ADVANCED PARTICLE CHARACTERIZATION FOR IMPROVED UNDERSTANDING OF SPRAY COATING QUALITY E. Pirard Univ. Liège (Belgium) F. Campana, J-P Janssen Advanced

ADVANCED PARTICLE ADVANCED PARTICLE CHARACTERIZATION FOR CHARACTERIZATION FOR

IMPROVED UNDERSTANDING IMPROVED UNDERSTANDING OF SPRAY COATING QUALITYOF SPRAY COATING QUALITY

E. PirardE. PirardUnivUniv. Liège (Belgium). Liège (Belgium)

F. Campana, J-P F. Campana, J-P JanssenJanssen

Advanced Coating, Liège (Belgium)Advanced Coating, Liège (Belgium)

ITSC Seattle 15-18 May 2006ITSC Seattle 15-18 May 2006 PirardPirard (Univ. Liège), (Univ. Liège), CampanaCampana & & JanssenJanssen (Advanced Coating ) (Advanced Coating )

IntroductionIntroduction

The interaction between the gas and the The interaction between the gas and the individual particle plays a key roleindividual particle plays a key role

A better understanding of the way individual A better understanding of the way individual particles are affected, will allow for developing particles are affected, will allow for developing more accurate powder specificationsmore accurate powder specifications

Existing norms provide only limited insight into Existing norms provide only limited insight into particle characteristicsparticle characteristics

Use innovative single particle digital imaging Use innovative single particle digital imaging and analysis to access pertinent informationand analysis to access pertinent information


Metal PowdersMetal Powders High velocity oxy-fuel (HVOF) spray coatings with High velocity oxy-fuel (HVOF) spray coatings with

four (Crfour (Cr33CC22-NiCr 75/25) comparable powders :-NiCr 75/25) comparable powders :

A B C D

SupplierSulzer Metco

Sulzer Metco Sylvania

Deloro Stellite

Size Range [µm] [-45+15] [-45+15] [-53+10] [-53+10]Flowability 50g

[sec.] N.A. 18,26 26 23App. density

[g/cm3] N.A. 3,67 3,6 3,62Carbon (%) 9,64 9,48 9,11 9,45

Manuf. Process A/S A/S/P.D. A/S/P.D. A/S/P.D.supplier data


Standard CharacterizationStandard Characterization ISO 3923/2: Determination of apparent densityISO 3923/2: Determination of apparent density

Part 2: Scott volumeter methodPart 2: Scott volumeter method

DensityDensity A B C D

Test 1 2,77 3,82 3,79 3,84

Test 2 2,75 3,87 3,79 3,8

Test 3 2,76 3,82 3,78 3,78

m 2,76 3,84 3,79 3,81


Standard CharacterizationStandard Characterization ISO 4490 : Determination of flow time by means of a ISO 4490 : Determination of flow time by means of a

calibrated funnel (Hall flowmeter)calibrated funnel (Hall flowmeter)

FlowFlow A B C D

Test 1 29,59 22,15 29,29 21,78

Test 2 29,73 22,23 29,37 21,18

Test 3 29,66 22,28 28,75 21,79

m 29,66 22,22 29,14 21,58

Suppl. data N.A. 18,26 26 23


Particle ImagingParticle Imaging

Particle AnalysisParticle Analysis

Digital Image Analysis Digital Image Analysis ofof

Individual ParticlesIndividual Particles Three essential steps requiring dedicated Three essential steps requiring dedicated

solutions :solutions :

Powder DispersionPowder Dispersion


Powder DispersionPowder Dispersion

Patented vacuum disperserPatented vacuum disperser Cylindrical chamberCylindrical chamber Pinhole with plastic membranePinhole with plastic membrane Settling onto circular glass slideSettling onto circular glass slide

AdvantagesAdvantages Perfect dispersion (1:500)Perfect dispersion (1:500) No breakage / deformation of No breakage / deformation of

particlesparticles Controlled (symmetrical) Controlled (symmetrical)

segregationsegregation

Occhio InstrumentsOcchio InstrumentsVDD270VDD270


Particle ImagingParticle Imaging

Occhio InstrumentsOcchio Instruments ALPAGA 500 nanoALPAGA 500 nano

Automated Digital MicroscopyAutomated Digital Microscopy Diascopic illumination @ 439nm Diascopic illumination @ 439nm

(LED)(LED) Superzoom telecentric lensSuperzoom telecentric lens Hi-resolution digital videoHi-resolution digital video Fully motorized glass plateFully motorized glass plate

AdvantagesAdvantages Typ. 10.000 particles/minTyp. 10.000 particles/min Controlled particle position and Controlled particle position and

velocityvelocity Dynamic range : 0,5 µm – 200 µmDynamic range : 0,5 µm – 200 µm

15 µm

a 15 µm particle is typically 800 pixels


Particle AnalysisParticle Analysis Accurate estimation of a “sieving diameter”Accurate estimation of a “sieving diameter”

ISO TC24SC4 : ISO TC24SC4 : Sizing by methods other than sievingSizing by methods other than sieving

Application oriented shape characterizationApplication oriented shape characterization Computation of a wear index :Computation of a wear index :

Computation of a satellity index :Computation of a satellity index :W 46,18 64,14 65,71 82,55

RND 99.6 % 97.2 % 66.7 % 61.6 % 50.9 %

EL 0.78 18.64 5.65 17.51 12.67


Results on Results on CrCr33CC22-NiCr 75/25 particles-NiCr 75/25 particles

Size DistributionsSize Distributions By Number of by VolumeBy Number of by Volume Sub-sieve analysis capabilitySub-sieve analysis capability


ResultsResults

MorphostatisticsMorphostatistics Quality control statisticsQuality control statistics Discriminant statisticsDiscriminant statistics

DIN

[µm]W [%]

RoundnessEl [%]

Elongation

A 33,66 65,67 25,68

B 33,35 74,83 21,70

C 28,97 58,29 21,70

D 30,02 79,00 16,10

Mean values


ResultsResults

Coating Deposition EfficiencyCoating Deposition Efficiency

Q Fl Th/r Th/p/Flg/(m²x0.1mm)

g/min µm µm/(g/min)

A1 Mean 1.184 39 11.8 0,3Std Dev 70 5.4 1.8 0,03

A2 Mean 1.252 38.1 11.4 0,3Std Dev 244 2.1 1.6 0,05

DMean 1.381 45.5 12.2 0,27Std Dev 142 7.3 1.3 0,05


ResultsResults

Coating Deposition EfficiencyCoating Deposition Efficiency

Th [µm]

Porosity Hardness [HV0,3]

Mean Min. Max. Mean Min. Max.

A 183 2,6% 2,1% 3,8% 1041 845 1255

D 159 1,1% 0,4% 1,4% 971 856 1173


Discussion & ConclusionsDiscussion & Conclusions Image analysis provides very accurate size Image analysis provides very accurate size

distributionsdistributions Perfect correlation with sievesPerfect correlation with sieves Number weighted distributions are unique Number weighted distributions are unique (e.g. A contains 90% (e.g. A contains 90%

<15µm)<15µm)

Image analysis provides unique shape information Image analysis provides unique shape information that correlates perfectly with flowability teststhat correlates perfectly with flowability testsDIN

[µm]W [%]

Roundness

El [%]

Elongation Scott Hall

A 33,66 65,67 25,68 2,76 29,66B 33,35 74,83 21,70 3,84 22,22C 28,97 58,29 21,70 3,79 29,14D 30,02 79,00 16,10 3,81 21,58


PerspectivesPerspectives

Image analysis offers a unique insight into metal Image analysis offers a unique insight into metal

powder properties (direct measurement !).powder properties (direct measurement !).

It opens the way to a better understanding of It opens the way to a better understanding of

coating qualities with respect to powder coating qualities with respect to powder

propertiesproperties

This new analytical technology allows to optimize This new analytical technology allows to optimize

powder specifications.powder specifications.

Documents

ADVANCED PARTICLE CHARACTERIZATION FOR IMPROVED UNDERSTANDING OF SPRAY COATING QUALITY E. Pirard Univ. Liège (Belgium) F. Campana, J-P Janssen Advanced