university turbines systems research fellowship 2013 › www2 › utsr › reports ›...

University Turbines Systems Research Fellowship

2013

Presenter: Kevin Luo

Coatings & NDE Development Manager: Kathleen Morey Mentor: Joshua Margolies

GE Power & Water

2 Kevin Luo

UTSR 2013 GE Power & Water

Agenda About Me

Project:

• Microstructure and Property Comparisons for AG1 Ceramic Coatings

• Inductance Heating for Rare Earth Disilicate Coatings onto Ceramic Matrix Composite (CMC) Specimens

Acknowledgements

3 Kevin Luo


About Me Education M.S. Mechanical Engineering, West Virginia University Morgantown, WV May 2014 (In Progress)

B.S. Mechanical Engineering, West Virginia University Morgantown, WV May 2012

Previous GE Experience Project Manager Intern, GE Transportation Erie, PA Summer 2012

Lean Manufacturing Engineering Intern, GE Transportation Grain Valley, MO Summer 2011

Project 1

Microstructure and Property Comparisons for

AG1 Ceramic Coatings

5 Kevin Luo


AG1 Ceramic Coatings Comparison

St-Gobain AG1 9237 Sulzer Metco SPM 2000-1

NiCrAlY (APS) CoNiCrAlY (HVOF)

TBC

EBC

SubstrateIN718

Project Specific Layers

General TBC Structure

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Saint-Gobain 9237 Sulzer Metco SPM 2000-1

AG1 Ceramic Coatings Comparison Objective: Study ceramic top coatings produced from St-Gobain AG1 9237 and Sulzer Metco SPM 2000-1 8YSZ powders.

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Variables

Bond Coat • BC-1- Air Plasma Spray (APS) (NiCrAlY) • BC-2- High Velocity Oxygen Fuel (HVOF)

(CoNiCrAlY)

Spray Parameter • Parameter A (New-Make) • Parameter B (Repair)

AG1 Top Coat • St-Gobain Norton AG1 9237

– Lot 1: SG1 – Lot 2: SG2

• Sulzer Metco SPM 2000-1 – Lot 1: SM1 – Lot 2: SM2

Responses

Deposit Efficiency

Tensile Adhesion Results

Microstructure Evaluations

• Vertical Crack Spacing and Length

• Horizontal Crack Length

• Crack Morphology

• Porosity

Design of Experiment (DoE)

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Bond Coat Roughness

Set-Up 8 Plates – 7 buttons on each

• 3 BC-1 Buttons for Tensile Testing

• 1 BC-1 Button for Microstructure Evaluation

• 3 BC-2 Buttons for Tensile Testing

Plates 1-4: St-Gobain 9237

Plates 5-8: Sulzer Metco SPM 2000-1

Odd Number Plates: Parameter A

Even Number Plates: Parameter B

Prep Work

Bond Coat Ra1 Ra2 Ra3 Ra4 AVGGT-21 670 740 740 680 707.5GT-33 370 400 380 440 397.5

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To determine the number of passes to obtain a predetermined spray temperature, preheat trials were conducted. While only 3 passes are needed to heat the plate up to specified temperature, 5 passes are used during the spraying.

Preheat Data

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

φ -

TC T

emp/

Desi

red

Tem

pera

true

Time (s)

Preheat Plate - Parameter A (Corner of the Plate)

Corner TC

0

0.2

0.4

0.6

0.8

1

1.2

1.4

φ -

TC T

emp/

Desi

red

Tem

pera

true

Time (s)

Preheat Plate - Parameter B (Corner and Center of the Plate)

Corner TC

Center TC

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Parameter A Parameter B

Coated Samples on Plates

9237

SPM 2000-1

9237 SPM 2000-1

Samples prior to heat treatment and shipping out to Protech Lab Corp.

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Gun continues moving over plate for t sec

D.E. = 100% x Weight gain Feed rate x t

Deposit Efficiency Calculation The D.E. plate is sprayed after each coating run.

The figure and equation below shows how the D.E. is measured.

12 Kevin Luo


Very Little Change in DE % due to powder type and spray parameter

Note: DE’s range from 71-74%

Lower than the expected 80-85%

Deposit Efficiency Results Accuraspray data*

D.E. @ 9lb/hr, 30.192s

Cell Number

Plate Number

Powder Lot ParameterSupply(kW)

Part. Temp.

(°C)

Part vel. (m/s)

IntensityPrior

weight (gm)

Post weight

(gm)D.E.% Passes Thickness mil/pass

2 1 9237 SG1 A 196 2850 225 736 1974.1 1995.7 72 22 0.033 1.501 2 9237 SG1 B 188 2822 222 600 1975 1998.2 73 22 0.034 1.552 3 9237 SG2 A 196 2849 225 714 1973.6 1995.1 71 22 0.033 1.501 4 9237 SG2 B 186 2815 219 596 1980.4 2003.7 74 22 0.031 1.41

Accuraspray data*

D.E. @ 9lb/hr, 30.192s

Cell Number

Plate Number

Powder Lot ParameterSupply(kW)

Part. Temp.

(°C)

Part vel. (m/s)

IntensityPrior

weight (gm)

Post weight

(gm)D.E.% Passes Thickness mil/pass

2 5 SPM 2000-1 SM1 A 197 2856 236 781 1975 1996.4 71 22 0.033 1.501 6 SPM 2000-1 SM1 B 186 2809 231 627 1983.1 2006.3 73 22 0.032 1.452 7 SPM 2000-1 SM2 A 196 2822 227 721 1979.6 2001.4 72 22 0.034 1.551 8 SPM 2000-1 SM2 B 187 2786 221 566 1966.1 1989.2 73 22 0.031 1.41

cell #1 DE based on 27.9 second program time

cell #2 DE based on 26.592 second program time

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Protech Results: St-Gobain AG1 9237 Tensile Adhesive Results

# Sample ID LBS. PSI Failure Mode1 1AG21T-1 5158 6571 100% Top Coat - Middle2 1AG21T-2 4849 6177 100% Top Coat - Middle3 1AG21T-3 4536 5778 100% Top Coat - Middle

Average Failure 4848 61754 1AG33T-1 4782 6092 100% Top Coat - Middle5 1AG33T-2 4919 6266 100% Top Coat - Middle6 1AG33T-3 4850 6178 100% Top Coat - Middle

Average Failure 4850 6179

Plate 1 TensilesTensile Adhesion Results

# Sample ID LBS. PSI Failure Mode1 2AT21T-1 5740 7312 100% Top Coat - Middle2 2AT21T-2 6297 8022 70% Top Coat – Middle / 30% Adhesive3 2AT21T-3 6820 8688 20% Top Coat – Middle / 80% Adhesive

Average Failure 6286 80074 2AT33T-1 6683 8513 20% Top Coat – Middle / 80% Adhesive5 2AT33T-2 6018 7666 20% Top Coat – Middle / 80% Adhesive6 2AT33T-3 6350 8089 10% Top Coat – Middle / 90% Adhesive



# Sample ID LBS. PSI Failure Mode1 4AT21T-1 5997 7639 70% Top Coat – Middle / 30% Adhesive2 4AT21T-2 6301 8027 100% Top Coat - Middle3 4AT21T-3 6247 7958 50% Top Coat – Middle / 50% Adhesive

Average Failure 6182 78754 4AT33T-1 6579 8381 20% Top Coat – Middle / 80% Adhesive5 4AT33T-2 6314 8043 30% Top Coat – Middle / 70% Adhesive6 4AT33T-3 5996 7638 20% Top Coat – Middle / 80% Adhesive



Comments: Plate 3 – Sample 3AG21T-2 has been highlighted due to possible testing error

# Sample ID LBS. PSI Failure Mode1 3AG21T-1 4872 6206 100% Top Coat - Middle2 3AG21T-2 3715 4732 90% Top Coat – Middle / 10% Adhesive3 3AG21T-3 4904 6247 100% Top Coat - Middle

Average Failure 4497 57284 3AG33T-1 4823 6144 100% Top Coat - Middle5 3AG33T-2 4900 6242 100% Top Coat - Middle6 3AG33T-3 4776 6084 100% Top Coat - Middle


Tensile Adhesion ResultsPlate 3 Tensiles

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Protech Results: Sulzer Metco SPM 2000-1 Tensile Adhesive Results

# Sample ID LBS. PSI Failure Mode1 5SG21T-1 2998 3819 100% Top Coat - Middle2 5SG21T-2 2664 3394 100% Top Coat - Middle3 5SG21T-3 3059 3897 100% Top Coat - Middle

Average Failure 2907 37034 5SG33T-1 5310 6764 100% Top Coat - Middle5 5SG33T-2 5702 7264 100% Top Coat - Middle6 5SG33T-3 5528 7042 100% Top Coat - Middle



# Sample ID LBS. PSI Failure Mode1 6ST21T-1 3342 4257 100% Top Coat - Middle2 6ST21T-2 3113 3966 100% Top Coat - Middle3 6ST21T-3 2602 3315 100% Top Coat - Middle

Average Failure 3019 38464 6ST33T-1 5885 7497 50% Top Coat – Bottom / 50% Top Coat – Top5 6ST33T-2 5514 7024 100% Top Coat - Middle6 6ST33T-3 5101 6498 100% Top Coat - Middle



# Sample ID LBS. PSI Failure Mode1 8ST21T-1 5406 6887 100% Top Coat - Middle2 8ST21T-2 5037 6417 100% Top Coat - Middle3 8ST21T-3 5084 6476 100% Top Coat - Middle

Average Failure 5176 65934 8ST33T-1 5057 6442 100% Top Coat - Middle5 8ST33T-2 4573 5825 100% Top Coat - Middle6 8ST33T-3 5073 6462 100% Top Coat - Middle



# Sample ID LBS. PSI Failure Mode1 7SG21T-1 2582 3289 100% Top Coat - Middle2 7SG21T-2 2460 3134 100% Top Coat - Middle3 7SG21T-3 2756 3511 100% Top Coat - Middle

Average Failure 2599 33114 7SG33T-1 2809 3578 100% Top Coat - Middle5 7SG33T-2 2687 3423 100% Top Coat - Middle6 7SG33T-3 2726 3473 100% Top Coat - Middle



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Main Effects Plot: 9237 > SPM 2000-1 Parameter B (repair) > Parameter A (new-make) BC-2 (HVOF) > BC-1 (APS)

Interaction Plot: Only interaction between the variables is between the powder type and the bond coat. 9237 is less affected by the type of bond coat it is adhered to than the SPM 2000-1.

Individual Tensile Results

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Average Tensile Results Powder Type Comparison

SG1, A, BC-1 SG1, A, BC-2

SG1, B, BC-1 SG1, B, BC-2

SG2, A, BC-1

SG2, A, BC-2

SG2, B, BC-1SG2, B, BC-2

SM1, A, BC-1

SM1, A, BC-2

SM1, B, BC-1

SM1, B, BC-2

SM2, A, BC-1SM2, A, BC-1

SM2, B, BC-1

SM2, B, BC-2

0

0.5

1

1.5

2

2.5

Tens

ile/G

E M

inim

umTe

nsile

Req

uire

men

t

Sample Set

St-Gobain AG1 9237 vs. Sulzer Metco SPM 2000-1Normalized Average Tensile Strength

SG 9237

SM SPM 2000-1

GE Minimum Ten

The SG 9237 is almost consistently better than the SPM 2000-1 based on average psi. 50% of the SPM 2000-1 sample sets fall below the GE minimum requirement.

Data Labels: SG# or SM# - Powder Lot A or B – Parameter BC-1 or BC-2 – Bond Coat

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Average Tensile Results Spray Parameter Comparison

SG1, BC-1 SG1, BC-2

SG2, BC-1

SG2, BC-2

SM1, BC-1

SM1, BC-2

SM2, BC-1SM2, BC-2

SG1, BC-1 SG1. BC-2SG2, BC-1

SG2, BC-2

SM1, BC-1

SM1, BC-2SM2, BC-1

SM2, BC-2

0

0.5

1

1.5

2

2.5

Tens

ile/G

E M

inim

umTe

nsile

Req

uire

men

t

Sample Set

Parameter A vs. Parameter BNormalized Average Tensile Strength

Parameter A

Parameter B

GE Minimum Ten

Based on the spray parameter, Parameter B produces a top coat with higher tensile. Parameter B has 1 nonconformity compared to 3 nonconformities from Parameter A .

Data Labels: SG# or SM# - Powder Lot BC-1 or BC-2 – Bond Coat

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Average Tensile Results Bond Coat Comparison

SG1, A

SG1, B

SG2, A

SG2, B

SM1, A SM1, B

SM2, A

SM2, B

SG1, A

SG1, B

SG2, A

SG2, B

SM1, A SM1, B

SM2, A

SM2, B

0

0.5

1

1.5

2

2.5

Tens

ile/G

E M

inim

umTe

nsile

Req

uire

men

t

Sample Set

BC-1 vs. BC-2Normalized Average Tensile Strength

BC-1

BC-2

GE Minimum Ten

The CoNiCrAlY BC-2 bond coat provided better adhesion for the top coats, Although the tensile difference is small for the St-Gobain samples, the Sulzer Metco top coat shows a noticeable difference in the first lot of the SPM 2000-1. Several SPM 2000-1 do not meet GE minimum requirements when the ceramic powder is deposited on the NiCrAlY BC-1 bond coat.

Comment: The results are opposite of what one should expect. The BC-1 has a rougher surface and should have better adhesive properties with the ceramic top coat.

Data Labels: SG# or SM# - Powder Lot A or B – Parameter

19 Kevin Luo


Protech Results: St-Gobain AG1 9237 Microstructure

Plate 1 Plate 2 Plate 3 Plate 4Characteristics Accept/Reject Accept/Reject Accept/Reject Accept/Reject

Porosity & Oxide Content Accept Accept Accept AcceptInterface Contamination Accept Accept Accept Accept

Unmelts / Volcanoes Accept Accept Accept Accept

Vertical Crack Spacing Accept Accept Accept AcceptVertical Crack Length Accept Accept Accept Accept

Horizontal Crack Length Reject Accept Accept AcceptCrack Morphology Accept Accept Accept Accept

Porosity Accept Accept Accept AcceptCOMMENTS HCL ≈ 13 mils

Bond Coat (mils) 10 9.8 9.9 9.1Top Coat (mils) 32 32.4 33.7 32.8

Number of Cracks 51 49 50 43Cracks Per Linear Inch 57 54 56 48

Bond Coat Microstructure

Top Coat Microstructure

Average Coating Thickness

Top Coat Crack Coat

<- Plate 1

Plate 2 ->

<- Plate 3

Plate 4 ->

Comments: The coatings are more porous than previously observed under the TGTS Parameter.

20 Kevin Luo


Protech Results: Sulzer Metco SPM 2000-1 Microstructure

Plate 5 Plate 6 Plate 7 Plate 8Characteristics Accept/Reject Accept/Reject Accept/Reject Accept/Reject

Porosity & Oxide Content Accept Accept Accept AcceptInterface Contamination Accept Accept Accept Accept

Unmelts / Volcanoes Accept Accept Accept Accept

Vertical Crack Spacing Accept Accept Accept AcceptVertical Crack Length Accept Accept Accept Accept

Horizontal Crack Length Reject Accept Reject AcceptCrack Morphology Accept Accept Accept Accept

Porosity Accept Accept Accept AcceptCOMMENTS HCL ≈ 12 mils HCL ≈ 11 mils

Bond Coat (mils) 9.9 9.4 9 9Top Coat (mils) 32.3 31.8 33.3 32.8

Number of Cracks 58 46 51 39Cracks Per Linear Inch 60 47 52 41

Bond Coat Microstructure

Top Coat Microstructure

Average Coating Thickness

Top Coat Crack Coat

<- Plate 5

Plate 6 ->

<- Plate 7

Plate 8 ->

Comments: The SPM 2000-1 coatings are less porous than the 9237 coatings.

21 Kevin Luo


Protech Microstructure Comparison Longer horizontal cracks can be directly linked to lower tensile strengths and makes the coating more susceptible to spallation.

Powder Type Nonconformities

(out of 4)Parameter

Nonconformities(out of 4)

SG 9237 1 A 3SM SPM 2000-1 2 B 0

Parameter B has 0 horizontal crack lengths that exceed minimum crack length. All Parameter B coated buttons pass GE specifications.

Higher porosity can increase the chance of the top coat spalling due to the higher residual stresses. It does increase thermal resistance but spallation has a higher priority.

Parameter A sprayed Sulzer Metco coatings provides the densest top coat.

Vertical cracks are beneficial in terms of strain tolerance and compliance. As the number of vertical cracks increase, the in-plane elastic modulus decreases.

The St-Gobain coat has more vertical cracks per linear inch. And by choosing Parameter A over Parameter B, one can achieve even more vertical cracks.

22 Kevin Luo


Conclusion

St-Gobain AG1 9237 Sulzer Metco SPM 2000-1Deposit Efficieny - -Tensile ✓

Horizontal Crack Length ✓

Vertical Cracks per Inch ✓

GVL OEM TGTSTensile ✓

Horizontal Crack Length ✓

Vertical Cracks per Inch ✓

GT-21 GT-33Tensile ✓

Powder

Parameter

Bond Coat

In terms of the powder comparison, the St-Gobain AG1 9237 powder produces a better ceramic top coat than the Sulzer Metco SPM 2000-1. The tensile strength is higher on the AG1 9237 coatings sprayed with either parameters or on top of either bond coat. In terms of metallography, the 9237 coatings also holds a distinct advantage in terms of having more vertical cracks per linear inch and having a better resistance to horizontal cracks. For parameters, the repair TGTS parameter sprayed better top coat. TGTS has a distinct advantage over the GVL OEM in the tensile results and the horizontal crack length nonconformity.

Further investigation should be done to examine the observed low deposit efficiency and for the 9237 its appearance of higher porosity. Examining an additional lot for each powder could verify the findings of this project and could initiate a services implementation plan to use the better powder and parameter.

Project 2

Inductance Heating for Rare Earth Disilicate

Coatings onto Ceramic Matrix Composite (CMC)

Specimens

24 Kevin Luo


Project Layers

Layer 2: Rare Earth Disilicate (RE2Si2O7) Allows the system to operate at higher temperature conditions and prevents environmental degradation Layer 1: Silicon Compatible coefficient of thermal expansion (CTE) with the substrate and have a very low rate of oxygen diffusion

Substrate - Ceramic Matrix Composite Combines the heat resistance of a ceramic with the strength of a metal.

Silicon-carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC/SiC CMCs)

Applied with Inductor Heating

25 Kevin Luo


Objectives

Project is based on a previous experiment with a helical heating coil, the silicon carbide piece was able to heat up to a specified temperature. The helical coil’s frequency is recorded.

A flat “pancake” coil was fabricated to perform at the same frequency. The new flat coil is brought in near the CMC bar, used to heat the bar to a specified temperature, and then retracted prior to each spraying pass. The objective will be completed by integrating a heating system into the spray process.

Advantages of Inductor Heating: By maintaining the CMC substrate at an elevated temperature greater than normally results from plasma spraying, the RE2Si2O7 layer cools to crystalline state which is volumetrically stable . This should lead to a decrease in defects and a higher quality coating.

Reduced cycle time ~ 20 hours

Introduce a heating source in between each rare earth disilicate spraying pass to produce a higher quality EBC in a more efficient manner.

Previous Disadvantages: By heat treating a coated CMC “steam” bar and then quenching to room temperature, the probability of defects increase due to the crystalline phase changes in the rare earth disilicate.

In the figure to the left, long vertical cracks appear in the top layer of a flat substrate after the heat treatment. Defects in the coat are even more common on rounded areas of the substrate.

Baseline heat treatment cycle time ~ 60 hours

26 Kevin Luo


Coating Set-Up

Steps:

1. Set spray parameters.

2. Turn on RF power supply and intercooler for the heat station.

3. Bring coil in and heat the bar to desired temperature.

4. Retract coil away from the bar.

5. Bring in APS gun and spray one pass of the RE2Si2O7 layer.

6. Repeat steps 3-5 for the number of necessary passes.

7. Turn off spray parameters, RF power supply, and intercooler.

27 Kevin Luo


Ambrell EasyHeat LI 8310 w/ Flat Heating Coil

Quick and clean source of heat

Repeatable and reliable

Non-contact form heating

Frequency range from 150-400 kHz

RF Terminal Power - 10 kW

RF coil current - 300-750A

Heating System

28 Kevin Luo


Frame

Material from 80/20

Aluminum T-slotted profiles - easy and quick assembly with simple hand tools

Easy to modify height and track length

Pneumatic Actuator

Bimba Ultran Rodless Slide Actuator

Model: UGS-0918-AD

Self-guided motion

Frame Design and Pneumatic Actuator

29 Kevin Luo


Fully Assembled Frame

30 Kevin Luo


Steady State Temperature vs. RF Input Current

0

100

200

300

400

500

600

700

0 500 1000 1500 2000 2500 3000

Tem

pera

ture

(°C)

Time (s)

FLIR Results - Current vs. Temperature

550A

600A

650A

700A

750A

FLIR Systems camera and ThermaCAM Researcher Pro to capture and record temperatures

Emissivity – 0.82 and Camera-to-Sample Distance – 6 ft

From the FLIR results, the 550A and the 600A results show that as the current increases, so does the temperature the steam bar temperature.

However, above the 600A mark, there isn’t much of an increase in temperature. The maximum steady state temperature is at roughly 600 °C for the currents from 650 to 750A. Disturbances around coil near the steam bar do not allow for the input current and the coil current to match when the input current exceeds 600A. For example, when the current is set to the maximum at 750A, the current the coil experiences fluctuates between 590-650A.

31 Kevin Luo


Coated Samples The SiC/SiC steam bars have the silicon coat applied onto its surface prior to any inductor heating. Once the steam bars are mounted in the cell, they have the RE2Si2O7 coat sprayed on at 70% (525A), 80% (600A), 90% (675A), and 100% (750A) of the max RF current for 20 passes. The coil is able to get within 5 mm of the surface of the steam bar during the heating.

Sample 1

Sample 2 Sample 3 Sample 4

0

2

4

6

8

10

12

14

300 350 400 450 500 550 600 650 700 750Th

ickn

ess

(mils

)

RF Current Range (A)

RF Current vs. Layer Thickness

Sample RF Current (A) Thickness (mils)1 750 9.42 675 123 600 12.44 525 13.2

• As the input current increases, the thickness of the RE2Si2O7 decreases. • If the requirement calls for a minimum thickness and pre-coating temperature, the number of

passes will need to be adjusted.

32 Kevin Luo


Conclusion The steam bars are successfully heated via inductance in between each coating pass, and each steam bar was sprayed.

Future Work:

Microstructure Evaluation of the Coated Steam Bars

• As-sprayed (Straight from being coated in the cell)

• After Heat Treatment – both 60 & 20 hour cycles

If microstructure proves to be higher quality, automation of the pneumatic inductor heating can be incorporated into the spraying process of rare earth disilicate and can be used for future similar applications.

33 Kevin Luo


Acknowledgments Special Thanks to:

GE Power & Water

• Joshua Margolies

• Y.C. Lau

• Kathleen Morey

• Don Baldwin

• Steve Dillon

• Jim Fisk

• Joe Albanese

• Chris Lochner

• Bob MacNary

• Chris Spinicci

Thanks for showing me the ropes of the thermal spraying and helping me complete my projects!

SwRI – UTSR Fellowship Program

Thank you for allowing me to come up to Schenectady, NY and learn for the summer. The program is a great experience, and I truly appreciate the opportunity.

WVU – Andrew Nix

Thanks for opening the door to the gas turbine world for me.

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