Ceramic Coatings Deposited from Aqueous Solutions
This paper reviews novel techniques developed in our laboratory to deposit ceramic thin films from aqueous solutions. All the techniques are based on the heterogeneous nucleation and growth phenomenon; ceramic precipitates are prone to be formed preferentially on substrate/solution interfaces when the rate of the formation of the precipitates is appropriately controlled. In “oxidative soak coating” method, metal ions with a lower valence state are oxidized in homogeneous solutions to those with a higher valence state; thereby coatings of SnO2, MnO2, CeO2, Co3O4 and Fe3O4 have been deposited. In “ligand decomposition” method, ligands of an indium peroxo- complex are decomposed to promote spontaneous hydrolysis of the indium ion; thereby In2O3 coating has been deposited. In “enzyme-assisted precipitation” method, precipitant of metal ions is supplied by urease immobilized on a substrate to promote local deposition of ceramics on the substrate, by which hydroxyapatite coating has been rapidly deposited. The control of the rate of the precipitation reactions is the most important parameter. Some properties of the resultant coatings are also presented.
Byung Tae Ahn, Hyeongtag Jeon, Bo Young Hur, Kibae Kim and Jong Wan Park
H. Unuma "Ceramic Coatings Deposited from Aqueous Solutions", Solid State Phenomena, Vols. 124-126, pp. 527-530, 2007