| Effect of reinforcing particles size on characteristics and hardness of Co/Al2O3 electrodeposits |
| Paper ID : 1244-UFGNSM-FULL |
| Authors: |
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Soheil Mahdavi *1, Mansoor Zolola Meibodi2, Mohamadreza Etminanfar3 1Sahand new town, Sahand University of Technology 2Research Center for Advanced Materials, Faculty of Materials Engineering, Sahand University of Technology, 5133511996, Tabriz, Iran 3Sahand University of Technology, 5133511996, Tabriz, Iran |
| Abstract: |
| Surface coatings are widely applied in different industrial areas to improve the desirable surface properties. Electrodeposition is a simple and economical method to produce metal or composite films. Properties of the electrodeposited coatings are significantly affected by deposition parameters. These parameters include electrolyte type, deposition technique, solution pH and temperature, current density, addition of micro or nano-sized particles to the bath and etc. Codeposition of fine particles into metallic electrodeposites as the second phase results in enhanced hardness, corrosion and wear resistance of metallic coatings. Different ceramic particles such as, ZrO2, CeO2, SiC, MWCNT, TiO2 and Al2O3 have been used in composite electroplating. However, there are limited studies about the effect of particles size on characteristics and properties of composite coatings. In this study, DC current was used for electrodeposition of cobalt coatings on steel substrates from cobalt sulfate baths. Current density, deposition time, bath temperature and pH were constant. Different Co/Al2O3 composite coatings were produced by adding 15 g/L alumina nano-particles (~30 nm) or micro-particles (~1 µm) to the electrodeposition bath. Effect of alumina particles size on current efficiency, morphology, composition, microstructure, preferred orientation and microhardness of the resultant deposits was investigated and the results were compared to the cobalt film. Results revealed that current efficiency of cobalt electrodeposition is higher than composite plating. According to SEM micrographs, cobalt coating had nodular morphology. Nodules became coarser by incorporation of micro-alumina particles within the cobalt film. However, this morphology was changed to needle shaped by co-deposition of nano-alumina particles. XRD results showed that all the coatings had hexagonal close-packed (hcp) structure. While crystallites size and [001] preferred orientation of cobalt coating was significantly changed by incorporation of nano-alumina particles, effect of micro-alumina particles was negligible. Microhardness tests results revealed that micro-composite coating had highest hardness between all the samples. |
| Keywords: |
| Electrodeposition; Cobalt; Composite; Al2O3; Microhardness |
| Status : Paper Accepted (Oral Presentation) |
