Light metal corrosion protection with water-borne silane systems

Transcription

1 Platzhalter Titelbild Light metal corrosion protection with water-borne silane systems Dr. Philipp Albert

2 Agenda 1. lanes, hydrolysis and condensation, sol-gel process 2. Water-borne sol-gel systems 3. Dynasylan SIV Possible applications of SIV 160 formulations on aluminium 5. Applications on magnesium 6. Summary Page 2

3 Evonik s production plants for organofunctional silanes Mobile Antwerpe Rheinfelden Rizhao Page 3

4 lanes, hydrolysis and condensation Most commercial organofunctional silanes feature the same molecular formula. Non hydrolyzable R Y (CH 2 ) R H n licon-functional group can react with fillers, metals, glass, rganofunctional group can react with polymers, resins, rubber, R Hydrolyzable Page 4

5 lanes, hydrolysis and condensation R = licon-functional group Y = rganofunctional group Adhesion promotion + R Y R R Polymer + lane + Surface + H H Y Y Page 5

6 Hydrolysis of alkoxy groups: Reactivity of silanes/silanols Reactivity lanols lanes ph ph-value Concentration Type of catalyst Solvent Temperature rganofunctional group: Y -functional group: Ac > Me > Et Y (CH 2 ) 3 (R) 3 H - - catalyzed Fast gelation (highly branched products) H + - catalyzed Slow gelation (linear products) Page 6

7 Condensation Influence of the ph-value Monomer Dimer Cyclic Acidic solution Alkaline solution Linear and branched structures Highly branched structures Page 7

8 Sol-gel process Animation Page 8

9 Agenda 1. lanes, hydrolysis and condensation, sol-gel process 2. Water-borne sol-gel systems 3. Dynasylan SIV Possible applications of SIV 160 formulations on aluminium 5. Applications on magnesium 6. Summary Page 9

10 Five generations of functional silanes developed by Evonik Degussa Development Water - Borne Sol Gel Technology Water - Borne lanes SIV SL Technology Special lanes Low VC ligomeric lanes Dynasylan Dynasylan HYDRSIL Traditional lanes Dynasylan VTM AME Dynasylan Time Page 10

11 Modification of water-borne sol-gel systems Different silanes used in the hydrolysis and co-condensation process open up the way for water-borne sol-gel systems. Hydrophilic, hydrophobic and adhesion properties as well as the curing temperature can be varied within a certain range. R (R ) 3 X (R ) 3 R H H H a X H R = hydrophobic, X = hydrophilic group b Page 11

12 Water-borne sol-gel systems Advantages : Water-borne, VC-free Long shelf-life Temperature curing Different applications possible (primer, additive, binder) Environmentally friendly Page 12

13 Agenda 1. lanes, hydrolysis and condensation, sol-gel process 2. Water-borne sol-gel systems 3. Dynasylan SIV Possible applications of SIV 160 formulations on aluminium 5. Applications on magnesium 6. Summary Page 13

14 Dynasylan SIV 160 A new water-borne low temperature curing sol-gel system Key properties H R H H a R 1 b R 1 Water-borne Nearly VC-free Shelf life time of 1 year R a H b H ph ~ 4,0 4,6 Solid content ~ 9 % H H R 1 b Colorless to yellow liquid Viscosity 9,1 mpa s (20 C) Page 14

15 Structure of Dynasylan SIV 160 The amount of silanol groups and the degree of branching of Dynasylan SIV 160 can be measured via 29 -NMR spectroscopy. H M- D- T- structure S i H H S i S i R R R Page 15

16 Dynasylan SIV 160 particle size of the sol Photon correlation spectroscopy SIV 160 Particle distribution of Dynasylan SIV 160 Volumetric median particle size: 5,4 nm Page 16

17 Example for the high reactivity of Dynasylan SIV 160 Solid droplets Dynasylan SIV 160 is highly reactive Droplets of Dynasylan SIV 160 that remain inside the top of the bottle will get solid due to evaporation of water Due to the reactivity, formulations with a high filler load are difficult Page 17

18 Agenda 1. lanes, hydrolysis and condensation, sol-gel process 2. Water-borne sol-gel systems 3. Dynasylan SIV Possible applications of SIV 160 formulations on aluminium 5. Applications on magnesium 6. Summary Page 18

19 Sol-gel systems for metal protection R H R R R R R R R H R Metal substrate Key benefits of silane systems Barrier protects against water and chloride Hydrophobic surface layer Better adhesion of subsequent coating Reaction with surface enables some passivation Passivation of metal surface due to reaction with substrate Page 19

20 Dynasylan SIV 160 on aluminum substrate Aluminium substrate Coated aluminum substrate SIV Dipping 2.Curing 80 C Layer thickness ~ nm Investigation of the surface via XPS * [atom %] * 0,89 Al* 33,2 19,6 0,0 10 % aqueous solution of Dynasylan SIV 160 coates aluminium substrate without defects Page 20

21 Application of Dynasylan SIV 160 on different aluminium alloys Substrate: Aluminium alloy 2024 clad / 5005 Decreasing/Cleaning: Alkaline solution Acid pickling for alloy 5005 Application: Dipping in SIV 160 dilution or SIV 160 formulation Curing at 80 C (10 min) Formulation in H 2 : 12,5 % SIV 160 0,02 % wetting agent 600 ppm Cr 3+ Page 21

22 Dynasylan SIV 160 for blank corrosion protection on aluminium 2024 clad Blank 600 hours NSS SIV 160 dilution SIV 160 formulation Corrosion No corrosion No corrosion Dry layer thickness: ~ µm Page 22

23 Dynasylan SIV 160 for blank corrosion protection on aluminium 5005 Blank 5005 Cr(III) solution 1000 hours NSS SIV 160 dilution SIV 160 formulation Corrosion Corrosion Some corrosion No corrosion Page 23

24 Blank corrosion protection of Dynasylan SIV 160 formulation on aluminum 5005 Blank 1000 h NSS SIV 160 formulation Chromated Pitting corrosion No pitting corrosion Little pitting corrosion Page 24

25 Corrosion protection on aluminum alloy 5005 with coil coating system 1000 h CASS Blank Chromated SIV 160 Substrate: Aluminum (5005) Cleaning: Alkaline degreasing Alkaline etching Acid pickling Pre-treatment: SIV 160 formul. Pre-dried at 60 C 10 min Topcoat: Coil coating a) Primer b) Top coat PMT 232 C Page 25

26 Agenda 1. lanes, hydrolysis and condensation, sol-gel process 2. Water-borne sol-gel systems 3. Dynasylan SIV Possible applications of SIV 160 formulations on aluminium 5. Applications on magnesium 6. Summary Page 26

27 Corrosion protection on magnesium - Cleaning procedure Alkaline degreasing acid pickling After cleaning Alkaline degreasing The cleaning procedure is most important for the performance of Dynasylan SIV 160 Substrate: Magnesium (AZ31B) Degreasing/Cleaning: Alkaline degreasing and acid pickling or Alkaline degreasing Page 27

28 Corrosion protection on magnesium with polyester powder coating 250 h CASS Cleaned Chromated SIV 160 Substrate: Magnesium (AZ31B) Degreasing/ Cleaning: Alkaline degreasing Acid pickling Pre-treatment: SIV 160 Pre-dried at 60 C, 10 min Topcoat: Polyester powder coating, 60 µ Cured at 180 C, 20 min Page 28

29 Corrosion protection on magnesium with polyester powder coating 1000 h CASS Blank Chromated SIV 160 Substrate: Magnesium (AZ31B) Degreasing/ Cleaning: Alkaline degreasing Pre-treatment: SIV 160 solution Pre-dried at 60 C, 10 min Dynasylan SIV 160 works best after alkaline degreasing Topcoat: Polyester powder coating, 60 µ Cured at 180 C, 20 min Page 29

30 Product range: Water-borne silanes and binder systems Dynasylan Functionality Solid content [%] ph-value Stability* in dilute aqueos solution at ph HYDRSIL 2627 Amino/alkyl/silanol turbidity HYDRSIL 2776 Diamino/alkyl/silanol HYDRSIL 2909 Amino/alkyl/silanol hours/days HYDRSIL 2926 Hydroxy/silanol SIV 112 Fluoro/alkyl/amino/silanol Advanced water-borne systems: SIV 110 Diol/ 2 particles/silanol SIV 160 Amino/silanol * at least 3 months Page 30

31 Evonik s value preposition within value chain Evonik Degussa Formulator Applicator End customer Provides new base high performance silanes and silane binder systems SIV SL Technology, e.g., SIV 160, SIV 110 Tailors high performance metal treatment systems to difficult end-use applications, e.g., electronics, automotive Page 31

32 Agenda 1. lanes, hydrolysis and condensation, sol-gel process 2. Water-borne sol-gel systems 3. Dynasylan SIV Possible applications of SIV 160 formulations on aluminium 5. Applications on magnesium 6. Summary Page 32

33 Summary Dynasylan SIV 160 is a water-borne nearly VC-free and stable sol-gel systems with low curing temperature Blank corrosion protection on aluminium can be improved with special formulations Water-borne sol-gel systems can work as adhesion promoters on aluminium and magnesium The cleaning procedure of the metal substrates is important and will influence the corrosion protection performance of silanes or water-borne sol-gel systems Page 33

34 Dynasylan brochures/ contact us 500 h NSS More information: or philipp.albert@evonik.com Page 34

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