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.

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]

scholarly journals Micron-Scale Deformation: A Coupled In Situ Study of Strain Bursts and Acoustic Emission

2017 ◽  
Vol 23 (6) ◽  
pp. 1076-1081 ◽  
Author(s):  
Ádám István Hegyi ◽  
Péter Dusán Ispánovity ◽  
Michal Knapek ◽  
Dániel Tüzes ◽  
Kristián Máthis ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Acoustic Emission ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Data Sampling ◽  
Deformation Curves ◽  
High Data ◽  
Excellent Control ◽  
As Stress

AbstractPlastic deformation of micron-scale crystalline materials differs considerably from bulk samples as it is characterized by stochastic strain bursts. To obtain a detailed picture of the intermittent deformation phenomena, numerous micron-sized specimens must be fabricated and tested. An improved focused ion beam fabrication method is proposed to prepare non-tapered micropillars with excellent control over their shape. Moreover, the fabrication time is less compared with other methods. The in situ compression device developed in our laboratory allows high-accuracy sample positioning and force/displacement measurements with high data sampling rates. The collective avalanche-like motion of the dislocations is observed as stress decreases on the stress–strain curves. An acoustic emission (AE) technique was employed for the first time to study the deformation behavior of micropillars. The AE technique provides important additional in situ information about the underlying processes during plastic deformation and is especially sensitive to the collective avalanche-like motion of the dislocations observed as the stress decreases on the deformation curves.

Electrical Properties of Half Heusler Coatings Depending on Spray Process

2021 ◽  
Author(s):  
Geoffrey Darut ◽  
Axel Portebois ◽  
Ludovic Vitu ◽  
Marie Pierre Planche ◽  
Hanlin Liao ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Electrical Properties ◽  
Practical Interest ◽  
Coating Properties ◽  
Spray Process ◽  
Coating Composition ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
P Type ◽  
Thermally Sprayed

Abstract Microstructure and physicochemical properties of a thermally sprayed coating depend on the dynamics of the particles interacting with the spray jet. This is especially the case for electrical properties. In this study, different spraying processes were used to spray p-type and n-type half-Heusler powders. Thermoelectric powders, Hf20Zr75Ti05CoSb80Sn20 (p-type) and Hf60Zr40NiSn98Sb02 (n-type), were selected due to their interesting electrical properties. The spray processes were evaluated based on coating composition and mechanical property measurements. The only coatings of practical interest were those that were plasma sprayed and they were examined in detail to assess the effect of process parameters on coating properties.

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.

In Situ Measurement Within Plasma-Sprayed Zirconia Coatings Under Industrial Conditions

1998 ◽  
Author(s):  
N. Baradel ◽  
L. Bianchi ◽  
F. Blein ◽  
A. Freslon ◽  
M. Jeandin
Keyword(s):  
Thermal Stresses ◽  
Cooling System ◽  
Deposition Process ◽  
Thermomechanical Properties ◽  
Stress Generation ◽  
Plasma Gun ◽  
Damage Level ◽  
Point Bend ◽  
Plasma Sprayed

Abstract The thermomechanical properties of plasma-sprayed deposits strongly depend on residual stress distribution. This latter is mainly attributed to the relative torch/substrate velocity as well as to the cooling system location and efficiency. The determining of both quenching and thermal stresses, which are generated respectively during spraying stage and cooling stage, is then required to improve coatings quality. A rather simple apparatus, which consists in monitoring the curvature of a beam substrate during the whole deposition process, has been developed to work under industrial conditions. It has been applied to partially stabilized zirconia coatings performed onto stainless steel and cast iron substrates. Spraying temperature and plasma gun velocity have been selected as relevant parameters for this study about stress generation and mechanical release. Finally, four point bend tests have been performed on deposited samples to measure coating mechanical properties and to evaluate damage level.

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.

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