susceptible to fracture. (c) Describe a chemical treatment process available for making glass less susceptible to fracture. • Describe the optical properties of glass with respect to optical lenses. Name a surface treatment process used in high quality camera lenses. What does it do? • Obsidian is a naturally occurring (usually dark) volcanic rock. Granite has large visible crystals and forms deep underground. Which one is more likely to be a glassy structure? Explain. • Discuss silicon based solar cell technology: mono, poly crystalline and amorphous http://en.wikipedia.org/wiki/Solar_cellhttp://www.planetarypower.com.au/solar_panels.htmhttp://www.ata.org.au/wp-content/renew/101_solar_panel_buyers_guide.pdf EMMAT101A Engineering Materials and Processes

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