Flexural characteristics of sunlight-aged polyester composites: influence of processing variables

[EN] This work presents the results of flexural tests carried out on samples aged for different periods of time in a UV-Visible light chamber. The processing variables studied were the type of reinforcing fabric, the resin type, and the cure conditions. The evolution of flexural characteristics with time exposure adjusts to a mathematical model that corresponds to a damped exponential curve. The aging degree varies between 16 and 41%, depending on the preparation of the composites and the mechanical characteristics of the material. The aged material featured losses of its mechanical properties, and more on toughness than on strength properties. The kind of unsaturated o-phthalic polyester resin used showed no influence on the loss of mechanical properties. High cure temperatures decreased the loss of toughness to a higher degree than that observed for the loss of strength. The configuration of the reinforced fabrics used also influenced the mechanical properties: a mixed taffeta-multiaxial reinforced configuration leads to a high loss index on toughness properties and modulus of the composite.Segovia-López, F.; Ferrer, C.; Salvador Moya, MD.; Amigó, V. (2002). Flexural characteristics of sunlight-aged polyester composites: influence of processing variables. Journal of Testing and Evaluation. 30(1):20-26. doi:10.1520/JTE12285JS202630

Dense nanostructured zirconia compacts obtained by colloidal filtration of binary mixtures

As starting materials two commercial nanosized zirconias doped with 3 mol% of Y 2O 3 were used: a powder of about 100 nm (TZ3YE, Tosoh, Japan) and a colloidal suspension of about 15 nm (Mel Chemicals, UK). Colloidal stability in water was studied for both zirconias in terms of zeta potential as a function of deflocculant concentration and pH. Concentrated suspensions were prepared by dispersing the powder in the colloidal suspension to solids loadings ranging from 5 to 30 vol.% using a sonication probe to achieve dispersion. The rheological behavior was optimized in terms of solids content, deflocculant content and sonication time. Optimized suspensions with up to 25 vol.% solids showed a nearly Newtonian behavior and extremely low viscosities and maintain stable for long times (days) which is an important drawback of conventional nanoparticle suspensions. Samples obtained by slip casting in plaster moulds were used for dynamic sintering studies and dense, nanostructured specimens were obtained at temperatures of 1300-1400°C.This work has been supported by Spanish Ministry of Science and Innovation (Projects MAT2009-14144-C03-02 and MAT2009-14369-C02-01). R. Moreno thanks to Universidad Politecnica de Valencia for the concession of a grant in the frame of its Programme of Support to R + D (PAID-02-11, R-1752).Benavente Martínez, R.; Salvador Moya, MD.; Alcázar, M.; Moreno, R. (2012). Dense nanostructured zirconia compacts obtained by colloidal filtration of binary mixtures. Ceramics International. 38(3):2111-2117. https://doi.org/10.1016/j.ceramint.2011.10.051S2111211738

Fatigue behaviour of GMAW welded aluminium alloy AA7020

[EN] The aim of this investigation is to evaluate the influence on fatigue behaviour of the finishing of the bulge in a welded aluminium zinc magnesium alloy AA7020. It was determined that total or partial elimination of the bulge has very little influence on its behaviour, giving a very similar result on both cases, where one is better than the other by only 3%.Bloem, C.; Salvador Moya, MD.; Amigó, V.; Vicente-Escuder, Á. (2009). Fatigue behaviour of GMAW welded aluminium alloy AA7020. Welding International. 23(10):111-116. doi:10.1080/09507110902843321S111116231

Microstructural change of the HAZ in an MIG welded bond on an AA7020 aluminium alloy: stress corrosion crack growth rate in dissimilar metal welds

[EN] Many researchers have undertaken studies into the mechanical behaviour of the welded bond,1,2 others have devoted their attentions to metallurgical phenomena, whether concerning phenomena inherent to the area immediately surrounding the weld interface or concerning models or simulations of the welded structure;3,4 in addition, there are those who have made comparisons between different welding methods2 or who have dedicated their time to post-welding treatments.5 However, very few researchers have devoted their attentions to studying microstructural change throughout the HAZ on welded test pieces.Bloem, C.; Salvador Moya, MD.; Amigó, V.; Busquets Mataix, DJ. (2004). Microstructural change of the HAZ in an MIG welded bond on an AA7020 aluminium alloy: stress corrosion crack growth rate in dissimilar metal welds. Welding International. 18(7):538-542. doi:10.1533/wint.2004.3287S53854218

Atmospheric plasma spraying coatings from alumina titania feedstockcomprising bimodal particle size distributions

In this work, Al2O3 13 wt% TiO2 submicron-nanostructured powders were deposited using atmospheric plasma spraying. The feedstocks were obtained by spray drying two starting suspensions of different solids content, prepared by adding nanosized TiO2 and submicron-sized Al2O3 powders to water. The spray-dried granules were heat-treated to reduce their porosity and the powders were fully characterised in both untreated and thermally treated state. Comparison with two commercial feedstocks was carried out. Characterisation allowed a temperature for the thermal treatment to be chosen on the basis of the sprayability of the feedstock and the preservation as much as possible of the submicron-sized structure of the unfired agglomerates. Optimisation of the deposition conditions enabled the reconstituted powdrs to be successfully deposited, yielding coatings that were well bonded to the substrate. The coating microstructure, characterised by SEM, was mostly formed by a matrix of fully molten particles where the presence of semi-molten feedstock agglomerates was also observed. Moreover, microhardness, toughness, adhesion and tribological behaviours were determined, and the impact of the granule characteristics on these properties was studied. It was found that changing the feedstock characteristics allows controlling the coating quality and properties. In general, good mechanical properties were obtained using a feedstock comprising a binary mixture of submicrometric Al2O3 and nanometric TiO2 particles in the spray-dried powderThis work has been supported by Spanish Ministry of Economy and Competitiveness (MAT2009-14144-C03 and MAT2012-38364-C03).Vicent, M.; Bannier, E.; Moreno, R.; Salvador Moya, MD.; Sanchez, E. (2013). Atmospheric plasma spraying coatings from alumina titania feedstockcomprising bimodal particle size distributions. Journal of the European Ceramic Society. 33:3313-3324. doi:10.1016/j.jeurceramsoc.2013.05.009S331333243

Solution concentration effect on mechanical injection and deposition of YSZ coatings using the solution precursor plasma spraying

[EN] YSZ coatings were developed by solution precursor plasma spraying from different solution concentrations. The solutions were characterized and correlated with the rheological properties (specific weight, viscosity and surface tension). The mechanical injection was used therefore a correct injection is essential to get a correct liquid jet break-up inside the plasma plume. The optimal injection pressure must be adjusted for each solution since the solution characteristics affect on the injection process. It was experimentally found out by the observation of the splats' morphology. The particles were not melted at low pressures but solidified prior to the deposition when the injection pressure is high. It was also found out that the optimal static pressure varies with the concentration, but the dynamic pressure is equal for every solution and slightly superior to the dynamic pressure of the plasma plume. After injection optimization, coatings using different solution concentrations were developed and their microstructures were investigated. The liquid jet fragmentations as well as the heat requirements were modified with the concentration so that coating microstructure was affected. The resulting coatings display a lamellar and porous microstructure with the presence of unmelted/unpyrolysed material. Coatings' porosity increased while coatings' grow-up was less intensive when diluted solutions were used as feedstock.This work has been supported by the Spanish Ministry of Economy and Competitiveness (project MAT2015-67586-C3-R). P. Carpio acknowledges the Valencia Government (APOSTD/2016/040) and the Spanish Ministry of Science, Innovation and Universities for his current post-doc contract (FJCI-2016-27822) for his post-doc contractCarpio-Cobo, P.; Candidato, RTJ.; Pawlowski, L.; Salvador Moya, MD. (2019). Solution concentration effect on mechanical injection and deposition of YSZ coatings using the solution precursor plasma spraying. Surface and Coatings Technology. 371:124-130. https://doi.org/10.1016/j.surfcoat.2018.10.088S12413037

Microstructural evolution of Ti-6Al-4V during the sintering of microspheres of Ti for orthopedic implants

[EN] There are also important complementary stabilization treatments of the microstructure by means of controlled cooling at high speeds it avoids the formation of beta phases in grain boundaries, at the same time that avoid the broken-up of the Widmanstaetten structure, developing in an increase in mechanical resistance and fatigue resistance of the prosthesis. (C) 2003 Elsevier Science B.V. All rights reserved.Amigó, V.; Salvador Moya, MD.; Romero, F.; Solves-Camallonga, C.; Moreno, J. (2003). Microstructural evolution of Ti-6Al-4V during the sintering of microspheres of Ti for orthopedic implants. Journal of Materials Processing Technology. 141(1):117-122. https://doi.org/10.1016/S0924-0136(03)00243-7117122141

Wear behavior of conventional and spark plasma sintered Al2O3-NbC nanocomposites

[EN] This study aims to investigate the dry sliding wear behavior of Al2O3-5vol.% NbC nanocomposites sintered by two different consolidation techniques: conventional sintering (CS) and spark plasma sintering (SPS) at temperatures ranging from 1450 to 1600 degrees C. The dry sliding wear tests were performed on a tribometer with a ball-on-disc configuration using an Al2O3 ball as a counterpart material, with a normal contact load of 15 and 30 N, a sliding distance of 2000m and a sliding speed of 0.1m/s at room temperature and ambient environment. The sintering methods, mechanical properties and applied load acted directly on the wear mechanism of the nanocomposites. The samples sintered by SPS exhibited higher densification and hardness, in addition to a lower friction coefficient and wear rate. Based on the wear rate, these nanocomposites exhibited a moderate regime with 15N of load, and several regimes when 30 N of applied load was used. The main wear mechanisms observed were plastic deformation, abrasion and grain pull-out. The excellent results show that Al2O3-NbC nanocomposites are ideal for the manufacture of new products such as cutting tools.Brazilian institution CAPES for the project CAPES-PVE A086/2013, Grant/Award Number: 23038.009604/2013-12Alecrim, L.; Ferreira, J.; Salvador Moya, MD.; Borrell Tomás, MA.; Pallone, E. (2018). Wear behavior of conventional and spark plasma sintered Al2O3-NbC nanocomposites. International Journal of Applied Ceramic Technology. 15(2):418-425. https://doi.org/10.1111/ijac.12800S418425152Wahi, R. P., & Ilschner, B. (1980). Fracture behaviour of composites based on Al2O3-TiC. Journal of Materials Science, 15(4), 875-885. doi:10.1007/bf00552097Tedesco, N. R., Pallone, E. M. J. A., & Tomasi, R. (2010). Effects of the Pin-on-Disc Parameters on the Wear of Alumina. Advances in Science and Technology, 65, 39-44. doi:10.4028/www.scientific.net/ast.65.39Rodriguez-Suarez, T., Bartolomé, J. F., Smirnov, A., Lopez-Esteban, S., Torrecillas, R., & Moya, J. S. (2011). Sliding wear behaviour of alumina/nickel nanocomposites processed by a conventional sintering route. Journal of the European Ceramic Society, 31(8), 1389-1395. doi:10.1016/j.jeurceramsoc.2011.02.011Gustafsson, S., Falk, L. K. L., Lidén, E., & Carlström, E. (2008). Pressureless sintered Al2O3–SiC nanocomposites. Ceramics International, 34(7), 1609-1615. doi:10.1016/j.ceramint.2007.05.005Qu, H., & Zhu, S. (2013). Two step hot pressing sintering of dense fine grained WC–Al2O3 composites. Ceramics International, 39(5), 5415-5425. doi:10.1016/j.ceramint.2012.12.049Alecrim, L. R. R., Ferreira, J. A., Gutiérrez-González, C. F., Salvador, M. D., Borrell, A., & Pallone, E. M. J. A. (2017). Sliding wear behavior of Al2O3-NbC composites obtained by conventional and nonconventional techniques. Tribology International, 110, 216-221. doi:10.1016/j.triboint.2017.02.028Pasotti, R. M. R., Bressiani, A. H. A., & Bressiani, J. (1998). Sintering of alumina-niobium carbide composite. International Journal of Refractory Metals and Hard Materials, 16(4-6), 423-427. doi:10.1016/s0263-4368(98)00053-5Acchar, W., & Segadães, A. M. (2009). Properties of sintered alumina reinforced with niobium carbide. International Journal of Refractory Metals and Hard Materials, 27(2), 427-430. doi:10.1016/j.ijrmhm.2008.05.004Huang, S. G., Liu, R. L., Li, L., Van der Biest, O., & Vleugels, J. (2008). NbC as grain growth inhibitor and carbide in WC–Co hardmetals. International Journal of Refractory Metals and Hard Materials, 26(5), 389-395. doi:10.1016/j.ijrmhm.2007.09.003Santos, C., Maeda, L. D., Cairo, C. A. A., & Acchar, W. (2008). Mechanical properties of hot-pressed ZrO2–NbC ceramic composites. International Journal of Refractory Metals and Hard Materials, 26(1), 14-18. doi:10.1016/j.ijrmhm.2007.01.008Meng, F., Liu, C., Zhang, F., Tian, Z., & Huang, W. (2012). Densification and mechanical properties of fine-grained Al2O3–ZrO2 composites consolidated by spark plasma sintering. Journal of Alloys and Compounds, 512(1), 63-67. doi:10.1016/j.jallcom.2011.09.015Sun, L., Yang, T., Jia, C., & Xiong, J. (2011). VC, Cr3C2 doped ultrafine WC–Co cemented carbides prepared by spark plasma sintering. International Journal of Refractory Metals and Hard Materials, 29(2), 147-152. doi:10.1016/j.ijrmhm.2010.09.004Bonache, V., Salvador, M. D., Fernández, A., & Borrell, A. (2011). Fabrication of full density near-nanostructured cemented carbides by combination of VC/Cr3C2 addition and consolidation by SPS and HIP technologies. International Journal of Refractory Metals and Hard Materials, 29(2), 202-208. doi:10.1016/j.ijrmhm.2010.10.007Sun, X., Wang, Y., & Li, D. Y. (2013). Mechanical properties and erosion resistance of ceria nano-particle-doped ultrafine WC–12Co composite prepared by spark plasma sintering. Wear, 301(1-2), 406-414. doi:10.1016/j.wear.2013.01.113Pallone, E. M. J. ., Trombini, V., Botta F, W. ., & Tomasi, R. (2003). Synthesis of Al2O3–NbC by reactive milling and production of nanocomposites. Journal of Materials Processing Technology, 143-144, 185-190. doi:10.1016/s0924-0136(03)00411-4Botta F, W. ., Tomasi, R., Pallone, E. M. J. ., & Yavari, A. . (2001). Nanostructured composites obtained by reactive milling. Scripta Materialia, 44(8-9), 1735-1740. doi:10.1016/s1359-6462(01)00789-8ISO 3078-1983 Hardmetals, vickers hardness test 1983Chen, W.-H., Lin, H.-T., Chen, J., Nayak, P. K., Lee, A. C., Lu, H.-H., & Huang, J.-L. (2016). Microstructure and wear behavior of spark plasma sintering sintered Al2O3/WC-based composite. International Journal of Refractory Metals and Hard Materials, 54, 279-283. doi:10.1016/j.ijrmhm.2015.07.030Espinosa-Fernández, L., Borrell, A., Salvador, M. D., & Gutierrez-Gonzalez, C. F. (2013). Sliding wear behavior of WC–Co–Cr3C2–VC composites fabricated by conventional and non-conventional techniques. Wear, 307(1-2), 60-67. doi:10.1016/j.wear.2013.08.003Alecrim, L. R. R., Ferreira, J. A., Gutiérrez-González, C. F., Salvador, M. D., Borrell, A., & Pallone, E. M. J. A. (2017). Effect of reinforcement NbC phase on the mechanical properties of Al2O3-NbC nanocomposites obtained by spark plasma sintering. International Journal of Refractory Metals and Hard Materials, 64, 255-260. doi:10.1016/j.ijrmhm.2016.10.021Bonny, K., De Baets, P., Vleugels, J., Huang, S., & Lauwers, B. (2009). Tribological Characteristics of WC-Ni and WC-Co Cemented Carbide in Dry Reciprocating Sliding Contact. Tribology Transactions, 52(4), 481-491. doi:10.1080/10402000802716921Kato, K., & Adachi, K. (2002). Wear of advanced ceramics. Wear, 253(11-12), 1097-1104. doi:10.1016/s0043-1648(02)00240-5Pasaribu, H. R., Sloetjes, J. W., & Schipper, D. J. (2004). The transition of mild to severe wear of ceramics. Wear, 256(6), 585-591. doi:10.1016/j.wear.2003.10.025Tucci, A., & Esposito, L. (2000). Second phases and material transfer in alumina ceramics sliding systems. Wear, 245(1-2), 76-83. doi:10.1016/s0043-1648(00)00467-1Borrell, A., Torrecillas, R., Rocha, V. G., Fernández, A., Bonache, V., & Salvador, M. D. (2012). Effect of CNFs content on the tribological behaviour of spark plasma sintering ceramic–CNFs composites. Wear, 274-275, 94-99. doi:10.1016/j.wear.2011.08.01

Microstructural control of ultrafine and nanocrystalline WC-12Co-VC/Cr3C2 mixture by spark plasma sintering

The aim of this present work is to study the effect of VC and/or Cr 3C 2 in densification, microstructural control and mechanical behaviour of WC-12Co ultrafine and nanocrystalline mixtures, consolidated by spark plasma sintering at 1100 °C, applying a pressure of 80 MPa in combination with a heating rate of 100 °C min -1. Nanocrystalline and ultrafine mixtures with an average size of 30 nm and 100-250 nm, respectively, with the addition of 1 and 0.5 wt.% of VC/Cr 3C 2 grain growth inhibitors, respectively, were investigated. The density, microstructure, hardness and fracture toughness of the consolidated samples were measured and observed. The addition of VC inhibitor allows an excellent grain growth control keeping microstructures with an average grain size of 154 nm. The hardness values and fracture toughness obtained were about 2000 HV 30 and above 10 MPa m 1/2, respectively. © 2010 Elsevier Ltd and Techna Group S.r.l.The work is supported financially by the Spanish Ministry of Science and Innovation by means of the project MAT 2006-12945-C02. A. Borrell, is grateful to this Ministry for the mobility grant to the Institute of Materials Technology (ITM) of the Polytechnical University of Valencia, Spain.Bonache Bezares, V.; Salvador Moya, MD.; García-Rocha, V.; Borrell Tomás, MA. (2011). Microstructural control of ultrafine and nanocrystalline WC-12Co-VC/Cr3C2 mixture by spark plasma sintering. Ceramics International. 37(3):1139-1142. https://doi.org/10.1016/j.ceramint.2010.11.026S1139114237

Multilayer and particle size-graded YSZ coatings obtained by plasma spraying of micro- and nanostructured feedstocks

This work was supported by the Spanish Ministry of Science and Innovation (Project MAT2012-38364-C03) and the Research Promotion Plan of Universitat Jaume I, action 3.1 (Ref. PREDOC/2009/10), and it has been co-funded by the European Regional Development Fund (ERDF). The authors also thank the SCIC of Universitat Jaume I for the FEG-SEM observationsCarpio, P.; Bannier, E.; Salvador Moya, MD.; Benavente Martínez, R.; Sanchez Vilches, E. (2014). Multilayer and particle size-graded YSZ coatings obtained by plasma spraying of micro- and nanostructured feedstocks. Journal of Thermal Spray Technology. 23(8):1362-1372. https://doi.org/10.1007/s11666-014-0143-9S13621372238D.R. Clarke and S.R. Phillpot, Thermal Barrier Coatings Materials, Mater. Today, 2005, 8, p 22-29N.P. Patdure, M. Gell, and E.H. Jordan, Thermal Barrier Coatings for Gas-Turbine Engine Applications, Science, 2002, 296, p 280-284L. Pawlowski, Finely Grained Nanometric and Submicrometric Coatings by Thermal Spraying: A Review, Surf. Coat. Technol., 2008, 205(43), p 18-28R.S. Lima and B.R. Marple, Thermal Spray Coatings Engineered from Nanostructured Ceramic Agglomerated Powders for Structural, Thermal Barrier and Biomedical Applications: A Review, J. Therm. Spray Technol., 2007, 16(1), p 40-63P. Fauchais, G. Montavon, R.S. Lima, and B.R. Marple, Engineering a New Class of Thermal Spray Nano-Based Microstructures from Agglomerated Nanostructured Particles, Suspensions and Solutions: An Invited Review, J. Phys. D, 2011, 44(9), 93001, p 1-131M. Gell, E.H. Jordan, Y.H. Sohn, D. Goberman, L. Shaw, and T.D. Xiao, Development and Implementation of Plasma Sprayed Nanostructured Ceramic Coatings, Surf. Coat. Technol., 2001, 146-147, p 48-54R.S. Lima and B.R. Marple, Nanostructured YSZ Thermal Barrier Coatings Engineered to Counteract Sintering Effects, Mater. Sci. Eng. A, 2008, 485, p 182-193H. Chen, X. Zhou, and C. Ding, Investigation of the Thermomechanical Properties of a Plasma-Sprayed Nanostructured Zirconia Coating, J. Eur. Ceram. Soc., 2003, 23, p 1449-1455K.A. Khor and Y.W. Gu, Thermal Properties of Plasma-Sprayed Graded Thermal Barrier Coatings, Thin Solid Films, 2000, 372, p 104-113A.M. Limarga, T.S. Widjajab, and T.H. Yip, Mechanical Properties and Oxidation Resistance of Plasma-Sprayed Multilayered Al2O3/ZrO2 Thermal Barrier Coatings, Surf. Coat. Technol., 2005, 197, p 93-102X. Chen, Y. Zhao, X. Fan, Y. Liu, B. Zou, Y. Wang, H. Ma, and X. Cao, Thermal Cycling Failure of New LaMgAl11O19/YSZ Double Ceramic Top Coat Thermal Barrier Coating Systems, Surf. Coat. Technol., 2011, 205, p 3293-3300G. Mauer, M.O. Jarligo, D.E. Mack, and R. Vassen, Plasma-Sprayed Thermal Barrier Coatings: New Materials, Processing Issues and Solutions, J. Therm. Spray Technol., 2013, 22(5), p 647-658A. Portinha, V. Teixeira, J. Carneiro, J. Martins, M.F. Costa, R. Vassen, and D. Stoever, Characterization of Thermal Barrier Coatings with a Gradient in Porosity, Surf. Coat. Technol., 2005, 195, p 245-251M. Vicent, E. Sánchez, G. Mallol, and R. Moreno, Study of Colloidal Behaviour and Rheology of Al2O3-TiO2 Nanosuspensions to Obtain Free-Flowing Spray-Dried Granules for Atmospheric Plasma Spraying, Ceram. Int., 2013, 39(7), p 8103-8111F. Müller, W. Peukert, R. Polke, and R. Stenger, Dispersing Nanoparticles in Liquids, Int. J. Miner. Process., 2000, 74, p S31-S34M. Vicent, E. Bannier, R. Moreno, M.D. Salvador, and E. Sánchez, Atmospheric Plasma Spraying Coatings from Alumina-Titania Feedstock Comprising Bimodal Particle Size Distributions, J. Eur. Ceram. Soc., 2013, 33, p 3313-3324C.W. Kang and H.W. Ng, Splat Morphology and Spreading Behaviour due to Oblique Impact of Droplets onto Substrates in Plasma Spray Coating Process, Surf. Coat. Technol., 2006, 200, p 5462-5477Y. Zeng, S.W. Lee, L. Gao, and C.X. Ding, Atmospheric Plasma Sprayed Coatings of Nanostructured Zirconia, J. Eur. Ceram. Soc., 2002, 22, p 347-351R.S. Lima, A. Kucuk, and C.C. Berndt, Integrity of Nanostructured Partially Stabilized Zirconia After Plasma Spray Processing, Mater. Sci. Eng. A, 2001, 13, p 75-82L. Wang, Y. Wang, X.G. Sun, J.Q. He, Z.Y. Pan, and C.H. Wang, Microstructure and Indentation Mechanical Properties of Plasma Sprayed Nano-bimodal and Conventional ZrO2-8 wt%Y2O3 Thermal Barrier Coatings, Vacuum, 2012, 86(8), p 1174-1185L.L. Shaw, D. Goberman, R. Ren, M. Gell, S. Jiang, Y. Wang, T.D. Xiao, and P.R. Strutt, The Dependency of Microstructure and Properties of Nanostructured Coatings on Plasma Spray Conditions, Surf. Coat. Technol., 2000, 130(1), p 1-8R.S. Lima, A. Kucuk, and C.C. Berndt, Bimodal Distribution of Mechanical Properties on Plasma Sprayed Nanostructured Partially Stabilized Zirconia, J. Mater. Sci. Eng. A, 2002, 327, p 224-232T. Wakui, J. Malzbender, and R.W. Steinbrech, Strain Dependent Stiffness of Plasma Sprayed Thermal Barrier Coatings, Surf. Coat. Technol., 2006, 200(16-17), p 4995-5002J. Malzbender and R.W. Steinbrech, Determination of the Stress-Dependent Stiffness of Plasma-Sprayed Thermal Barrier Coatings Using Depth-Sensitive Indentation, J. Mater. Res., 2003, 18(8), p 1975-198