Search

AISI 420 Martensitic stainless steel is the major precursor for steam turbine blades. Under the operational conditions of the steam turbine, this steel undergoes erosion because of the impingement of water droplets. The aim of this research is the laser cladding of NiCr and NiCr–TiC powders and producing metal matrix composite NiCr–TiC on stainless steel substrate to enhance the rigidity and erosion resistance of AISI 420 stainless steel. The laser cladding was performed using pulsed Nd: YAG laser with concurrent powder injection. By setting the powder feeding rate, power, and laser scanning rate, the effect of each parameter on the laser cladding process was investigated and the optimal parameters for laser cladding were chosen. The elemental, phasic, and microstructural assessments and characterizations of the obtained coatings were done by optical microscope, scanning electron microscope, alongside energy dispersive spectroscopy (EDS), X-ray diffraction. It was observed that the structure of the clad from the interface upwards consists of cellular, columnar, and coaxial dendrites. It was also seen that the hardness of the composite clad containing reinforcement particles was far greater than that of cladding without such particles because of the increased effect of nucleation and the presence of TiC particles. It was also found that the weight loss of the composite clad of NiCr–TiC was less than that of NiCr and stainless steel substrate, while its erosion resistance was greater compared to NiCr and steel substrate.

In this study, the oxidation behavior of WC-12Co and electroless Ni/WC-Co coatings is investigated by Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and scanning electron microscope (SEM). Time dependence of weight gain showed a linear behavior for WC-Co coating and a parabolic-like behavior for Ni/WC-Co coating. This behavior is related to the reaction-controlled and diffusion-controlled oxidation processes in the WC-Co and Ni/WC-Co coatings, respectively. Oxidation resistance of coatings was determined by phase composition and formation mechanism of the protective oxide layer. The results demonstrated that the use of Ni/WC-Co powder could reduce significantly the porosity and cracks and lead to a compact and protective (Ni, Co)WO 4 layer. The apparent activation energy was measured to be about 98.3 and 229.4 kJ/mol for WC-Co and Ni/WC-Co coatings, respectively.

CoxNi1−xFe2O4 ferrites (x=0, 0.2, 0.4, 0.4, 0.6, 0.8 and 1) were prepared by a sol-gel auto-combustion method. The samples were structurally characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), and Fourier transform infrared spectroscopy (FTIR). The XRD patterns confirmed single phase formation of spinel structure. Cation distribution estimated from XRD data suggested the mixed spinel structure of ferrite. The EDX analysis was in good agreement with the nominal composition. The results of FTIR analysis indicated that the functional groups of Co-Ni spinel ferrite were formed during the combustion process. According to FE-SEM micrographs, by addition of cobalt ion the average particle size of substituted nickel ferrite was gradually became smaller from 450 nm to 280 nm. Magnetic measurement using vibrating sample magnetometer (VSM) showed an increase in saturation magnetization and coercivity by Co2+ substitution in nickel ferrite. For Co0.8Ni0.2Fe2O4 sample, Ms and Hc reaches as high as 93 emu/g and 420 Oe, respectively. The reflection loss properties of the nanocomposites were investigated in the frequency range of 8–12 GHz, using vector network analyzer (VNA). Cobalt substitution could enhance reflection loss of NiFe2O4 ferrite. The maximum reflection loss value of the Co2+ substituted Ni ferrite was ~ −26 dB (i.e. over 99% absorption) at 9.7 GHz with bandwidth of 4 GHz (RL

CoFe 2 O 4 /FeCo hard/soft core-shell system with different shell thickness was obtained by precise control of surface treatment conditions of the CoFe 2 O 4 nanoparticles under reduced condition. CoFe 2 O 4 nanoparticles were subjected to surface reduction treatment for various period of times (10, 15, 20, 25, and 30 min) at 550 °C in order to optimize the thickness of FeCo soft shell. The phase evolution, morphology, coercivity and magnetization of the nanocomposites were examined by X-ray diffraction, electron diffraction pattern, transmission electron microscope, and vibrating sample magnetometer. The single-phase-like hysteresis loops and Henkel plot reflect the existence of the exchange coupling phenomenon in the core-shell nanocomposite. The enhancement of maximum energy product, (BH) max , by 50% with respect to the pure CoFe 2 O 4 nanoparticles is obtained for a sample treated at 20 min.

In the present study, 3.0 at% ZrO2-Y2O3 nanopowder was prepared by ball milling for 20 h, and the particle size was reduced significantly down to 78±3.8 nm. Transparent pure yttria and zirconia-doped yttria ceramics were fabricated through spark plasma sintering (SPS) with a heating rate of 100 °C/min at 1500 °C for 20 min, under a pressure of 100 MPa. The average grain size of zirconia-added yttria ceramic decreased from 0.83±0.29 µm to 0.23±0.09 µm, whereas its lattice parameter slightly decreased. With addition of zirconia the transparency of yttria ceramics increased markedly in the visible region. The highest transmittance of the 3.0 at% zirconia–doped yttria ceramic reached 83.18% at the wavelength of 5 µm for 2.5 mm thick, which is very close to the theoretical value of yttria.

In the present study, the laser cladding of Al 2 O 3 on the top surface of air plasma sprayed (APSed) yttria stabilized zirconia (YSZ) coatings was carried out to improve the hot corrosion resistance of the thermal barrier coatings (TBCs) in the presence of molten salts. The coatings with and without laser cladding were subjected to a hot corrosion test at 1000 °C for 30 h in which a mixture of 55 wt% V 2 O 5 and 45 wt% Na 2 SO 4 was used as the corrosive salt. SEM micrographs and EDS analysis confirmed the formation of YVO 4 rod-shaped crystals dispersed on the surface of the APSed YSZ coatings after hot corrosion test, while these crystals were hardly detected in the laser clad coatings. The SEM micrograph of the cross section of the APSed YSZ coatings revealed cracks and a thermally grown oxide (TGO) layer in the bond coat/top coat interface, which led to the complete delamination of the coatings. Supporting the SEM micrographs, XRD patterns indicated the transformation of metastable tetragonal zirconia (t ′ -ZrO 2 ) to monoclinic zirconia (m-ZrO 2 ) after hot corrosion test. This structural transformation was due to the reaction of the molten salts with Y 2 O 3 (zirconia stabilizer) which destabilized the t ′ -ZrO 2 . To compare the hot corrosion resistance of the APSed YSZ and the laser clad coating, the volume percentage of the undesirable m-ZrO 2 was then calculated after the hot corrosion test. This calculation revealed a higher amount of m-ZrO 2 in YSZ (about 70 vol%) compared to that of the laser clad coating (about 13 vol%).

CoFe2O4 nanoparticles were synthesized by a low temperature co-precipitation method. In the present research, size-controlled CoFe2O4 was achieved by systematically tailoring the supersaturation condition during the nucleation and crystal growth processes. In order to investigate the size properties of synthesized particles, the experimental design was done using central composite method (CCD) of response surface methodology (RSM). For this purpose, the temperature, pH, and feeding rate of reactant solutions were selected as influential factors. Based on designed runs, the various responses such as hydrodynamic size of particles, size distribution, crystallite size, and magnetic size were evaluated by dynamic light scattering (DLS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Based on the results, the quadratic polynomial model was fitted for each response that could predict the response amounts. In following, the study of factors effects was carried out using software that showed the flow rate, temperature, and their interactions had higher effectiveness. Finally, by optimizing, the maximum average crystallite size were gained in maximum amounts of temperature (100 °C) and pH (13) value and minimum feeding rate of initial reactant (1 ml/min). The coercivity of cobalt ferrite nanoparticles reached 2029 Oe at optimal synthesis conditions.

CoFe 2−x Gd x O 4 nanorods were synthesized by a hydrothermal process without use of any template and surfactant. X-ray diffraction, field-emission scanning electron microscope, energy dispersive X-ray microanalyzer, and vibrating sample magnetometer were employed to evaluate structural and magnetic properties of synthesized nanorods. The X-ray diffraction analysis indicated that single phase spinel ferrites were obtained. The XRD data were processed for Rietveld refinement of structure by Reflex program. The FE-SEM micrographs of the synthesized samples showed the presence of large-area arrays of ferrite nanorods . The possible formation mechanism for the synthesis of ferrites nanorods has been preliminarily explained. Based on the EDS analysis, it was suggested that the applied process for preparation of CoFe 2−x Gd x O 4 nanorods is a suitable method for the synthesis of spinel ferrites with homogeneity in composition. It was observed from the magnetic hysteresis loop at a room temperature that with substitutions of gadolinium cations, the coercive field increased from 590.35 Oe for x=0–826.10 Oe for x=0.05. It was also found that with an increase in gadolinium content, the values of saturation magnetization decreased from 72.36 emu/g for x=0–53.61 emu/g for x=0.05. Likewise, the demagnetizing factors of ferrite nanorods is calculated. Based on the FE-SEM micrographs, it was observed that with an increase in gadolinium content, the axial ratio c / a of nanorods decrease from 21 for x=0–13 for x=0.05. Therefore, with the substitutions of gadolinium cations, the values of demagnetizing factor along c increased from 0.006 for x=0–0.013 for x=0.05. We can say that at a maximum axial ratio of about 20, the shape-anisotropy constant K s is lower than the first crystal-anisotropy constant K 1 (neglecting K 2 ). Consequently, we proposed that with an increase in gadolinium content, the intrinsic magnetocrystalline anisotropy dominates over the shape anisotropy and thus dictates the magnetic behavior of the system in the present work.

Cobalt ferrite nano-crystals were synthesized by a low temperature co-precipitation method without post-annealing. In this work, size-controlled CoFe2O4 was achieved by systematically tailoring the supersaturation condition during the nucleation and crystal growth processes. For this purpose, the effect of temperature, pH, and flow rate of addition of reactant solutions were evaluated. X-ray diffraction analysis (XRD), field emission scanning electron microscope (FE-SEM), and vibrating sample magnetometer (VSM) were carried out at room temperature to study the structural and magnetic properties of nanoparticles. M–H measurements verified the strong influence of synthesis conditions on the particle size and consequence magnetic properties of ferrite nanoparticles. The coercivity values up to 2029 Oe was obtained under optimum synthesis conditions.

In this research, zirconium lanthanum and neodymium tri-doped yttria nanopowder was synthesized using the sol–gel combustion method. Citric acid (CA) and glycine (G) were used for the gel and fuel agent, respectively. The effect of CA:G:TM (TM=transition metal) mole ratios on the particle size and morphology of the product was evaluated. As-synthesized samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy dispersion spectrum (EDS), photoluminescence (PL) spectrum, Inductively coupled plasma (ICP), UV–visible (UV–vis spectroscopy), thermal gravimetric-differential thermal analysis (TG/DTA) and Fourier transform infrared (FTIR)analysis. The optimized sample synthesized with CA:G:TM mole ratio of (1.06:1.06:1) had the average particle size of 30–40 nm with a spherical morphology. Moreover, the optimized sample showed visible photoluminescence, at 400–800 nm.

Yttria nanopowder was used to fabricate transparent yttria ceramics by spark plasma sintering at temperatures ranging from 1200 °C to 1600 °C for 20 min. The microstructure of fracture cross section and optical transmittance of the products were characterized by Field Emission-Scanning Electron Microscope (FE-SEM) and Fourier-transform infrared spectrophotometer (FTIR). With increasing the sintering temperature, densification occurs up to 1500 °C, whereas the mean grain size of yttria ceramics was first increased and then decreased markedly. The highest density and the lowest mean grain size of yttria ceramic reached to 99.58% and 0.53 μm at 1500 °C, respectively. The best in-line transmittance was at 1500 °C, with transmittance being about 80% in the range of 3–5 μm, which was close to the theoretical value of yttria.

Cobalt ferrite nanoparticles were synthesized by chemical co-precipitation, hydrothermal and sol gel auto-combustion methods. X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM) were used to investigate the structural characteristics and magnetic properties of cobalt ferrite nanocrystals. X-ray patterns revealed the production of a broad single cubic phase with the average crystallite size of 16, 18 and 178 nm for co-precipitation, hydrothermal and combustion methods, respectively. The FTIR measurements between 400 and 4000 cm −1 confirmed the intrinsic cation vibrations of spinel structure. The FE-SEM micrographs of the synthesized samples indicated the presence of two distinct groups of grains exhibiting different sizes and, different shapes for hydrothermal route. The results of magnetic hysteresis at a room temperature showed that the magnetic properties depend on the particle size and shape of particles, whereas the role of particle size is more significant.

The hot corrosion behavior of plasma-sprayed ceria–yttria co-stabilized zirconia (CYSZ) nanostructured coatings (with the chemical composition of ZrO2–2.5 wt%Y2O3–25 wt%CeO2) was studied in the presence of 45 wt% Na2SO4+55 wt%V2O5 as the corrosive molten salts, for 6, 12, 18, 30, 72, 156, and 300 h at 1000 °C. As the hot corrosion products, YVO4, CeVO4 and Ce0.75O2Zr0.25 crystals were formed by leaching Y2O3 and CeO2 from CYSZ due to the reaction between the corrosive salts and (Y2O3, CeO2) stabilizers of zirconia. The CYSZ nanostructured coating showed remarkable resistance to degradation throughout the hot corrosion test, irrespective of an additional reaction with the corrosive salts. A mechanism was suggested based on the prohibition of the further diffusion of molten salts into the deeper layers of the coating, via diffusional resistance in the nanoporous media.

A CoWSi/WSi2 coating was cladded on a nickel substrate using Nd:YAG pulsed laser. Microstructure and composition of the coating were characterized by X-ray diffraction (XRD) as well as scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). The microstructure evaluations demonstrated that a uniform free cracks coating was formed, which metallurgically bonded to the substrate. XRD and EDS analysis results showed that some Ni dilution occurred at the coating/substrate interface and that the coating consisted of CoWSi, WSi2 and γ-Co. Cyclic oxidation behavior of the coating indicated that the CoWSi/WSi2 coating could effectively prevent the oxidation of nickel at 1100 1C in air up to 40 h. The oxide scale was composed of CoO, SiO2 ,W O3 and NiCo2O4. & 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

ZnO nanopigments with five different morphologies were synthesized by a simple low temperature hydrothermal process by using zinc nitrate hexahydrate without using additives. ZnO nanopowders were characterized by X-ray diffraction and field-emission scanning electron microscopy. Optical properties of the ZnO nanostructures were investigated by UV/vis/NIR spectrophotometer and room-temperature photoluminescence spectroscopy. The obtained results indicated that ZnO nanopigments had high UV absorption and vis/NIR reflectance. Sizes of ZnO powders were strongly affected by hydrothermal conditions and increased gradually with the increase of the reaction temperature. The UV absorption increased with the reduction of particle size and nanoparticles showed higher UV absorption at 332 nm. The vis/NIR reflectance had the highest amount at sample 4 (with particle size distribution of 250–350 nm). The photoluminescence spectra from the ZnO nanostructures revealed a strong UV emission peak at 380 nm and no green emission band at ~530 nm. The photoluminescence spectra of the other samples exhibited a broad emission peak at ~420 nm and a weak visible green emission at 530 nm.

The suspensions of nanosized YSZ powder with different binder (polyvinyl alcohol, PVA) contents were agglomerated into plasma sprayable feedstocks. The agglomeration was performed by the spray drying method. Two types of morphologies (spherical and non-spherical) were obtained after spray drying of the ball milled and non-ball milled nanopowders. The suitable granules size distributions (25–150 µm, average size=45±3 µm) with good apparent density (before calcination treatment=800 kg/m3 and after calcination=900 kg/m3) and flowability (before calcination=0.31 g/s and after calcination=0.41 g/s) for plasma spraying were obtained with 5 wt% PVA and calcination temperature up to 800 °C. Finally, the correlation between the granules shape and the resulting coating porosity and thermal insulation capability was investigated.

Nanostructured scandia (4.6 mol%), yttria (0.4 mol%) doped zirconia (5SYSZ) and 7 wt% yttria stabilized zirconia (7YSZ) thermal barrier coatings (TBCs) were produced by plasma spraying on nickel-based superalloy substrates with NiCrAlY as the bond coat. The thermal shock behavior of the two as-sprayed TBCs at 1000 °C was investigated. The results indicated that the thermal cycling lifetime of 7YSZ TBCs was longer than the 5SYSZ TBCs due to the lower thermal mismatch stress between the ceramic layer and the metallic layer at high temperature. However, the nanostructured 5SYSZ coating had higher thermal stability than 7YSZ TBC.

The main goal of this paper was to evaluate the effects of laser glazing on the microstructure and thermal shock resistance of nanostructured thermal barrier coatings (TBCs). To this end, nanostructured yttria stabilized zirconia (YSZ) top coat and NiCrAlY bond coat were deposited on Inconel 738LC substrate by air plasma spraying (APS). The Nd:YAG pulsed laser was used for laser treatment of top coat surface. The thermal shock behavior of plasma-sprayed and laser-glazed coatings was investigated by quenching the samples in cold water from 1000 °C. The microstructure and phase composition of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Energy dispersive spectroscopy (EDS) was used to analyze the interface diffusion behavior of the bond coat elements. The results of SEM revealed that the laser glazing process reduced the surface roughness, eliminated the porosity of the surface and produced network cracks perpendicular to the surface. XRD results also indicated that both as-sprayed and laser glazed coatings consisted of non-transformable (T′) phase. Thermal shock test results showed that the lifetimes of the plasma-sprayed TBCs were almost doubled by laser glazing. Continuous network of segmented cracks perpendicular to the surface produced by laser glazing improved the strain accommodation and recognized it as the main enhancement mechanism for TBC life extension.

The main goal of this paper was to evaluate and compare the microstructure and mechanical properties of plasma-sprayed nanostructured and conventional yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs). To this end, NiCrAlY bond coat, nanostructured, and conventional YSZ coatings were deposited on Inconel 738LC substrate by atmospheric plasma spraying (APS). The mechanical properties of the coating were evaluated using nanoindentation and bonding strength tests. The microstructure and phase composition of the coating were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffractometry (XRD). The nanostructured YSZ coating contained both nanosized particles retained from the powder and microcolumnar grains formed through the resolidification of the molten part of the powder, whereas the microstructure of the conventional YSZ coating consisted of columnar grain splats only. The phase composition of the as-sprayed nanostructured coating consisted of the non-transformable tetragonal phase, while the conventional coating showed the presence of both the monoclinic and non-transformable tetragonal phases. The results of nanoindentation and bonding strength tests indicated that the mechanical properties of the nanostructured coating were better than those of the conventional coating.

Nanostructured thermal barrier coatings (TBCs) consisting of yttria stabilized zirconia (YSZ) ceramic top coat and NiCrAlY metallic bond coat were prepared by atmospheric plasma spraying (APS). The Nd:YAG pulsed laser was used for laser treatment of top coat surface. The microstructure and thermal insulation capability of plasma-sprayed and laser-glazed thermal barrier coatings were investigated. The microstructure and phase composition of the coating were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffractometry (XRD). The nanostructured plasma-sprayed coating contained non-melted or partially melted nanosized particles and columnar grains, whereas the microstructure of laser-glazed coating consisted of columnar grains in the fracture surface and equiaxed grains on the surface. Laser glazing, which helps to eliminate the surface porosities and other structural defects of coatings deposited by the plasma spraying method, should contribute to the improvement of their surface roughness. XRD results revealed that both as-sprayed and laser-glazed coatings consisted of non-transformable tetragonal (T′) phase. The results of the thermal insulation capability test indicated that the thermal insulation capability of the laser-glazed coating, as compared to the as-sprayed coating, was slightly lower due to the microstructural change in the glazed layer of top coat.

Non-transformable tetragonal scandia, yttria doped zirconia (SYDZ) nanopowders were prepared in large scale by the citric acid (CA) based gel method. The effect of ethylene glycol monobutyl ether (EGM):CA ratios and pH on the structure, morphology and SYDZ particle size was investigated. The microstructure of SYDZ was characterized by XRD, Raman scattering, TG–DTA, SEM, TEM, and FTIR analyses. The SYDZ nanopowders, synthesized with 1Zr 4+ :4EGM:4CA mole ratio in acidic medium (pH ∼1) at 700 °C, had an average diameter of 15±2 nm. Finally, air plasma spray (APS) coatings were produced from nanostructured SYDZ agglomerated powders.

In this study, Inconel 738 LC superalloy coupons were first sprayed with a NiCoCrAlY bond coat and then with a ceria and yttria stabilized zirconia (CYSZ) top coat by air plasma spraying (APS). After that, the plasma sprayed CYSZ thermal barrier coatings (TBCs) were treated using a Nd:YAG pulsed laser. The effect of laser glazing on the microstructure of the coatings was investigated. The microstructures and surface topographies of both as-sprayed and laser glazed samples were investigated using field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The phases of the coatings were analyzed with X-ray diffractometry (XRD). The microstructural analysis results revealed that laser surface glazing of ceramic top coat reduced the surface roughness considerably, eliminated the surface porosities and produced a network of continuous cracks perpendicular to the surface. XRD patterns also showed that both as-sprayed and laser glazed top coats consisted of nonequibrium tetragonal (T′) phase.

In the present work, well-dispersed two new structures of scale- and spindle-like ZnO were successfully synthesized by using zinc nitrate hexahydrate as the starting material and also the low temperature hydrothermal process and any additional surfactant, organic solvents or catalytic agent. The ZnO structures were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Optical property of the ZnO structures was investigated by room-temperature photoluminescence (PL) spectroscopy. The results revealed that ZnO powders have hexagonal (wurtzite-type) crystal structure and a large amount of well-dispersed ZnO scale- and spindle-like structures was formed. The thickness of scales was in the range 40–60 nm and the diameter of spindles was in the range 50–70 nm. Room-temperature PL spectra from the ZnO structures showed a weak UV emission peak at ∼382 nm and a very strong visible green emission at ∼530 nm, that was ascribed to the transition between V o Zn i and valence band.

In this study, substrates of Inconel 738 LC superalloy coupons were first sprayed with a NiCoCrAlY bondcoat and then with a ceria and yttria stabilized zirconia (CYSZ; ZrO 2 −25 wt%CeO 2 −2.5 wt%Y 2 O 3 ) topcoat by air plasma spraying (APS). Hot corrosion studies of plasma sprayed thermal barrier coatings (TBCs) were conducted in 45 wt%Na 2 SO 4 +55 wt%V 2 O 5 molten salt at 1000 °C for 30 h. The results showed that the coating defects, such as pores and microcracks play important roles as effective paths for the salt penetration in hot corrosion. Based on the results, the reaction between molten salt and stabilizers of zirconia (Y 2 O 3 and CeO 2 ), the formation of YVO 4 , CeVO 4 and CeO 2 crystals, the detrimental phase transformation of zirconia from tetragonal to monoclinic due to the depletion of stabilizers and finally, the creation of stresses were recognized to be in the degradation mechanism of CYSZ ceramic coatings in the presence of molten sulfate–vanadate salt.

The main goal of the current study is evaluation and comparison of thermal shock behavior of plasma-sprayed nanostructured and conventional yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs). To this end, the nanostructured and conventional YSZ coatings were deposited by atmospheric plasma spraying (APS) on NiCoCrAlY-coated Inconel 738LC substrates. The thermal shock test was administered by quenching the samples in cold water of temperature 20–25 °C from 950 °C. In order to characterize elastic modulus of plasma-sprayed coatings, the Knoop indentation method was employed. Microstructural evaluation, elemental analysis, and phase analysis were performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffractometry (XRD) respectively. The results revealed that failures of both nanostructured and conventional TBCs were due to the spallation of ceramic top coat. Thermal stresses caused by mismatch of thermal expansion coefficients between the ceramic top coat and the underlying metallic components were recognized as the major factor of TBC failure. However, the nanostructured TBC, due to bimodal unique microstructure, presented an average thermal cycling lifetime that was approximately 1.5 times higher than that of the conventional TBC.