4 anodiseringeloxering hai horsens
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ALUMECO – 19-5-2015
Esben Øster
B.Sc.Chem. Eng.
Working whit surface treatment since 1999 at HAI Horsens, Denmark.
10 Years as Quality Manager.
5 Years as Technology Manager.
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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
Cobber containing alloy.Typical 4,0-4,58 % cobber.
20072011201420172024
High strength.Good for cutting.Bad corrosion .Difficult for welding.
BoltsMachine partsHydraulic components
Magnesium containing alloy.
50055754
5005-best anodizing quality.
Facade.Other construction
Magnesium and silicon.
60606012606362626082
High strength.Good for welding.Good for decorative anodizing.
ConstructionWindows Door
Zink containing alloy
7075 Very high stength. CarAeroplaneSpace
A
Rating for different anodizing proces:
WHY SURFACE TREATMENT?
OVERVIEW
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.
Methods• Glass
• Aluminium oxid
• steel
• Sand
•Plastic
CHEMICAL PRE-TREATMENT
Alkaline etch E6Acid etchChemical brightning Elektrolytic 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 GLOSS
Dip proces. Good for complex shape. Whitout current.
Gloss up to ca. 100
Good in combination
whit blastion and
grinding.
Cheapest brighting
method.
CHEMICAL BRIGTNING – HIGH GLOSS
Dip proces. Good for complex shape. Whitout current.
Gloss up to ca. 400.
Good in combination
whit blasting and
grinding.
Containing HNO3. Produce hazard gasses
during 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
Aluksering
Rafbrynjun
Anodisering
Anodizing
Eloksering
Anodisieren
Anodischen oxidation
Hård aluksering Hörd Rafbrynjun Hard Anodizing Hard coat Teknisk 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
Anode
kato
de
kato
de
ANODIC LAYER
LAYER GROWTH
Type II ca. 1/3 Type III ca. ½
Vary from alloy – test.
THE ANODIC LAYER
Layer thicknessDensity – coating veightElements
HARDANODIZING Lower temerature. Change electrolyte. Maybe additive to electrolyte. Longer treating time. Higher current density. Better agitation.
PROPERTIES - HARDANODIZING
Hårdhed Abrasion resistance Corrosion resistance Elektrical insolation Layer thichness Natural color Addition color Heat 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-TREATMENT COLORING
Electrolytic color.
UV resistance.
Few color.
Organic color Not 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 pigment not UV stabile. Indoor Many color
anodic producedoxide layer
anodic producedoxide layer
anodic producedoxide layer
Integral Colouring:
Adsorptive Colouring:
Electrolytic Colouring:
oxide layer with inherent colour
barrier layer
aluminium
barrier layeraluminium
barrier layer
aluminium
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 system
Navn Kemisk navn Kemisk struktur Temp. max.°C
c Smeltepunkt °C
PTFE Polytetra-fluorothylen
F 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
F F-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 / CERTIFICATEA lot of standards for……ask your supplier.
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
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