Oxidation protection of carbon/carbon composites with a plasma-sprayed ZrB2–SiC–Si/Yb2SiO5/LaMgAl11O19 coating during thermal cycling

Abstract Plasma sprayed thermal barriers are used as insulating materials in the hot sections of gas turbines to decrease the metal temperatures during service and men allow a higher combustion temperature for better engine efficiency. They usually contain a bond coating to protect the substrate from high temperature oxidation and a top coat with a low thermal conductivity. This study evaluate and identify the mechanisms of degradation of a vacuum plasma sprayed NiCoCrAlYTa bond coat subjected to thermal cycling at high temperature. The microstructure and micro-composition of the coating layer were analyzed by scanning electron microscopy and energy dispersive X-ray analysis to elucidate the improvement and degradation mechanisms of the material. The thermal cycling provokes some morphological and chemical modifications changes within this material. These modifications provoke a perturbation of the heat transfer within the material.

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Advanced Oxidation Protection System for Carbon-Carbon Composites

Volume 2: Aircraft Engine; Marine; Microturbines and Small Turbomachinery ◽

10.1115/89-gt-314 ◽

1989 ◽

Author(s):

D. A. Eitman ◽

R. W. Kidd ◽

R. B. Dirling

Keyword(s):

Advanced Oxidation ◽

High Strength ◽

Carbon Composite ◽

Protection System ◽

Carbon Composites ◽

Oxidation Protection ◽

Low Thermal Expansion ◽

The Matrix ◽

Strength And Stiffness ◽

Orthotropic Properties

Carbon-carbon composites possess a number of desirable attributes including low density, high strength and stiffness at temperatures well beyond the capabilities of refractory alloys, low thermal expansion coefficient, tailorable orthotropic properties, absence of strategic materials, and resistance to thermal shock, fatigue, and brittle failures. However, for many applications of interest (such as aircraft and aerospace vehicle structure and engines) resistance to oxidation in high-temperature air or engine exhaust streams is a requirement which is not satisfied by unprotected carbon-carbon composites. The elements of an advanced oxidation protection system for carbon-carbon composites are described in this paper. The system is comprised of both an oxidation resistant coating intended to provide the primary barrier to oxygen ingress and inhibitors added to the matrix of the carbon-carbon composite to increase its oxidation resistance without significant losses in mechanical properties. The composite inhibition system is designed to be complementary to the coating and to enhance its long-term performance. A description of the principal elements of the system is presented along with recent test data and current research directions.

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Studies on solution-derived ceramic coatings for oxidation protection of carbon-carbon composites

Carbon ◽

10.1016/0008-6223(94)00168-y ◽

1995 ◽

Vol 33 (4) ◽

pp. 435-440 ◽

Cited By ~ 35

Author(s):

L.M. Manocha ◽

Satish M. Manocha

Keyword(s):

Ceramic Coatings ◽

Carbon Composites ◽

Oxidation Protection

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Influence of Zirconia Plasma-Sprayed Coating on Creep of the Ti-6Al-4V Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.530-531.690 ◽

2006 ◽

Vol 530-531 ◽

pp. 690-695 ◽

Cited By ~ 3

Author(s):

Danieli A.P. Reis ◽

Cosme Roberto Moreira Silva ◽

Maria do Carmo de Andrade Nono ◽

M.J.R. Barboza ◽

Francisco Piorino Neto ◽

...

Keyword(s):

Creep Resistance ◽

Surface Oxidation ◽

Constant Load ◽

Nitrogen Atmosphere ◽

High Temperature Strength ◽

Secondary Creep ◽

Creep Tests ◽

Oxidation Protection ◽

Sprayed Coating ◽

Plasma Sprayed

The titanium affinity by oxygen is one of main factors that limit the application of their alloys as structural materials at high temperatures. Notables advances have been obeserved in the development of titanium alloys with the objective of improving the specific high temperature strength and creep-resistance properties. However, the surface oxidation limits the use of these alloys in temperatures up to 600°C. The objective of this work was estimate the influence of the plasma-sprayed coatings for oxidation protection on creep of the Ti-6Al-4V alloy, focusing on the determination of the experimental parameters related to the primary and secondary creep states. Constant load creep tests were conducted with Ti-6Al-4V alloy in air for coated and uncoated samples and in nitrogen atmosphere for uncoated samples at 500°C to evaluate the oxidation protection on creep of the Ti-6Al-4V alloy. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V specimens. Results indicated the creep resistance of the coated alloy was greater than uncoated in air, but nitrogen atmosphere was more efficient in oxidation protection. Previously reported results about the activation energies and the stress exponents values indicate that the primary and stationary creep, for both test conditions, was probably controlled by dislocation climb. Occurred a decreasing of steady state creep in function of the reduction of oxidation process, showing that Ti-6Al-4V alloy lifetime was strongly affected by the atmosphere due the oxidation suffered by the material.

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