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Selected information about high velocity thermal spraying method were presented in this article. Three generations of thermal spraying processes based on oxygen with propane mixture, liquid fuel with oxygen and propane with air were characterized. A powder of WC-Co-Cr 86-10-4 was used for coatings deposition on a steel substrate. Four coatings were deposited by different thermal spraying systems such as Diamond Jet, JP 5000, Micro HVOF and HVAF.

The article presents the results of research related to the impact of pretreatment plasma sprayed NiCrAlY coating on the kinetics of the oxidation. The analysis covered the shell subjected to thermal spraying. The test were performed at a temperature of 1000ºC and 1100ºC the samples were removed from the furnace after 25, 300, 500, 750 and 1000 hours. The investigations range included analysis of top surface of coatings by XRD characterization oxides formed types and microscopic investigations of coatings morphology.

The paper presents the study on synthesis and thermal diffusivity of europium zirconate. Both materials were synthesized using two methods: conventional solid-state reaction (SSR) and polymerized-complex method (PCM). Thermal analysis of constituent oxides, their mixture and synthesized organic precursor was conducted. Structural characterization included analysis of morphology, chemical composition and phase composition, both for powders and sinters. Thermal diffusivity was measured in the temperature range from 25 to 700 °C. The materials obtained via chemical synthesis exhibited much better structural homogeneity. Eu 2 Zr 2 O 7 has ca. 23% lower thermal diffusivity than Eu 2 Hf 2 O 7 , regardless of synthesis method. There was also noticeable difference in measured thermal diffusivity depending on synthesis method which could be possibly attributed to the presence of non-stoichiometric phases.

The accelerated decomposition of an Sm2Zr2O7+8YSZ system in the form of air plasma spraying (APS) thermal barrier coatings of composites, double ceramic layer (DCL), and functional graded system (FGS) types under hot corrosion conditions were analyzed. Hot corrosion tests were performed using liquid sodium sulfate salt deposits and then X-Ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS) were performed to identify the reaction products. The obtained data indicated that negligible amounts of sulfates or oxysulfates were formed, but significant decomposition of pyrochlore Sm2Zr2O7 to the fluorite phase was detected. These phenomena were also observed in a much higher temperature range during pure oxidation tests, but the lowest decomposition temperature (920 °C) was observed in the sodium sulfate assisted process. The described observations were confirmed during similar tests and realized using model powder mixtures. Microstructural analysis of thermal barrier coatings (TBC) cross-sections revealed a complex decomposition process that was localized to areas near the Sm2Zr2O7 splats. The decomposition of the observed pyrochlore phase was mainly related to interactions between Sm2Zr2O7 and 8YSZ in accordance with the fluxing mechanism typical for the hot corrosion process of Ni-based superalloys. Additionally, the effect of eutectic Na-Sm-O was determined.

The determination of thermal resistance related to splat boundaries in composite TBC (thermal barrier coating) systems and expressed as splat-to-splat heat transfer coefficient was analyzed. Sm2Zr2O7 and conventional 8YSZ powders were used for coatings deposition by atmospheric plasma spraying. Two types of internal morphology were deposited: monolayered type (Sm2Zr2O7, 8YSZ) and composite TBCs (Sm2Zr2O7 + 8YSZ with weight ratios of 75/25, 50/50 and 25/75). The primary investigation was related to microstructural characterization of ceramic layers (pores and cracks architecture description), thermal diffusivity and conductivity characterization by laser flash analysis and theoretical models. The thermal conductivity was initially calculated on the basis of thermal diffusivity, heat capacity and density measurement as a function of temperature. Those values were corrected due to the presence of pores (microstructural analysis) and effective vales of thermal conductivity were calculated. These values were used as the basis for additional calculations based on the Hasselman-Johnson model of thermal conductivity for composite materials. Based on quantitative data from image analysis and porosity corrected thermal conductivity for monolayered and composite TBC systems, the thermal boundary conductivity (splat-to-splat heat transfer coefficient) was calculated as a function of temperature for Sm2Zr2O7 + 8YSZ composite systems.

A detailed characterization of the primary microstructure of laser-cladded NiCrAlY coatings deposited on two different substrate materials is presented in this article. Amdry 962 powder was used to deposit coatings by LENS (Laser Engineered Net Shaping) on Inconel 625 Ni-based superalloy and 316L stainless steel. An overall characterization of coatings was performed from a qualitative point of view with particular attention paid to cracks and pores. A description of microstructural aspects of the internal morphology of coatings, such as the microstructure, chemical, and phase composition were also investigated. The distribution of alloying elements, such as Fe, Mo, Nb, and Y, was investigated in cladded coatings on two different substrates. It was revealed that the cladded coatings contained cracks and gas voids typical for laser-cladding processes. The dendritic microstructure was the result of rapid solidification due to differences in the chemical composition of dendritic and interdendritic areas, which was related mainly to the yttrium concentration. Additionally, epitaxial growth during the initial stages of solidification was determined to be related to the diffusion of substrate alloying elements into the dilution zone. The strong influence of substrate materials, especially iron, in the final microstructure of coatings was analyzed. The oxidation of yttrium and the formation of Y-Al-O oxides were also analyzed.

One of the major barriers limiting the suitability of TiAl intermetallic alloys for use in the demanding aircraft and automotive industries is their susceptibility to degradation as a result of oxidation at temperatures exceeding 760 °C. Paper presents the characteristics of resistance to cyclic oxidation at 950 °C for Ti–45Al–8Nb–0.5(B, C) alloy with and without protective coating obtained as a result of aluminizing using out of pack method. The characteristics of surface condition were determined by scanning electron microscope with EDS system, transmission electron microscope, and X-ray diffractometer. The favorable behavior of the Ti–45Al–8Nb–0.5(B, C) alloy with a protective coating under cyclic oxidation conditions is a result of a higher content of Al2O3 in the microstructure of the scale and the presence of Al and Nb-rich phases at the substrate interface, which probably constitue a barrier for oxidation process. The high temperature oxidation test revealed that aluminide coating was responsible for a remarkable improvement in the oxidation resistance.

The presented article characterized microstructural aspects of thermal barrier coatings (TBCs) analysis using methods of electron microscopy such as electron backscatter diffraction (EBSD), transmission/scanning electron microscopy (S/TEM), and TEM. The analyzed TBC system is based on gadolinium zirconate deposited by air plasma spraying method, and additionally, it was subjected to an oxidation test for 500 hr at a temperature of 1,100°C. Moreover, the morphological characterization of feedstock powder was showed. EBSD analysis revealed the inhomogeneity of feedstock materials in the form of complex phase composition. In the case of deposited coating, this method was used to characterize the crystallite size of zirconate coating and phase composition of thermally grown oxide zone. S/TEM and TEM analysis showed morphological details of this zone but not revealed such phase as perovskite oxide of GdAlO

The zirconates of rare earth elements, such as Sm2Zr2O7, can be an alternative material for zirconia modified by yttria (8YSZ) usually used as an insulation layer in thermal barrier coatings (TBC) systems. This chapter describes the morphology of feedstock zirconate powder, internal morphology and selected properties of different samarium zirconate TBC systems. These included: composite TBC coatings of Sm2Zr2O7 + 8YSZ type with different ratio of both used to coatings deposition powders (25/75, 50/50 and 75/25) as well as the TBC of double ceramic layer (DCL) type with an 8YSZ internal layer and an outer layer of Sm2Zr2O7 type, and a monolayer TBC based on Sm2Zr2O7. Another presented subject is related to the oxidation resistance of TBC systems during static oxidation test at temperature 1100°C. In this case, the special emphasis was taken on the characterization of thermally grown oxides (TGO) zone thickness where the most important phenomena related with overall live-time of TBC systems usually take place.

The presented study defines the impact of aluminizing process by out-of-pack method on the oxidation resistance of cast Ti–47Al–2W–0.5Si alloy after homogenising and hot isostatic pressing. The surface condition was characterized, as well as chemical and phase composition of scale formed on examined alloy with and without protective coating, when subjected to cyclic oxidation at 950 °C. It was established that the generated hermetic and compact aluminium diffusion coating with a thickness of about 7.5 μm, consisting mainly of TiAl 2 phase, has a significant effect on the improvement of cyclic oxidation resistance in the case of investigated alloy. It was confirmed that the scale formed after the oxidation process on the surface of alloy with protective coating was composed mainly of Al 2 O 3 oxide, contrary to the scale formed on the alloy without protective coating, which was mainly consisting of TiO 2 oxide.

The work presents studies of a new ceramic-metallic material. The base is a ZrO2-Mo cermet which is modified with metallic Mo or Mo85Re15 alloy coating. The structure and microstructure of Mo85Re15 alloy powders and the composite were characterized. The annealing procedure was found to influence phase composition of powder composites but not their morphology. The plasma sprayed powders, both metallic and alloyed, form coatings that adhere well to the cermet substrate. The coatings show a better homogeneity in comparison to powders and more favourable phase composition.Keywords: cermets, plasma spraying, corrosion resistance

In this paper, microstructure and some properties of various coatings based on WC-Co obtained by the High Velocity Air Fuel technique are discussed. Initially, two WC-Co 83-17 powders of standard and superfine size were examined as a feedstock for a coatings deposition on a steel substrate. A standard Amperit 526.074 powder and an Inframat superfine powder were applied. Then three different sub-micrometric powders, WC, Cr3C2 and TiC were applied to modify the microstructure of WC-Co (Amperit 526.074). The aim of the investigations was to compare the microstructure and basic properties of coatings deposited from different components. The influence of sub-micrometric additions on mechanical properties of basic coatings was analyzed. Microstructure characterization of powders by using SEM and characterization of their technological properties as well, are presented. For all manufactured coatings obtained by a High Velocity Air Fuel method, the microhardness, porosity, adhesion to a substrate, and fracture toughness were determined. An improvement in WC-Co coating properties, as a result of sub-micrometric carbides addition, was revealed.

The article presents the issues related to materials and the fabrication process of protective coatings by thermal spraying methods used for the protection of power plant boiler elements in Poland. The basic mechanisms of destruction processes occurring in the fluidized bed power boilers and the associated equipment were presented. The basic methods of thermal spraying were characterized, which allow the production of coatings with the chemical composition, phase structure and properties appropriate for a functional performance. The advantages and disadvantages of the methods of thermal spraying were discussed. The basic groups of coatings with a high resistance to corrosion and erosion wear produced by thermal spraying methods, which can be used in the power industry, were described.

Characterization of microstructure of pack cemented silicide coatings based on MoSi2phase was described in this article as well as a short term oxidation resistance of these types of coatings at temperature 1200oC. Silicide coatings were deposited on top surface of Mo and Mo alloys of TZM type by diffusional process of siliconizing in activated powders. Morphology of coatings was characterized by evaluation of chemical and phase’s composition of deposited coatings by EDS and XRD methods respectively. In the case of Mo sheet after diffusion process of siliconizing single layer of MoSi2type was obtained, but in the case of TZM alloy, in the same conditions of process, double layered coating was generated. Thick outer layer was build form MoSi2phase, but very thin internal layer consist Mo5Si3phase. The thicknesses of coatings were ca. 45μm, and were uniform. Morphology of coatings was free from inclusion and contaminations in their cores. The isolated cracks were observed, but their volume was very small. The oxidation test was performed at temperature 1200oC. The specimens were tested at 25, 500 and 100 hours of test. After each period of test characterization of coatings top surface was made. Total destruction of specimens was observed in range between 50 and 100 h of test.

Characterization of top surfaces of WC-Co coatings obtained during deposition process of high velocity thermal spraying type was showed in this article. The feedstock powder was so called “superfine” powder of WC-17Co types produced by Inframat. In first part of article short characterization of powder was presented, especially characterization of it morphology including shape, internal microstructure and grain size description. The second part of article is dedicated to characterization of microstructure and topography of top surface of coatings deposited by two different methods of high velocity thermal spraying. In this case analysis of top-surface condition by scanning microscopy with chemical analysis in microareas was used and as well as a qualitative and quantitative analysis of topography of carbides surface by traditional non-contact and laser profilometry.

Characterization of top-surface of NiCrAlY coating deposited by plasma spraying process on Inconel 625 Ni based superalloys was analyzed in two different completely conditions. First of them was as sprayed state of NiCrAlY coating and the second one was condition after grinding process. The basic aim of this treatment was related to obtain totally different conditions of coatings surface especially from roughness point of view. Those two types of top surface morphology was a base to comparison of oxidation resistant during static oxidation test at temperature of 1000°C and 1100°C. The temperature of static oxidation test was 1000°C and 1100°C. The specimens were moved out from furnace after 25, 300, 500, 750 and 1000 hours of exposition in laboratory air. The range of investigations after each interval included top surface characterization of specimens by SEM, XRD and EDS method. Those investigations showed that different types of top surface conditions had a fundamental influence on oxides layer morphology. Especially in the case of phase`s constituent of oxides zone. More detailed investigations were made on the cross sections of two types of investigated specimens. Analysis of oxides layer morphology showed in this case basic differences in thickness of oxides zone which was much higher in the case of as sprayed NiCrAlY coating.

Characterization of top surface and microstructure of silicide coatings obtained during diffusion process of pack cementation type and laser remelting treatments was showed in this article. The basic materials were pure Mo sheet and TZM molybdenum alloy. The coatings were deposited in powder process and glazed by different types of lasers. In first step the phase’s compositions of coatings was described by XRD analysis in initial condition and after remelting process. The morphology of the coatings top surface was described as well. All types of coatings were characterized by network of cracks on top surface of the coatings. Laser treatment of the silicide top surface changed morphology of the top surface, especially their cracks network. LM and SEM analysis revealed that internal coatings morphology was very similar in all cases.

This paper proposes a 3D optical topometry as a thickness evaluation method of ceramic layers in a sprayed state and after exposition. The measurements were taken using the advanced topometric sensor system, which allows for fast measurements of the element's geometry with high resolution. The results of evaluations are presented in the form of spot numerical values, coloured cross sections and 3D maps of thickness distributions. These data provide simple and quick localisations of non-uniform thickness areas or places of failure initiations with relatively high accuracy. This information is important for production engineers in failure analysis processes.

Microstructure and basic mechanical properties of WC–Co coatings obtained by HVOF and HVAF technique were described in this paper. A standard powder of WC–Co 83-17 (Amperit526.074) type was used for coating deposition on steel substrate. Sub-microcrystalline TiC powder was used to modify coatings deposited from Amperit526.074. The aim of the investigations was to compare microstructure and selected mechanical properties of coatings deposited by different methods of high velocity spray processes. The influence of sub-microcrystalline additions on the basic mechanical properties of coatings was analyzed. Deposited coatings were characterized from a morphological point of view. Their overall quality, porosity and adhesion of coatings to substrate were described.

Results of investigations related to synthesis and thermal properties analysis of the Dy2Zr2O7phase was presented in this article. This material was obtained during high temperature synthesis in an actual pressure of 15 MPa, in vacuum of 3×10-6MPa, and at 1350°C with 2 hours of exposure. Feedstock materials were submicrocrystalline powders of dysprosia Dy2O3and zirconia ZrO2. Both powders were mechanically blended in alcohol before the sintering process. The final product was analysed from the phase’s composition point of view. It was revealed that main constituent elements were dysprosium zirconate with an overall formula of Dy2Zr2O7and others were Dy zirconates with a non-stoichiometric character. The presence of zirconia was found with tetragonal types of unite cell. This fact evidences that partial dissolution of Dy2O3in ZrO2took place. The obtained material was characterized by calorimetric investigations in the thermal range from 25 to 1450°C.

Characterization of microstructure of silicide coatings obtained during diffusion process of pack cementation type was showed in this article. The basic materials were pure Mo sheet and TZM molybdenum alloys as well. The coatings were deposited in out of pack process with three different times of exposure. The temperature of deposition process was constant. In first step the phases compositions of coatings was described by XRD analysis. In each cases the MoSi2 phase was obtained on top surface of the coatings. The morphology of the coatings was very similar as well. All types of coatings were characterized by network of cracks on top surface of the coatings. There was no influence of depositions time on phases constituent and coatings topography. LM and SEM analysis revealed that internal coatings morphology was very similar in all cases. Basic differences was related to the thickness of coatings. All coatings were good quality without deep cracks. Microstructure was a columnar-like type without pores and voids.

In the article are presented investigations of the reflectance and the absorption coefficient of yttrium partially stabilized zirconia (YPSZ), for 10,6μm wavelength electromagnetic radiation as well as for the wavelengths in the range of 0,5-1,1μm. Based on an experimentally obtained absorption coefficients, the amount of laser power densities absorbed within YPSZ was calculated. Also, experimental investigations with Disk laser and CO2 laser radiation annealing were conducted. It was shown that for different lasers wavelengths and for the same laser beam intensities the microstructural changes in YPSZ are different.

The study concerns electron beam physical deposition (EB‐PVD) of yttria stabilized zirconia (YSZ) deposited on pre‐oxidized Pt‐modified aluminide bond coating. The coating was prepared by the means of Pt galvanizing followed by vapor phase aluminizing at 1050 8C. During annealing at 1100 8C in air atmosphere for 4h a 1µm thick layer of thermally grown oxide (TGO) consisting of equiaxed a‐alumina grains was formed. Focused ion beam and scanning/ transmission electron microscopy analysis revealed the presence of nanoscale Cr‐richprecipitatesdistributed intheTGOaswellasCrprecipitation inthegrain boundaries of the b phase at the interface between the TGO and bond coat. Deposition of the YSZ on a pre‐oxidized substrate provided mechanical keying with the TGO. Void formation was observed at the TGO and bondcoat interface presumably due to initial transient alumina formation.

The paper presents the study results concerning microstructural characteristics of the Ni(Co)CrAlY type powders designed for the bondcoat spraying with the plasma method for TBC layers obtained by the atmospheric plasma spraying (APS). Three types of powders with the following chemical composition Ni-23Co-17Cr-12.5Al-0.45Y, Co-32Ni-21Cr-8Al-0.5Y and Ni-22Cr-10Al-Y were subjected to analysis. The assessment of surface morphology and inner structure of powders (SEM) was made. Chemical composition (EDX, OES-ICP) of the powders was determined. Phase composition by using XRD and EBSD methods was also analysed.

The article presents results of microstructural investigations of plasma sprayed ceramic thermal barrier coatings obtained using Sm2Zr2O7+8YSZ and 8YSZ powders in 50/50, 25/75 and 75/25 proportions. The coatings thickness is evaluated and spherical, horizontal and vertical porosity is quantitatively and qualitatively characterized. The results obtained in this investigation were used for adjusted values of thermal conductivity calculations on the basis of results obtained from thermal diffusivity measurements at temperatures between 20 and 1100°C.

The paper presents results of simple, Pt/Pd- and Pt-modified aluminide coatings' cyclic oxidation-induced degradation analysis. The coatings were deposited by Pt and Pt + Pd electroplating, followed by vapor phase aluminizing at 1050 °C. Cyclic oxidation tests were performed at 1100 °C in 23 h cycles. Microstructural and phase analysis conducted using XRD, SEM, EDS and EBSD methods revealed that the oxide layers that formed on the coatings were composed of three distinctive types of oxides growing according to a specific pattern which is described. The oxide layer that formed on the simple aluminide coating exhibited low adhesion in comparison to Pt- and Pt,Pd-modified aluminide coatings which managed to maintain an adherent oxide layer that contained higher amount of desirable α-alumina. The Al-depleted βNiAl grains remained much larger in the modified aluminide coatings, even after failure. What is more, stripes characteristic for martensitic transformation were discovered in the β phase grains in all coatings.

Metal matrix composites comprising a magnesium matrix and Mg2Si/MgO dispersoids obtained by hot pressing silica nanoparticle agglomerates and metal powder in a Degussa press were characterized. Two powder mixtures having weight proportions of Mg:SiO2 of 10:0.3 and 10:1 were identically sintered. Their microstructures were characterized by optical microscopy and X-ray diffraction. The size and distribution of the Mg2Si and MgO dispersoids formed in situ were assessed as a function of the original nanosilica content. The behaviour of the composites under compression testing was assessed in 3D by X-ray microtomography using 225kV Nikon X-tek and 150kV Xradia MicroXCT scanners. This provided insights into composite strengthening mechanisms and matrix particle decohesion.

The microstructure of following thermal barrier coatings (TBC) was characterised in this paper: monolayer coatings Nd 2 Zr 2 O 7 and 8YSZ; a double ceramic layered (DCL) coating. Coatings were characterised by thicknesses that did not exceed 300 μm and porosities of approx. 5%. The chemical and phase composition analysis of the DCL layers revealed an external Nd 2 Zr 2 O 7 ceramic layer approx. 80 μm thick, a transitional zone approx. 120 μm thick and an internal 8YSZ layer 100 μm thick. For the case of the monolayer coating, the Nd 2 Zr 2 O 7 pyrochlore phase was the only one-phase component. The surface topography of both TBC systems was typical for plasma sprayed coatings, and compressive stress state had a value of approx. 5–10 MPa. Measurements of the thermal parameters, i.e., thermal diffusivity, point to considerably better insulative properties for both new types of layers when compared to the standard 8YSZ layers.

We present herein a characterization of the microstructure and thermal properties of thermal barrier coatings (TBCs), which we obtained via plasma spraying of powder Gd2Zr2O7. By using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD), we evaluated the phase composition of a ceramic layer and estimated the ceramic-layer stress state by the sin2ψ method. The tests revealed that the TBC layer consisted of a single-phase structure of Gd2Zr2O7, namely, an Fd3m lattice. The thermal diffusivity of the outer ceramic layer was determined based on a bilayer model and corrected with a factor to account for the presence of pores. The results reveal that the use of the standard parameters in a standard spraying process gives good-quality Gd2Zr2O7 TBCs with a thermal conductivity considerably lower than 8YSZ-type TBCs.

In the present study, the thermal diffusivity of four sand casting magnesium alloys: Mg-9Al-1Zn, Mg-6Al-2Sr, Mg-9Al-1.5Ca-0.3Sr and Mg-9Al-2.2Ca-0.8Sr were studied. Sand casting was performed at 730-780°C temperatures. Thermal diffusivity was measured by a LFA 427 Netzsch apparatus. The thermal diffusivity of the investigated alloys was chemical composition and temperature dependent and increased with increasing temperature. The thermal diffusivity of Mg-Al-Ca-Sr alloys was higher than that of Mg-Al alloy, because the total volume fraction of intermetallic phases in alloys containing calcium and strontium is larger than that in Mg-Al alloy. The formation of intermetallic phases caused the consumption of the solute element in the α-Mg matrix, and improved the thermal diffusivity of the Mg-Al-Ca-Sr magnesium alloy.

The paper presents test results concerning characteristics of the selected thermal properties of ceramic powders based on rare earth zirconates with a pyrochlore structure of RE2Zr2O7 type, intended for thermal spraying of TBCs. Gadolinium, lanthanum, samarium and neodymium based powders were tested. The scope of the tests encompassed thermal diffusivity analysis of the powders in a compressed pellets form within temperature range 25-1500°C, and also tests of specific heat and thermal expansion coefficient within similar temperature range. Standard powder of 8YSZ type on the basis of zirconium oxide modified with yttrium oxide was used as a reference material. Specific heat measurements of the powders showed that the highest values within the entire test temperature range were obtained for the standard YSZ type powder. In the case of new type of powders, the results obtained are very similar and only slightly lower in comparison with YSZ powder. The lowest values were obtained for the samarium based powder (temperature range corresponding to operating temperature). Character of the curves obtained do not show course of strong reactions connected with phase changes. Dilatometric tests of materials made it possible to determine thermal expansion coefficient. Mean coefficient values are included within the range from 5.5 x 106mm/°C to 10.0 x 106mm/°C. The highest mean value of thermal expansion coefficient was obtained for Nd2Zr2O7 powder and the lowest one for La2Zr2O7 powder. The lowest thermal diffusivity value at room temperature was shown by Nd2Zr2O7 powder, and the highest one by 8YSZ powder (0.215 mm2/s).

Alloys based on intermetallic phases of a Ti–Al system are materials that, thanks to their resistance characteristics, can be widely used in automotive and aerospace applications. The main restriction for the use of Ti–Al materials is their insufficient oxidation resistance above 850 °C. Oxidation parameters might be improved by aluminide coatings based on TiAl 2 and TiAl 3 phases, which could induce the creation of an Al 2 O 3 scale in the oxidation process. This type of aluminide could be deposited on the surface of TiAl alloys by various methods such as pack cementation, plasma spraying or magnetron sputtering. This article presents a new method of aluminide coating deposition on TiAl intermetallic alloys: out of pack technology. The investigated coating was deposited on turbine blades made of a Ti45Al5Nb intermetallic alloy. The surface morphology, structure, phase and chemical composition have been investigated using XRD phase analysis, SEM and EDS. The phase analysis showed that TiAl 3 and TiAl 2 were the main components of the deposited coating. An isothermal oxidation test of the TiAl turbine blades was conducted as well. After 1000 h of testing at 950 °C, the scale formed on the surface of the uncoated blades underwent spallation. The scale on the turbine blade with deposited aluminide coatings was very thin and no spallation was observed.

This article presents a study and results concerning the characteristics of selected thermal properties of the powders intended for deposition of gradient structure layers of the TBC type. The study included evaluation of the thermal diffusivity and specific heat of the powders in the initial state, and also calorimetric analysis of powder mixtures. Thermal diffusivity tests were performed with the laser-flash method. The temperature range of the tests was 25°C-1400°C. Specific heat and calorimetric analyses were performed with the heat flux method within a similar temperature range. The Gd2Zr2O7 powders obtained by spray drying method and standard ZrO2 x 8Y2O3 powder were analysed. The thermal diffusivity analysis and calorimetric analysis were performed for the samples obtained by pressing the Gd2Zr2O7 - ZrO2 x 8Y2O3 powder mixture of equal weight fractions. Specific heat measurements were taken for pure powders. The calorimetric analysis performed showed that no significant thermal effects were observed in both pure powders and their mixture within the temperature range of 800°C-1400°C. A small endothermic effect (approx.-7J/g) was observed for gadolinium powder within the temperature range of 350°C-615°C. Specific heat measurements revealed that gadolinium powder was characterized by stable values of that parameter within the whole temperature range like zirconium powder. The analyses performed showed that the powders were characterized by small mutual reactivity, and gadolinium powder showed a definitely lower thermal diffusivity, which is advantageous as regards obtaining TBC layers with a gradient structure on the basis of those two powders.

In the present study, the thermal diffusivity and conductivity of WE54 and Elektron 21 alloys were studied. The results showed the thermal diffusivity of WE54 and Elektron 21 alloys were temperature and microstructure dependent. The thermal diffusivity of both alloys was dependent on the content of the solute element in the α-Mg matrix. The solid solution of Y and Gd in Mg has a lower thermal conductivity than alloys where the intermetallic Mg3(Nd,Gd) and Mg14Y2Nd phases are present. The formation of strengthening phases during ageing caused the consumption of the solute element in the α -Mg matrix, and improved the thermal conductivity of the alloys.

The paper presents microstructural assessment results of thermal barrier coatings deposited by plasma spraying of powders with the formula Gd2Zr2O7. Standard parameters of the air plasma spraying (APS) method were used. A visual assessment of layers and quantitative and qualitative characteristics of an outer ceramic layer with the laser microscopy method were performed. Roughness and other geometric parameters describing the TBC surface were determined. Phase composition analysis of the ceramic layer was also carried out. Microstructural assessment of the layers for meeting the assessment criteria of the ceramic coatings was also carried out. The bondcoat and ceramic layer porosity assessment was performed. The TBC system general quality was assessed for presence of cracks, delamination and massive porosity. It was found that the new type of layers obtained meet the quality requirements used for assessment of the conventional layers obtained by spraying 8YSZ zirconia.

The paper presents test results and characterizes the structural stability of powders, which form a mixture of aluminium oxide (Al2O3) and gadolinium, based on rare earth zirconates. This mixture is provided to create thermal barrier coatings (TBCs) by spraying. The purpose of the tests was to determine the influence of temperature on reactions, occurring between those powders within a temperature range from 25°C to 1500°C, while such conditions were to simulate the conditions, which occur during creation of TBCs and they give an answer to the question concerning mutual reactivity of the powders. The requirements for new materials, provided to spray the TBCs, indicate the necessity to prepare the materials, which do not show tendency towards reactions with the Al2O3, formed during oxidation of Ni (Co) CrAlY, while this reaction is of type bond coat. The tests included differential scanning calorimetric (DSC) analysis and differential thermal analysis (DTA) of powder mixtures. Diffraction analysis was also performed before and after the tests have been finished. The DSC analysis results, obtained at a range of high temperature, did not show any thermal effects, which indicate a low level of mutual reactivity of the powders. However, the DTA analysis suggests presence of such effects at temperature close to 1300°C, and it indicates the necessity to verify exactly the obtained results. Results of the XRD measurement showed that after annealing process already at 1100°C the perovskite oxide of GdAlO3 was present.

The paper presents the microstructure test results of carbide layers with bond coat obtained on the magnesium alloy with WC/Co – NiCr – AZ91D type thermal spraying method. Layers were sprayed with the APS method on the sandblasted surfaces of approx. 5 mm thick elements manufactured with high pressure die casting (HPDC). The standard process parameters were used for the powders sprayed. The scope of the tests included characteristics of the AZ91D alloy top surface after HPDC process and after sandblasting. The stereometric analysis of surface was performed by using the laser profilometer. The top surface geometric parameters were determined and presented in the form of numbers and topographic maps. Both surfaces were subject to SEM analysis by using the Hitachi S3400N microscope and chemical composition analysis in micro areas (EDX analysis by using the Noran System Six software) to determine presence of impurities and other type of artefacts on the alloy surface before plasma spraying. The alloy surfaces were also subject to detailed tests after spraying process (on lateral micro-sections) to determine the influence of the spraying process on the substrate quality and consequently layer adhesion. Phase composition assessment of the NiCr 80/20 type bond coat and carbide layers WC/10Co and WC/8Co was also performed. Further tests referred to top surface morphology of both carbide layers and chemical composition assessment in micro areas.

The paper presents the results of basic thermal properties of thermal barrier coatings on the base of rare earth zirconate of type Gd2Zr2O7, deposited by the air plasma spraying (APS) method. Measurements of thermal diffusivity with the laser-flash method were performed within the temperature range of 25°C-1100°C with two and ten hours of annealing. The measurements were performed on the single-layer (AMS 5599 alloy), double-layer (AMS 5599 alloy + NiCrAlY interlayer) and three-layer samples (AMS 5599 alloy + NiCrAlY interlayer + ceramic layer of RE2Zr2O7). By using the NETZSCH Proteus software and the results for the single-layer sample, thermal diffusivity of the interlayer itself was determined by means of the double-layer model. A similar method was used to determine the thermal diffusivity of the ceramic layer. The obtained results showed lower thermal diffusivity and thermal conductivity for the new type of coatings in comparison with the standard zirconium concerning TBCs. Those results are slightly different compared with the results obtained for the initial powders, which indicates a crucial role of the ceramic layer microstructure (architecture of cracks and porosity).

The paper presents results of tests concerning influence of accuracy in measurements of selected thermal properties of materials of a ceramic mould, insulating mat and an alloy itself on effects of simulation of a casting process provided for elements of an aero-engine. A simulation process was realized by means of the PROCAST program. In initial simulations, thermal parameters were applied and they are accessible in literature and concern materials of a mould and nickel superalloys. Results of simulation revealed presence of numerous defects in a form of gaps, pores and cracks. These results were proved in trial casting. In consequence, it was impossible to select correctly right casting parameters. In order to solve this problem, a value of thermal conductivity was defined experimentally and basing on it, coefficients of heat exchange in metal – mould, mould – insulation mat systems were defined as well. A value of partial coefficients of heat exchange was used to determine values of substitute coefficient of heat exchange for the whole metal – mould, mould – insulation mat systems. By introducing the got data, one managed to define parameters of a casting process, providing improvement in a level of quality of cast elements.

The evaluation of microstructure and the thermal diffusivity of copper subjected to severe plastic deformation using multi-axial compression was investigated. The investigations were performed on copper (M1E grade) processed to effective strain at range f =1-14.9. The multi- axial compression resulted in an refining structure. The evolution of dislocation structure, misorientation distribution, crystalline size were observed by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipment with electron back scattered diffraction (EBSD) facility. The thermal diffusivity measurements were performed by using the LFA427 apparatus based on the laser-flash method. Subgrain and grain size for f =3.7 reaches about 250 nm and 550 nm respectively. The local recrystallization occur in analyzed microarea especially at f =7.5 and delay the reduction of sub(grain) size. In consequence no more large changes in structure occur during further processing up to the largest strain. The microstructural phenomena have an influence on the thermal parameters. The value of this parameters insignificantly decreased with increasing of accumulated strain.

This article describes the microstructures, chemical and phase compositions, surface morphologies, and internal structures of three ZrO2 x 8Y2O3-type of powders obtained by different manufacturing methods. The first of the analyzed powders was a conventionally prepared form of the material obtained by the spraying method. The second powder was a spherically shaped form of the material obtained from the spray drying process. It displayed a distinctive surface morphology characterized by a rough structure with visible cavities. The particle sizes of these two powders were comparable. The third form of the powder was classified as “nano” and was obtained by a grinding and crushing method. The shapes of individual particles were generally polyhedral with smooth surfaces and no visible porosity. A study of the chemical composition of each form of the powder did not show significant differences, similar to the results obtained from the phase composition study. The results of thermal diffusivity and electrical impedance studies indicated that the electrical and thermal properties of the powders with spherical structures, i.e., sprayed and spray drying, were very similar. The thermal diffusivity and impedance properties of these two powders were greater than those of the ground powder with a finer grain size.

In article the influence of large effective deformation on microstructure, thermal diffusivity and electrical conductivity is described. The tested material was monocrystalline aluminum deformed by the cyclic extrusion compression (CEC) method. The evolution of misorientation distribution, sub(grain) size was determined by using electron back scattered diffraction (EBSD) technique. The second part of the study was to evaluation of thermal diffusivity by using the laser-flash method. The LFA 427 laser-flash facility were applied. The electrical properties as electrical impedance was made by impedance bridge RLC type. The obtained results show that with increase of deformation the insignificant decrease in thermal diffusivity and electrical conductivity occurred.

In the present work, zirconium gadolinium oxide (Gd2Zr2O7) ceramics were prepared by annealing in different conditions and with APS (air plasma sprayed) techniques for thermal barrier coating (TBC) application. Thermal properties, phase transformation, crystal structure and cross-sectional morphologies of these materials were investigated. The thermal behaviour of the material was investigated from room temperature to 1500°C using the differential thermal analysis (DTA). The X-ray diffraction methods were used for the qualitative phase analysis. The structure of the studied samples has been characterized by employing powerful Rietveld’s whole X-ray profile fitting technique using the DBWS 9807a program. The SEM and EDS techniques were used to in the ceramic samples morphology analysis and for their chemical composition, respectively. The research showed that further stages of annealing result in the phase transformation of the parent substances and the main phase Gd2Zr2O7. It was found out that complete phase transformation into Gd2Zr2O7 phase takes place only for the air plasma sprayed sample. The analysis of the morphology of the initial powder revealed the spherical shape of the powder particles, which have a porous internal structure.

This study was done on the IN-738 type alloy with thermal barrier coatings. On the basic surface of the NiCoCrAlY superalloy, VPS-sprayed powder was applied as the bond-coat. In addition, ZrO(2)x 8%Y(2)O(3) powder was used for a deposition outside the top surface of a ceramic layer by the APS method. Appropriate control of the spraying process parameters permitted to obtain a gradient of porosity on the thickness of the ceramic coating. Then a static oxidation test at 1100 degrees C and for 1100 h was performed. The basic conclusions of that testing showed that main degradation modes of the gradient thermal barrier coating system were connected with formation of porous NiAl(2)O(4) oxides in the thermally grown oxide area and, consequently, formation of micro-cracks, delamination of a ceramic layer and final spallation of a ceramic top-coat.

The selection of new TBC materials is restricted by few basic requirements such as: high melting point, no phase transformation between room and the operation temperatures, low thermal conductivity, chemical inertness to the combustion gases and environment, thermal expansion match with the metallic substrate, good adherence to the metallic substrate and low sintering rate of the porous microstructure. Among these properties, one of the most important is thermal diffusivity. The number of material that can be used as TBCs is limited and so far only a few materials have been found to basically satisfy these requirements. Recent research has shown that certain rare-earth zirconates, such as Gd2Zr2O7, have even lower thermal conductivities than 7YSZ, and this has spurred an intensive research in discovering alternative TBC materials. The results of microstructure tests performed on the powders intended for thermally sprayed TBCs with APS method were presented in this article. The tests of phase and chemical composition of the analysed powder were performed. The carbon, sulphur and gas nitrogen contents were, among other things, determined during those tests. The x-ray powder diffraction phase identification in as received material was determined. The tested material showed the presence of Gd2Zr2O7 compound as the predominant one and Gd2O3 and ZrO2 oxides. The surface morphology analysis of the powder was carried out and its internal structure was characterized. The tested material shows porous structure typical for agglomerated powders. The second testing area applied to analysis of the powder thermal properties. The thermal diffusivity of the compressed samples with density similar to the solid material was determined with the laser flash (LF) method. The measurement results show that requirements for the materials used for new generation TBCs are met.

The thermal barrier coatings (TBC) enable to lower temperature (at approx. 170°C) of operating elements in a hot section of gas turbine to a range, which enables to operate for a long time in conditions of high temperature influence and prolongs operation of them even three or four times. Usually, the TBC coverings are constructed of four layers: • superalloys on a base of nickel; • outer ceramic zone, from which low thermal conduction is required. It is, in most cases, ZrO2 oxide stabilized with Y2O3 (YSZ – yttria stabilized zirconia), material of one of lowest values of thermal conductivity in high temperature of a rank 2.3 Wm-1K-1 in 1000°C for 100% density and thermal expansion of a rank 11×10-6°C-1, what enables to reduce thermal stresses. Usually, thickness of an outer ceramic layer is within a range 250-375μm; • bond coat of a type Ni(Co)CrAlY or diffusion layer of a type (Ni,Pt)Al; • layer of barrier oxides, accrueting as a result of temperature growth TGO (thermally grown oxide). In the present study characterization of conventional micro-sized YSZ powders stabilized by 8% of yttria and in comparison nano-sized YSZ will be presented. The tests performed showed that the monoclinic phase content in the nanocrystalline powder is approx. 8.8%, and approx. 7.5% in the conventional powder. The chemical composition analysis and test of powder microstructure were also performed. Carbon, sulphur and gas nitrogen contents were determined and the results received were similar. The surface morphology and powder microstructure on the cross-sections were also characterized. The standard powder with spherical shape and relatively smooth surface is predominant. The internal structure is characterized by the presence of tiny sintered particles and low porosity. The nanocrystalline powder tests showed the presence of particles in the form of tiny polyhedrons with bimodal size distribution of particles (approx. 1μm and 10μm).

A novel sonochemical method for direct preparation of nanocrystalline antimony selenoiodide (SbSeI) has been established. The SbSeI gel was synthesized using elemental Sb, Se, and I in the presence of ethanol under ultrasonic irradiation (35 kHz, 2 W/cm 2 ) at 50 °C for 2 h. The product was characterized by using techniques such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and optical diffuse reflection spectroscopy (DRS). The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with lateral dimensions of about 20–50 nm and lengths reaching up to several micrometers and single crystalline in nature.

This paper presents the design and fabrication of a light deflector made from textured polycrystalline antimony sulfoiodide (SbSI) obtained by gradient freezing during the rapid quenching from the liquid state. The piezoelectric and electrostriction parameters of the textured polycrystalline SbSI are evaluated from the reflection measurements. First time the electrostrictive constant of this material (4.6(1) × 10−13 m2/V2) is reported.