the role of coatings and other surface treatments in the...
TRANSCRIPT
The Role of Coatings and Other Surface
Treatments in the Strength of Glass
Carlo G Pantano
Department of Materials Science and Engineering
Materials Research Institute
The Pennsylvania State University
University Park, PA 16802
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outline• introduction to the issues
• quick review of generic approaches
• what works and why?
- hot end/cold end coatings on containers
- coatings on glass fibers
• water/corrosion versus mechanical damage
• tools for the evaluation of coatings
• summary
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fundamental issues in glass strength
• mechanical damage/flaws at the glass surfaces
• intrinsic strength/fracture toughness of the glass
• fatigue (water chemisorption and corrosion)
• residual stress and bond strain
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Important Roles for Coatings in Strength
• mechanical barrier: modulus and thickness
• abrasion resistant: hard and low friction (smooth &lubricious)
• water barrier
• compressive residual stress
• flaw healing, especially at cut edges
>>>> what about the coating/glass interface?
>>>> coatings for strength are necessarily application specific.
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GLASS
• intrinsic strength and damage tolerance of the glass (E, γ, K1C, H)
Coatings for Strength
GLASS
H20
• intrinsic strength and damage tolerance of the glass (E, γ, K1C, H)
• condition of the original surface (flaws, moisture, roughness)
Coatings for Strength
GLASS
H20
• intrinsic strength and damage tolerance of the glass (E, γ, K1C, H)
• condition of the original surface (flaws, moisture, roughness)
• properties of the coating (E, H, friction, diffusion, residual stress)
Coatings for Strength
GLASS
H20
• intrinsic strength and damage tolerance of the glass (E, γ, K1C, H)
• condition of the original surface (flaws, moisture, roughness)
• properties of the coating (E, H, friction, diffusion, residual stress)
• interfaces (weak vs strong)
Coatings for Strength
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Surface Treatments for Glass Strength
• flaw healing (eg, flame polishing or acid etching)
• compressive residual stress (eg, ion exchange strengthening)
• dealkalization treatments (eg, fluorine treatment)
>>>> perhaps best applied in combination with a coating…..
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partial list of patents for ion-exchange strengthening, many by “spray-on”
• [1] A. R. Hess and G. B. Sleighter, “Method of Strengthening Glass by Ion exchange and Articles Therefrom”, US 3,287,200; Nov 22, 1966. (PPG) • *2+ D. W. Rinehart, “Method of Strengthening a Glass Article by Ion Exchange”, US 3,357,876; Dec. 12, 1967. • [3] F. J. Marusak, “Double Ion Exchange Method for Making Glass Article”, US 3,410,673; Nov. 12, 1968. (Corning) • [4] A. E. Saunders and R. E. Kubichan, “Strengthening Glass by Multiple Alkali Ion exchange”, US 3,433,611; March 18, 1969. (PPG). • [5] H. M. Garfinkel and J. S. Olcott, “Method for Strengthening Glass Articles”, US 3,630,704; Dec 28, 1971. (Corning) • [6] Ellen L. Mochel, “Alkali Aluminosilicate Glass Article Having an Ion-Exchanged Surface Layer”, US 3,790,430; Feb 05, 1974. (Corning). • *7+ D. W. Rinehart, “Ion Exchange Strengthened Glass Containing P2O5,” US 4,055,703; Oct 25, 1977. (PPG). • *8+ D. W. Rinehart, “Chemical Strengthening of Glass”, US 4,119,760; Oct 10, 1978. (PPG). • *9+ D. W. Rinehart, “Lithium Containing Ion Exchange Strengthened Glass”, US 4,156,755; May 29, 1979. (PPG). • 4,164, 402 Strengthening of Thin-Walled Light Glass Containers; Watanabe; Yamamura Glass Kabushika Kaisha (August 14, 1979)• 4,206,253 Method of chemically strengthening a glass container; Watanabe; Yamamura Glass Kabushika Kaisha (June 3, 1980)• 4,218,230 - Method of glass strengthening by ion exchange; Hogan, Brockway Glass • 4,273,832 - Glass Article Strengthened by Ion Exchange Substitution; Hogan, Brockway Glass• 4,290,793 Fluidized bed chemical strengthening of glass articles; Brockway; Liberty Glass Company (September 22, 1981)• 4,702,760 Method for strengthening glass articles through ionic interaction;Garcia de Leon; Vitro-Tec Fideicomiso (October 27, 1987)• [16] W. C. LaCourse and M. Akhtar, “Process for Strengthening Glass”, US 4,872,896; Oct 10, 1989. (Alfred Univ) • [17] B. Speit, “ Chemically Prestressable Aluminosilicate Glass and Products Therefrom”, US 5,895,768; April 20, 1999. (Schott). • [18] Marie-Helen Chopinet, E. Rouyer and O. Gaume, “Glass Composition and Chemically Tempered Glass Substrate”, US 6,333,285; December 25,
2001. (Saint-Gobain Vitrage). • [19] John M. Bradshaw, I. H. Smith, A. C. Torr and S. Lythgoe, “Chemically Toughened Glasses”, US 6,518,211. Feb 11, 2003. (Pilkington Plc). • [20] D. J. Green, V. M. Sglavo, and R. Tandon, “Strengthening, Crack Arrest and Multiple Cracking in Brittle Materials Using Residual Stresses”, US
6,516,634; Feb 11, 2003. (Penn State Research Foundation). • [21] L. L. Shelestak, G. B. Goodwin, A. Mishra and J. M. Baldauff, “Lithia-Alumina-Silica Containing Glass Compositions and Glasses Suitable for
Chemical Tempering and Articles Made Using the Chemically Tempered Glass”, US Patent Application 2005/009030377 A1; April 28, 2005. (PPG).
METHOD AND APPARATUS FOR STRENGTHENING GLASS………. 2004
Gy, 2008
The exchanged/strengthened “case” depth is limited in the ion-exchange method, especiallyWhen a rapid throughput “spray-on” method isEmployed.
Can a coating make a difference?
What kind of coating? 90um
600um
eg, aqueous spray; Brockway
JP 58064248 A - Surface Treatment of Glass Bottle to Improve Strength - Involves Simultaneous
Alkali Removal and Compressive Stress Layer Formation
Nippon Taisan Bin K; 10/13/81 (Derwent)
Surface dealkalization is achieved with the addition of a alkali-removing agent (SO2, (NH4)2SO4) inside of
the glass bottles at a temperature which is higher than the strain point and lower than the softening point
(1075oF to 1200oF) for 10 to 40 minutes. Cooling air is then blown against the inner and outer surfaces
to simultaneously remove the alkali products and to develop a compressive stress layer (thermal
strengthening). A synthetic resin emulsion or surfactant (paraffin and fatty acids, etc.) is then applied to
the outer surface of the bottle to improve its lubricity and anti-wear properties.
JP 57129845 A; JP 91023494 B - Glass Having Good Chemical Resistance and Mechanical Strength
Nippon Taisan Bin K; 8/12/82, 3/29/91; Derwent)
JP 55056042 A; JP 85022662 - Strong, Lightweight Chemically Durable Glass Bottle - Surface Dealkalization and Ion
Exchange
Ishizuka Glass KK; 4/24/80, 6/3/85 (Derwent)
Glass bottle is simultaneously exposed to surface dealkalization and ion exchange at high temperatures.
JP 54142227 A; JP 82001502 - Increasing Strength and Chemical Resistance of Soda-Lime Glass by Treating with
Potassium Thiocyanate which the Enhances Ion Exchange and Dealkalization Reactions
Nippon Taisanbin KO; 11/6/79, 1/1/82; (Derwent)
JP 54107921 A - Preparation of Strengthened Glass Bottle by Immersing Bottle Immediately After Shaping in a
Molten Salt of Alkali Metal and Annealing
Ishizuka Glass KK; 8/24/79 (Derwent)
JP 54107920 A - Uniformly Thin Strengthened Glass Bottle With Stress Layer on Surface Formed by Ion Exchange
Ishizuka Glass KK; 8/24/79 (Derwent)
simultaneous tempering or ion exchange, and dealkalization
Strengthening of Glass and Pyroceram With Hydrophobic CoatingsAuthors: Curtis E. Johnson; Daniel C. Harris; John G. Nelson; Clare F. Kline Jr.; Brandy L. Corley; NAVAL AIR WARFARE CENTER WEAPONS DIV CHINA LAKE CA
July 2003
Abstract: The objective of this study was to determine whether significant improvements in strength of soda-lime glass and Pyroceram 9606 could be obtained by applying thin hydrophobic coatings. Soda-lime glass slides were coated with a few different hydrophobic compounds (containing organosilicon groups) and then subjected to strength tests in flexure. The glass slides were acid etched to remove surface defects and to slightly mimic the
outer fortified surface of Pyroceram. A hydrophobic coating of octadecyl dimethylchlorosilane on soda-lime glass slides led to doubling or more of the strength. The increase in strength is attributed to a reduced role of stress corrosion cracking that is promoted by moisture at the surface. Similar
hydrophobic treatments were not effective on Pyroceram bars. Thick coatings on dry Pyroceram surfaces were successful at improving the strength by about 40%, similar to the effects of dipping in silicone oil.
JP 54054124 A - Surface Treating of Glass Bottles by Etching with an Aqueous
Fluorine Compound Solution and Coating with PlasticToyo Glass Co. Ltd. 4/28/79
The outer surface of the bottle is treated with a 1-10% aqueous solution of ammonium fluoride, hydrogen
fluoride or ammonium fluoride by immersing or spraying. After water washing, it is coated with polyurethane.
4,039,310 Process of strengthening glass bottles and the like
Sipe, et. al.; Duraglass Research and Development Corporation (no listing in Boulder CO) (August 2, 1977)
Glass strengthening technique in which a fatty acid is applied (sprayed, mold coating) to the glass bottle at temperatures between 900 and 1300oF. Fatty acids evaluated were behemic, stearic, glutamic and combinations of stearic and behemic. Bottle drop heights increased from 2 feet (control) to up to 15 feet (stearic/behemic applied at 1100oF. The theory is that the fatty acids chemically reacts with the atoms in the glass surface, strengthening the tips of the microcracksand preventing further crack propagation when the surface is under stress.
High temperature fluorocarbon treatments of glass containers
Strengthening glass articles with electromagnetic radiation and resulting product Document Type and Number:United States Patent 5102833
Abstract:Alkali metal- and alkaline earth metal-oxide aluminosilicate amorphous glass articles can be strengthened by providing such glass with a cerium dioxide sensitizer and a nucleating agent, irradiating the article with electromagnetic radiation, heating the irradiated article to a temperature between about the annealing and softening points of the glass, and cooling the heated, irradiated glass article. The treated article has a thick lower layer of the amorphous glass, but a thin layer of this glass at the surface of the article has been converted to a crystalline state. In this surface layer, some of the cerium has been converted from a +3 to a +4 ionic state and some of the metal element in the nucleating agent has been changed to a metallic state. The adjacent location of the lower and surface layers creates large compressive stresses at the surface layer which imparts great strength to the glass article.
Damage resistance of tin-oxide/organic coated glass containers
•Mechanical effects- abrasion/sliding friction = f (roughness, hardness, chemistry)
- contact/Hertzian Efilm vs Esubstrate, thickness
- impact Efilm vs Esubstrate, thickness
•Chemical effects- tin oxide is an adhesion promoter for the organic-coating
- aqueous attack of the glass is reduced (diffusion barriers)
- Sn diffusion modifies the glass properties (Si-O-Sn)
- gettering sodium? (NaCl, NaSnO3 )
Materials Research Institute
Baseline Properties
Property Soda Lime Silica Glass Tin Oxide
Hardness (GPa) 6.3 10–14 (Ref. 24)
Young’s Modulus (GPa) 72 263 (Ref. 25)†
Poisson’s ratio 0.23 0.294 (Ref. 25)
Thermal Expansion
Coefficient (/0C)
8.3 4.13* (Ref. 27)
Density (Mg/m3) 2.53 6.990
Materials Research Institute
V
2.0nm 3.0nm 4.0nm
tin-oxide (pyrolytic) coatings on glass containers
Materials Research Institute
H2O Contact Angle vs SnO2
0 200 400 600 800 1000
20
25
30
35
40
45
50
55
60
65
H2O
Con
tact A
ngle
(°)
SnO2 Thickness (Å)
CGW 1737
P16 sls
0 10 20 30 40 50 60 70 80 90 100
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
C3H
6O
2
+
C3F
2
+
C2H
5O
+
C2H
3
+
C2H
5
+
H2O
+
CH3
+
CF+
C5H
9
+
C4H
5O
+
CF3
+
41K
+
C3H
5
+
C4H
7
+
C4H
9
+
39K
+
Na+
C3H
7
+
C2H
3O
+
H+
X+ In
ten
sit
ym/e
TOF-SIMS spectra shows corresponding hydrocarbon adsorption
10 day equilibration time (90% in 48h)
Sn-oxide and (hydro)carbon adsorption
x<2 x~2 x>2
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
OH
- / O
-
O:Sn
Ratio of negative TOF-SIMS OH- / O- peak areas
for unaged 100s tin oxide films on CGW 1737
• Sn-oxide has a high density of (hydro)carbon adsorption OH
• Those “ reactive OH” species are
associated with the “Sn” on the
surface
• Na impurities in the film surface (e.g
PL16 SLS) or exposed substrate (e.g.
CGW 1737) influence the amount of
Sn-OH groups (hydro)carbon
adsorption contact angle
SnSn Sn Sn
OH OH OH OH
organic species
Impurity Effect on Friction
Coefficient of friction vs. scratch time for a
500 µN ramp load on 4 nm films
Normal Load = 320 mN
• Sodium effect on contact
angle results in higher
friction coefficient on the tin
oxide coated SLS
• Sodium weakens the
bonding between tin oxide
film and glass substrate, and
causes film breakdown
conclusions about tin-oxide on bottles
1. The tin oxide coated surfaces are more hydrophobic (higher H2O contact angle) than bare glass surfaces. This is consistent with the empirical observation that Sn-oxide coated glasses have better adhesion to organic substances than bare glass.
2. TOF-SIMS shows a high concentration of hydroxyl species (which act as adsorption sites) on the Sn-oxide coated surfaces; the observed stoichiometry effects suggest that Sn-OH is the important adsorption site for (hydro)carbon species.
3. The tin oxide films on CGW 1737 samples have higher H2O contact angle (more hydrophobic) than corresponding tin oxide films on SLS due to the presence of sodium in the tin oxide films on SLS.
4. Sodium at the interface, and within the heat-treated SnO2 films, deteriorates the film adhesion under load.
5. The dynamic aspect of (hydro)carbon adsorption may help to explain the empirical observation that Sn-oxide films enhance scratch resistance; i.e. reduced friction due to the (hydro)carbon and its continual replenishment
Coatings on optical fiber….. fatigue
taken from Kurkjian, SPIE
Carbon Coated Fibers, Lu
Akiyama, et al; 1991
Carbon also provides a hydrogen barrier
Kurkjian
fiber strength versus Oxidative removal of the carbon coating
Fiber Draw
The roller with horizontal motion:
reducing the fiber damage during
collecting
Sealed in plexiglass: atmosphere control
Sufficient space: various coating methods
Surface Treatments
and Their Evaluation
smooth rod
rough rod
mist from nebulizer
Strengthening Effect dip coating for 1 min
Pristine
Pristine + R.O. Water
Pristine + APS 1 wt%
Pristine + Polyamide 1wt%
-1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8
-4
-3
-2
-1
0
1
2
Ln
(Ln
(1/(
1-F
)))
Ln GPa
Damaged
Damaged + Polyamide 1 wt%
Polyamide : excellent on both Pristine and Damaged
APS: none
Damaged
1wt% APS + Damaged
1wt%PA + Damaged
Pristine + 1wt%PA dip
Lubrication effectPolyamide : excellent
APS: none
-1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
-4
-3
-2
-1
0
1
2
Ln
(Ln
(1/(
1-F
)))
Ln GPa
10wt%PA + Damaged
Method of Strengthening a Brittle Oxide Substrate with a Weatherable Coating
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Development and Evaluation of Coatings for Strength
• surface properties of the glass• intrinsic film properties• elastic and plastic response of the coated surface• ‘strength’ of the coated surface• damage mechanisms and failure modes• manufacturing effects• service performance• cost
TriboIndenter
Lateral Force
Transducer
Vertical Force
TransducerZ
X
Feedback
Indenter
The Hysitron TriboIndenter® uses a two-dimensional transducer to collect lateral
force and normal force measurements at the same time. It has nanoscratch and
nanoindenter capabilities with in-situ imaging similar to that of the AFM. Using
this instrument allows for the collection of quantitative information.
http://www.inex.org.uk/page.asp?pageid=104
http://www.hysitron.comPiezoelectric
Kolluru, Muhlstein, Green and Pantano, Penn State, to appear
Indentation Pile-up
4
5º
1
1
2
2
4 4
3
3
• Must be accounted for in calibration and measurements
38
Soft and Hard Regions
ROUGH REGIONSOFT REGION
SMOOTH REGION HARD REGION
Er = 72.0 GPaH = 7.34 GPa
Er = 78.0 GPaH = 8.16 GPa
6500 µN
6500 µN
Kolluru, Muhlstein, Green and Pantano, Penn State, to appear
Hardness Trends in Aged Float Glass
• Hardness varies with depth and glass thickness
Kolluru, Muhlstein, Green and Pantano, Penn State, to appear
40
Float Glass – Hardness (H)• Corrosion decreased air
side hardness
• Tin side hardness was relatively invariant
• (H)air-side > (H)tin-side
before corrosion
• (H)tin-side > (H)air-side
after corrosion
Kolluru, Muhlstein, Green and Pantano, Penn State, to appear
“Nanoindentation of Glass Wool Fibers”, Nadja Lonnroth, Christopher L. Muhlstein, Carlo Pantano and Yuanzheng YueJournal of Non-Crystalline Solids 354 (2008) 3887-3895.
Nanoscratch Testing
Using a triboindenter, one can determine the film thickness and load necessary to break through organic films on glass
glass substrate glass substrate
tipload
continuously
increased
glass substrate
film break through
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Nanoscratch Testing
Normal Force: 13.95mN
Film Thickness: 2.46nm
Scratch tests were performed using a tip with a < 1mm radius while continuously
increasing the normal force. When the tip broke through the film, the normal
force and displacement were recorded.
Rinsed polymeric film Unrinsed polymeric film
Normal Force: 49.20mN
Film Thickness: 10.43nm
Figure 6. Wear test on SnO2 films on P16 SLS before and after 2 passes at 20mN normal force
.
Figure 7. Wear test on SnO2 films on P16 SLS after 2 and 4 passes at 50mN.
WEAR RESISTANCE OF TIN-OXIDE ON GLASS
Hertzian Indentation
Quasi-plastic Damage Zone
First Ring CrackConcentric
Ring CracksRadial Cracks
Cone CrackMedian Cracks
Green and Pantano
Penn State
glasses tested
Glass Type Coating
Float Glass (Air) None
Float Glass (Tin) None
Permabloc® CVD ‘silica-like’ (70 nm)
TEC Glass (Uncoated) None
TEC Glass (Tin oxide) SnO2 coating (300 nm) on ‘silica-like’ underlayer
(70 nm)
Optitherm® SnO2 coating (30 nm) on TiO2 (3 nm), Ag (8nm),
NiCr (3nm), TiO2 (3 nm), SnO 2 (30 nm)
Gold Eclipse® SnO2 (10–20 nm) on Si (10–20 nm)
Penn State
Cone Crack Initiation - Coated Glass
10008006004002000
0.0
0.2
0.4
0.6
0.8
1.0
Float (Air)Float (tin)
Permabloc
INDENTATION LOAD (N)
FA
ILU
RE
PR
OB
AB
ILIT
Y
8006004002000
0.0
0.2
0.4
0.6
0.8
1.0
Optitherm
Gold Eclipse®
TEC glass
Uncoated
INDENTATION LOAD (N)
FA
ILU
RE
PR
OB
AB
ILIT
Y
Coating ‘Strengths’
1.61.41.21.00.80.60.0
0.2
0.4
0.6
0.8
1.0
Float (0)
Float (Sn)
Permabloc
TEC glass
Uncoated
Maximum Indentation Stress (GPa)
Fa
ilu
re P
rob
ab
ilit
y
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Crack Morphology
Permabloc® TEC-Glass
200 mm
Crack Morphology
Gold Eclipse® Optitherm®
200 mm
Summary of Hertzian Indentation
• Hertzian indentation is a useful technique to characterize the surface strength and contact damage resistance of coated glasses.
• Various commercial glasses show the coatings may enhance or degrade the damage resistance by changes in the surface flaw sizes.
• Further study is needed to identify the processing and material parameters that control this behavior.
● Scratch resistant
● Low maintenance
● Highly transparent
● Chemically inert
DiamondGuard®Glass that’s nearly diamond-like -- tough and beautiful.DiamondGuard is a family of permanent protective coatings that provides glass with exceptional scratch
resistance. In fact, glass with one of our DiamondGuard coatings is proven to be over 10 times more
scratch resistant than tempered and chemically strengthened glass.
Developed by Guardian’s Science and Technology Center using a
patented process of diamond-like carbon deposition on glass, these
coatings are not only renowned for their toughness, but their versatility
and beauty as well.
DiamondGuard is available on clear glass and sold in thicknesses ranging from 1.7 mm to 12 mm.
Nanoscale Carbon Coatings for Glass
a potentially multi-functional coating• water barrier• low friction• electrical conductivity• high contact angle
The long-range goal is to deposit or grow coat this layer on glass to enhance surface properties and add functionality.
Nanoscale Carbon Coatings for Glass
Carlo Pantano, et alMaterials Research Institute
Penn State University
“Processing and Characterization of Ultrathin Carbon Coatings on Glass”, Hoikwan Lee, Ramakrishnan Rajagopalan, Joshua Robinson and Carlo PantanoApplied Materials and Interfaces, Vol 1 No. 4 927-933 (2009).
summary• there is no universal coating for glass strength• a combination of approaches, perhaps based on
a platform of surface treatment(s) plus multifunctional coatings, is required
• the development of new coating systems is the real challenge: -size effects make scale-up a generic issue-lab scale testing versus the service environment-lab scale processing versus manufacturing-development costs can be substantial
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