Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization. The effects of current density （CD） on microhardness, structur...Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization. The effects of current density （CD） on microhardness, structure, composition and surface topography of the oxide layer formed at various CDs （0.1-0.25 A/cm^2） have been studied. Crystalline coatings formed at 0.25 A/cm^2 have been （width 95 nm） observed with a relatively uniform distribution confirmed by scanning electron microscopy. Additionally, the average microhardness value of ceramic nanocomposite coatings fabricated from lithium sulphate-zirconium silicate bath is approximately 8.5 times higher than that of the as-received aluminium. The surface statistics of the coatings is discussed in detail to explain the roughness and related parameters for better understanding. These observations demonstrate the importance of surface statistics in controlling the morphology of the coatings and its properties. From the X-ray diffraction investigations, it can be concluded that the formed nanocomposite coatings are crystalline in nature and that the crystallinity of the coatings decreases with increasing applied current density.展开更多
We have synthesized a series of the ceramic coatings by anodization of aluminium using lithium sulphate and sodium silicate additive. Our experiments show that the present coatings are nanocomposites in nature, consis...We have synthesized a series of the ceramic coatings by anodization of aluminium using lithium sulphate and sodium silicate additive. Our experiments show that the present coatings are nanocomposites in nature, consisting of a mixture of nanocrystalline alumina, silica, aluminium silicate and mullite; the formation of alumina was similar to conventional anodizing technology, while the formation of mullite was attributed to an addition of sodium silicate. The microhardness of the coatings progressively increased with the increasing current density up to 0.2 A/cm2, which could mainly be attributed to the decrease of porosity in the interfacial region of the oxides up to the range. From the performance of the coatings against corrosion （Tafel/Nyquist plots）, it was inferred that the coatings fabricated by lithium sulphatesodium silicate bath have enhanced corrosion resistance （Rp = 3.12 kΩ）, as well as better microhardness value than that of the lithium sulphate bath alone （Rp = 660.96 Ω） which confirm the perception that the silica particles included in the anodized alumina matrices randomly. Presence of Al, Si and O indicated that the electrolyte components had been intensively incorporated into the coatings.展开更多
基金the Council of Scientific and Industrial Research, New Delhi for awarding CSIR-SRF(senior research fellow ship- 09/810(0011) 2010 EMR)
文摘Ceramic nanocomposite coatings have been synthesized on aluminium by using lithium sulphate electrolyte with zirconium silicate additive by anodization. The effects of current density （CD） on microhardness, structure, composition and surface topography of the oxide layer formed at various CDs （0.1-0.25 A/cm^2） have been studied. Crystalline coatings formed at 0.25 A/cm^2 have been （width 95 nm） observed with a relatively uniform distribution confirmed by scanning electron microscopy. Additionally, the average microhardness value of ceramic nanocomposite coatings fabricated from lithium sulphate-zirconium silicate bath is approximately 8.5 times higher than that of the as-received aluminium. The surface statistics of the coatings is discussed in detail to explain the roughness and related parameters for better understanding. These observations demonstrate the importance of surface statistics in controlling the morphology of the coatings and its properties. From the X-ray diffraction investigations, it can be concluded that the formed nanocomposite coatings are crystalline in nature and that the crystallinity of the coatings decreases with increasing applied current density.
基金the Council of Scientific and Industrial Research, New Delhi for awarding CSIR-SRF (senior research fellow ship-09/810(0011)2010 EMR)
文摘We have synthesized a series of the ceramic coatings by anodization of aluminium using lithium sulphate and sodium silicate additive. Our experiments show that the present coatings are nanocomposites in nature, consisting of a mixture of nanocrystalline alumina, silica, aluminium silicate and mullite; the formation of alumina was similar to conventional anodizing technology, while the formation of mullite was attributed to an addition of sodium silicate. The microhardness of the coatings progressively increased with the increasing current density up to 0.2 A/cm2, which could mainly be attributed to the decrease of porosity in the interfacial region of the oxides up to the range. From the performance of the coatings against corrosion （Tafel/Nyquist plots）, it was inferred that the coatings fabricated by lithium sulphatesodium silicate bath have enhanced corrosion resistance （Rp = 3.12 kΩ）, as well as better microhardness value than that of the lithium sulphate bath alone （Rp = 660.96 Ω） which confirm the perception that the silica particles included in the anodized alumina matrices randomly. Presence of Al, Si and O indicated that the electrolyte components had been intensively incorporated into the coatings.
