Single-layer submicron-thick BaTiO3 coatings from poly(vinylpyrrolidone)-containing sols: Gel-to-ceramic film conversion, densification, and dielectric properties

2001 ◽  
Vol 16 (11) ◽  
pp. 3116-3123 ◽  
Author(s):  
Hiromitsu Kozuka ◽  
Atsushi Higuchi
Keyword(s):  
Heat Treatment ◽  
Condensation Reaction ◽  
Single Layer ◽  
Dip Coating ◽  
Single Step ◽  
Dielectric Constants ◽  
Isothermal Heat Treatment ◽  
Coating Films ◽  
Ceramic Film ◽  
C Decomposition

BaTiO3-coating films were prepared from a solution containing poly(vinylpyrrolidone) (PVP) of molar composition Ba(CH3COO)2:Ti(OC2H5)4:PVP:CH3COOH:H2O: C2H5OH = 1:1:0.5:27:4:5, via nonrepetitive, single-step dip-coating. The gel films were found to be converted into BaTiO3 films via evaporation of the solvent and CH3COOH below 210 °C, decomposition of PVP at 210–360 °C, decomposition of CH3COO− below 440 °C, and crystallization at 500–610 °C. The decomposition of PVP was accompanied by the progress of the condensation reaction, which resulted in significant reduction in film thickness. When the gel films were heated isothermally at 700 °C, crack-free BaTiO3 films as thick as 0.9 μm were obtained. When the gel films were heated isothermally at 360 °C and then at 700 °C, the film became denser. Higher dielectric constants around 290 were found for the film that underwent the isothermal heat treatment at 360 °C. A slower rate of PVP decomposition was thought to be the key for the film densification.

Synthesis and Dielectric Properties of SrBi2Nb2O9 Layered Perovskite by Sol-Gel Processing

1998 ◽  
Vol 541 ◽  
Author(s):  
Y. Wu ◽  
F. S. Ohuchi ◽  
G. Z. Cao
Keyword(s):  
Heat Treatment ◽  
Sol Gel ◽  
Dip Coating ◽  
Dielectric Constants ◽  
Layered Perovskite ◽  
Condensation Process ◽  
Complexing Agent ◽  
Low Dielectric ◽  
Gel Processing ◽  
Multiple Step

AbstractFerroelectric layered perovskite strontium bismuth niobium oxide SrBi2Nb2O9(SBN) ceramics and films were made by sol-gel processing. A multiple step hydrolysis-condensation process was applied to the synthesis of the SBN sol by using inorganic salts as precursors with citric acid as a complexing agent. Single phase polycrystalline SBN was obtained after heat-treatment at 650°C. It was found that the dielectric constants of SBN ceramics were dependent on heat-treatment. SEM, XPS, TGA/DTA and XRD analyses indicated that bismuth-deficiency may contribute to the relatively low dielectric constants. While a prolonged firing time at high temperatures may lead to a lattice expansion resulting in a significant decrease of the dielectric constant. C-oriented SBN films were obtained by dip-coating onto SrTiO3 substrates and the films are dense and crack-free with a thickness of 900 nm.

Epitaxial growth of gadolinium oxide on roll-textured nickel using a solution growth technique

2000 ◽  
Vol 15 (3) ◽  
pp. 621-628 ◽  
Author(s):  
Jonathan S. Morrell ◽  
Ziling B. Xue ◽  
Eliot D. Specht ◽  
Amit Goyal ◽  
Patrick M. Martin ◽  
...  
Keyword(s):  
Single Layer ◽  
Dip Coating ◽  
Base Layer ◽  
Coating Films ◽  
Growth Technique ◽  
Force Microscopy ◽  
Atomic Force ◽  
Out Of Plane ◽  
Nickel Substrates ◽  
High Degree

Chemical solution epitaxy was used to deposit an epitaxial film of Gd2O3 on roll-textured nickel. A 2-methoxyethanol solution of gadolinium methoxyethoxide was used for spin-coating and dip-coating. Films were crystallized using a heat treatment at 1160 °C for 1 h in 4% H2/96% Ar. Single-layer films were approximately 600 Å in thickness, and thicker films could be produced using multiple coatings. θ/2θ x-ray diffractograms revealed only (0041) reflections, indicating a high degree of out-of-plane texture. A pole-figure about the Gd2O3 (222) reflection indicated a single in-plane epitaxy. Scanning electron microscopy showed that the films were smooth, continuous, and free of pin holes. Atomic force microscopy revealed an average surface roughness of 53 Å. Electron diffraction indicated that the misalignment of the majority of the grains in the plane was less than 10°. High-current (0.4 MA/cm2) Yba2Cu3O7–δ films were grown on roll-textured nickel substrates using Gd2O3 as the base layer in a three-layer buffer structure.

Crystallization and dielectric properties of SrO–BaO–Nb2O5–GeO2 tungsten–bronze glass–ceramics

2001 ◽  
Vol 16 (7) ◽  
pp. 2057-2063 ◽  
Author(s):  
Jiin-Jyh Shyu ◽  
Hsin-Wei Peng
Keyword(s):  
Heat Treatment ◽  
Dielectric Properties ◽  
Tungsten Bronze ◽  
Glass Ceramics ◽  
Dielectric Behavior ◽  
Dendritic Morphology ◽  
Dielectric Constants ◽  
Two Stage ◽  
Tetragonal Tungsten Bronze ◽  
Stage Heat Treatment

The crystallization and dielectric properties of SrO–BaO–Nb2O5–GeO2 glass–ceramics were investigated. One- and two-stage heat-treatment methods were used to convert the parent glass to glass–ceramics. Strontium barium niobate (SBN) with a tetragonal tungsten-bronze structure formed as the major crystalline phase. When the crystallizing temperature/time was increased, the secondary crystalline BaGe2O5 phase coexisted with SBN. BaGe2O5 formed as a surface layer grown from the surface into the interior of the sample. The dendritic morphology of SBN crystals was examined. The glass–ceramics crystallized by two-stage heat treatment have higher dielectric constants than those crystallized by one-stage heat treatment. The highest dielectric constant that was obtained in the present glass–ceramics was 320. The glass–ceramics showed relaxor-type dielectric behavior.

Facile single-step ammonia heat-treatment and quenching process for the synthesis of improved Pt/N-graphene catalysts

2013 ◽  
Vol 266 ◽  
pp. 433-439 ◽  
Author(s):  
Bin Xiong ◽  
Yingke Zhou ◽  
Ryan O’Hayre ◽  
Zongping Shao
Keyword(s):  
Heat Treatment ◽  
Single Step ◽  
Quenching Process

On the Influence of a Heat Treat for an Aluminizing Progress Based on Al Microparticles Slurry for Model Ni and Ni20Cr. Experimental and Theoretical Approaches.

2012 ◽  
Vol 323-325 ◽  
pp. 373-379 ◽  
Author(s):  
B. Rannou ◽  
M. Mollard ◽  
B. Bouchaud ◽  
J. Balmain ◽  
G. Bonnet ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Substrate Surface ◽  
Single Step ◽  
Alloying Element ◽  
Aluminum Particles ◽  
New Approach ◽  
Theoretical Approaches ◽  
Barrier Coating ◽  
Coating Characteristics ◽  
Good Agreement

The use of thermal barrier coating systems allows superalloys to withstand higher operating temperatures in aeroengine turbines. Aiming at providing oxidation protection to such substrates, an aluminum-rich layer is deposited to form the α-Al2O3scale over which a ceramic layer (i.e. YSZ layer) is applied to provide thermal insulation. A new approach is now being investigated within the FP7 European project « PARTICOAT », in which a single step process is employed by applying micro-sized aluminum particles. The particles are mixed in a binder and deposited by brushing or spraying on the substrate surface. During a heat treatment, the particles sinter and oxidize to form a top coat composed of hollow con-joint alumina spheres and simultaneously, an Al-rich diffusion zone is formed in the substrate. For a better understanding of the diffusion / growth processes, preliminary tests were carried out on pure nickel and Ni20Cr model alloys prior to further application on commercial superalloys. The effect of the heat treatment on the coating characteristics (number of layers, thickness, composition, homogeneity, etc.) was particularly investigated to emphasize the mechanisms of diffusion governing the growth of the coatings. The establishment of the diffused layers occurred very readily even at intermediate temperatures (650 and 700°C). However, the layers formed did not match perfectly with the thermodynamic modeling because of the quick incorporation of Ni into molten Al at intermediate temperatures (650°C). In contrast, at higher temperatures (700 and 1100°C) the phases predicted by Thermocalc are in good agreement with the observed thickness of the diffused layers. The incorporation of Cr as an alloying element restrained Al ingress by segregation of Cr even at very low temperatures aluminizing temperatures (625°C).

Effect of isothermal heat treatment on microstructure and mechanical properties of Reduced Activation Ferritic Martensitic steel

2013 ◽  
Vol 435 (1-3) ◽  
pp. 128-136 ◽  
Author(s):  
K.S. Chandravathi ◽  
C.S. Sasmal ◽  
K. Laha ◽  
P. Parameswaran ◽  
M. Nandagopal ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Martensitic Steel ◽  
Isothermal Heat Treatment ◽  
Microstructure And Mechanical Properties

scholarly journals Influence of Microstructure on Mechanical Properties of Bainitic Steels in Railway Applications

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 778 ◽  
Author(s):  
Omid Hajizad ◽  
Ankit Kumar ◽  
Zili Li ◽  
Roumen H. Petrov ◽  
Jilt Sietsma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Behavior ◽  
Mechanical Performance ◽  
Electron Backscatter Diffraction ◽  
Bainitic Ferrite ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Uniaxial Tensile ◽  
Isothermal Heat Treatment

Wheel–rail contact creates high stresses in both rails and wheels, which can lead to different damage, such as plastic deformation, wear and rolling contact fatigue (RCF). It is important to use high-quality steels that are resistant to these damages. Mechanical properties and failure of steels are determined by various microstructural features, such as grain size, phase fraction, as well as spatial distribution and morphology of these phases in the microstructure. To quantify the mechanical behavior of bainitic rail steels, uniaxial tensile experiments and hardness measurements were performed. In order to characterize the influence of microstructure on the mechanical behavior, various microscopy techniques, such as light optical microscopy (LOM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), were used. Three bainitic grades industrially known as B360, B1400 plus and Cr-Bainitic together with commonly used R350HT pearlitic grade were studied. Influence of isothermal bainitic heat treatment on the microstructure and mechanical properties of the bainitic grades was investigated and compared with B360, B1400 plus, Cr-Bainitic and R350HT in as-received (AR) condition from the industry. The results show that the carbide-free bainitic steel (B360) after an isothermal heat treatment offers the best mechanical performance among these steels due to a very fine, carbide-free bainitic microstructure consisting of bainitic ferrite and retained austenite laths.

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