Thermal and Mechanical Properties of Zirconia Coatings Produced by Electrophoretic Deposition

Baufeld, Bernd; Biest, Omer Van der; Rätzer‐Scheibe, H.‐J.

doi:10.1002/9780470339510.ch1

Cited by 3 publications

(9 citation statements)

References 19 publications

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“…can be described as follow: I(z) is the laser intensity Gaussian profile in zirconia,

I false(z false) = {normale}^{\frac{- z^{2}}{0.4 D z^{2}}}

, with D z , the axial resolution of the objective ( D z = 1.4 n λ/NA eff 2 ), n, the zirconia refractive index ( n = 2.2), λ , the laser wavelength (λ=632 nm) and NA , the objective numerical aperture (NA ×10 =0.25 and NA ×80 = 0.75). OP( z ), zirconia optical properties (absorption and scattering),

OP false(z false) = {normale}^{- ({normalμ}_{a} + {normalμ}_{s}) z}

. The optical properties is described by the Beer–Lambert law with μ a and μ′ s the zirconia absorption and reduced scattering coefficients, respectively (μ a = 0135 cm −1 and μ′ s = 100 cm −1 ). Transformation progression in depth, V fm (z) As described in, we assume that a theoretical sigmoid model can be used to simulate the V fm variation in depth.

V_{normalfm} false(z false) = V_{fm 0} \frac{1 + {normale}^{- T z_{0}}}{1 + {normale}^{- T (z - z_{0})}}

.…”

Section: Methodsmentioning

confidence: 99%

3Y‐TZP In‐Depth Phase Transformation by Raman Spectroscopy: A Comparison of Three Methods

2014

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Zirconia phase transformation is usually studied on surface. For in-depth study, three methods were proposed using Raman microspectroscopy quantitative evaluation: direct measurement on sample cross section, confocal Raman spectroscopy (CRS), and progressive pinhole aperture enlargement (PPAE). The aim of this study was to compare transformation profiles obtained with these three methods on the same sample. Three 3Y-TZP samples were aged, respectively, for 25, 72, and 90 h in artificial saliva. Transformation profiles were determined with cross-sectional measurement, CRS and PPAE. A transformation profile simulation model based on PPAE measurements is proposed, using the convolution of the excitation intensity profile and the Beer-Lambert law (optical properties of zirconia). The simulation model was validated with the determination of 3Y-TZP transformation factor, T = 1.15 lm -1 , identical for the three aging durations. Both cross section and PPAE measured similar in-depth transformation decrease, but with a 10 lm-shift: transformed zirconia layer is more important in cross-sectional protocol (36 lm with PPAE and 46 lm with cross-sectional after 90 h aging). Complementary measurements on a 10 h aged sample, where transformation is initiated by Low-Temperature Degradation, showed that sample preparation and polishing, necessary in the crosssectional method, were responsible for the higher transformation. PPAE method enables noninvasive in-depth measurements with limited optical and mechanical biases.

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“…can be described as follow: I(z) is the laser intensity Gaussian profile in zirconia,

I false(z false) = {normale}^{\frac{- z^{2}}{0.4 D z^{2}}}

OP false(z false) = {normale}^{- ({normalμ}_{a} + {normalμ}_{s}) z}

V_{normalfm} false(z false) = V_{fm 0} \frac{1 + {normale}^{- T z_{0}}}{1 + {normale}^{- T (z - z_{0})}}

.…”

Section: Methodsmentioning

confidence: 99%

3Y‐TZP In‐Depth Phase Transformation by Raman Spectroscopy: A Comparison of Three Methods

2014

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“…7 shows that the EPD coatings are relatively porous and that despite the low heat treatment temperature sintering has been achieved. The porosity seems to be comparable with the one of conventional EPD coatings sintered at 1200 • C. 13 Yet, it is obvious that suspension B resulted in a lower porosity than suspension A.…”

Section: Microstructurementioning

confidence: 84%

“…Values of about 0.8 W/(m K) for APS and 1.6 W/(m K) for EB-PVD coatings are reported for coatings in the initial state at room temperature, decreasing to 0.7 and 1.25 W/(m K), respectively, at 1150 • C 13,17 After corresponding heat treatment in air at 1100 • C for 100 h, these commercial coatings also showed a considerable increase in thermal conductivity to 1.3 W/(m K) for APS and 2.1 W/(m K) for EB-PVD thermal barrier coatings at room temperature, which are significantly higher values than for the EPD coatings. EPD allows therefore the fabrication of thermal barrier coatings with remarkably low thermal conductivity.…”

Section: Thermal Conductivitymentioning

confidence: 87%

“…13 Yet, despite the fact that it has a lower porosity than the one derived from suspension B (46%), it has a slightly lower thermal conductivity than the one from suspension B. Since their microstructural architecture is comparable, the difference in thermal conductivity may be related to the difference in yttria concentrations.…”

Section: Thermal Conductivitymentioning

confidence: 91%

“…For comparison, a third type of suspension C was prepared under similar conditions, but without the addition of ZrN. 13 The suspension was prepared by adding n-butylamine (BA) and Dolapix CE64 as suspension stabilization additives (see Table 1) to the powder/ethanol slurry. The suspension was first stirred mechanically, then ultrasonically, and finally again mechanically (15 min each sequence).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Lowering the sintering temperature for EPD coatings by applying reaction bonding

Baufeld¹,

Biest²,

Rätzer‐Scheibe³

2008

Journal of the European Ceramic Society

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Ceramic Coatings by Electrophoretic Deposition: Processing and Properties

Baufeld

Rätzer‐Scheibe

Biest

2009

AMR

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Electrophoretic deposition (EPD) allows the fabrication of ceramic coatings at lower cost and higher speed than most other deposition techniques. The processing consists of powder deposition from a suspension under the influence of an electric field and subsequent consolidation of the coating by sintering. Adherent zirconia coatings with coating thicknesses up to 0.1 mm were obtained from different suspensions, one methyl-ethyl-ketone and the other ethanol based. The standard sintering temperature is 1200°C, which easily may damage or change the substrate and also means high production costs. In order to reduce the sintering temperature, suspensions with the addition of ZrN were investigated. Due to reaction bonding, sintering in air at a remarkable low temperature of 1000°C was successful. The elastic modulus of the EPD coatings has been derived from impulse excitation experiments and the thermal conductivity from laser flash analysis. The elastic modulus was about 22 GPa and the thermal conductivity between 0.4 and 0.6 W/(m•K) at room temperature, both decreasing slightly with temperature. Especially the exceptionally low thermal conductivity makes EPD coatings a promising candidate for thermal barrier coatings.

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Thermal and Mechanical Properties of Zirconia Coatings Produced by Electrophoretic Deposition

Cited by 3 publications

References 19 publications

3Y‐TZP In‐Depth Phase Transformation by Raman Spectroscopy: A Comparison of Three Methods

3Y‐TZP In‐Depth Phase Transformation by Raman Spectroscopy: A Comparison of Three Methods

Lowering the sintering temperature for EPD coatings by applying reaction bonding

Ceramic Coatings by Electrophoretic Deposition: Processing and Properties

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