Comparison of Particle In-Flight Characteristics and ... · Autoren: S. Siegmann, N. Margadant, A....

Autoren: S. Siegmann, N. Margadant, A. Zagorski and M. Arana-AnteloPubliziert in: ITSC 2003 International Thermal Spray Conference - Advancing the Science and Applying the Technology, Orlando, FL, 2003,ISBN/ISSN: 0-87170-785-3Seite: 1591-1598

Comparison of Particle In-Flight Characteristics andCoating Properties

St. Siegmann, N. MargadantSwiss Federal Laboratories for Materials Testing and Research, EMPA Thun, Switzerland

A. Zagorski, M. Arana-AnteloAlstom Power Gas Turbines, Baden, Switzerland

Abstract

In thermal spraying, the knowledge of process basic inputparameters and their influence on the final coating propertiesis crucial. The optimization and reliability ofatmospherically sprayed (APS) coatings, especially highlyporous thermal barrier coatings (TBC), is closely linked toprocess understanding.

This investigation aims to elucidate the correlation betweenthe basic plasma spraying parameters (like current, plasmagas, stand-off distance, etc.) and the deduced physicaldimensions like particle temperatures and velocities and thecoating mechanical properties. Within this project, a largerange of parameter field was chosen as long as stable plasmaworking conditions permitted. The influence of preparationon the microstructure analysis and data of mechanicalcoating measurements are shown.

Introduction

In 1980, one of the first “study of the influence of particletemperature and velocity distribution within a plasma jetcoating formation” was published by A. Vardelle et al. [1].Since that time, it is widely accepted that particle velocities(v) and temperatures (T) are the main factors (besidesubstrate topography [2]) responsible for the splashing,wetting and anchoring of the particles during impact. In thisearly time, simultaneous measurement of both properties (v,T) was difficult and required mainly separate measurementdevices for velocities (e.g. laser Doppler velocimetry) andtemperatures (high speed pyrometers) aligned to a singleprobe volume. Nowadays, many sophisticated equipmentsare available providing single particle information as well asstatistical information covering the application fromscientific based research to on-line process control in sprayshops.

Diagnostics of the particles in the plasma jet is still the mostforward method relating the process based input parameters(like plasma gases, current, etc.) to the coating propertieslike porosity, hardness, toughness, etc.

For developing coatings with predictable microstructure andtechnological behavior, the knowledge of the dimensions Tand v and of their influences in coating structure is crucial.

Experimental

Yttria Stabilized Zirconia PowderFor the spraying study, a commercially available 8 wt%Yttria stabilized ZrO2 powder (YSZ) was used. The sizefraction was -136 +30 µm and the scanning electronmicroscopy (SEM) images show the typical morphology(Figure 1).

Figure 1: SEM pictures showing the typical morphology ofthe YSZ powder used for this investigation (magnificationleft: ~37.5 x, right: ~375 x).

Plasma Spray EquipmentThe coating application was done using a vacuum plasmaspray facility type Medicoat M60 with a modified F4 torch.The spraying tests were carried out at atmospheric pressureconditions using different plasma gas compositions and


amounts (Ar, H2). The plasma current as well as the nozzlediameter and stand-off distance between nozzle exit andsamples were varied and the resulting particle speed andtemperatures were monitored by a Tecnar DPV 2000particle monitoring system. The parameter field covered awide range of temperatures (1800 to 2900 0C) and particlespeed (50 to 300 m/s). The variation of the input parametersfor this study were given by the criteria of stable plasmaconditions and are shown in

Table 1.

Table 1: Plasma parameter variations.

Plasma Gas (Argon) 22 ... 40 l/minAdditional Gas (Hydrogen) 0 ... 9 l/minPlasma Current: 600 ... 800 AElectrical Input Power (EIP): 20 ... 40 kWStand-off Distance: 75 ... 200 mmNozzle Diameter: 6 ... 8 mmRobot Speed: 200 ... 400 mm/sPowder Feed Rate: 10 ... 40 g/min

For most of the parameter settings, samples were sprayed ondifferent substrate materials like stainless steel andHastelloy and afterwards metallographically andmechanically inspected.

For the metallographic preparation different epoxies weretested to see the influence of embedding media on thestatistical results of apparent porosity measured by imageanalysis. Furthermore mechanical properties were measuredby a three-point bending test.

Three-Point Bending TestsFor investigating the mechanical coating properties, threepoint bending tests using Dynamic-Mechanical Analysis(DMA) were performed on a PerkinElmer DMA 7e device(PerkinElmer Inc., Norwalk, Connecticut, USA). Themaximum applicable force was 8,5 N and an increment of500 mN/min was applied until the sample broke. Thegeometry of the free standing coatings were approximately1.8 x 11 x D mm, where D was the coating thicknessranging from approx. 0.3 to 0.6 mm. The elastic moduluswas extracted from the slope of the stress-strain curvemeasured at room temperature.It could be shown by Bürkle et al. [3], that even for stronglyporous and oxide rich metal coatings, there exists a goodagreement between the three-point bending tests andstatistical nanoindentation results.

Results / Discussion

Influence of Spray Parameters on Particle Speed andTemperatureFor different positions from the nozzle exit (75 ... 250 mm),particle velocities and temperatures were measured using the

DPV 2000 and afterwards samples were sprayed onHastelloy and stainless steel substrates using the sameconditions. Figure 2 shows as an example the typicalparticle speed and temperature distributions in the cross-section (horizontal- and vertical-axe) of the plasma jet at100mm from the nozzle exit ensuring homogeneous andsymmetrical particle spreading.

-10 -5 0 5 10-10

010

80

90

100

110

120

Spee

d (m

/s)

Horizontal Axe (mm)

Vertical Axe (mm)

110-120100-11090-10080-90

-10 -5 0 5 10-10

010

2800

2820

2840

2860

2880

2900

Tem

pera

ture

(oC

)

Horizontal Axe (mm)

Vertical Axe (mm)

2880-29002860-28802840-28602820-28402800-2820

Figure 2: Examples of velocity (upper) and temperature(lower) distributions of YSZ-particles in cross section of theplasma jet measured 100 mm from the nozzle exit(coordinate system (0/0) = torch center line at 26 kW power.

The experiments were done for different plasma gascompositions and amounts, different current levels andfinally nozzle diameters. Figure 3 shows the distinctregimes of the cumulative results of the following variationswith stable plasma conditions (current: 600 ...800 A, plasmagases Ar: 24 ...37 l/min, H2: 3 ...7 l/min and stand-offdistances: 75 ...200 mm) for the two different nozzlediameters, namely 6 and 8 mm.


2100

2200

2300

2400

2500

2600

2700

2800

2900

3000

0 50 100 150 200 250 300 350

Speed (m/s)

Tem

pera

ture

(oC

)

8mm Nozzle

6mm Nozzle

Figure 3: Influence of nozzle diameter on the distribution ofparticle speed and temperatures for all parameter variationstested.

There are distinct v-T-regimes for the two nozzle types. Themain influence caused by the different nozzle diameters canbe seen for the particle speed, whereas the meantemperatures of the particles do not differ much. The slopebetween temperature and speed is steeper for the 8 mmnozzle compared to the 6 mm nozzle.

Influence of Robot Speed on Coating MicrostructureFor one plasma parameter setting (26.5 kW, 100 mm stand-off), samples were sprayed using two different robot speeds,namely 200 mm/s and 400 mm/s. This test was done forstudying the influence of thermal load on the constitutingcoating as well as on the substrate [4]. In both cases, theparticle temperatures were in the range of (mean /maximum) 2800 / 2900 oC and the speed was in the range of86 / 105 m/s.

Figure 4: Influence of robot speed on the microstructure ofthe constituting coating (left side sprayed with robot speedof 200 mm/s resulting in a coating thickness of about 800µm; right side sprayed with robot speed of 400 mm/sleading to a coating thickness of about 400 µm;Magnification: ~70 x).

To see the additional influence of substrate and/or coatingheating during the deposition process with lower robot speed,the number of passes have been kept constant. The resulting

coating thickness increased by approximately a factor of 2,as expected due to longer exposition time. However, theporosity level looked similar for both regimes, 24 % and 29% for 200 mm/s and 400 mm/s, respectively (Figure 4).However, there is a certain difference in the distribution ofmicro-cracks.These mainly horizontal cracks at the higher robot speed canbe caused due to not sufficient substrate temperature whichwould be need for good splat cohesion. It was shown earlier[25] that the coating integrity essentially depends on thespeed of spraying gun.

Influence of Embedding Media on Apparent PorosityThe sprayed samples were metallographically prepared forstructure and porosity measurements. To see in advance theinfluence of preparation on the apparent porosity level, eightdifferent epoxy media were tested (non-vacuum infiltrated)with specimen taken from a single sample. Table 2 showstypical properties of the different embedding media used forthis study like curing temperatures and times. The hardnesswas tested using the ball indentation method described in thestandard EN ISO 2039-1 [13]. The ball diameter was 5 �0.05 mm and the corresponding load used was 358 N.

Table 2: Properties of eight different Epoxies: Typicalcuring temperatures and times, as well as mean hardnessmeasured by ball indentation method (EN ISO 2039-1).

Curing Temp. (°C)

Curing Time (h)

Mean Hardness (N/mm2) SDEV

Araldit 20 < 4 110.0 1.4Demotec 10 23 < 4 160.6 3.2Epo-Color 79 1-2 118.4 0.9Epomet 150 < 1 391.6 3.8Scandiplex 21 < 4 160.4 4.6Scandiquick 22 < 4 149.2 2.0Specifix 20 20 > 4 126.0 3.2Specifix 40 40-60 < 4 107.8 0.8

The influence of the viscosity of the different epoxies andthe degree of infiltration can be visually seen from thedifferent gray levels in Figure 5. Three different stages ofthe preparation are shown for each embedding media forpolishing steps ending with diamond of 10 µm, 1 µm andthe final stage (suspension of amorphous SiO2, pH ~10).The apparent coating qualities, as seen in Figure 5, showtotally different amount of pores and coating/substrateinterfaces depending on the different type of epoxies.Obvious large break-outs as well as apparent bad bonding ofthe coating to the substrates can easily lead to wronginterpretation of the real structure.


10µm

1µm

OPU

10µm

1µm

OPU

Demotec10

ScandiquickEpomet Specifix 40

Epo-ColorAraldit

Scandiplex

Specifix 20

Figure 5: Influence of 8 different embedding media and steps of preparation (10 µm, 1 µm, OPU = SiO2 suspension) on theinterpretation of the obvious porosity of the same TBC sample (Magnification: ~55x).

To get quantitative results, image analysis was performedafter the last preparation step on 5 different locations foreach sample (Table 3). The variation in apparent porosity(factor � 2) can be attributed to the difference in embeddingmedia (shrinkage, hardness, etc.), as known frommetallographic preparation procedures [5-12] and others.

Table 3: Eight different embedding media sorted in order ofincreasing mean apparent porosity from image analysis.

Mean Apparent Porosity (Area%) SDEV

Specifix 20 16.9 3.6Demotec 10 22.5 1.8Epo-Color 23.3 0.7Araldit 24.0 2.2Specifix 40 24.5 1.4Scandiquick 25.5 4.3Scandiplex 30.9 1.6Epomet 41.0 4.2


0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

0 100 200 300 400 500

Mean Hardness (N/mm2)

App

aren

t Por

osity

(Are

a%)

Figure 6: Mean apparent porosity measured by imageanalysis of the same TBC coating in function of the differenthardness measured by ball indentation according to [13] ofeight varied embedding media.

There is a tendency of increasing apparent porosity withincreasing hardness of the embedding media as seen inFigure 6. Unfortunately, specific data on shrinkage were notavailable for all materials being tested. Especially for brittlecoatings like TBC the shrinkage of the embedding mediamay play an important role and can cause significantbreakouts which leads to overestimating the coatingporosity. Thus, results of image analysis are expected to bestrongly dependent on the preparation procedure as well asthe software settings and should be used mostly forcomparison of different coating microstructures. Stability ofthe metallographic procedure is a critical requirement forstudying coatings of such type.

Influence of Particle Velocity and Temperature on Micro-structural Properties:The structural differences of the coatings sprayed at vastlydifferent parameters were examined using image analysisand mechanical testing. Figure 7 shows the dependencies ofparticle temperature and speed in relation to the totalporosity measured by image analysis. It could be seen thatfor decreasing particle speed and temperature the porosityincreased and the microstructures showed less cracks,compared to the dense coatings sprayed at “hot” and “fast”conditions. In Figure 7, one can also see that the pronouncedtrend of porosity increase with the lowering of particle in-flight parameters vanishes when the mean particletemperature drops below the melting point (ca. 2600 0C forYSZ). The explanation could be that the temperature ofparticles, which actually form the coating, stays nearlyunchanged, whereas the deposit rate dramatically decreasesdue to bouncing-back effect.

245025002550260026502700

27502800285029002950

20 25 30 35 40 45 50

Total Porosity [%]

Parti

cle

Tem

pera

ture

s [°

C]

0

50

100

150

200

250

300

350

Parti

cle

Velo

citie

s [m

/s]

TemperatureVelocity

Figure 7: Comparison of differently sprayed TBC coatingsand their total porosity (mean value measured at 5 differentplaces) compared to corresponding particle temperatureand velocity.

The images reveal entirely different microstructures for theparameter range depicted in Figure 7. Two candidates fromthe “extreme” positions (i.e. “hot/fast” and “cold/slow”) areshown in Figure 8 and Figure 9.

Figure 8: Coating microstructure sprayed with high particlevelocity (Vmax = 307 m/s) and high temperature (Tmax = 2925oC) showing an overall porosity of about 26 % and verticalcracks with a crack density of 2.7 cracks/mm in length(magnification: ~150x).

The sample sprayed with high velocity (Vmax = 307 m/s) andhigh temperature (Tmax = 2925 oC) shows less porosity(approximately 26 %), but a high level of vertical cracks with


a density of 2.7 cracks/mm in length (Figure 8) compared tothe coating sprayed with low velocity (Vmax = 115 m/s) andlow temperature ( Tmax = 2520 oC) showing approximately44 % porosity, but no visible cracks (Figure 9).

Figure 9: Coating microstructure sprayed with low particlevelocity (Vmax = 115 m/s) and low temperature ( Tmax = 2520 oC)showing higher porosity (about 44 %) than Figure 8, but nocracks (magnification: ~150 x.).

The higher the particle speed and temperatures are, thehigher the degree of melting and spreading will be, whichresulted in a higher coating density. However, due to largerinternal stresses, the coatings tended to crack, as alreadyknown from literature [14-16]. In contrast, the lower thetemperature and the particle speed are, the more porous thecoatings have been until no more adhesion and blasting withcold particles took place.

The gun electric input power (EIP), argon and hydrogenflow rates varied for each nozzle diameter andcorresponding changes in the coating porosity wereanalyzed. As far as power is concerned, results of theexperiments followed the well known trend of generalincrease in particle speed and temperature with the powerand decrease of the coating porosity [17-24]. However,variations of the total gas flow rate and of relative content ofthe gas components when keeping the input powerapproximately constant have not revealed any clear trends inthe particle temperatures. Nor there was any clearcorrelation between those parameters and the coatingmicrostructure. Generally, increase in the flow rate of one orboth gas components led to higher particles velocities whilethe temperature could decrease due to the reduction ofparticle dwelling time and specific plasma enthalpy.

Mechanical Analysis by Three-Point Bending TestsThe results from the three-point bending tests showed for allcoatings the typical brittle behavior and a total bendingstrain of about 0.3 %. The pseudo-plastic behavior may beattributed to the crack propagation through the porouscoatings. Figure 10 represents a typical stress-strain curve ofa three-point bending measurement for a TCB coatingsprayed with reference conditions and with higher hydrogencontent.

0

5

10

15

20

25

30

35

40

45

50

0 0.05 0.1 0.15 0.2 0.25 0.3Strain [%]

Stre

ss [M

Pa] "Higher Hydrogen"

"Reference"

Figure 10: Stress-Strain curve of two samples sprayed with“reference” and “higher hydrogen” parameters at 100 mmfrom the nozzle exit (porosity approximately 20 %).

Out of the DMA data from Figure 10, the tangent E-Modulus was determined from the stress-strain slope and isshown as function of strain in Figure 11.

0

5000

10000

15000

20000

25000

30000

0 0.05 0.1 0.15 0.2 0.25Strain [%]

Elas

tic M

odul

us [M

Pa] "Higher Hydrogen"

"Reference"

Figure 11: Tangent E-Modulus of the TBC samples as afunction of strain at “reference” and “higher hydrogen”parameters leading to the same porosity (about 20 %), butapprox. 65 % higher E-Modulus.

It could be seen that for coatings sprayed with differenthydrogen content, the resulting porosity remained unchanged


at about 20 %, whereas the mechanical testing showed largedifferences with about 65 % higher E-Modulus.

A typical fracture surface of the “reference” sample afterthree point bending test is shown in Figure 12. The zones ofbrittle fracture as well as cracks and pores can be seen.

Figure 12: SEM image of fracture surface of a free standingTBC coating sprayed with reference condition after DMA-testing (Magnification ~1200 x).

Conclusions

Changes in plasma input parameters and conditions stronglyaffect the final coating microstructure. From theexperiments, the following consequences can be drawn:

� Strong influence of nozzle diameter on v,T-regimes;� Proper stable metallographic preparation is needed for

correct microstructure interpretation (porosity, crackdensity, etc.);

� For this specific TBC system, the influence of robotspeed on final coating porosity is minor, whereas somedifference in the micro-crack pattern could be expected,especially in the near-substrate area;

� Variations of plasma gas flow rates could haveambiguous influence on the coating properties and canbe hardly used for the purpose of coating qualitycontrol;

� Same level of porosity can show different E-Modulus;� Three point bending tests can reveal mechanical coating

data rather than porosity level can show frommicroscopy data.

Acknowledgements

The metallography team of EMPA Thun is acknowledgedfor the stimulating discussions and support in the samples

preparation. G. Bürkle from University of Ulm (Faculty ofEngineering, Dep. of Materials) is acknowledged for hissupport in the Dynamic-Mechanical Analysis (DMA).

References

1. A. Vardelle, M. Vardelle, R. McPherson, and P.Fauchais: "Study of the Influence of ParticleTemperature and Velocity Distribution Within aPlasma Jet Coating Formation," in Proceedings of 9thInternational Thermal Spraying Conference - GeneralAspects of Thermal Spraying, The Hague, Netherlands,1980, pp. 155-161.

2. S. Siegmann, and C. A. Brown: "A Method forDetermining the Characteristic Scale for Adhesion for aDiscrete Bonding Model on a Rough Substrate," inProceedings of X. International Colloquium of Surface,Chemnitz, Germany, 2000, pp. 196-204.

3. G. Bürkle, H. J. Fecht, A. Sagel, and C. Wanke:"Dynamical Mechanical Analysis of the MechanicalProperties of AI- and Fe-Based Thermal SprayCoatings," in Proceedings of Thermal Spray 2001 -New Surfaces for a New Millennium, Singapore, 2001,pp. 999-1002.

4. A. Zagorski, F. Szuecs, V. Belashchenko, A. Ivanov, S.Siegmann, N. Margadant: "Experimental study ofsubstrate thermal conditions at APS and HVOF";(included in the same proceedings).

5. E. Leistner: "Gefügeatlas zur Präparation undAuswertung thermischer Spritzschichten - StructuralAtlas for the Preparation and Evaluation of ThermallySprayed Coats," DVS Verlag, München, 2001, pp.

6. K. Geels: "Das wahre Mikrogefüge fester Materialien— Materialographische Probenpräparation - von Sorbybis heute / The True Microstructure of Solid Materials— Materialographic Specimen Preparation - FromSorby the the Present," Praktische Metallographie,2000, 37 (12), pp. 658-683.

7. E. Kharlanova, S. Lafrenière, G. E. Kim, and T. A.Brzezinski: "Development of Tailored MetallographicPreparation Techniques for Thermally SprayedCoatings," in Proceedings of 1st International ThermalSpray Conference - Thermal Spray: SurfaceEngineering via Applied Research, Montréal, Québec,Canada, 2000, 1, pp. 967-970.

8. J. P. Sauer: "The Use of Metallographic Standards inCalibration of the Polishing Process," in Proceedings of1st United Thermal Spray Conference - Thermal Spray:A United Forum for Scientific and TechnologicalAdvances, Indianapolis, Indiana, 1997, pp. 955-957.

9. J. P. Sauer, T. Leonhardt, and A. R. Geary: "The Effectof Mounting Technique on the Microstructure ofThermal Barrier Coatings," in Proceedings of 1stUnited Thermal Spray Conference - Thermal Spray: AUnited Forum for Scientific and TechnologicalAdvances, Indianapolis, Indiana, 1997, pp. 959-964.

10. G. A. Blann: "The Effects of Manual vs. Semi-Automatic Metallographic Specimen Preparation ofThermally Sprayed Coatings," in Proceedings of 1stUnited Thermal Spray Conference - Thermal Spray: A


United Forum for Scientific and TechnologicalAdvances, Indianapolis, Indiana, 1997, pp. 965-971.

11. J. P. Sauer: "Metallographic Preparation of ThermalSpray Coatings: Coating Sensitivity and the Effect ofPolishing Intangibles," in Proceedings of 9th NationalThermal Spray Conference - Thermal Spray: PracticalSolutions for Engineering Problems, Cincinnati, Ohio,1996, pp. 777-783.

12. J. Karthikeyan, A. K. Sinha, and A. R. Biswas:"Impregnation of Thermally Sprayed Coatings forMicrostructural Studies," Journal of Thermal SprayTechnology, 1996, 5 (1), pp. 74-78.

13. EN ISO 2039-1: "Kunststoffe - Bestimmung der Härte- Teil 1: Kugeleindruckversuch (ISO 2039-1:1993) /Plastics - Determination of hardness - Part 1: Ballindentation method (ISO 2039-1:1993) / Plastiques -Determination de la durete - Partie 1: Methode depenetration a la bille (ISO 2039-1:1993)," 1996-10.

14. P. Bengtsson, T. Johannesson, and J. Wigren: "CrackStructures in Plasma Sprayed Thermal Barrier Coatingsas a Function of Deposition Temperature," inProceedings of 14th International Thermal SprayConference: Thermal Spraying-Current Status andFuture Trends, Kobe, Japan, 1995, 1, pp. 513-518.

15. H. Nakahira, Y. Harada, N. Mifune, T. Yogoro, and H.Yamane: "Advanced Thermal Barrier CoatingsInvolving Efficient Vertical Micro-Cracks," inProceedings of 13th International Thermal SprayConference - Thermal Spray: International Advances inCoatings Technology, Orlando, Florida USA, 1992, pp.519-524.

16. M. Prystay, P. Gougeon, and C. Moreau: "Structure ofPlasma-Sprayed Zirconia Coatings Tailored byControlling the Temperature and Velocity of theSprayed Particles," Journal of Thermal SprayTechnology, 2001, 10 (1), pp. 67-75.

17. S. Das, V. K. Suri, U. Chandra, and K. Sampath: "One-Dimensional Mathematical Model for Selecting PlasmaSpray Process Parameters," Journal of Thermal SprayTechnology, 1995, 4 (2), pp. 153-162.

18. J. H. Harding, P. A. Mulheran, S. Cirolini, M.Marchese, and G. Jacucci: "Modeling the DepositionProcess of Thermal Barrier Coatings," Journal ofThermal Spray Technology, 1995, 4 (1), pp. 34-40.

19. H. Fukanuma: "A Porosity Formation and FlatteningModel of an Impinging Molten Particle in ThermalSpray Coatings," Journal of Thermal SprayTechnology, 1994, 3 (1), pp. 33-44.

20. P. A. Mulheran, J. H. Harding, R. Kingswell, and K. T.Scott: "Modeling the Structural Development in aPlasma Sprayed Coating," in Proceedings of 13thInternational Thermal Spray Conference - ThermalSpray: International Advances in Coatings Technology,Orlando, Florida USA, 1992, pp. 749-753.

21. G. Jacucci, S. Dirolini, M. Marchese, and J. H.Harding: "Computer Modelling of the ManufacturingProcess of Ceramic Thermal Barrier Coatings," inProceedings of Computational Plasticity:Fundamentals and Applications, Barcelona, Spain,1992, II, pp. 1683-1695.

22. C. C. Berndt, W. Brindley, A. N. Goland, H. Herman,D. L. Houck, K. Jones, R. A. Miller, R. Neiser, W.Riggs, S. Sampath, M. Smith, and P. Spanne: "CurrentProblems in Plasma Spray Processing," Journal ofThermal Spray Technology, 1992, 1 (4), pp. 341-356.

23. S. Cirolini, J. H. Harding, and G. Jacucci: "ComputerSimulation of Plasma-Sprayed Coatings. I. CoatingDeposition Model," Surface and Coatings Technology,1991, 48 (2), pp. 137-145.

24. M. Ferrari, J. H. Harding, and M. Marchese:"Computer Simulation of Plasma-Sprayed Coatings. II.Effective Bulk Properties and Thermal StressCalculations," Surface and Coatings Technology, 1991,48 (2), pp. 147-154.

25. V. E. Belashchenko, and Y. B. Chernyak: "StochasticApproach to the Modeling and Optimization ofThermal Spray Coating Formation," Journal ofThermal Spray Technology, 1993, 2 (2), pp. 159-164.

Comparison of Particle In-Flight Characteristics and ... · Autoren: S. Siegmann, N. Margadant, A....

Documents

Transcript of Comparison of Particle In-Flight Characteristics and ... · Autoren: S. Siegmann, N. Margadant, A....