Investigation Of Cracking Mechanisms Of Plasma Sprayed Alumina-13% Titania By Acoustic Emission

1995 ◽  
Vol 409 ◽  
Author(s):  
C.K. Lin ◽  
S.H. Leigh ◽  
R.V. Gansert ◽  
K. Murakami ◽  
S. Sampath ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
High Amplitude ◽  
High Energy ◽  
Physical Models ◽  
Free Standing ◽  
Water Stabilized Plasma ◽  
Heat Treated ◽  
Cracking Mechanisms ◽  
Point Bend ◽  
Plasma Sprayed

AbstractFree standing alumina-13% titania samples were manufactured using high power water stabilized plasma spraying. Heat treatment was performed at 1450°C for 24 hours and then at 1100°C for another 24 hours. Four point bend tests were performed on the as-sprayed and heat-treated samples in both cross section and in-plane orientations with in situ acoustic emission monitoring to monitor the cracking during the tests. Catastrophic failure with less evidence of microcracking was observed for as-sprayed samples. Energy and amplitude distributions were examined to discriminated micro- and macro-cracks. It was found that the high energy (> 100) and high amplitude (say > 60 dB) responses can be characterized as macro-cracks. Physical models are proposed to interpret the AE responses under different test conditions so that the cracking mechanisms can be better understood.

Acoustic Emission Studies of Alumina-13% Titania Free-Standing Forms during Four-Point Bend Tests

2005 ◽  
Vol 80 (9) ◽  
pp. 2382-2394 ◽  
Author(s):  
Chung-Kwei Lin ◽  
Christopher C. Berndt ◽  
Sang-Ha Leigh ◽  
Kenji Murakami
Keyword(s):  
Acoustic Emission ◽  
Free Standing ◽  
Bend Tests ◽  
Point Bend ◽  
Emission Studies

scholarly journals Deformation of Plasma Sprayed Thermal Barrier Coatings

1999 ◽  
Author(s):  
Ufuk Senturk ◽  
Rogerio S. Lima ◽  
Carlos R. C. Lima ◽  
Christopher C. Berndt
Keyword(s):  
Acoustic Emission ◽  
Composite System ◽  
Coating Properties ◽  
Failure Characteristics ◽  
Deformation Curves ◽  
Metallic Bond ◽  
Point Bend ◽  
Plasma Sprayed ◽  
Thermally Sprayed

The deformation behavior of thermally sprayed partially stabilized zirconia (PSZ) coatings are investigated using Hertzian indentation and four-point bend testing, with in situ acoustic emission monitoring. The experimental deformation curves, together with the corresponding acoustic emission responses and the fracture properties of the material are used in defining the deformation characteristics of the coating (ceramic overlay with metallic bond coal where applicable) and substrate composite system. Experiments are aimed in examining the influence of the bond coat and the coating properties on the form of deformation. Substrate temperature and pauses during spraying are demonstrated to strongly effect the coating properties and the resulting fracture/failure characteristics of the composite system.

Phase Composition Changes in Annealed Plasma-Sprayed Zircon-Alumina Coatings

1997 ◽  
Author(s):  
J. Dubsky ◽  
K. Neufuss ◽  
B. Kolman
Keyword(s):  
Phase Composition ◽  
Spinel Phase ◽  
Eutectic Mixture ◽  
X Ray Diffraction ◽  
Free Standing ◽  
Amorphous Sio2 ◽  
X Ray ◽  
Water Stabilized Plasma ◽  
Plasma Sprayed ◽  
Fast Quenching

Abstract Phase transformations and/or decomposition of deposited compounds have an indisputable influence on materials properties of plasma sprayed deposits. Using water stabilized plasma, free-standing parts were manufactured from a mechanical mixture of zircon and alumina powders and annealed. The phase composition was determined by X-ray diffraction and the chemical composition was checked by x-ray microanalysis. ZrSiO4 during plasma spraying decomposes into ZrO2 and SiO2. In the as-sprayed condition, after a relatively fast quenching, the following phases can be found: a very fine eutectic mixture of tetragonal and monoclinic ZrO2, amorphous SiO2 and a spinel phase of Al2O3. On annealing for 2 hours at 1300 and 1500 °C the spinel Al2O3 transformed to corundum. At the same time, amorphous silica crystallized. Tetragonal ZrO2 transformed to the monoclinic modification and together with SiO2 formed again ZrSiO4. At the highest annealing temperature Al2O3 and SiO2 partialy reacted to form a small amount of mullite (3Al2O3.2SiO2).

Deformation of Plasma Sprayed Thermal Barrier Coatings

2000 ◽  
Vol 122 (3) ◽  
pp. 387-392 ◽  
Author(s):  
Ufuk Senturk ◽  
Rogerio S. Lima ◽  
Carlos R. C. Lima ◽  
Christopher C. Berndt
Keyword(s):  
Acoustic Emission ◽  
Bond Coat ◽  
Composite System ◽  
Coating Properties ◽  
Failure Characteristics ◽  
Deformation Curves ◽  
Point Bend ◽  
Plasma Sprayed ◽  
Thermally Sprayed

The deformation behavior of thermally sprayed partially stabilized zirconia (PSZ) coatings are investigated using Hertzian indentation and four-point bend testing, with in situ acoustic emission monitoring. The experimental deformation curves, together with the corresponding acoustic emission responses and the fracture properties of the material are used in defining the deformation characteristics of the coating (ceramic overlay with metallic bond coat where applicable) and substrate composite system. Experiments are aimed in examining the influence of the bond coat and the coating properties on the form of deformation. Substrate temperature and pauses during spraying are demonstrated to strongly effect the coating properties and the resulting fracture/failure characteristics of the composite system. [S0742-4795(00)02503-5]

Acoustic Emission Studies of Thermal Barrier Coatings during Cyclic Four Point Bend Tests

1996 ◽  
Author(s):  
J. Voyer ◽  
F. Gitzhofer ◽  
M.L. Boulos ◽  
J. Dionne
Keyword(s):  
Acoustic Emission ◽  
Thermal Barrier Coatings ◽  
Peak Frequency ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Emission Signal ◽  
Barrier Coating ◽  
Bend Tests ◽  
Point Bend ◽  
Plasma Sprayed

Abstract In this study, Acoustic Emission (AE) signals are used to monitor the degradation of plasma sprayed Thermal Barrier Coatings (TBC) using cyclic four point bend tests. Signal analysis both in time and frequency domains is carried out in order to identify the key parameters which can be used to classify the acoustic emission signals as a function of the damage mechanisms. This classification offers a mean of prediction of the long-term behavior of the thermal barrier coating based on the acoustic emission signal signature at the early stages of bench testing. The samples consist of a Nickel-based alloy blade coated with a duplex TBC made of a 150 μm thick bond coat covered with a 300 μm thick partially-stabilized zirconia coating. Tests were performed on unnotched and perpendicularly notched samples in order to discriminate the AE from perpendicular cracks. Two broadband transducers are used for acquisition of acoustic emission signals. Measuring the time between signal detection by each of the two transducers provides a means of determination of the location of the source of the acoustic signals. A classification of the signals based on their energy and their maximum peak frequency is presented. A comparison is made between the degradation mechanisms of TBC under thermal cycling conditions that were presented elsewhere (1) and the results of four point bend tests presented here.

Thermochemical Compatibility and Optical Properties of Gd2Zr2O7 and YSZ for Thermal Barrier Coatings

2012 ◽  
Author(s):  
Li Wang ◽  
Peigen Zhang ◽  
M. H. Habibi ◽  
S. M. Guo ◽  
Jeffrey I. Eldridge
Keyword(s):  
Wavelength Range ◽  
Treatment Time ◽  
Ceramic Coatings ◽  
Lattice Parameter ◽  
Ion Diffusion ◽  
Interface Failure ◽  
Free Standing ◽  
Turbine Engine ◽  
Heat Treated ◽  
Plasma Sprayed

In this paper, the phase stability of 50wt% gadolinium zirconate (Gd2Zr2O7, GZ) and 50wt% yttria-stabilized zirconia (YSZ) powder mixture heat treated at 1300 °C for different time was investigation by X-ray diffraction (XRD). Results showed that due to the gadolinium and yttria ion diffusion, the lattice parameter of GZ decreased with increase of the heat treatment time, and a part of YSZ had phase transformation which might be one of the reasons for the interface failure in double-layered or functionally gradient TBC systems. In addition, the room-temperature hemispherical reflectance, transmittance and absorptance spectra over the wavelength range from 0.8 to 15 μm were also determined for free standing GZ, YSZ and 50wt% GZ+50wt% YSZ plasma sprayed coatings. All of the ceramic coatings are semitransparent due to the high transmittance in the wavelength range <6 μm where turbine engine thermal radiation is concentrated. GZ is transparent to longer wavelengths than 8YSZ and has unique small peaks at wavelength 2.4 μm. The mixed coating is intermediate in behavior to GZ and YSZ coatings.

Organic solvent-assisted free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 on 3D graphene as a high energy density cathode

2015 ◽  
Vol 51 (91) ◽  
pp. 16381-16384 ◽  
Author(s):  
Yuelong Xin ◽  
Liya Qi ◽  
Yiwei Zhang ◽  
Zicheng Zuo ◽  
Henghui Zhou ◽  
...  
Keyword(s):  
Energy Density ◽  
Organic Solvent ◽  
Freeze Drying ◽  
Large Scale ◽  
High Energy ◽  
High Energy Density ◽  
Free Standing ◽  
3D Graphene ◽  
Active Particles

A novel organic solvent-assisted freeze-drying pathway, which can effectively protect and uniformly distribute active particles, is developed to fabricate a free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 (LR)/rGO electrode on a large scale.

scholarly journals Mechanochemical Synthesis and Nitrogenation of the Nd1.1Fe10CoTi Alloy for Permanent Magnet

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3854
Author(s):  
Hugo Martínez Sánchez ◽  
George Hadjipanayis ◽  
Germán Antonio Pérez Alcázar ◽  
Ligia Edith Zamora Alfonso ◽  
Juan Sebastián Trujillo Hernández
Keyword(s):  
Mechanochemical Synthesis ◽  
Applied Field ◽  
Volume Fraction ◽  
Synthesis Method ◽  
High Energy ◽  
Direction Parallel ◽  
Best Value ◽  
Heat Treated ◽  
Bcc Phase ◽  
First Time

In this work, the mechanochemical synthesis method was used for the first time to produce powders of the nanocrystalline Nd1.1Fe10CoTi compound from Nd2O3, Fe2O3, Co and TiO2. High-energy-milled powders were heat treated at 1000 °C for 10 min to obtain the ThMn12-type structure. Volume fraction of the 1:12 phase was found to be as high as 95.7% with 4.3% of a bcc phase also present. The nitrogenation process of the sample was carried out at 350 °C during 3, 6, 9 and 12 h using a static pressure of 80 kPa of N2. The magnetic properties Mr, µ0Hc, and (BH)max were enhanced after nitrogenation, despite finding some residual nitrogen-free 1:12 phase. The magnetic values of a nitrogenated sample after 3 h were Mr = 75 Am2 kg–1, µ0Hc = 0.500 T and (BH)max = 58 kJ·m–3. Samples were aligned under an applied field of 2 T after washing and were measured in a direction parallel to the applied field. The best value of (BH)max~114 kJ·m–3 was obtained for 3 h and the highest µ0Hc = 0.518 T for 6 h nitrogenation. SEM characterization revealed that the particles have a mean particle size around 360 nm and a rounded shape.

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