2016-June-15-Glass - An unsung hero of scientific revolution
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. 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
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. 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. 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.
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. 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. 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.
18. 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
21. 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
23. 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
26. 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.
27. 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…
28. 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
29. 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.
30. 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) .
31.
32. 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.
33. 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
34. 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]
35. 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
36. 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.
37. 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!!
38. 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.
