Effect of Deposition Conditions on Phase Content and Mechanical Properties of Yttria-Stabilized Zirconia Thin Films Deposited by Sol-Gel/Dip-Coating

The effect of yttria concentration (0-33.4 mol%), extraction rates (0.17, 0.33, 0.50, and 0.67 mm s-1), and the number of layers (up to four) on the phase content, surface defects, thickness, hardness, adhesion strength, and wear rate of yttria-stabilized zirconia coatings produced by sol-gel/dip-coating were studied for its use on thermolabile substrates. At 700°C, a metastable tetragonal phase ( t ″ ) was obtained even with 33.4 mol% yttria when heat treated for 24 hours; however, a fully cubic structure was attained by extending the heat treatment up to 48 hours as confirmed by Raman spectroscopy. Furthermore, it was necessary to use withdrawal speeds of at least 0.67 mm s-1 to produce defect-free coatings. Although the coatings were produced at low temperature, they showed 41% lower wear rate than steel and an adhesion strength of 30 MPa. Our work stresses the importance of the heat treatment history on the stabilization of the cubic phase in sol-gel YSZ coatings.

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Electrochemical and Oxidation Behavior of Yttria Stabilized Zirconia Coating on Zircaloy-4 Synthesized via Sol-Gel Process

International Journal of Corrosion ◽

10.1155/2013/453835 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 6

Author(s):

S. Rezaee ◽

Gh. R. Rashed ◽

M. A. Golozar

Keyword(s):

Heat Treatment ◽

Electrochemical Impedance ◽

Sol Gel ◽

Dip Coating ◽

Open Circuit ◽

Treatment Temperature ◽

Yttria Stabilized Zirconia ◽

Coated Sample ◽

Stabilized Zirconia ◽

Temperature Oxidation

Sol-gel 8 wt.% Yttria Stabilized Zirconia (YSZ) thin films were prepared on zirconium (zircaloy-4 alloy) by dip-coating technique followed by heat treating at various temperatures (200°C, 400°C, and 700°C) in order to improve both electrochemical corrosion and high temperature oxidation properties of the substrate. Differential thermal analysis and thermogravimetric analysis (DTA-TG) revealed the coating formation process. X-ray diffraction (XRD) was used to determine the crystalline phase structure transformation. The morphological characterization of the coatings was carried out using scanning electron microscopy (SEM). The electrochemical behavior of the coated and uncoated samples was investigated by means of open circuit potential, Tafel, and electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution. The homogeneity and surface appearance of coatings produced was affected by the heat treatment temperature. According to the corrosion parameters, the YSZ coatings showed a considerable increase in the corrosion resistance, especially at higher heat treatment temperatures. The coating with the best quality, from the surface and corrosion point of view, was subjected to oxidation test in air at 800°C. The coated sample presented a 25% reduction in oxidation rate in comparison with bare substrate.

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Identification of tetragonal and cubic structures of zirconia using synchrotron x-radiation source

Journal of Materials Research ◽

10.1557/jmr.1991.1287 ◽

1991 ◽

Vol 6 (6) ◽

pp. 1287-1292 ◽

Cited By ~ 110

Author(s):

Ram Srinivasan ◽

Robert J. De Angelis ◽

Gene Ice ◽

Burtron H. Davis

Keyword(s):

Particle Size ◽

Radiation Source ◽

Sol Gel ◽

Yttria Stabilized Zirconia ◽

Tetragonal Structure ◽

Cubic Phase ◽

X Ray Diffraction ◽

Stabilized Zirconia ◽

Synchrotron Source ◽

Three Samples

X-ray diffraction from a synchrotron source was employed in an attempt to identify the crystal structures in zirconia ceramics produced by the sol-gel method. The particles of chemically precipitated zirconia, after calcination below 600 °C, are very fine, and have a diffracting particle size in the range of 7–15 nm. As the tetragonal and cubic structures of zirconia have similar lattice parameters, it is difficult to distinguish between the two. The tetragonal structure can be identified only by the characteristic splittings of the Bragg profiles from the “c” index planes. However, these split Bragg peaks from the tetragonal phase in zirconia overlap with one another due to particle size broadening. In order to distinguish between the tetragonal and cubic structures of zirconia, three samples were studied using synchrotron radiation source. The results indicated that a sample containing 13 mol% yttria-stabilized zirconia possessed the cubic structure with a0 = 0.51420 ± 0.00012 nm. A sample containing 6.5 mol% yttria stabilized zirconia was found to consist of a cubic phase with a0 = 0.51430 ± 0.00008 nm. Finally, a sample which was precipitated from a pH 13.5 solution was observed to have the tetragonal structure with a0 = 0.51441 ± 0.00085 nm and c0 = 0.51902 ± 0.00086.

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The adhesion strength and indentation toughness of plasma-sprayed yttria stabilized zirconia coatings

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2009.11.035 ◽

2010 ◽

Vol 204 (14) ◽

pp. 2136-2141 ◽

Cited By ~ 22

Author(s):

S.A. Sadeghi-Fadaki ◽

K. Zangeneh-Madar ◽

Z. Valefi

Keyword(s):

Adhesion Strength ◽

Yttria Stabilized Zirconia ◽

Stabilized Zirconia ◽

Indentation Toughness ◽

Plasma Sprayed

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High Performance Mixed Potential Type NO2 Gas Sensor Based on Porous YSZ Layer Formed with Graphite Doping

Sensors ◽

10.3390/s19153337 ◽

2019 ◽

Vol 19 (15) ◽

pp. 3337 ◽

Cited By ~ 1

Author(s):

Hao Hong ◽

Jianwen Sun ◽

Cinan Wu ◽

Zewen Liu

Keyword(s):

High Performance ◽

Sol Gel ◽

Yttria Stabilized Zirconia ◽

Mixed Potential ◽

Stabilized Zirconia ◽

No2 Gas Sensor ◽

Potential Type ◽

Measurement Results ◽

Good Repeatability ◽

Sensor Measurement

High performance mixed potential type NO2 sensors using porous yttria-stabilized zirconia (YSZ) layers doped with different concentration graphite as solid electrolyte and LaFeO3 as sensing electrode were fabricated and characterized. LaFeO3 was prepared by a typical citrate sol–gel method and characterized using XRD. The surface morphology and porosity of porous YSZ layers were characterized by field emission scanning electron microscope (FESEM). The sensor doped with 3 wt% graphite shows the highest response (−76.4 mV to 80 ppm NO2) and the response is linearly dependent on the logarithm of NO2 concentration in the range of 10–200 ppm. The sensor measurement results also present good repeatability and cross-sensitivity.

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Elaboration of Sol-Gel Derived Hydroxyapatite / Yttria Stabilized Zirconia Composite Coatings Obtained for Biomedical Application

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.312-315.894 ◽

2011 ◽

Vol 312-315 ◽

pp. 894-899

Author(s):

Sahar Salehi ◽

Mohammad Hosseien Fathi

Keyword(s):

Grain Size ◽

Crystallite Size ◽

Grain Growth ◽

Biomedical Application ◽

Composite Coatings ◽

Sol Gel ◽

Yttria Stabilized Zirconia ◽

Stabilized Zirconia ◽

Nanostructured Composite

In this study, nanostructured composite coatings of hydroxyapatite (HA)/ 30wt% yttria stabilized zirconia (YSZ) coatings containing 0, 3, 5, and 8 mol% Y2O3 (namely; HA-0YSZ, HA-3YSZ, HA-5YSZ, and HA-8YSZ) were successfully synthesized using the sol-gel method. The crystallite size of the coating was about ~44-58 nm for tetragonal and cubic zirconia grain size and 75-87 nm for hydroxyapatite grain size. Crack-free and homogeneous HA-YSZ composite coatings were obtained with no observable defects. The uniform distribution of zirconia particles in a composite would be highly beneficial for obtaining homogeneous coatings of HA-YSZ film and would hinder grain growth of HA phase during calcinations. In vitro evaluation in 0.9% NaCl showed that Ca2+ dissolution rate of composite coatings was lower than pure HA coatings.

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