Hastelloy Substrate Research Articles

The flux pinning effect of different doping element combinations on metal-organic deposition-derived YBa2Cu3O7−δ nanocomposite films

Elemental doping has been proven effective in improving the flux pinning of yttrium barium copper oxide (YBa2Cu3O7−δ, YBCO) nanocomposite thin films. In the present work, we increased the number of doping elements to five to investigate the flux pinning effect of YBCO. The Zr-doped, Zr, Hf and Sn co-doped, Zr, Hf, Sn and Ta co-doped, and Zr, Hf, Sn, Ta and Mn co-doped YBCO films deposited on LaMnO3/MgO/Y2O3/Al2O3/ Hastelloy substrate were systematically studied. The samples were prepared by low-fluorine metal-organic deposition method, with a total dopant of 8 mol%. All films exhibit good c-axis growth and the multi-doping helps refining the surface particles, resulting in a smoother surface. The in-field properties of the films increase with the increase of co-doped element numbers, especially at a low temperature of 30 K. The pinning force density (Fp) and critical current density (Jc) are significantly improved by five-element Zr, Hf, Sn, Ta and Mn co-doped, which is about 3 times and 1.6 times higher, respectively, than that of the undoped film at 30 K and 1 T.

Evidence of disordered local structure of ZnO buffered MgB2 films via polarized extended X-ray absorption fine structure analysis

Herein, we investigated the mechanism by which the critical temperature (Tc) of a magnesium diboride (MgB2) superconductor is altered by the buffer layer. Zinc oxide (ZnO) layers with different thicknesses (28, 80, and 134 nm) were deposited epitaxially on a Hastelloy substrate beneath a ∼ 1 μm MgB2 film. To measure the local structural distortion of the boron plane, three different angle polarizations (0°, 45°, and 90° parallel to the ab-axis) on the Mg K-edge, extended X-ray absorption fine structure (EXAFS) measurements were performed. The EXAFS analyses revealed that the ZnO buffer layer caused the boron layer to disorient, leading to buckling between the Mg and B layers, which affected the charge transfer capability in the intra-layer structure. Furthermore, the uneven distribution of B atoms amid the surrounding Mg atoms resulted in an asymmetric crystal structure, which leads to Tc fluctuation. This study reveals the relationship between modifications made to the boron plane condition of MgB2 by the ZnO buffer layer and the superconducting Tc behavior of MgB2.

In Situ Growth of (−201) Fiber‐Textured β‐Ga2O3 Semiconductor Tape for Flexible Thin‐Film Transistor

AbstractHigh‐temperature in situ growth of Ga2O3 thin film on flexible substrates for flexible/portable electronic devices is never realized because the conventional polymer substrates cannot meet the thermal‐stability requirements. In the research, for the first time, Ga2O3 thin films are directly grown on SiOx/Al2Ox buffered Hastelloy substrates. With pulsed laser deposition under high temperature, as‐grown Ga2O3 thin films have a fabric texture with a preferred out‐of‐plane orientation along (−201) and a good field‐effect mobility of 18.07 cm2 V−1 s−1. The Ga2O3 coated tape is patterned with transistor arrays and exhibited good performance homogeneity. The representative transistor devices have a threshold voltage of ≈−2.75 V and a breakdown voltage of 116 V measured under a −20 V gate voltage. Moreover, the tape transistors also have good mechanical robustness. The transistors’ good electrical performance, high uniformity, and mechanical robustness suggest that the in situ deposition technique using Hastelloy tape is promising for fabricating various flexible Ga2O3 channeled electronic circuits. Furthermore, it is believed that this technique can be extended to other flexible semiconductor devices that require high‐temperature processing.

The physical properties of Hastelloy® C-276TM and Hastelloy® C-276TM with Al2O3/Y2O3/MgO/LaMnO3 buffer layers down to cryogenic temperatures for applications in superconducting magnets

For many years, the Ni–Mo–Cr superalloy Hastelloy® C-276™ has been employed as a substrate material for depositing superconducting REBa2Cu3O7-x (RE - rare earth element) and MgB2 layers with various intermediate buffer layers. The resulting superconducting tapes are widely used in various industrial applications. However, the presence of various intermediate buffer layers between the substrate and the superconducting layer can influence the magnetic and thermal properties. At present, there is a dearth of significant data in literature concerning the impact of buffer layers. In this study, we provide data on the physical properties of a commercial Hastelloy® C-276™ tape with deposited Al2O3/Y2O3/MgO/LaMnO3 buffer layers, along with an electro-polished Hastelloy® C-276™ substrate. Physical properties such as magnetic susceptibility (dc) and specific heat, Cp, were measured from 5 to 300 K and the chemical composition was investigated. In low magnetic fields and relevant temperature range (5–200 K), the magnetization of a Hastelloy substrate demonstrates the Curie law, while Hastelloy with deposited buffer layers demonstrates Curie-Weiss law. At the magnetic field of 9 T and temperature 5 K, the resultant relative specific magnetization, compared to electro-polished Hastelloy, was lower by 16%. For heat capacity, Debye T3 law provides a good approximation from 22 to 48 K but the impact of buffer layers at 100 K was higher by 9.5%, compared to electro-polished Hastelloy, and decreases gradually with decreasing the temperature.

Novel two-step procedure for measuring I c vs. tensile stress of commercial REBCO tape

This paper presents a novel two-step procedure for measuring the critical current (I c) properties as a function of tensile stress. The proposed method completely eliminates the possible negative effect of the voltage tap used during the tensile procedure, allowing the actual I c irreversible degradation stress to be clearly determined. Six different commercial REBCO tapes from five manufacturers were tested. The I c value does not degrade until the stress reaches the ‘inflection area’ in the tensile curve, which corresponds to the most pronounced transformation step from elastic to plastic deformation. This allows easy estimation of the stress corresponding to I c irreversible degradation by a simple and accurate cryogenic tensile curve instead of complicated in-situ I c tensile measurement. A feasible composite-material tensile model is established to explain the phenomenon. In addition, fatigue measurements on a commercial REBCO tape from Shanghai Superconductor technology show that the tape can withstand 10 000 cycles under 580 MPa and over 5000 cycles under 695 MPa, which also is consistent with the proposed composite-materials tensile model and is confirmed by the EBSD experiments on the Hastelloy substrate. This research provides better insight and tools for designing and fabricating extremely high-field magnets.

Numerical analysis on the thermal mismatch stress of quasi-isotropic strand with square cross section during cool-down

The quasi-isotropic strands (Q-IS) with high current-carrying capacity can effectively improve the anisotropy of the critical current in the magnetic field. However, when a quasi-isotropic strand is cooled from room temperature (300 K) to the liquid helium temperature (4.2 K), it may cause the irreversible degradation of the critical current, the plastic deformation, and even mechanical damage. In order to achieve the safe and stable operation of quasi-isotropic strands, it is important to analyze the thermal mismatch stress during cool-down. In this study, two mechanical models (i.e. a bulk model and a contact model) were developed by considering different material elastoplastic characteristics to study the mechanical behaviors of quasi-isotropic strands with square cross section in the cooling process. Compared with the bulk model, the contact model can simulate the contact and separation between adjacent REBCO conductors in quasi-isotropic strands. Therefore, the contact model should be chosen to estimate the thermal mismatch stress of quasi-isotropic strands during cool-down. In addition, plastic deformation was clearly observed in the Cu and Ag layers with peak equivalent plastic strains of 0.016% and 0.171%, respectively. When the stainless steel sheath is replaced by the copper sheath to encase a quasi-isotropic strand, the interlaminar normal tensile stress between the superconducting layer and Hastelloy substrate was decreased from 101 MPa to 16.2 MPa. Therefore, a quasi-isotropic strand encased in a copper sheath could reduce the risk of delamination during cool-down.

Flexible self-powered DUV photodetectors with high responsivity utilizing Ga2O3/NiO heterostructure on buffered Hastelloy substrates

In this research, β-Ga2O3/NiO heterostructures were grown directly on CeO2 buffered Hastelloy flexible substrates. With pulsed laser deposition under high temperatures, as-grown β-Ga2O3 and NiO thin films have a preferred out-of-plane orientation along the ⟨−201⟩ and ➎111➉ directions. This is due to the ideal epitaxial ability of the CeO2 buffer layer, which serves as a perfect template for the epitaxial growth of single-oriented NiO and β-Ga2O3 by creating a constant gradient from CeO2 (2.7 Å along ➎001➉) to NiO (2.9 Å along ➎110➉), and eventually to β-Ga2O3 (3.04 Å along ➎010➉). The Hastelloy substrates endow photodetectors with good deformability and mechanical robustness. Moreover, owing to the type-II band alignment of β-Ga2O3/NiO heterostructures, the photodetectors have a good photocurrent at zero bias under 284 nm of light illumination. In addition, the photocurrent is significantly higher than when using an analogous heterostructure (as described in some previous reports), because the β-Ga2O3 and NiO thin films are crystalized along a single orientation with fewer defects.

Delamination behaviors of an epoxy-impregnated REBCO pancake coil during a quench

For the epoxy-impregnated high-temperature superconducting (HTS) REBa2Cu3O7-x (REBCO) magnets, the quench cannot be still avoided in the operation, which may induce the mechanical damage of the magnets and even burning out. In this research, an electromagnetic-thermo-mechanical coupling model is proposed to explore the delamination mechanisms of an epoxy-impregnated REBCO pancake coil during a quench, and thereinto, a cohesive zone model (CZM) based on the mixed-mode traction-separation law is used to simulate the onset and growth of the delamination. The numerical results indicate that the delamination of the coil is mainly concentrated in the quenching turns. The reason is that localized high-temperature gradients are generated in these turns due to the large temperature increase during a quench, and thus the accumulated stress induced by the thermal mismatch stress locally leads to the cracking of the interface between the superconducting layer and Hastelloy substrate. Meanwhile, the delamination onset of the coil is predicted by mixed-mode delamination according to the quadratic failure criterion, and the delamination propagation is mainly determined by shear stress. Up to now, the delamination mechanisms of the epoxy-impregnated pancake coil during a quench are clarified in detail, which is different from those during cooling down. To further understand the delamination behaviors of the epoxy-impregnated pancake coil during a quench, the effects of the location and height of the heater, and the thickness of the epoxy resin on the interface delamination failure are discussed in the paper.

Influence of fault current on electromagnetic-thermal characteristics of HTS coated conductors

In this paper, the electromagnetic-thermal coupling numerical model is used to study the loss and temperature distribution of two typical high temperature superconducting (HTS) coated conductors (CCs) under short-circuit fault, as well as the dynamic evolution law with time. The electromagnetic module adopts the widely used H-formulation, and the thermal module adopts the general form of heat conduction equation. The coupling between the two module is realized by using the loss calculated by the electromagnetic module as the heat source of the thermal module and combining the Jc0(B, T) relationship. A modified E-J relation suitable for any current density range is used to describe the resistivity of superconductors. Due to the difference of magnetic and thermal properties of the two kinds of structural tape substrate materials and geometric dimensions of copper stabilized layer, the losses of the two kinds of structural tape under different fault currents show obvious differences. At low fault transport current, the magnetic substrate of type B tape (NiW substrate) will obviously make the magnetic flux density perpendicular to the superconducting layer greater than that of type A tape (Hastelloy substrate), thus making the loss of type B tape greater. Under the condition of high fault transport current, the fault current will be shunted between different layers of the tape. Type B tape has a thicker copper stabilizer, which makes the current density of type B tape copper layer lower than that of type A tape, and the temperature rise and loss of type B tape are lower. Specifically, when Ip/Ic0 is less than about 0.65, the total loss of type A tape is less than that of type B tape. When Ip/Ic0 is greater than about 0.65, the total loss of type A tape is greater than that of type B tape.

Measurement of AC loss down to 25 K in a REBCO racetrack coil for electrical aircraft motor

The development of full superconducting motors for electric distributed aircraft propulsion requires to test the stator coils at the operation temperature, usually between 20 and 40 K. Here, we study the AC loss of a test racetrack coil made of REBCO tape. We developed a measurement system within a non-metallic cryostat where a cryocooler cools the test coil in combination with liquid or solid nitrogen. We present transport AC loss measurements by electrical means down to 25 K for current amplitudes up to 140 A and frequency 18–576 Hz. The AC loss increased with second power with current, and did not depend on frequency or temperature. Later, we measured the AC parallel magnetization loss in a stack of tapes made of the same material as the coil, and in a stack of tapes without superconducting layer. The results in both samples is almost identical and presents the same behavior as the coil. We conclude that the main contribution to the AC loss in the tape stack and in the coil was from the magnetism of the Hastelloy substrate or buffer layers. Therefore, researchers need to take this into account in tape production and in superconducting motor design.

High-Temperature Corrosion Behavior of Bi3.75La0.25Ti3O12 and Bi3La1Ti3O12 Coating Prepared by rf Magnetron Sputtering

Using the rf magnetron sputtering technique, Bi3.75La0.25Ti3O12 and Bi3La1Ti3O12 coatings were formed and obtained as a thin film on Hastelloy substrates. When subjected to high-temperature conditions, the effect of lanthanum on the anti-corrosive properties of the coatings was investigated. The anti-corrosive response was evaluated by electrochemical impedance spectroscopy and potentiodynamic curves, which are rarely reported. Hot corrosion occurs through the electrochemical mechanism, and more information can be obtained through electrochemical corrosion tests, which are very effective and fast. The electrochemical behavior at high temperatures was studied via molten salt corrosion tests, potentiodynamic polarization curves, and electrochemical impedance spectroscopy. Additionally, the coatings were evaluated via scanning electron microscopy and transmission microscopy to determine their morphology. With X-ray diffraction, the crystallinity of the films was determined. It was determined that the corrosion rate directly correlates with the temperature, attributed to the mechanisms induced by the Na2SO4 and V2O5 salts that generated condensation. As the temperature increases, the density of the corrosion current increases in the thin films of Bi3.75La0.25Ti3O12 and Bi3La1Ti3O12. When comparing the two compounds, it is determined that the increase in lanthanum alters the positive acid character, thus reducing the dissolution of the oxides and increasing protection.

Plastic Deformation Simulation of REBCO Tapes Using Particle Methods

Ultra-high field superconducting magnets are facing a mechanical degradation problem. On 2017, a world-record high DC magnetic field of 45.5 T was generated by insert no-insulation (NI) Rare-Earth Barium Copper Oxide (REBCO) pancake coils (14.4 T), called “LBC3”, and an outsert resistive magnet (31.1 T). Although the experiment showed a high potential of the NI REBCO magnets for ultra-high field generation, the insert NI REBCO pancake coils and the REBCO tapes were plastically deformed. The critical current properties of damaged REBCO tapes were degraded although the Hastelloy substrate of REBCO tapes is stiff and it has a high yield point of approximately 1 GPa. However, the mechanisms of the damaging REBCO tapes are not clarified. Therefore, it is necessary to clarify the mechanical phenomenon of REBCO tapes. In this paper, we model a REBCO tape with a smoothed particle hydrodynamics (SPH) method, which can represent plastic deformation. The SPH simulation is coupled with electromagnetic analysis with a partial element equivalent circuit (PEEC) model which we have previously developed. In the simulation, an external field, which linearly increases to 5 T and then decreases to 0 T, is applied to a short-length REBCO tape. The simulation results show that the REBCO tape largely deforms during the external field excitation and deexcitation.

Flexible miniaturized thin film thermocouples arrays for high temperature applications

Thin film thermocouples (TFTCs) are critical for surface temperature measurements of hot components in high temperature environments. In this paper, miniaturized Pt/Pt-10%Rh thin film thermocouple arrays were fabricated on flexible Hastelloy substrates by magnetron sputtering. The morphology and microstructure of Al2O3/Y2O3 insulating films were investigated by a field-emission scanning electron microscope with an energy dispersive X-ray spectroscopy system. The thermoelectric performance of the TFTCs arrays was investigated by cyclic calibration and bending tests. During the whole calibration process, the average maximum temperature differences (ΔT′ ) of measuring points 2, 3, and 4 are 637 °C, 617 °C, and 574 °C, respectively, which differ from the maximum temperature difference (ΔT max ) of measuring point 1 by -13 °C, -34 °C, and -76 °C, respectively. The calibration results show that each single measuring point has good repeatability and stability during the five calibration processes, and the temperature difference between multiple measuring points is obvious, stable and reliable. The thermoelectric properties of the thin film thermocouple arrays barely change after 10,000 cyclic bending tests.

Electromagnetic-thermal-structure multi-layer nonlinear elastoplastic modelling study on epoxy-impregnated REBCO pancake coils in high-field magnets

• Multi-physics elastoplastic nonlinear FE model with main constituent materials of epoxy impregnated REBCO pancake winding is developed. • Discrete stresses appear on all the constituent materials. • Stress of each constituent material induced by thermal mismatch cannot be ignored. • Plastic failure mainly induced by hoop stress propagates from inner to outer turns with transport current increasing. • Failure of the superconducting layer occurs before yield in Hastelloy due to the direct action of Lorentz force. The elastoplastic mechanical behaviour of an epoxy-impregnated REBCO pancake winding under cryogenics and high magnetic field is investigated in the frame of finite element (FE) modelling. A two-dimensional axisymmetric electromagnetic-thermal-structure multi-physics multi-layer FE model with main layers of the coated conductor and insulation materials is developed. The radial stress and hoop stress on each constituent layer induced by thermal mismatch stress during cooling are investigated. The mechanical behaviour of each constituent material is also analysed by considering the thermal mismatch stress and electromagnetic force under 20 T background field. The results show that discrete stresses appear in all the constituent materials indicating that the multi-layer winding model containing the main constituent materials is necessary for the accurate stress analysis in an epoxy-impregnated REBCO winding. The stress of each constituent material induced by thermal mismatch during cooling process are too high to be ignored in the subsequent electromagnetic structure analysis. The mechanical-magnetic coupling analyses show that the stresses of all the constituent materials increase with the transport current. The plastic failure mainly induced by hoop stress successively occurs on copper stabilizer and Hastelloy substrate of the innermost turn, and the plastic region propagates from the inner turns to the outer turns with the increase of transport current. The failure of the superconducting layer occurs before the yield in Hastelloy due to the direct action of Lorentz force on the superconducting layers. The transverse tensile stress increases with the increasing transport current, indicating that the risk of transverse delamination failure increases with the increase of transport current. The mechanical failure modes including delamination within the conductor, plastic deformation in substrate and crack in superconducting layer should be seriously considered.

Highly conductive and flexible electrodes based on ultrathin aluminum-doped zinc oxide epitaxial films

Aluminum-doped zinc oxide (AZO) thin films are popular transparent electrodes for optoelectronics and photovoltaics. However, next generation flexible devices demand not only high conductivities but also low thicknesses in AZO electrodes to stay robust against deformations. The two requirements contradict each other due to the scattering of carriers at grain boundaries in polycrystalline AZO electrodes. Herein, this work develops ultrathin, highly conductive, single-crystalline, and mechanically robust AZO electrodes on flexible Hastelloy substrates. The epitaxial growth of AZO on polycrystalline Hastelloy is empowered by an advanced buffer architecture topped with a biaxially-textured MgO layer. Thereby, a c-axis epitaxial strain is generated in the AZO electrodes and then regulated by varying the thickness of the electrodes. Abnormally high carrier concentrations are detected in the AZO electrodes likely caused by the piezopotential generated by the epitaxial strain. While the highest resistivity value of the epitaxial AZO electrodes is within the mainstream values of AZO electrodes on various substrates, a resistivity as low as ~22 μΩ•cm is demonstrated in the ultrathin electrode with a thickness of ~28 nm. The mechanical durability of the ultrathin AZO electrode is validated by bending tests of 1000 cycles.

Strong cube-textured titanium nitride conductive films directly on flexible metal substrate

Single crystal-like titanium nitride (TiN) by ion beam assisted deposition (IBAD) method is a potential conductive and thermally-stable template for growing highly-oriented REBa2Cu3O7−x (RE = rare earth) superconductor tapes as well as optoelectronics on flexible metal substrates. Previously, amorphous seed layers such as Al2O3 and Y2O3 were necessary for the biaxially-textured film growth by IBAD. Such nonconductive seed layers prevent an electrically-conductive path between functional film and bottom metal substrate such as flexible, electro-polished Hastelloy (EPH). An approach of Argon ion (Ar+) pre-treatment of EPH surface, followed by roll-to-roll IBAD process has been developed for a simplified architecture of cube-textured TiN directly on flexible metal substrate. Strong cube-textured TiN films with out-of-plane texture spread of 1.8° and in-plane texture spread of 5.6° were obtained by IBAD technique on flexible Hastelloy substrate without any intervening layers; this provides a conductive template for functional layers. Also, the ion pretreatment step is easily achieved in an IBAD system which simplifies the fabrication process.

Nanoscale Texture and Microstructure in a NdFeAs(O,F)/IBAD-MgO Superconducting Thin Film with Superior Critical Current Properties

This paper reports the nanoscale texture and microstructure of a high-performance NdFeAs(O,F) superconducting thin film grown by molecular beam epitaxy on a textured MgO/Y$_2$O$_3$/Hastelloy substrate. The NdFeAs(O,F) film forms a highly textured columnar grain structure by epitaxial growth on the MgO template. Although the film contains stacking faults along the $ab$-plane as well as grain boundaries perpendicular to the $ab$-plane, good superconducting properties are measured: a critical temperature, $T _{\rm c}$, of 46 K and a self-field critical current density, $J_{\rm c}$, of $2 \times 10^6 \,{\rm A/cm^2}$ at 4.2 K. Automated crystal orientation mapping by scanning precession electron diffraction in transmission electron microscopy is employed to analyze the misorientation angles between adjacent grains in a large ensemble (247 grains). 99% of the grain boundaries show in-plane misorientation angles ($\Delta \gamma$) less than the critical angle $\theta_{\rm c}$, which satisfies one of the necessary conditions for the high $J_{\rm c}$. Comparing the columnar grain size distribution with the mean distance of the flux line lattice, the triple junctions of low-angle grain boundaries are found to be effective pinning centers, even at high temperatures ($\ge$35 K) and/or low magnetic fields.

Towards high-performance linear piezoelectrics: Enhancing the piezoelectric response of zinc oxide thin films through epitaxial growth on flexible substrates

Ferroelectrics are popular for sensors, actuators and transducers. However, the energy barrier for reversing the polarization leads to extra energy losses, while the hysteresis causes phase-lags and non-linearities between input and output signals. The high piezoelectric constants of ferroelectrics dictate the figure-of-merit of piezoelectric devices. Enhancing the piezoelectric constant of linear-piezoelectrics potentially leads to next-generation piezoelectric devices free from issues associated with ferroelectrics. By epitaxial growth of undoped ZnO films on flexible Hastelloy substrates, we demonstrated an ~85% improvement in the piezoelectric constant, and more importantly maintained the linearity of the piezoelectric response. Strong out-of-plane and in-plane crystallographic alignments are detected in the epitaxial sample, yet modeling of the effective thin-film piezoelectric constant shows only a limited contribution of the optimized textures. The improvement in the piezoelectric response is ascribed mostly to the in-plane epitaxial strain resulted from the lattice mismatch of ZnO to the substrate. The epitaxial ZnO film on Hastelloy promisingly offer high-precision positioners with nano-/pico-meter resolutions. Enhancing the piezoelectric constant by strain engineering potentially removes the barrier for applications of linear-piezoelectrics and enriches the piezoelectric research community.

Ultra-fast growth (up to 100 nm s−1) of heavily doped EuBa2Cu3O7 film with highly aligned BaHfO3 nanocolumn structure

Ultra-fast growth (up to 100 nm s−1) of high temperature superconducting film was demonstrated by using an advanced pulsed laser deposition technique. Highly textured EuBa2Cu3O7−δ (EuBCO) film with 8 mol.% of BaHfO3 (BHO) was deposited on the IBAD-based Hastelloy substrates. Structure characterizations reveal formation of high density of BHO nanocolumns with diameter of ∼5 nm in the film, which is well beyond the expectation. Comparison study on different amount of BHO in EBCO film confirmed that nanocolumn formation strongly depends on the dopant level. The epitaxial growth process of BHO is dominated by ultra-fast self-assembly associated with enhanced diffusion of high flux element and liquid phase. Due to the correlated pinning landscape, a pronounced broad peak appears at B//c in the J c(θ) curves at 30 K 5 T, while a strong pinning force of about 900 GN m−3 at 4.2 K, 10 T (B//c) are achieved.

The influence of pyrolysing Al2O3 precursor on the high temperature properties of the YSZ-Al2O3 composite coating

ABSTRACT In this research, YSZ-Alumina top coat was deposited on the Hastelloy substrate with a NiCrAlY bond coat by Atmospheric plasma spraying process. YSZ-10 wt-% Al2O3 composite coatings with pyrolysed and un-pyrolysed Al2O3 powder were deposited. High temperature oxidation and thermal shock resistance of both coatings were investigated. Thermal shock test results showed that the lifetime of the YSZ-10 wt-% Al2O3 coating was increased by the pyrolysation of the un-pyrolysed Al2O3. The network of micro-segmented cracks produced by the pyrolysation of the un-pyrolysed Al2O3 improved the strain accommodation, introducing it as the main enhancement mechanism for TBC life extension. Using of pyrolysed alumina, resulted increased in the flattening degree of the splats, and so reduction of porosity and intra-splat cracks. This, in turn, reduced the permeability of the top coat and decreased the rate of oxide growth on the bond coat.