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

2006 ◽  
Vol 530-531 ◽  
pp. 690-695 ◽  
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.

scholarly journals Comparation between Pulsed Nd:YAG Laser Superficial Treatment and Ceramic Coating in Creep Test of Ti-6-4V Alloy

2010 ◽  
Vol 660-661 ◽  
pp. 229-234 ◽  
Author(s):  
Adriano G. Reis ◽  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
Javier Onõro ◽  
H.S. Oliveira ◽  
...  
Keyword(s):  
Laser Treatment ◽  
Creep Test ◽  
Nd:Yag Laser ◽  
Creep Resistance ◽  
Ceramic Coating ◽  
Constant Load ◽  
Creep Tests ◽  
Pulsed Nd:Yag Laser ◽  
Load Mode ◽  
Plasma Sprayed

The objective of this work was evaluating the creep resistance of the Ti-6Al-4V alloy with superficial treatment of pulsed Nd:YAG laser and ceramic coating in creep test of Ti-6Al-4V alloy. It was used Ti-6Al-4V alloy as cylindrical bars under forged and annealing of 190oC by 6 hours condition and cooled by air. The Ti-6Al-4V alloy after the superficial treatment of pulsed Nd:YAG laser and ceramic coating was submitted to creep tests at 600°C and 125 at 319 MPa, under constant load mode. In the Nd:YAG pulsed laser treatment was used an environment of 40 % N and 60 % Ar, with 2.1 W of power and 10 m/s of speed. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. The obtained results suggest the laser treatment on Ti-6Al-4V alloy improved its creep resistance.

Evaluation of Heat Treatment and Ceramic Coating in Creep of Ti-6Al-4V

2010 ◽  
Vol 660-661 ◽  
pp. 235-240 ◽  
Author(s):  
Tarcila Sugahara ◽  
L.A.N.S. Briguente ◽  
L.M. Yogi ◽  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Creep Resistance ◽  
Stress Condition ◽  
Ceramic Coating ◽  
High Stress ◽  
Life Time ◽  
Constant Load ◽  
Stabilized Zirconia ◽  
Creep Tests ◽  
Plasma Sprayed

This study aimed to evaluate the resistance of a Ti-6Al-4V alloy in creep after heat treatments. It was used a Ti-6Al-4V alloy in cylindrical bars forms, forged condition and annealing at 190oC for 6 hours and cooled in air. The microstructure of Ti-6Al-4V alloy was evaluated after heat treatment and was submitted to creep tests at 600oC and stress conditions from 125 to 319 MPa at constant load. The Widmanstätten structure was obtained by heat treatment. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. The alloy with Widmanstätten structure and ceramic coating shows greater resistance to creep and oxidation with a longer life time in creep. At higher stress condition, 600°C and 319 MPa, the Ti-6Al-4V alloy with ceramic coating didn’t show higher creep resistance. This condition presented higher tp value and the value. It occurred because at high stress condition the coating is very fragile, decreasing your creep resistance.

Comparation between PIII Superficial and Ceramic Coating in Creep Test of Ti-6Al-4V Alloy

2010 ◽  
Vol 660-661 ◽  
pp. 225-228
Author(s):  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
M.M. Silva ◽  
Mario Ueda ◽  
V.S. Oliveira ◽  
...  
Keyword(s):  
Creep Test ◽  
Creep Resistance ◽  
Ceramic Coating ◽  
Constant Load ◽  
Creep Tests ◽  
Time Intervals ◽  
Treat Ment ◽  
Load Mode ◽  
Nitrogen Ions ◽  
Plasma Sprayed

The objective of this work was evaluating the creep resistance of the Ti-6Al-4V alloy with superficial treatment of PIII superficial treatment and ceramic coating in creep test of Ti-6Al-4V alloy. It was used Ti-6Al-4V alloy as cylindrical bars under forged and annealing of 190oC by 6 hours condition and cooled by air. The Ti-6Al-4V alloy after the superficial treat-ment of PIII and ceramic coating was submitted to creep tests at 600°C and 250 and 319 MPa under constant load mode. In the PIII treatment the samples was put in a vacuum reactor (76x10-3 Pa) and implanted by nitrogen ions in time intervals between 15 and 120 minutes. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. The obtained results suggest the ceramic coating on Ti-6Al-4V alloy improved its creep resistance.

Creep Behavior of the Titanium Alloy with Zirconia Plasma Sprayed Coating

2010 ◽  
Vol 660-661 ◽  
pp. 221-224
Author(s):  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
M.J.R. Barboza ◽  
H.R. Silva ◽  
Cosme Roberto Moreira Silva ◽  
...  
Keyword(s):  
Constant Load ◽  
Coated Sample ◽  
Stabilized Zirconia ◽  
Creep Tests ◽  
Uncoated Sample ◽  
Second Stage ◽  
Experimental Parameters ◽  
Sprayed Coating ◽  
Plasma Sprayed

The proposal of this research has been the study of the plasma spayed coating on creep of the Ti-6Al-4V, focusing on the determination of the experimental parameters related to the first and second creep stages. Yttria (8 wt %) stabilized zirconia (YSZ) (Metco 204B-NS) with CoNiCrAlY ( AMDRY 995C) has been plasma sprayed coated on Ti-6Al-4V substrate. Creep tests with constant load had been done on Ti-6Al-4V coated samples, the stress level was from 250 to 319 MPa at 600 °C. Highest values of tp and the decrease of the second stage rate had shown a better creep resistance on coated sample. Results indicate that the coated sample was greater than uncoated sample, thus the plasma sprayed coating prevent the sample oxidation efficiently.

Microstructural Evaluation of the Zirconia Plasma Sprayed Coating on Ti-6Al-4V Alloy after Creep Test

2008 ◽  
Vol 591-593 ◽  
pp. 839-844
Author(s):  
Danieli A.P. Reis ◽  
Cosme Roberto Moreira Silva ◽  
Claudinei dos Santos ◽  
Carlos de Moura Neto ◽  
M.J.R. Barboza ◽  
...  
Keyword(s):  
Creep Test ◽  
Constant Load ◽  
Stabilized Zirconia ◽  
Creep Tests ◽  
Test Conditions ◽  
Microstructural Evaluation ◽  
Main Factors ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Internal Level

The titanium affinity by oxygen is one of main factors that limit the application of their alloys as structural materials at high temperatures. The objective of this work was evaluating the microstructure of the of the zirconia plasma sprayed coating Ti-6Al-4V alloy in creep test. Yttria (8 wt.%) stabilized zirconia (YSZ) (Metco 204B-NS) with a CoNiCrAlY bond coat (AMDRY 995C) was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco. Constant load creep tests were conducted with Ti-6Al-4V alloy in air and in nitrogen atmospheres in uncoated samples and in air in coated samples at stress level of 56 MPa at 700°C. The microstructural analyze show that the predominant mechanism in the test conditions was characterized by formation and coalescence of micro cavities with shape and size varieties. The cavities are corrugated in discontinue regions, like inclusions and points involving dislocation. The size and shape of dimples are governed by number and distribution of nucleated micro cavities and by stress internal level present in the material.

scholarly journals A Comparison between CoNiCrAlY Bond Coat and Zirconia Plasma Sprayed Coatings on Creep Tests

2008 ◽  
Vol 591-593 ◽  
pp. 30-35
Author(s):  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
Antônio Augusto Couto ◽  
Cosme Roberto Moreira Silva ◽  
Francisco Piorino Neto ◽  
...  
Keyword(s):  
Bond Coat ◽  
Ceramic Coating ◽  
Constant Load ◽  
Creep Tests ◽  
Engineering Ceramic ◽  
Wide Range ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Engine Components ◽  
Sprayed Coatings

Thermomechanical and electrical properties of zirconia-based ceramics have led to a wide range of advanced and engineering ceramic applications like solid electrolyte in oxygen sensors, fuel cells and furnace elements and its low thermal conductivity has allowed its use for thermal barrier coatings for aerospace engine components. A comparison between CoNiCrAlY bond coat and zirconia plasma sprayed coatings on creep tests of the Ti-6Al-4V alloy was studied. The material used was commercial Ti-6Al-4V alloy. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. Constant load creep tests were conducted on a standard creep machine in air on coated samples, at stress levels of 520 MPa at 500°C to evaluate the oxidation protection on creep of the Ti-6Al-4V alloy. Results indicate that the creep resistance of the ceramic coating was greater than metallic coating.

Determination of Creep Parameters of Ti-6Al-4V with Bimodal and Equiaxed Microstructure

2012 ◽  
Vol 326-328 ◽  
pp. 520-524 ◽  
Author(s):  
L.A.N.S. Briguente ◽  
Antônio Augusto Couto ◽  
Nara Miranda Guimarães ◽  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
...  
Keyword(s):  
Creep Resistance ◽  
Room Temperature ◽  
Life Time ◽  
Constant Load ◽  
Bimodal Microstructure ◽  
Creep Tests ◽  
Equiaxed Microstructure ◽  
Specific Strength ◽  
Heat Treated

Ti-6Al-4V is the most used of titanium alloy and presents some important properties as metallurgical stability, high specific strength, corrosion and creep resistance [. The aim of this study is to evaluate the creep behavior of Ti-6Al-4V alloy with equiaxed and bimodal microstructures and determine the creep parameters of Ti-6Al-4V in these conditions. It was used a Ti-6Al-4V alloy forged and annealed at 190°C for 6 hours and cooled in air. The material in this condition shows an equiaxed microstructure. For bimodal microstructure, the material was heat-treated at 950°C for 60 minutes and cooled in water until room temperature. After this the material was heat-treated at 600°C for 24 hours and cooled in air until room temperature. Creep tests were performed at 600°C in stress conditions of 125, 250 and 319 MPa at constant load. The alloy with Bimodal microstructure shows higher creep resistance with a longer life time in creep.

Comparative Study of Creep Resistance of a Ti-6Al-4V Alloy with Metallic and Ceramic Coatings

2014 ◽  
Vol 802 ◽  
pp. 472-476 ◽  
Author(s):  
Flávio Perpétuo Briguente ◽  
Luciana Aparecida Narciso da Silva Briguente ◽  
Danieli Aparecida Pereira Reis ◽  
Maria Margareth da Silva
Keyword(s):  
Creep Resistance ◽  
Ceramic Coating ◽  
Spray Deposition ◽  
Ceramic Coatings ◽  
Constant Load ◽  
Industrial Applications ◽  
Material Surface ◽  
Steam Turbines ◽  
Creep Tests ◽  
Reduction Methods

Titanium and its alloys are largely used for many industrial applications due to their high mechanical and corrosion resistance and low specific mass. Ti-6Al-4V alloy is the most used in aerospace industry and it is applied for the manufacturing of aircraft blades and steam turbines. This alloy has high affinity with oxygen which constrains its application at high temperatures due to creep resistance reduction. Methods to increase creep resistance of Ti-6Al-4V alloys includes the use of metallic coatings and its combination with ceramic thermal barrier coating deposition on the material surface. The aim of this work is to compare the creep behavior of Ti-6Al-4V alloy in three different conditions: uncoated, metallic coated, metallic + ceramic coated specimens. The metallic coating layer (CoNiCrAlY) and the ceramic coating (ZrO2+ 8wt%Y2O3) are both applied by plasma spray deposition technique. The specimens were submitted to constant load creep tests at 600oC and stress conditions of 125, 250 and 319MPa. Specimens of metallic + ceramic coating have presented higher creep resistance, longer lifetime and lower stationary creep rate when compared to uncoated and metallic coated specimens.

scholarly journals Tensile Strength and Creep Resistance in Nanocrystalline Cu, Pd and Ag

1990 ◽  
Vol 206 ◽  
Author(s):  
G. W. Nieman ◽  
J. R. Weertman ◽  
R. W. Siegel
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Yield Strength ◽  
Creep Resistance ◽  
Room Temperature ◽  
True Strain ◽  
Constant Load ◽  
Creep Tests ◽  
Grain Sizes

ABSTRACTMeasurements of tensile strength and creep resistance have been made on bulk samples of nanocrystalline Cu, Pd and Ag consolidated from powders by cold compaction. Samples of Cu-Cu2O have also been tested. Yield strength for samples with mean grain sizes of 5–80 nm and bulk densities on the order of 95% of theoretical density are increased 2–5 times over that measured in pure, annealed samples of the same composition with micrometer grain sizes. Ductility in the nanocrystalline Cu has exceeded 6% true strain, however, nanocrystalline Pd samples were much less ductile. Constant load creep tests performed at room temperature at stresses of >100 MPa indicate logarithmic creep. The mechanical properties results are interpreted to be due to grain size-related strengthening and processing flaw-related weakening.

scholarly journals Observations of the creep of polar firn

2021 ◽  
pp. 1-19
Author(s):  
Yuan Li ◽  
Ian Baker
Keyword(s):  
Total Porosity ◽  
Constant Load ◽  
Primary Creep ◽  
Secondary Creep ◽  
Micro Ct ◽  
Creep Tests ◽  
Thin Sections ◽  
Compressive Stresses ◽  
Optical Images ◽  
Before And After

Abstract Constant-load creep tests were performed at −10°C at various compressive stresses from 0.05 to 0.75 MPa on specimens taken every 10 m along a firn core extracted at Summit, Greenland in June 2017. The microstructures before and after creep testing were examined using both X-ray microtomography (micro-CT) and optical images from thin sections. An Andrade-like equation was used to describe the primary creep behavior and yielded the time exponent k of 0.17–0.76. The onset of secondary creep occurred at strains of ~0.5–3% but was sometimes not observed at all in shallow firn specimens and at stresses ⩽0.43 MPa even for strain up to 32%. For the 50–80 m firn crept at stresses ⩾0.55 MPa, secondary creep occurred at strains of 2.6 ± 0.28%, and the stress exponent, n, in Glen's law, was found to range from 4.1 to 4.6, similar to those observed for fully dense ice. Micro-CT observations of crept specimens showed that in most cases, the specific surface area, the total porosity and the structure model index decreased, while the structure thickness increased with increasing density. These microstructural characteristics are consistent with the densification of the firn. Optical images from thin sections showed that recrystallization occurred in some specimens that had undergone secondary creep.

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