Collaborative research project Hardalt (Grant No. 606110) funded by the EU's seventh framework programme

Alberto Miranda

Alexandros Zoikis-Karathanasis

Alishahi

Brian McKay

Chen

Cohen

Collins

Dawood

DiLeo

Elansezhian

Hamid

Hazan

Hosseinabadi

Ioanna Deligkiozi

Islam

Karthikeyan

Kostas Hrissagis

Luca Magagnin

Mafi

Mauro Callisti

Nava

Novak

Oliver

Panja

Protsenko

Qianzhi Wang

Rahaman

Ranjbar

Risk & Policy Analysts Limited

Sakharova

Sandstrom

Scherrer

Shibli

Sonntag

Srivastava

Sudhakar

Suzuki

Tatjana Kosanovic Milickovic

Tomas Polcar

U.S. Department of Health and Human Services

Wang

Yang

Zarebidaki

Zhang

Zhou

Surface and Coatings Technology

Crossref

Evolution of structural, mechanical and tribological properties of Ni–P/MWCNT coatings as a function of annealing temperature

Wang, Q

Callisti, M

Miranda, A

McKay, B

Deligkiozi, I

Kosanovic Milickovic, T

Zoikis-Karathanasis, A

Hrissagis, K

Magagnin, L

Polcar, T

Brunel University Research Archive

Evolution of structural, mechanical and tribological properties of Ni-P/MWCNT coatings as a function of annealing temperature

The structural, mechanical and tribological properties of Ni-P/MWCNT coatings annealed at various temperatures (350-500 °C) were investigated using XRD, SEM, nanoindentation and tribometer to determine the optimal annealing temperature for their enhanced tribological properties. The results showed that the annealed coatings comprised a hard Ni3P phase, and consequently presented a higher hardness (from 7.0 ± 0.3 to 8.2 ± 1.4 GPa) than the as-plated sample (6.0 ± 0.9 GPa). With the annealing temperature increasing from 350 °C to 500 °C, the crystallinity of coating was enhanced with larger crystal grains of Ni and Ni3P, which led to a decline in hardness (from 8.2 to 7.0 GPa) due to the Hall-Petch effect. Owing to the lubrication effect of H3PO4 arising from the tribochemical reaction of Ni3P with ambient environment, the annealed samples exhibited lower friction coefficients (0.71 ~ 0.86) compared to the as-plated coating (0.87). A combination of low surface roughness and the reduction of oxides on wear track contributed to the lowest friction coefficient of Ni-P/MWCNT annealed at 400 °C. However, the decomposition of amorphous carbon in MWCNT over 380 °C produced less dense coatings (for annealing temperatures 400-500 °C), and their incompact structure led to a higher wear rate (2.9-3.0 × 10-5 mm3/Nm) compared to the as-plated sample (2.4 × 10-5 mm3/Nm). In contrast, Ni-P/MWCNT coating annealed at 350 °C (&lt;380 °C) exhibited a better wear resistance (4.3 × 10-6 mm3/Nm). Thus, 350 °C was found to be the optimal annealing temperature to lower the friction coefficient and enhance the wear resistance of Ni-P/MWCNT coatings

Evolution of structural, mechanical and tribological properties of Ni-P/MWCNT coatings as a function of annealing temperature

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Brunel University Research Archive

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