Durability of composites in the marine environment

1. Durability of compositesin the marine environment John Summerscales Plymouth University

2. Plymouth • Advanced Composites Manufacturing Centre • only UK undergrad. composites degrees: BEng (honours)Mechanical Engineering with Composites BSc (honours)Marine and Composites Technology Marine Centre at Coxsideunder re-development for diving and diver training plus technical support tomarine-based projects andresearch activities.

3. Plymouth Sound • Third largest natural harbour in the world • Hosted America’s Cup in September 2011

4. External presentations • Ifremer/ONR International Workshop onDurability of Marine CompositesNantes - France, 23 August 2012. • Wuhan University of TechnologyWuhan – China, 06 September 2013. • ICACME 2013: First International Conference Advanced Composites for Marine Engineering Beijing – China, 10 September 2013

5. Key references • J Summerscales and TJ Searle (1999)Review of the durability of marine laminatesin G Pritchard (ed.)Reinforced Plastics DurabilityWoodhead Publishing, Cambridge, pp 219–266. • J Summerscales (2014)Durability of composites in the marine environment in P Davies and YDS Rajapakse (eds.)Durability of composites in a marine environmentSpringer,Dordrecht (NL),pp1-13.

6. Applications • marine renewable energy • offshore oil and gas • defence vessels • submarines • lifeboats • powerboats • sterngear • yachts • canoes • surfboards • … and all the others

7. Durability • defined as good for the full intended working life of the system • the downside is end-of-life considerations • only a limited number of museumswant to keep artefacts for ever  • if sufficiently desirableobjects may be trading in the antiques market • if too durablethen difficulties arise in “recycling”

8. Outline of lecture

9. Temperature

10. Glass transition temperature Wright (Composites, July 1981) found "as a rough rule-of-thumb“that there was a drop in Tg of epoxy resins of 20°C for each 1% of water pick-up (up to 7% moisture content).

11. Peak surface temperature vs ambient air temperature 120 100 80 60 40 20 surface °C black brown redgreen orange tan purple blue light blue Al yellow white redrawn from SP Systems design allowable booklet The response is dependent on the chemical nature of the dye/pigment andthe heating may be reduced by choosing low solar absorbance materials. 0 10 20 30 40 50 ambient °C

12. Moisture diffusion

13. Moisture (Fickian diffusion) … or Flory-Huggins or Langmuir/Henry/clustering models ? equilibrium/saturation Moisture content √(time)

14. Saturation moisture content (M%)* • M% dependent on (resin) chemistry • M%max <0.5% (only apolar groups) • polyolefins, PTFE, polystyrene, polydimethylsiloxane • M%max<3.0% (non-hydrogen donors) • polyethers, polyesters • M%max<10% (H-donors in hydrogen bonding) • polyvinylalcohol, polyacrylic acid, polyacrylamide * Xavier Colin and Jacques Verduat Ifremer-ONR workshop on Durability of composites, 2012.

15. Osmosis … and blistering

16. Osmosis ... • Osmosis can be defined (Clegg, 1996) as “the equalisation of solution strengthby passage of a liquid (usually water) through a semi-permeable membrane Weak solution membrane Strong solution

17. Osmosis ... • normally the fluid will pass through the material without affecting it • but, there may be soluble materials ….

18. Osmosis and blistering • a little solvent and a lot of solute-> a strong solution • strong driving force for osmotic cell • high pressures generated cause/expand void containing strong solution • swelling leads to blisters with associated surface undulation • Image from:http://www.wessex-resins.com/westsystem/wsosmosis.html

19. http://www.insightmarinesurveyors.co.uk/osmois%20ringed.jpg

20. Osmosis and blistering: causes

21. Osmosis and blistering • For marine applications, consider • changing from orthophthalicto isophthalic polyester resin • and to improve “iso” resin further,use NPG (neo pentylglygol): • HO-CH2-C(CH3)2-CH2-OH • 2,2-dimethyl-1, 3-propanediol • Durability: • ortho < iso < NPG Chemical structure from: http://chemicalland21.com/specialtychem/perchem/NEOPENTYL%20GLYCOL.htm

22. Natural fibre composites • fibre composed primarily ofcellulose, hemicellulose, lignin and pectin • limited solubility in water • successful applications include • Araldite: 6.5 metre racing yacht • Flaxcat: light-weight catamaran/Delft • … but time will tell ? • LCA important if product life< “traditional” equivalent

23. Cavitation erosion

24. Cavitation = spherical bubble collapse • The following slides use images extracted fromnumerical simulation in Kawitachnik video (http://www.youtube.com/watch?feature=player_detailpage&v=Ibd-v1YbD8c ) • vapour bubble collapse caused by cavitationcreates impinging jet of liquid onto solid surface$ • pressure pulse* • impact stress may exceed 1000 MPa • duration of pulse ~2-3 μs $ W Lauterborn and H Bolle, … cavitation bubble collapse …, J Fluid Mechanics, 1975, 72(2), 391-399. * A Karimi and JL Martin, Cavitation erosion of materials, International Metals Reviews, 1986, 31(1), 1-26.

25. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

26. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

27. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

28. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

29. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

30. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

31. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

32. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

33. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

34. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

35. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

36. Cavitation erosion • Collapsing bubble: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

37. Cavitation erosion • Collapsing bubble creates jettowards a hard surfaceloosens structure and removes material: Solid surfacemodel from Lauterborn and Bolle- video from Kawitachnik

38. Cavitation erosion in NAB propeller photographs courtesy of Peter Dyson

39. Cavitation erosion • very limited public domain dataon fibre-reinforced composites  • how much good data is locked away in publicly-funded defence “stealth” research ? • National Technical Information Service(US NTIS) search for “cavitation erosion”:returned “0 document found”. • OpenGrey SIGLE (System for Information on Open Grey Literature in Europe) search for “cavitation erosion composite(s): 1(2) non-polymer items returned. • Karimi and Martin review:2 references (of 231) for rain erosion of composites

40. Cavitation erosion • composites may perform better than metals because fibre > grain size • student projects* suggested CFRP proportional loss in weightonly 40% of that for Al under identical conditions • but difficult experiment • CFRP absorbs some water • may have low initial - but accelerating - loss rate * Handley ..and.. Ladds (1995)

41. Cavitation erosion/ADCOAbu Dhabi Commercial Oil • oil pipe diffuser section • steel component replaced every month • composite “temporary” replacementremoved from service after nine months

42. Galvanic corrosion

43. Galvanic corrosion • corrosion involves flow of an electric current • most constituents of fibre-composites are insulators and henceelectrochemical corrosion is not an issue • However, carbon (graphite) acts as a noble metal, lying between platinum and titanium in the galvanic series. 

44. Galvanic corrosion • Carbon fibres should not come into contact with structural metals(especially Al or Mg)in the presence of a conducting fluid(eg sea-water). • A thin glass fibre surface layer may be sufficient to prevent the formation of such a galvanic corrosion cell.

45. Marine coatings including antifouling paints

46. Marine coatings • Surface coatings may be for • provide aesthetic finish • improve resistance to corrosion • protect against fouling • especially for marine or process plant applications • gel-coat is normally applied to the mould before the laminate is laid-up/injected • a major issue in the marine industry is“print-through” • surface echoes topology of reinforcement

47. Benefit of antifouling • Aristotle (fourth century BCE) observed that small fish (barnacles) could slow down ships. • US Navy [New Scientist, 1975] reported that barnacles and other marine encrustationson hulls increase drag, slow the vessel down and estimate this consumes 25% of the fuel. • US NSWC Carderockestimated • biofoulingreduces vessel speed by 10% • added drag increases fuel consumption by 40%.

48. Antifouling paints

49. Flame, smoke and toxicity

50. Flame, Smoke and Toxicity (FST)