physical characterization of glassy materials using ultrasonic non destructive
DESCRIPTION
Physical characterization of glassy materials using ultrasonic non destructive techniqueTRANSCRIPT
Physical Characterization of Glassy Materials Using Ultrasonic Non-Destructive Technique
Sidek Ab Aziz Department of Physics, Faculty of Science Universiti Putra Malaysia 43400 UPM Serdang, Selangor
Seminar on Materials Science and Technology 2013, June 24, 2013, ITMA
General Discussion
Glass (amorphous)
Crystalline
Scope of Presentation
Free Web 2.0 Apps. http://mindmap.crazenut.org
What is a glass?
Glass - hard, brittle solid material that is normally lustrous and
transparent in appearance and shows great durability under
exposure to the natural elements.
Obsidian - super-heated sand or rock that rapidly cooled.
Moldavite formed by meteorite impact (Besednice, Bohemia)
4
Natural heat-producing processes like volcanoes and lightning strikes are responsible for creating various forms of natural glass.
obsidianites, kind of alumino-silicate
(SiO2–Al2O3) glasses containing
crystalline particles such as Fe2O3.).
Man-Made Glass
Principles of Glass Formation
5
Glass (amorphous) Crystalline
The viscosity increases with undercooling until the liquid freezes to a glass
Crystals ordered atomic
structures mean smaller volumes (high density) & lower energies
thermodynamically stable phase
Glasses lack of long-range
order results in larger volumes (lower density), higher energies;
thermodynamically metastable phase
Knowledge of glass structure is important which relates to other
Free Web 2.0 Apps. http://www.text2mindmap.com
Silicate Borate
• Glass structure has short range order but no long range order.
• Silicate tetrahedra link up to form 3D glass network. • Some ions such as Na will modify the network but are
not part of it.
Some structural groupings in borate glasses as indicated
from nuclear magnetic resonance experiments (Bray
1985).
Small solid circles represent boron atoms, open circles
oxygen atoms and an open circle with negative sign
indicates non-bridging oxygen.
Glass Structure
Bonding Structure of Tellurite
2D chain: crystalline TeO2
TeO2 chains
Deformation and breaking of TeO2 chain by modifier
The structure
basic TeO2 –based glass structural unit namely, TeO4 trigonal
bipyramids (tbp) and TeO3 trigonal pyramid (tp) .
TeO4 tbp TeO3 tp
Both structure have a lone pair of electron in one of its
equatorial /axial sites.
7
Phosphate
Basic glass former, P2O5
Effects of Mg
cation content on
the phosphate glass
Glass Sample Preparation
www.glassforever.co.uk/howisglassmade/
glass furnace cooling systems
8
9
Some pigments used to produce coloured glass
Compounds Colors Compounds Colors
iron oxides greens, browns selenium compounds reds
manganese oxides deep amber, amethyst,
decolorizer
carbon oxides amber/brown
cobalt oxide deep blue mix of mangnese, cobalt,
iron
black
gold chloride ruby red antimony oxides white
uranium oxides yellow green (glows!) sulfur compounds amber/brown
copper compounds light blue, red tin compounds white
lead with antimony yellow
Research Project To produce the fiber optics and flat glasses for the
future applications
Glass Research @ UPM
Fiber Optics are cables that are made of optical fibers that can transmit large amounts of information at the speed of light. (www.dictionary.com)
Dominated by Silicate based glass
Glass Research @ UPM
Key Researchers
A goal of solid-state science, which intends to give universal understandings of
macroscopic properties through simple theories on the basis of known atomic
structures. 11
Glass Research @ UPM
12
Tellurite (TeO2)
Phosphate (P2O5)
Borate (B2O3)
Lithium
Chloroborate
Lead Borate
Lead Bismuth
Borate
Bismuth Borate Zink Chloride Phosphate
Silver Phosphate
Lithium Phosphate
Lithium Chlorophosphate
Lead Magnesium
Chlorophosphate
Lead Bismuth Phosphate
Lithium Chloride Phosphate
Lithium Zink Phosphate
Lead Zink Metaphosphate Zinc magnesium phosphate
Zinc Tellurite
Borotellurite
Zinc oxyfluorotellurite
Lead Borotellurite
Silver Borotellurite Zinc Neodymium
Tellurite
Zinc borotellurite
Zinc oxyfluorotellurite
Ferum Tellurite
Glass research activities conducted at the Universiti Putra Malaysia.
Formation
Physical Studies
Elastic Properties
Optical
Characterization
Thermal Properties
Dielectric Properties
Research Scope
Glass Research @ UPM
13
Tellurite (TeO2)
Phosphate (P2O5)
Borate (B2O3)
Selected some of the prepared binary and ternary glass samples at the Department of Physics, Universiti Putra Malaysia.
Ag2O-B2O3
PbO-B2O3
Bi2O3-B2O3
Li2O-P2O5
PbO-B2O3
PbCl2-P2O5
LiCl-P2O5
ZnCl2-P2O5
B2O3-TeO2
ZnO-TeO2
Fe2O3-TeO2
PbO-Bi2O3-B2O3
LiCl-Li2O-P2O5
PbCl2-MgO-
P2O5
Li2O-ZnO-P2O5
PbO-ZnO-P2O5
PbO-Bi2O3-P2O5
Cu2O-CaO-P2O5
Ag2O-B2O3-TeO2
PbO- B2O3-TeO2
ZnO- B2O3-TeO2 Nb2O5- ZnO- TeO2
AlF-ZnO-TeO2
binary
ternary
Glass Oxide Former Modifier Glass Samples Researchers
Binary Oxide Glass Series
Borate (B) Silver (Ag) Ag2O-B2O3 Sidek et al. (1994)
Lead (Pb) PbO-B2O3 Azman et al. (2002)
Bismuth (Bi) Bi2O3-B2O3 Sidek et al.(2007)
Phosphate (P) Lithium (Li) Li2O-P2O5 Low et al. (1999)
Sidek et al.(2003)
Lead (Pb) PbO-B2O3 Azman et al. (2002)
Talib et al. (2003)
Lead Chloride (PbCl2) PbCl2-P2O5 Talib et al. (2003)
Lithium Chloride (LiCl) LiCl-P2O5 Loh et al. (2005)
Tellurite (Te) Boron (B) B2O3-TeO2 Halimah et al.(2005)
Sidek et al.(2006)
Zink (Zn) ZnO-TeO2 Rosmawati et al. (2008)
Sidek et al.(2009)
Ferrum (Fe) Fe2O3-TeO2 Zarifah et al. (2010)
PbO-P2O5
B2O3-TeO2
Ag2O-B2O3
Glass samples prepared by melt
quenching technique @ UPM
Glass Former Network Modifier Glass Samples Researchers
Ternary Oxide Glass Series
Borate (B) Bismuth (Bi) Lead (Pb) PbO-Bi2O3-B2O3 Sidek et al. (2005)
Hamezan et
al.(2006)
Phosphate (P) Lithium (Li) Lithium Chloride
(LiCl)
LiCl-Li2O-P2O5 Low et al. (1999)
Sidek et al.(2003)
Magnesium (Mg) Lead Chloride
(PbCl2)
PbCl2-MgO-P2O5 Sidek et al.(2004)
Zink (Zn) Lithium (Pb) Li2O-ZnO-P2O5 Sidek et al.(2005)
Zink (Zn) Lead (Pb) PbO-ZnO-P2O5 Sidek et al.(2005)
Bismuth (Bi) Lead (Pb) PbO-Bi2O3-P2O5 Sidek et al.(2006)
Calsium (Ca) Copper (Cu) Cu2O-CaO-P2O5 Talib et al. (2008)
Tellurite (Te) Boron (B) Silver (Ag) Ag2O-B2O3-TeO2 Halimah et al.
(2005)
Zink (Zn) Aluminum Floride
(AlF)
AlF-ZnO-TeO2 Sidek et al.(2009)
Boron (B) Lead (Pb) PbO- B2O3-TeO2 Iskandar et al.
(2010)
Zink (Zn) Neodymium (Nb) Nb2O5- ZnO- TeO2 Mohamed et al.
(2010)
Boron (B) Zink (Zn) ZnO- B2O3-TeO2 Ayuni et al (2011)
Selected some of the prepared ternary glass samples at the Department of Physics, Universiti Putra
Malaysia.
GeO2-PbO-Bi2O3
AgI-B2O3-TeO2
PbO-B2O3
SEM Photos XRD Pattern of Starting Materials
TeO2 powder
TeO2 glass
ZnO Powder
TeO2-ZnO glass
0200400600800
1000120014001600180020002200240026002800300032003400
10 20 30 40 502 theta
Inte
nsi
ty (
a.u)
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
10 20 30 40 502 Theta
Inte
nsi
ty (
a.u)
0
5000
10000
15000
20000
25000
30000
35000
10 20 30 40 50
2 Theta
Inte
nsi
ty (
a.u)
TeO2-ZnO-AlF3
glass
AlF3 (97.0%) Powder 16
XRD patterns
100
600
1100
1600
2100
10 20 30 40 502 theta
Inte
ns
ity
(a
.u)
TZ7
TZ6
TZ5
TZ4
TZ3
TZ2
TZ1
TZ0
• no discrete or continuous sharp peaks
• but broad halo at around 2 260 - 300, which reflects the characteristic of
amorphous materials.
• absence of long range atomic arrangement and the periodicity of the 3D network
in the quenched material
400
600
800
1000
1200
1400
1600
1800
10 20 30 40 50
2 thetaIn
ten
sity
(a.u
)
S5
S4
S3
S2
S1
TeO2)1-x (ZnO)x (x = 0.1 to 0.4 in 0.05) (TeO2)90(AlF3)10-x(ZnO)x (x = 1 to 9)
binary ternary
17
Ultrasonic System
Schematic representation of (a) simple pulse ultrasonic system. (b) Envelope of pulse echo train and (c) detail of each echo as seen on oscilloscope display
18
Ultrasonic Pulse Echo Overlap System
Pulse echo overlap system Pulse echo overlap waveforms
Block diagram of the experimental
set up – ultrasonic wave velocity
and attenuation measurement
(Mepco Engineering College,
INDIA)
19
Ultrasonic System
Ultrasonic – MBS
8000 Ultrasonic Data
Acq. System
20
21
Important Physical Properties
Density is defined as the mass per unit volume.
– Density is an intensive property of matter, meaning it remains the same regardless of sample size.
– It is considered a characteristic property of a substance and can be used for material’s classification
Density Measurement (Archimedes Method)
acaca
as ww
w
Molar volumes
MV
Physical Properties
Variation of density and molar volume with mol% Bi2 O3
in Bi2 O3–B2 O3 glass systems.
The increase of the density of the glasses
accompanying the addition of Bi2 O3 is probably
attributable to a change in cross-link density and
coordination numbers of Bi3+ ions.
26
26.5
27
27.5
28
28.5
29
0.55 0.6 0.65 0.7 0.75 0.8 0.85
Mole fraction of TeO2
Mo
lar
vo
lum
e(c
m3 m
ol-1
)
4650
4700
4750
4800
4850
4900
4950
5000
Den
sit
y (
kg
m-3
)
Density and molar volume of TeO2.B2O3 glasses
28
28.5
29
29.5
30
30.5
0.05 0.10 0.15 0.20 0.25 0.30 0.35
Pecahan Mol Ag2O
Isip
ad
u m
ola
r (c
m3)
4800
4900
5000
5100
5200
5300
Ketu
mp
ata
n (
kg
/m3)
Density and molar volume of [(TeO2)x (B2O3)1-x)]1-y [Ag2O]y
22
Density and Molar Volume
3500
4500
5500
6500
7500
0 20 40 60 80
Bismuth Oxide (mol%)
Den
sit
y (
kg
m-3
)
Dependence of density on the composition of bismuth oxide
glass systems as measured by El-Adawy and Moustafa (1999)
(5 - 45 mol%), Wright et al (1977) (20 – 42.5 mol%) and
present works (40 – 70 mol%).
23
Density & Molar Volume
4700
4800
4900
5000
5100
5200
5300
5400
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4
Mole fraction of ZnO
De
ns
ity
(k
g/m
3)
22
24
26
28
30
32
34
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4
Mole fraction of ZnO
Mo
lar v
olu
me
(1
0-6
m3m
ol-1
)
•Similar behaviour as El-
Mallawany (1993).
•Addition of ZnO causes some
type of structural
rearrangement of the atoms (Hoppe et al. (2004).
•Possibility for the alteration of
the geometrical configuration
upon substitution of ZnO into
the tellurite glassy network.
24
Density & Molar Volume
4700
4800
4900
5000
5100
5200
5300
5400
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4
Mole fraction of ZnO
De
ns
ity
(k
g/m
3)
22
24
26
28
30
32
34
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4
Mole fraction of ZnO
Mo
lar v
olu
me
(1
0-6
m3m
ol-1
)
•The increase in density indicates zinc ions enter
the glassy network
•The decreases in the molar volume was due to the
decrease in the bond length or inter-atomic spacing
between the atoms
• The stretching force constant (216 N/m – 217.5
N/m) of the bonds increase resulting in a more
compact and dense glass.
• Atomic Radius (Shelby, 2005).
•R(Zn2+)(0.074 nm) << R(Te2+)(0.097 nm)
•there is no anomalous structural change (non-linear
behaviour)
25
Elastic constants of the glasses
Longitudinal modulus
Shear modulus
Bulk modulus
Poisson’s ratio
Young’s modulus
Debye Temperature
2
lVL
2
sVG
22
3
4sl VVK
22
22
2
2
sl
sl
VV
VV
22
22243
sl
sls
VV
VVVE
mDt VM
Np
k
h 3
1
4
9
3
1
33
12
lS
mVV
V
26
27
[(TeO2)65(B2O3)35]1–y[Ag2O]y glasses
(Halimah et al. 2010)
Pure and WO3 dopedCeO2–PbO–B2O3 glasses
(Singh & Singh 2011)
Figure 17 Density and molar volume of selected glass samples.
Table 6 Measured density (ρ), molar volume (V), longitudinal ultrasonic velocity (vl), shear
ultrasonic velocity (vs), elastic moduli, Poisson's ratio (σ), and fractal dimension (d = 4G/K )
and (E/G) ratio of (TeO2)90(AlF3)10-x(ZnO)x glasses (Sidek et al. 2009).
Elastic modulus of zinc oxyfluorotellurite glasses
Ultrasonic Wave Velocity
Compositional dependence of the velocity of
longitudinal and shear acoustic waves in Bi2
O3–B2 O3 glass systems.
Both increase at first with increasing Bi2 O3
mol% up to a maximum at 25 mol% Bi2 O3
and then decrease as the Bi2 O3 mol%
increases further.
1000
1500
2000
2500
3000
3500
4000
0.05 0.10 0.15 0.20 0.25 0.30 0.35
Pecahan mol of Ag2O
Hala
ju u
ltraso
nik
(m
/s)
Compositional dependence of the velocity of longitudinal and
shear acoustic waves in [(TeO2)x (B2O3)1-x)]1-y [Ag2O]y glass
1500
2000
2500
3000
3500
4000
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4
Mole fraction of ZnO
Ve
loc
ity
(m
/s)
Longitudinal
Longitudinal
Shear
Shear
Compositional dependence of the velocity of longitudinal and shear acoustic waves in [(ZnO)(TeO2) glass
28
Ultrasonic Wave Velocity
Lead Magnesium Chloride
Phosphate Glass
29
Elastic Modulus
Dependence of longitudinal modulus on
the composition of Bi2 O3–B2 O3 glass
systems.
One reason for this difference may come from the
volume effect, in that C44 expresses the resistance
of the body to deformation where no change in
volume is involved, while C11 expresses the
resistance where compressions and expansions
are involved.
10
20
30
40
50
60
70
0.05 0.10 0.15 0.20 0.25 0.30 0.35
Pecahan mol Ag2O
Mo
du
lus k
en
yal (G
Pa)
L
E
K
G
Compositional dependence of the longitudinal and shear modulus of [(TeO2)x (B2O3)1-x)]1-y [Ag2O]y glass
30
Elastic Moduli
15
20
25
30
35
40
45
50
55
60
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4
Mole fraction of ZnO
Elastic M
od
uli (G
Pa)
Longitudinal Modulus, L
Young’s Modulus, E
Bulk Modulus, K
Shear Modulus, G
31
Elastic Properties
Mole fraction, x 0.3 0.4 0.45 0.5 0.6
Elastic stiffness (GPa)
C11
C44
C12
48.9
18.0
12.9
48.8
18.0
12.7
47.5
17.4
12.7
47.3
17.5
12.3
47.3
17.2
13.0
Young's modulus, E
(GPa)
43.5 43.5 42.2 42.2 41.8
Bulk modulus, B (GPa) 24.9 24.7 24.3 24.0 24.4
Poisson's ratio, 0.208 0.207 0.211 0.207 0.215
Fractal dimension 2.90 2.92 2.87 2.92 2.82
Molar volume, V
(cm3/mole)
34.2 33.8 34.2 33.9 33.3
Number of atoms per
volume (x1028
atoms/m3)
9.67 8.90 8.37 8.00 7.24
Debye Temperature (K) 291 275 263 255 238
The room temperature elastic properties
of (PbO)x(P2O5)1-x glasses
Mole fraction, y 0.04 0.06 0.07 0.1
Elastic stiffness (GPa)
longitudinal, c11
shear, c44
c12
50.4
17.1
16.3
44.3
16.0
12.3
43.0
15.9
11.2
35.7
14.8
6.03
Young's modulus, E
(GPa)
42.4 39.0 38.4 33.9
Bulk modulus, B (GPa) 27.6 23.0 21.8 15.9
Poisson's ratio, 0.244 0.217 0.206 0.145
Fractal dimension 2.47 2.79 2.92 3.73
Molar volume, V
(cm3/mole)
33.5 33.5 33.3 33.4
Number of atoms per
volume (x1028
atoms/m3)
9.60 9.65 9.72 9.78
Debye Temperature (K) 276 266 264 251
Room temperature elastic properties of
(PbCl2)y(PbO.2P2O5)1-y glasses
32
Elastic Properties
33
34
Elastic properties of ZnO-TeO2 glasses (Sidek et al. 2010)
1500
2000
2500
3000
3500
4000
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Mole fraction of ZnO
Ve
loc
ity
(m
/s)
15
20
25
30
35
40
45
50
55
60
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Mole fraction of ZnO
Elastic M
od
uli (G
Pa)
0.19
0.2
0.21
0.22
0.23
0.24
0.25
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Mole fraction of ZnO
Po
isso
n's
Rati
o
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Mole fraction of ZnO
Mic
ro
hard
ness (
GP
a)
Shear
Longitudinal L
E
K
G
Ultrasonic velocities Elastic moduli
Poisson’s ratio Micro-hardness
35
Elastic moduli of selected binary glassy materials.
Elastic Moduli (GPa)
Material Density L G K E References
15Sm2O3-85P2O5 3.280 66.42 23.63 34.91 57.84 0.224 Sidek et al. (1988)
15La2O3-85P2O5 3.413 67.63 23.05 36.90 57.23 0.241 Sidek et al. (1988)
15Nd2O3-85P2O5 3.233 70.50 24.80 37.40 60.90 0.229 Senin et al. (1993)
15Bi2O3-85P2O5 4.418 56.8 19.2 31.2 47.9 0.244 Sidek et al. (2011)
20Ho2O3-80P2O5 3.327 73.1 24.7 40.1 Senin et al. (1996)
20Nd2O3-80P2O5 3.358 67.4 24.1 35.3 58.8 0.22 Sidek et al. (1993)
20Sm2O3-80P2O5 3.326 63.1 23.4 31.9 56.5 0.20 Sidek et al. (1993)
20Ce2O3-80P2O5 3.254 74.4 25.0 41.1 62.3 0.23 Sidek et al. (1993)
14Ag2O-86B2O3 2.850 44.15 13.37 26.32 Saunders et al. (1987)
20PbO-80B2O3 3.801 45.4 14.70 25.90 43.0 0.262 Azman et al. (2002)
40PbO-B2O3 4.852 76.09 25.15 42.54 63.04 0.253 Sidek et al. (2003)
40Bi2O3-B2O3 5.262 74.67 27.70 37.75 66.75 0.205 Sidek et al. (2003)
30PbO-70B2O3 4.019 71.40 22.80 41.00 57.60 0.265 Azman et al. (2002)
30PbO-70P2O5 4.135 47.30 15.70 24.00 39.20 0.252 Azman et al. (2002)
26Tb2O3-74P2O5 3.578 76.2 25.4 42.00 64.0 0.246 Senin et al. (1994)
26Ce2O3-74P2O5 3.234 72.5 24.00 40.60 60.00 0.233 Saunders et al. (2001)
26Pr2O3-74P2O5 3.338 74.3 24.3 41.9 61.1 0.257 Senin et al. (2000)
33Ag2O-67B2O3 4.030 72.18 19.17 46.61 Saunders et al. (1987)
30ZnO-70TeO2 5.211 56.06 19.39 30.21 47.92 0.236 Rosmawati et al. (2008)
36
Elastic moduli of selected binary glassy materials (cont)
33ZnCl2-67TeO2 4.63 50.8 15.10 30.6 39.0 0.289 El-Mallawany et al.
(1998)
30V2O5-70TeO2 4.564 44.1 11.5 28.8 30.5 0.289 El-Mallawany et al.
(1998)
30B2O3-70TeO2 4.89 63.62 23.33 32.51 56.48 0.21 Halimah et al. (2007)
30B2O3-70TeO2 4.78 0.21 Sidek et al.(2006)
TeO2 (pure glass) 5.101 56.40 19.90 Sidek et al. (1989)
TeO2 (pure glass) 5.105 59.1 20.6 31.7 50.7 0.233 El-Mallawany et al.
(1998)
TeO2 (pure crystal) 6.02 56.0 27.2 Arlt & Schweppe (1968)
P2O5 (pure glass) 2.52 12.1 Bridge et al. (1984)
SiO2 (pure glass) 2.203 30.7 Borgadus et al. (1965)
So far silicate based glasses are
practically well employed by
engineers for optoelectronic
devices development and
application.
However silicate glass has some disadvantages. As an alternative, more researchers are now preferred tellurite based glass to be used as a host matrix in laser applications. We also found that tellurite is the best glass host due to low melting temperature and in absence of hygroscopic properties as compared to borate and phosphate based glasses.
Potential Application of Glassy Materials
CD memory device
Optical switching device
Non-linear optical
devices
Electrochemical devices
Laser host
Infra-Red Fiber Optics
37
38
Next-generation large-scale panels
Glass substrates for LCDs
Next-generation large-scale panels by
contributing to form various functional films on
glass substrates. 39
…you could see what was in the fridge without opening it?
…you could have a
fish tank which is self
cleaning?
Self cleaning glass
40
When water hits a hydrophilic surface, it flattens and spreads out to form a thin sheet.
Hydrophilic
surface
=wetting
Water spreads
HYDROPHOBIC (WATER HATING)
When water hits a hydrophobic
surface, it beads.
Hydrophobic
surface
= beading
Water
beads
HYDROPHILIC (WATER LOVING)
Poor wetting
(beading)
Contact
angle > 90°
Good wetting Contact angle < 90°
When water hits a hydrophilic surface, it flattens and spreads out to form a thin sheet.
Hydrophilic surface
=wetting
Water spreads
HYDROPHOBIC (WATER HATING)
When water hits a hydrophobic
surface, it beads.
Hydrophobic
surface
= beading
Water
beads
HYDROPHILIC (WATER LOVING)
Poor wetting
(beading)
Contact
angle > 90°
Good wetting Contact angle < 90°
41
SELF CLEANING GLASS
THE LOTUS LEAF EFFECT The leaves of Lotus plants have the unique ability to avoid getting dirty. They are coated with wax crystals around 1 nanometre in diameter and have a special rough surface. Droplets falling onto the leaves form beads and roll off taking dirt with them, meaning the leaves are self-cleaning. Sometimes referred to as “The Lotus Leaf effect”
Scientists have mimicked nature at the nanoscale to create glass surfaces that are ‘self-cleaning’ like the Lotus leaf.
No more scrubbing of shower
screens!
Self cleaning glass Normal glass
No more Spiderman
window cleaner!
42
SELF CLEANING GLASS
HOW DOES IT WORK?
Glass is coated with a layer of nanocrystalline titanium dioxide (TiO2).
The titanium dioxide reacts to the ultraviolet (UV) component of sunlight causing a gradual break down and loosening of dirt.
This is known as the ‘photocatalytic’ stage
The reaction also causes the glass surface to become super hydrophilic. This forces water to spread across the surface like a sheet, rather than beading, thereby washing away the loosened debris on the surface of The glass as it falls. This is the ‘hydrophilic’ stage.
APPLYING A MONOLAYER TO GLASS
GLASS NANO COATINGS
OptiView Anti-reflective glass made by
Australian company Pilkington.
Switchable glass changes from transparent to opaque.
A nano-layer of a rod-like particle suspension is placed between two layers of glass.
Under normal conditions, the suspended particles are arranged in random orientations and tend to absorb light, so that the glass panel looks frosted or opaque.
But when a voltage is applied, the suspended particles align and let light pass, turning the glass clear.
SWITCHABLE GLASS
CONCLUSION
Glass is one of the most versatile and most
fascinating materials
Their uniqueness in physical, optical, thermal,
mechanical and chemical properties offer an
almost unlimited range of applications.
Ultrasonic system has been employed to
characterize their elastic properties.
Extensive series of investigation using borate,
phosphate and tellurite based glasses have
been carried out to study the effect of certain
oxides into those glass formers in terms of
physical properties such as density, molar
volumes and elasticity.