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ALUMECO 19-5-2015

Esben ØsterB.Sc.Chem. Eng.

Working whit surface treatment since 1999 at HAI Horsens, Denmark.

10 Years as Quality Manager.

5 Years as Technology Manager.

------------------------------------------------------------------------------A/S HAI Horsens 102 år Surface treatment of

aluminium Anodizing.

AGENDA

Why surface treatment ?Anodizing mechanism. Pre-treatment.After-treatment.How to specify. Alloy.Case study.

MOST COMMON USED ALLOY

Cobbercontainingalloy.Typical 4,0-4,58 % cobber.

20072011201420172024

High strength.Good for cutting.Bad corrosion .Difficult for welding.

BoltsMachinepartsHydrauliccomponents

Magnesium containingalloy.

50055754

5005-best anodizingquality.

Facade.Otherconstruction

Magnesiumand silicon.

60606012606362626082

High strength.Good for welding.Good for decorativeanodizing.

ConstructionWindows Door

Zinkcontainingalloy

7075 Very high stength. CarAeroplaneSpace

A

Rating for different anodizing proces:

WHY SURFACE TREATMENT?

TextureGlossStructureMatt surfaceColor

Visuel properties

PittingGenerel corrosionFiliform corrosionOthers

Corrosionprotection Hardness

Electrical insulationRoughnessAbrasion resistance

Mechanicalproperties

OVERVIEW

Pretreatment

Cleaning and activate surface. Etching, blasting, Polishing. Chemical and Mechanical methods. Gloss, structure, rougness, smootness

Anodizing

Std. anodizing, hardanodizing, chromic acidanodizing, phosphos acid anodizing. Hardness, insulation, corrosion resistens, abrasionresistance, adhedsions properties.

Aftertreatment

Coloring, screen printing, sealing, organic coating.Color, increase corrosions resistance, chemicalresistance.

Pre-treatment

Mechanialmethods

Chemical methods

EFFECT OF PRE-TREATMENT

VIBRATION TECHNIQUE

Roughness.Gloss.Remove sharp edges

GRINDING

Grinding Brushing Polishing

Band Pads

BLASTING

Uniform surface.

Remove scratches.

Decorative surface.

Roughness.

MethodsGlass

Aluminium oxid

steel

Sand

Plastic

CHEMICAL PRE-TREATMENT

Alkaline etch E6Acid etchChemical brightningElektrolytic brightning

Dip or spray

EFFECT OF ETCHING

Treating time ?

ACID ETCH DEOXIDING OR E0 ETCH

Minimum attach - 0,1 micron.Keep tolerances.

No visuel effekt.

Example: diameter - 6 mm H7 +0,015 mm Alkaline etch 6 minutes. 6*3 micron =18 micron

Alternativ: Masking of hole.

CHEMICAL BRIGHTNING SEMI GLOSSDip proces.Good for complex shape.Whitout current.

Gloss up to ca. 100

Good in combination whit blastion and grinding.

Cheapest brightingmethod.

CHEMICAL BRIGTNING HIGH GLOSSDip proces.Good for complex shape.Whitout current.

Gloss up to ca. 400.

Good in combination whit blasting and grinding.

Containing HNO3.Produce hazard gassesduring brightning.

ELECTROPOLISHING

Whit current, 5 amp/dm2

Gloss up to ca. 400-500

Good in combination whit blasting and grinding.

Difficult to control.

Old proces.

Deburring effect.

ISO 7599 PRE-TREATMENT

ANODIZING

AlukseringRafbrynjunAnodiseringAnodizingElokseringAnodisierenAnodischen oxidation

Hård alukseringHörd RafbrynjunHard AnodizingHard coatTeknisk Eloksering

A lot of names

THE PROCESS

Dissoziation: 3 H2SO4 = 3 SO42- + 6 H+

Anodic reaction: 3 SO42- - 6 e = 3/2 O2 + 3 SO3

3 Al + 3/2 O2 = Al2O3

Acid formation: 3 SO3+3 H2O = 3 H2SO4

Kathodic reaction: 6 H++6 e = 3 H2

Total reaction: 3 Al +3 H2O = 3 H2 + Al2O3

Sulfuric acid

IN PRACTICE

Water

10 % sulfuric acid

ANODIC LAYER

LAYER GROWTH

Type II ca. 1/3Type III ca. ½

Vary from alloy test.

THE ANODIC LAYER

Layer thicknessDensity coating veightElements

HARDANODIZINGLower temerature.Change electrolyte.Maybe additive to electrolyte.Longer treating time.Higher current density.Better agitation.

PROPERTIES - HARDANODIZING

Hårdhed Abrasion resistanceCorrosion resistanceElektrical insolationLayer thichnessNatural colorAddition colorHeat resistance

Application for hardanodizing.Offshore, machine parts, moving parts, etc.

Bigger than 350 HV. Taber test. Maks 35 mg.Saltspray test 1000 h.Break down ca. 1500-2000 volt.30-150 micron.Brown / grey.Black, normal black.Short up to 2000 degree.

CROMIC ACID ANODIZING CAA

1-5 micron layer thichness, maximum.Natural color: grey. Different methods.

Adhesion properties, painting and bonding.Good corrosion properties.Smooth surface.

Aeroplane.Old process.

Containing Cr6+

Not RoHS.

PHOSPHORIC ACID ANODIZING, PAA

Thin layer thichness.Natural color: grey.

Adhesion properties, painting and bonding.

Aircraft and aerospace alloy sheets.

According to RoHS.

POROSITY

Number of porer, and size of the porer, gives the porosity.

WHY CORROSION RESISTANCE?

Compact surface.Electrical insulation.No bad intermediate layer.

Aluminium Aluminium

Anodic layer Paint

AFTER-TREATMENTCOLORING

Electrolytic color.UV resistance.Few color.

Organic colorNot UV resistance.Indoor application.Many color.

In generelNeed normally 15 micron.

Best whit surfuric acid method, anodizing, pore size.

Spray or dip process.

AFTERTREATMENT

In OrganicUV stabileOutdoor useLess numbers of color

Organic pigmentnot UV stabile.Indoor Many color

anodic producedoxide layer

anodic producedoxide layer

anodic producedoxide layer

Integral Colouring:

Adsorptive Colouring:

Electrolytic Colouring:

oxide layer withinherent colour

barrier layeraluminium

barrier layeraluminium

barrier layeraluminium

adsorbed dye

electroplatedmetal

THE DIFFERENT COLOURING METHODS

MANY COLOR

Dip proces

Alloy

Jigging

SEALING CORROSION RESISTANCE

Dicromatsealing, not RoHS.Hot water sealing, Bøhmit.Cold sealing, Nickel and Cobalt.

Reduce hardness and abrasion resistance, approx. 20 %.Dicromate gives gren color.Others are invisible.

RESISTANCE - CHEMICAL

Corrosion resistance.Neutral pH (6-9).

Organic coating can improve properties.pH resistens.

Painting and unsealed pre-anodic layer.

5-8 micron + topcoat big amount of color, including white.

PTFE ON ANODIC LAYER

Extra corrosion resistance.Non stick.FDA approvel.Chemical resistanceHigh temeratur.Low friction. Many color.

Need baking.

Many different methods.

Also multi layer systemNavn Kemisk navn Kemisk struktur Temp.

max. Cc Smeltepunkt

C PTFE Polytetra-

fluorothylenF F

-C-C-F F

260 18 327

PVDF Polyvinyliden-fluoride

F H -C-C-F H

140 25 170

E-CTFE Ethylen chloro-trifluorethylene

H H F F-C-C-C- C-H H CL F

150 31 245

FEP Fluorinated ethylene propylene

FF-C-F

F F F |(-C-C-)-(-C-C-)

F F F F

205 16 270

PFA/TFA

Perfluoroalkoxy (R = -C3F7)

F F F O(-C-C-)- (-C-C-)F F F F

260 17 305

ETFE Ethylentetra-fluorothylene

H H F F(-C-C-C-C-)

H H F F

150 25 270

PE Polyethylene H H(-C - C-)

H H

70 31 100

PRE-ANODIZING FOR PAINTING

Pre-anodizing according to GSB.

STANDARD / CERTIFICATE

DIN 17611

MIL-A-8625F Type ?

ASTM B580

AMS-2468

ISO7599

GSB

Custumer specific standards.

Sometimes requirement for COC.

CASE STUDY

Stainless steel, look - high gloss

Can we use Aluminium ?

No Pretreatment -only anodizing for corrosion protection -alloy 1050

Anodic layer

CASE STUDY

Let us develop new visuel surfaces.

Color

NEWS

New color serie: Desert

Tak for opmærksomheden