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OXIDATION RESISTANT
HIGH TEMPERATURE COATINGS
Zbigniew Grzesik
Department of Physical Chemistry and Modelling
http://home.agh.edu.pl/~grzesik
REFERENCES
1. N. Birks, G.H. Meier and F.S Pettit, Introduction to the high temperature oxidation
of metals, Cambridge, University Press, 2009.
2. P. Kofstad, „High-Temperature Oxidation of Metals”, John Wiley & Sons, Inc, New
York-London-Sydney, 1978.
3. A.S. Khanna, „Introduction to High Temperature Oxidation and Corrosion”, ASM
International, Materials Park, 2002.
4. S. Mrowec, „An Introduction to the Theory of Metal Oxidation”, National Bureau
of Standards and the National Science Foundation, Washington, D.C., 1982.
5. Wei Gao and Zhengwei Li ”Developments in high-temperature corrosion and
protection of metals”, Ed, Woodhead Publishing Limited, Cambridge, England,
2008.
6. R. Cottis, M. Graham, R. Lindsay, S. Lyon, J. Richardson, J. Scantlebury, F. Stott,
„Basic Concepts, High Temperature Corrosion”, vol. I, in „Shreir’s Corrosion”,
Elsevier, Amsterdam, 2010.
Oxidation resistance of selected metals
10-7
10-5
Cu
Mn
Co
Fe
cm-4
s-11573 1473 1373 1273 1173
T / K
6 7 810-13
10-11
10-9Mn
Ni-Li2O
Ni
Cr
.
k p /
g2 cm
T -1 104 / K-1
Oxidation resistance of selected metals
Ni-Al phase diagram
Degradation rate of noble metals at high temperatures
The influence of dopping effect on oxidation resistance
The influence of dopping effect on oxidation resistance
10-11
10-10
10-9
-4s-1
1573 1373 1173 973
Ni-30CrCo-35Cr
UTLENIANIE
T / K
Oxidation resistance of selected alloys
6 7 8 9 10 1110-15
10-14
10-13
10-12
.T-1 104 / K-1
k p /
g2 cm-4
chromia formersalumina formers
β-NiAl
Fe-5Cr-4Al Ni-10Cr-5Al
Fe-20Cr
The influence of Y on the oxidation rate of the Fe-25Cr-5Al alloy
The influence of Y and Sc on the degradation rate of the Fe-25Cr-5Aland Ni-20Cr alloys under thermal shock conditions
0 25 50 75 100-5
-4
-3
-2
-1
0
1very good
good
ratherbad
mas
s ch
ange
/sur
face
are
a
/ a.u
.
Number of thermal shocks
1 cycle = 2 h
extremalybad bad
0 50 100 150 200 Time / h
MATERIALS USED AS PROTECTIVE COATINGS IN OXIDIZING ATMOSPHERES
Cr – Cr2O3
Al – Al2O3
Si – SiO2Si – SiO2
MCrAlY (where M = Co, Ni, Co/Ni) – Al2O3, Cr2O3
MCrAlY-Si – Al2O3, Cr2O3
MCrAlY-RE (where RE = Y, Hf, Zr) – Al2O3
NiAl – Al2O3
Cross-section of the Ni-Cr-Al-Y coating obtained by the EB-PVD method
Surface and cross-section of the Co-Cr-Al-Y coatingobtained by the EB-PVD method on the IN-738 alloy
Micrograph of Pt modified aluminide coatingon nickel-base superalloy
PtAl2 phase (white color) in a matrix of β-NiAl
Micrograph of cross-section of an EB-PVD Co-Cr-Al-Y coating, deposited on IN-738
Micrograph of cross-section of Pt-modified aluminide coating on nickel-base single-crystal superalloy
after oxidation at 1200oC for 20 h
The original grain structure of the β-phase is evident and γ’ has begunto nucleate at β grain boundaries as a consequence of Al depletion
Micrograph of cross-section of Pt-modified aluminide coating on nickel-base single-crystal superalloy
after oxidation at 1200oC for 200 h
The coating had been converted almost completely to γ’, as a result of Al depletion. Further exposure would result in the γ’ transforming to γ.
Micrograph of cross-section of a Ni-Co-Cr-Al-Y coatingon a single-crystal Ni-base superalloy
after 200 one-hour cycles at 1100oC in air
Micrograph of cross-section of a Ni-Co-Cr-Al-Y coatingon a single-crystal Ni-base superalloy
after 1000 one-hour cycles at 1100oC in air
Cyclic oxidation data for a straight aluminide and a platinum aluminide on IN-738 at 1200oC in air
Cyclic oxidation data for a sputtered Ti-Cr-Al coating on γ−TiAl at 900oC and the cross-section
of coating after exposure
Thermal barrier coatings (TBC)
Thermal barrier coatings (TBC) are highly advanced materials systemsusually applied to metallic surfaces, such as on gas turbine or aero-engineparts, operating at elevated temperatures, as a form of exhaust heatmanagement.These coatings serve to insulate components from large and prolongedheat loads by utilizing thermally insulating materials which can sustain anheat loads by utilizing thermally insulating materials which can sustain anappreciable temperature difference between the load-bearing alloys andthe coating surface. TBC coatings can allow for higher operatingtemperatures while limiting the thermal exposure of structural components,extending part life by reducing oxidation and thermal fatigue. In conjunctionwith active film cooling, TBCs permit working fluid temperatures higherthan the melting point of the metal airfoil in some turbine applications.
Scheme of a typical TBC system
Scheme of a typical TBC system
a) before and b) after oxidation
Scheme of the structure of a thermal barrier coatingwith a temperature profile
Scheme of the structure of a thermal barrier coatingwith a temperature profile
The parts of an aircraft engine using a plasma spray coating
View of Engine Alliance GP7200 aircraft engine with photograph of aturbine blade ( ∼ 10 cm long) with thermal-barrier coating (TBC) from the
high-pressure hot section of an engine, and a scanning electron microscope (SEM) image of a cross-section of an electron beam physical vapor
deposited 7 wt% yttria-stabilized zirconia TBC.
Cross-sections of TBC coatings
Surface and cross-sections of a layer of TBC protective coating after oxidation
EB-PVD YSZ TBC
Pt-modified bond coat
Cross sections of a layer of TBC protective coating after oxidation
EB-PVD YSZ TBC
Photograph of a plasma spray physical vapor deposition (PSPVD) plumecoating (a) and (b) scanning electron microscopy images of PSPVD
microstructures from splat/cluster deposition all the way to vapor depositionobtained at different deposition rates
Progression of temperature capabilities of Ni-based superalloys and thermal-barrier coating (TBC) materials over the past 50 years. The red lines indicate progression of maximum allowable gas temperatures in
engines, with the large increase gained from employing TBCs.
Thermal conductivity summary of the emerging ceramics for thermal-barrier coatings, whose conductivities vary with temperature (a) and
temperature-independent thermal conductivities of ceramics (b)
Schematic illustration of the multilayer, multifunctional nature of the thermalbarrier coating system. The ceramic topcoat is deposited by electron beam
physical vapor deposition (EBPVD) or air plasma-spraying (APS).
Failure mechanisms typical of current thermal-barrier coatings (TBCs):delamination cracks propagating through the TBC, chemical attack of the thermally grown oxide (TGO) with concomitant loss of adherence, creep
cavitation of the bond coat below a heavily penetrated TBC
Thermal barrier coatings in automobiles
Cross section of four-cylinder in-line engine with spark ignition, Fiat
Construction of an exhaust valve
1 – mushroom - austenitic steel Cr-Ni-W-Mo in supersaturated and aged state,
2 – handle - Cr-Si-Mo steel thermally improved,
3 – place of friction welding, 4 – valve face hard coated of stellite Co-Cr-W
Working conditions of valves in car engines
• aggressive atmosphere of combustion gases
• high temperature (T ≈ 1173 K)
• rapid changes of temperature (thermal shocks)• rapid changes of temperature (thermal shocks)
Temperature distribution in the exhaust valve- petrol engine with spark ignition
Componentsof exhaust gases
Units Method of ignition Toxicity evaluationspark ignition spontaneous
Nitrogen % vol. 74-77 76-78 neutral
Oxygen % vol. 0,3-8,0 2,0-18,0 as above
Water vapor % vol. 3,0-5,5 0,4-5,0 as above
Carbon dioxide % vol. 5,0-12,0 1,0-10,0 as above
Chemical compositions of an engine gaseswith spark and spontaneous ignition (wt. %)
Carbon dioxide % vol. 5,0-12,0 1,0-10,0 as above
Carbon monoxide % vol. 5,0-10,0 0,01-0,5 toxic
Nitrogen oxides % vol. 0,0-0,8 0,002-0,5 as above
Hydrocarbons % vol. 0,2-3,0 0,009-3,0 as above
Aldehydes % vol. 0,0-0,2 0,001-0,009 as above
Soot g/m3 0,0-0,04 0,01-1,1 as above
3,4 benzopyrene g/m3 to 15,0 to 10,0 carcinogenic
Merkisz J., Ekologiczne problemy silników spalinowych Tom I i II. Wydawnictwo Politechniki Poznańskiej, Poznań 1999
a.
Exhaust valves after the 1000 hour test- engine with spontaneous ignition
The chemical composition of valve steels (% wt.)
Type of steel C Mn Si Cr Ni N W Nb S P Mo Fe
X33CrNiMn23-8 0.35 3.3 0.63 23.4 7.8 0.28 0.02 - <0.005 0.014 0.11 bal.
X50CrMnNiNbN21-9 0.54 7.61 0.30 19.88 3.64 0.44 0.86 2.05 0.001 0.031 - bal.
X53CrMnNiN20-8 0.53 10.3 0.30 20.5 4.1 0.41 - - <0.005 0.04 0.12 bal.
X55CrMnNiN20-8 0.55 8.18 0.17 20.0 2.3 0.38 - - <0.005 0.03 0.11 bal.X55CrMnNiN20-8 0.55 8.18 0.17 20.0 2.3 0.38 - - <0.005 0.03 0.11 bal.
The corrosion test of valve steels under thermal shock conditions in engine house
Hybrid reactive head
Corrosion kinetics of tested valve steelsunder thermal shock conditions
-0.15
-0.10
-0.05
0.00
0.05
combustion gases of fuel oil B5
combustion gases of fuel oil B10
1 cycle = 2h
air
∆m/S
/
g cm
-2
X33CrNiMn23-8T = 1173 K
0 100 200 300 400 500
-0.3
-0.2
-0.1
0.0
combustion gases of fuel oil B10
combustion gases of fuel oil B5 air
1 cycle = 2h
∆m
/S
/g c
m-2
X50CrMnNiNbN21-9T = 1173 K
0 100 200 300 400 500 600-0.15
Number of thermal shocks
0 100 200 300
-0.3
-0.2
-0.1
0.0
0.1
combustion gases of fuel oil B10
combustion gases of fuel oil B5
air
1 cycle = 2h
Number of thermal shocks
∆m
/S
/g c
m-2
X53CrMnNiN20-8T = 1173 K
0 100 200 300-0.3
-0.2
-0.1
0.0
0.1
1 cycle = 2h
combustion gases of fuel oil B10
combustion gases of fuel oil B5
air
Number of thermal shocks
∆m/S
/ g
cm
-2
X55CrMnNiN20-8T = 1173 K
0 100 200 300 400 500
Number of thermal shocks
0 20 40 60 80 100-0.4
-0.3
-0.2
-0.1
0.0
0.1
combustion gasesof petrol E50
combustion gasesof petrol E90
combustion gasesof petrol E95
1 cycle = 2h
air
∆m/S
/
g cm
-2
X50CrMnNiNbN21-9T = 1173 K
0 20 40 60 80 100-0.10
-0.05
0.00
0.05
0.10
combustion gasesof petrol E50
combustion gasesof petrol E90
combustion gasesof petrol E95
1 cycle = 2h
air
∆m/S
/
g cm
-2
X33CrNiMn23-8T = 1173 K
Corrosion kinetics of tested valve steelsunder thermal shock conditions
0 20 40 60 80 100
Number of thermal shocks
0 20 40 60 80 100-0.4
-0.3
-0.2
-0.1
0.0
0.1
combustion gasesof petrol E50
combustion gasesof petrol E90
combustion gasesof petrol E95
Number of thermal shocks
1 cycle = 2h
air
∆m/S
/
g cm
-2
X53CrMnNiN20-8T = 1173 K
0 20 40 60 80 100-0.4
-0.3
-0.2
-0.1
0.0
0.1
combustion gasesof petrol E50
combustion gasesof petrol E90
combustion gasesof petrol E95
Number of thermal shocks
1 cycle = 2h
air
∆m/S
/
g cm
-2
X55CrMnNiN20-8T = 1173 K
0 20 40 60 80 100
Number of thermal shocks
-0.03
-0.02
-0.01
0.00
0.01
combustion gasesof fuel oil B5
combustion gasesof fuel oil B10
1 cycle = 2hX33CrNiMn23-8
∆m/S
/
g cm
-2
aircombustion gasesof petrol 95Al
combustion gasesof petrol 90Al
combustion gasesof petrol 50Al
-0.4
-0.3
-0.2
-0.1
0.0
0.1
combustion gasesof petrol 50Al
combustion gasesof fuel oil B5
combustion gasesof fuel oil B10
combustion gasesof petrol 90Al
combustion gasesof petrol 95Al
∆m/S
/
g cm
-2
X50CrMnNiNbN21-91 cycle = 2h
air
Comparison of corrosion kinetics of valve steelsunder thermal shock conditions at different atmospheres
0 20 40 60 80 100
Number of thermal cycles
0 20 40 60 80 100-0.4
Number of thermal cycles
0 20 40 60 80 100-0.4
-0.3
-0.2
-0.1
0.0
0.1
combustion gasesof petrol 50Al
combustion gasesof fuel oil B5
combustion gasesof petrol 90Al
combustion gasesof petrol 95Al
combustion gasesof fuel oil B10
Number of thermal cycles
1 cycle = 2hair
∆m/S
/
g cm
-2
X53CrMnNiN20-8
0 20 40 60 80 100-0.4
-0.3
-0.2
-0.1
0.0
0.1
combustion gasesof petrol 50Al
combustion gasesof fuel oil B10 combustion gases
of petrol 90Al
combustion gasesof fuel oil B5
combustion gasesof petrol 95Al
Number of thermal cycles
1 cycle = 2hair
∆m/S
/
g cm
-2
X55CrMnNiN20-8
Images of valve steel samples corroded under thermal shock conditions in a number of aggressive atmospheres
T = 1173K
Images of valve steel samples corroded under thermal shock conditions in a number of aggressive atmospheres
outer layer of the coatingZrO2⋅Y2O3
Cross-section of valve steel covered by protective coatingwith TBC layer
steel
inner layer of the coating
Ni22Cr10AlY
Surface of TBC layer
Photographs of surfaces of coated and uncoated valve steelsafter corrosion tests at 1173 K
a) before tests
b) after 500 shocks
a) after 300 shocks
b) after 500 shocks
The results of corrosion tests of uncoatedand coated valve steels
10
15
/ g
cm-2
coated X50CrMnNiNbN21-9 steel
0 200 400 600 800 1000 Time / h
The results of corrosion tests of coatedtwo different valve steels
0 100 200 300 400 5000
5
coated X33CrNiMn23-8 steel
Number of thermal shocks
∆m/S
104
/ g
cm
1 cycle = 2 h
.
10-3
10-2
10-1
-4s-1
1573 1373 1173 973
Ni-30CrCo-35Cr
Oxidation
T / K
Temperature dependence of the oxidation rate of steel coated with a protective coating
6 7 8 9 10 1110-7
10-6
10-5
10-4
.T-1 104 / K-1
k p
/ g2 m
-4
chromia formersalumina formers
coated steel
β-NiAl
Fe-5Cr-4Al Ni-10Cr-5Al
Fe-20Cr
steel
THE ENDTHE END