1. LOGO Effect of nickel salts on the wear properties of electrodeposited nanocrystalline Ni-Co coating Chao Ma Supervised by : Dr. Shuncai Wang Prof. Frank Walsh

2. LOGO Outline 1. INTRODUCTION 1. INTRODUCTION 2. METHODOLOGIES 2. METHODOLOGIES 3. RESULTS AND DISCUSSIONS 3. RESULTS AND DISCUSSIONS 4. CONCLUSION 4. CONCLUSION 5. FUTURE WORK 5. FUTURE WORK

3. LOGO Cr(VI) Hard Cr Electrodeposition Introduction Nanocrystalline Wear and Corrosion Resistant Coatings as an alternative to hard Cr deposits Eletrodeposition is a low-cost and versatile technique to form the nano- crystalline coatings, which exhibit unique properties derived from their large number of grain boundaries compared to coarse-grained surface. www.newworldencyclopedia.org/entry/Electroplating http://jolisfukyu.tokai-sc.jaea.go.jp/fukyu/tayu/ACT02E/06/0603.htm

4. LOGO Good wear resistance Nanocrystalline Ni-Co coating Introduction High hardness Good corrosion resistance

5. LOGO Electrochemical Corrosion Behavior Crystal Morphology &Microstructure Hardness Process of Electroplating Introduction Tribology Properties

6. LOGO Microstructureanalysis 2 Electroplating 1 METHODOLOGIES SEM&EDS, TEM, XRD g/lSS1SS2SS3SS4 NiSO 4 6H 2 O 200 -50 NiCl 2 6H 2 O -50200 CoSO 4 H 2 O 100 Additives

7. LOGO Hardness test Tribology test 3 METHODOLOGIES 4 Wear volume was measured by an optical 3D surface profilometer Friction and wear behaviour were tested on a reciprocating pin-on-disc TE-77 tribometer

8. LOGO RESULTS AND DISCUSSIONS XRD Mixed structure of fcc and hcp Mixed structure of fcc and hcp with (111)α preferred orientation Independent of the nickel salts The finest grain size (5-10nm) is obtained from the coating prepared by NiSO 4 electrolyte. TEM NiCl 2 electrolyte NiSO 4 electrolyte

9. LOGO RESULTS AND DISCUSSIONS SEM Morphologies NiSO 4 electrolyte Adding NiCl 2 fine granular grains lens shape lens shape NiSO 4 -dominant electrolyte

10. LOGO RESULTS AND DISCUSSIONS The lens morphology significantly reduces the microhardness, which leads to the increasing coefficient of friction and wear rate. Tribology test NiSO 4 -dominant electrolyte Hardnesskg/mm2 503 352 Wear rate 10-4 mm3/Nm K= V/SF V is the wear volume (in mm 3 ) S the total sliding distance (in m) F is the normal load (in N) 2.345.32 NiSO 4 electrolyte

11. LOGO RESULTS AND DISCUSSIONS SEM Morphologies NiCl 2 electrolyte Adding NiSO 4 pyramidal crystals NiCl 2 -dominant electrolyte

12. LOGO Tribology test Hardnesskg/mm2 477469 Wear rate 10-4 mm3/Nm 4.95 7.03 RESULTS AND DISCUSSIONS Decrease of internal stress Decrease of internal stress Variations of wear rate as a function of hardness Debris Traditional Archard’s Law Q=KLN/H NiCl 2 electrolyte NiCl 2 -dominant electrolyte

13. LOGO CONCLUSION Wear properties of electrodeposited nanocrystalline Ni-Co coatings are affected by different kind of nickel salts in electrolyte The corresponding changes of the morphology and the crystal may lead to different wear mechanisms The coating formed from NiSO 4 electrolyte performs better tribological behaviour, which can be attributed to the finest grain size and the fine granular grain morphology. NiCl 2 can increase the internal stress.

14. LOGO FUTURE WORK Electrodeposited Ni-Co coating Nucleation and growth of nanocrystalline Morphology Grain size Phase structure Hardness, Surface roughness, Adhesive interaction Internal stress Friction Wear Relationship of processing-microstructure and crystal morphology- tribological properties

15. LOGO UK-China Summer School on Tribology & Surface Engineering 23-25 th August 2010 23-25 th August 2010 Chilworth Manor Hotel Chilworth Manor Hotel (2 mile away from the University of Southampton) (2 mile away from the University of Southampton) Sponsored by RCUK –Research Councils UK Sponsored by RCUK –Research Councils UK General Chair (UK and China): Prof. R.J.K. Wood, Vice President of the International Tribology Council Prof. Weimin Liu, Vice President of the Chinese Tribology Institute CONTACT DETAILS OF ORGANIZING COMMITTEE: Dr. S.C. Wang E-mail: wangs@soton.ac.uk Tel. +44-(0)23-80594638

16. LOGO Thank you for listening Questions?