Effect of nickel salts on the wear properties of electrodeposited nanocrystalline Ni-Co coating

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

3. Cr(VI) Hard Cr Electrodeposition Introduction Nanocrystalline Wear and Corrosion Resistant Coatingsas an alternative to hard Cr deposits Eletrodepositionis 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. Nanocrystalline Ni-Co coating Introduction High hardness Goodwear resistance Good corrosion resistance

5. Process of Electroplating Introduction the effect of nickel salts Hardness Tribology Properties Electrochemical Corrosion Behavior Crystal Morphology & Microstructure

6. 2 1 METHODOLOGIES Microstructure analysis Electroplating SEM&EDS, TEM, XRD Additives

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

8. RESULTS AND DISCUSSIONS Mixed structure of fcc and hcp with (111)αpreferred orientation XRD Independent of the nickel salts TEM NiCl2 electrolyte NiSO4 electrolyte The finest grain size (5-10nm) is obtained from the coating prepared by NiSO4 electrolyte.

9. RESULTS AND DISCUSSIONS SEM Morphologies NiSO4 electrolyte NiSO4-dominant electrolyte Adding NiCl2 fine granular grains lens shape

10. RESULTS AND DISCUSSIONS Tribology test NiSO4 electrolyte NiSO4-dominant electrolyte K= V/SF Hardness kg/mm2 503 352 V is the wear volume (in mm3) S the total sliding distance (in m) F is the normal load (in N) Wear rate 10-4 mm3/Nm 2.34 5.32 The lens morphology significantly reduces the microhardness, which leads to the increasing coefficient of friction and wear rate.

11. RESULTS AND DISCUSSIONS SEM Morphologies NiCl2-dominant electrolyte NiCl2 electrolyte Adding NiSO4 pyramidal crystals

12. RESULTS AND DISCUSSIONS Tribology test NiCl2-dominant electrolyte NiCl2 electrolyte Decrease of internal stress Hardness kg/mm2 Debris 477 469 Wear rate 10-4 mm3/Nm 7.03 4.95 Traditional Archard’s Law Q=KLN/H Variations of wear rate as a function of hardness

13. CONCLUSION Wear properties of electrodeposited nanocrystalline Ni-Co coatings are affected by different kind of nickel salts in electrolyte The coating formed from NiSO4 electrolyte performs better tribological behaviour, which can be attributed to the finest grain size and the fine granular grain morphology. NiCl2 can increase the internal stress. The corresponding changes of the morphology and the crystal may lead to different wear mechanisms

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

15. UK-China Summer School on Tribology & Surface Engineering 23-25th August 2010 Chilworth Manor Hotel (2 mile away from the University of Southampton) 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. Thank you for listening Questions?