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2016-June-15-Glass - An unsung hero of scientific revolution

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2016-June-15-Glass - An unsung hero of scientific revolution

  1. 1. Ashutosh Goel Department of Materials Science and Engineering Rutgers, The State University of New Jersey Glass – An unsung hero of the scientific revolution
  2. 2. Picture, if you can, a world without glass. There would be no microscopes or telescopes, no sciences of microbiology or astronomy. People with poor vision would grope in the shadows, and planes, cars won’t exist. Artists would draw without the benefit of three-dimensional perspective, and ships would still be steered by what stars navigators could see through the naked eye. A. Macfarlane and G. Martin, “Glass: A World History”, The University of Chicago Press, 2002 Grumpy cat with Google Glass A world without glass
  3. 3. What is glass?
  4. 4. What is glass? Classical definition: “Glass is a super-cooled liquid.” If this statement is “true”, does glass flow over time? Are medieval windows melting/flowing? Italian stained-glass windows, from medieval times, are often round - like this one from the Basilica di Santa Maria del Fiore in Florence. Courtesy: www.awesomestories.com In medieval European cathedrals, the glass sometimes looks odd. Some panes are thicker at the bottom than they are at the top. The seemingly solid glass appears to have melted. This is evidence, say tour guides, internet rumors and even high school chemistry teachers, that glass is actually a liquid. And, because glass is hard, it must be a supercooled liquid. - C. Curtin, “Fact or Fiction?: Glass is a (supercooled) liquid”, Scientific American, Feb 22, 2007.
  5. 5. What is glass? According to a study conducted by Professor Edgar D. Zanotto, window glasses may flow at ambient temperature only over incredibly long times, which exceed the limits of human history. - E.D. Zanotto, “Do cathedral glasses flow?”, American Journal of Physics, 66 (1998) 392. Glass is actually neither a liquid – supercooled or otherwise – nor a solid. It is an amorphous solid – a state somewhere between those two states of matter. And yet, glass’s liquid-like properties are not enough to explain the thicker-bottomed windows, because glass atoms move too slowly for changes to be visible. - C. Curtin, “Fact or Fiction?: Glass is a (supercooled) liquid”, Scientific American, Feb 22, 2007. Can we still define glass to be a supercooled liquid? If medieval windows are not flowing, why the bottom part of these windows is thicker than the remaining window?
  6. 6. If medieval windows are not flowing, why the bottom part of these windows is thicker than the remaining window? Crown glass manufacture, C18th Courtesy: Corning Museum of Glass The reason behind non-uniform thickness of medieval windows may be attributed to their manufacturing process. At that time, glassblowers created glass cylinders that were then flattened to make panes of glass. The resulting pieces may never have been uniformly flat and workers installing windows preferred, for one reason or another, to put the thicker sides of the pane at the bottom. This gives them a melted look, but does not mean glass is true liquid. - C. Curtin, “Fact or Fiction?: Glass is a (supercooled) liquid”, Scientific American, Feb 22, 2007.
  7. 7. Glass in Modern World
  8. 8. Four things a normal human being wants… Good Health
  9. 9. Four things a normal human being wants… Good Environment
  10. 10. Four things a normal human being wants… Good Communication Although mode of communication has changed…..
  11. 11. Four things a normal human being wants… Good Entertainment
  12. 12. How does glass help us in this pursuit?
  13. 13. Glass and medicine
  14. 14. First compound microscope A clinical mercury-in-glass thermometer Glass Lab ware Microscope: One of the first major developments leading to saving of lives was the optical microscope (Year: 1590). The invention of the microscope using glass spheres to focus on the objects was the seminal step towards discovering microscopic life, for example: pathogens. This discovery led to the treatment and eventually elimination of many diseases. Other examples: Thermometers, Lab ware, Eye glasses This enormous social change can be termed a revolution in life preservation. A major consequence of life preservation was an expansion of the human lifespan from an average of 45 years to 78 years. It is projected that by 2050, there will be more than 1 billion people alive on earth aged 60 years or older. Hench et al., Glass and Medicine, Int. J. Appl. Glass Sci. 1(2010) 104-117
  15. 15. The second revolution in healthcare has occurred in last 50 years, i.e. a revolution in tissue replacement. Bio-inert Biomaterials CellProteins Bioactive Biomaterials Cell Adhesion, spreading, migration, growth, apoptosis and differentiation Human “spare parts” is a huge business worth tens of billions of dollars http://www.synergybiomedical.com/technology.htm
  16. 16. 45S5 Bioglass® (mol.%): 46.1 SiO2 - 26.9 CaO - 24.4 Na2O - 2.5 P2O5 First bioactive materials were discovered by Hench et al. in 1971. They designed melt-derived Na2O-CaO-P2O5-SiO2 based glasses which have the ability to bond to bone and soft tissues in human body through a sequence of chemical processes. The most bioactive composition discovered until today from this class of materials is 45S5 Bioglass®, which has been used in > 650,000 human cases already. J. Am. Ceram. Soc. 74 (1991) 1487
  17. 17. Scaffold fabrication from bioactive glass Trinity of an ideal biomaterial for tissue engineering and regenerative medicine - Underlying concept of tissue engineering is the belief that cells can be isolated from the patient, and its population then can be expanded in a cell culture and seeded onto a carrier. The resulting tissue engineering construct is then grafted back into the same patient to function as the introduced replacement tissue. - This new paradigm requires scaffolds that balance temporary mechanical function with mass transport to aid biological delivery and tissue regeneration in three dimensions (3D). - The choice of a suitable material for fabrication of scaffold with desired properties is the biggest challenge. Desired properties  Right surface chemistry to promote cell attachment  Biodegradability – degradable into non- toxic components  Mechanical strength – needed for creation of macroporous scaffold that will retain the structure after implantation
  18. 18. Our research in the field of bioactive glasses
  19. 19. Our research in the field of bioactive glasses
  20. 20. Our research in the field of bioactive glasses 2 Merino sheep (Age: 1 year) We created 5 non-critical defects with 5 mm diameter in lateral diaphysis in the femur 1st defect: Empty (control) 2nd defect: 45S5 (Reference) 3rd – 5th defect: FastOsTM Defects in femur diaphysis 3 mm 45S5 3 mm Control FastOs 3 mm
  21. 21. Glass and environment
  22. 22. Nuclear waste management in USA Hanford site - 586 mi.2 of desert next to Columbia river in southeastern Washington Hanford site was established in 1943 to produce plutonium for the production of nuclear weapons that were used in World War II and continued throughout the Cold War. B-Reactor (1944-1968) Produced the plutonium used in “Fat man” bomb dropped over Nagasaki in August 1945.  The production of plutonium ceased in 1987.  55 million gallons of high level radioactive waste was stored in 177 underground tanks.  Clean-up began May 15, 1989. www.hanford.govWaste tanks at Hanford site in Washington
  23. 23. What is the solution to this problem? “Glass”
  24. 24. Why glass?
  25. 25. Why glass? - Reduces the volume of waste by 75%. - High chemical durability over long term. - Commercial vitrification plants operate in France, U.K. an Belgium produce about 1000 metric tons per year of such vitrified waste (2500 canisters) and some have been operating for more than 16 years. The nuclear waste from the production of nuclear electrical energy of one person’s entire life is contained in the glass in hand.
  26. 26. Nuclear waste vitrification in USA The U.S. Department of Energy (DOE) is building a Tank Waste Treatment and Immobilization Plant (WTP) at Hanford site in Washington state. Vitrification plant at Hanford View inside a Joule Heated Ceramic Melter (JHCM) that will be used to vitrify the nuclear waste into borosilicate glass at 1150 °C. Although the process of nuclear waste immobilization via vitrification seems simple, it is plagued by several complex practical problems starting from design of glass compositions (owing to the compositional complexity of nuclear waste), to processing in glass melters, and finally to long term performance of the vitrified waste forms. Our research is focused on the following three problems…
  27. 27. Challenges with vitrification - USA Problem#1 Spinel crystallization in glass melters The cost of vitrifying radioactive waste is directly proportional to the volume of glass to be produced. It is therefore desirable to maximize waste loading in glass to decrease the overall volume, but without posing unacceptable risk for the melter operation. The major factor limiting waste loading in nuclear waste glasses is the precipitation, growth, and subsequent accumulation of spinel crystals (Fe, Ni, Mn, Zn, Sn)II(Fe, Cr)III 2O4 in the glass discharge riser of the melter during idling. Once formed, spinels are stable to temperatures much higher than the typical JHCM operating temperatures (1150–1200 °C). This can result in clogging of the melter discharge channel, and interfere with the flow of glass from the melter
  28. 28. Challenges with vitrification - USA Problem#2 Crystallization vs. chemical durability Schematic cross-section of an underground steel tank depicting layer by layer arrangement of the radioactive and chemical waste. - The high level radioactive waste at Hanford is rich in sodium and alumina (Al2O3). - The strategy is to convert this waste into borosilicate glass, with maximized waste loading. - Increasing concentration of Na2O and Al2O3 in these glasses results in crystallization of nepheline (Na2O•Al2O3•2SiO2) based phases. - Since nepheline crystallization results in removal of 1 mole of Al2O3 and 2 moles of SiO2, this decreases the chemical durability of final waste form.
  29. 29. Challenges with vitrification - USA Problem#3 Volatile radioactive species – for example, iodine - The 2011 Fukushima Daiichi nuclear disaster was one of the worst nuclear incidents in World history. - The release of large amount of radioactive iodine (129I, t1/2 = 1.6 x 107 y), and cesium in Pacific ocean will be disastrous for the flora and fauna of ocean. - According to scientists, these radioactive elements will be adsorbed by marine life, and will eventually make their way up the food chain, to fish, marine animals, and humans. Fukushima Nuclear Disaster No country has a defined protocol for immobilization of radioactive iodine as iodine is not amenable to vitrification. For example, radioactive iodine in U.K. is currently discharged to sea. Innovative synthesis routes need to explored for development of ceramic waste forms for immobilization of radioactive iodine at low temperature (<200 °C) .
  30. 30. But glass still breaks…. https://youtu.be/7j9hluDLWIU Brittleness of glass has been perceived as its gravest handicap. Over the centuries, accepting this handicap and benefitting from optical properties and universal processability, glasses have found their role in applications with low levels of tensile stress. There is very high demand for novel approaches towards stronger, or more precisely, damage resistant glasses.
  31. 31. Aluminosilicates – Backbone of specialty glasses Corning Gorilla Glass Ultra-smooth and Ultra-Strong Ion exchanged Glass [Adv. Funct. Mater. 23 (2013) 3233-3238] Used as cover glass on 4.5 billion devices Property Value Density 2.42 g/cm3 Young’s Modulus 65.8 GPa Poisson’s ratio 0.22 Shear Modulus 26.0 GPa Vickers hardness (200 g load) Un-strengthened 489 kgf/mm2 (4.79 GPa) Strengthened 596 kgf/mm2 (5.84 GPa) Fracture Toughness 0.67 MPa m0.5
  32. 32. Aluminosilicates vs. Aluminates Glass forming region in Na2O-Al2O3 SiO2 system (mol.%) [Ref: Mysen and Richet, Silicate Glasses and Melts, Elsevier] Vicker’s hardness: 4 – 6 GPa Young’s modulus: 60 – 85 GPa Fracture toughness: ~0.7 – 1 MPa m1/2 [Yoshida et al., J. Non-Cryst. Solids, 344 (2004) 37-43] 40 SiO2 – 60 Al2O3 (mol.%) Vicker’s hardness: 8.07 GPa Young’s modulus: 134.2 GPa [Rosales-Sosa et al., Sci. Rep., 6 (2016) 23620]
  33. 33. Density: 2.55 – 2.85 g/cm3 Vicker’s hardness: 7.23 – 8.07 GPa Young’s modulus: 74 – 134 GPa Cracking Probability curves for the xAl2O3 – (100-x) SiO2 glasses Cracking resistance of 40 SiO2- 60Al2O3 glass is ~7 times higher in comparison to SiO2 glass!! [Rosales-Sosa et al., Crack – resistant Al2O3 – SiO2 glasses, Sci. Rep., 6 (2016) 23620] Aluminosilicates vs. Aluminates
  34. 34. Challenges in synthesis of aluminate glasses Two major challenges 1. High melting and processing temperatures – not amenable for synthesis in conventional glass melting furnaces 2. Small glass forming region – high tendency towards crystallization 76 79 82 85 88 97 Al2O3 mol.% 1800 1850 2000 1950 Phase diagram of the alumina- rich La2O3-Al2O3 system [Fritsche and Tensmeyer, J. Am. Ceram. Soc. 50 (1967) 167] Example La2O3-Al2O3 glasses Al2O3-rich glasses near eutectic of La2O3–Al2O3 have been synthesized. [Rosenflanz et al., Nature, 430 (2004) 761] - Processing temperature: >1800 °C - Small glass forming region - Synthesized either by flame spray method or aero-levitation technique - Difficult to obtain monolith glasses for practical applications.
  35. 35. Strategy to overcome these challenges Synthesis route – melt quench vs. aero-levitation Depending on processing temperatures Melt-quenching T ≤ 1650 °C Glasses with Al2O3 ≤ 55 mol.% Fabricate monolith samples – ready to use T > 1650 °C Aero-levitation technique In collaboration with Prof. Mario Affatigato, Coe College, Cedar Rapids, IA Will provide glass beads which will require further processing!!
  36. 36. Ultra-strong glasses and glass-ceramics Map of hardness against Al2O3 content in different material classes. It has been shown that transparent aluminate glass-ceramics with hardness similar to Al2O3 can be synthesized. Bulk rare-earth aluminate glass-ceramics Rosenflanz et al., Bulk glasses and ultrahard nanoceramics based on alumina and rare-earth oxides, Nature, 430 (2004) 761.

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