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In this investigation, the thermal analysis of W-free cobalt-based superalloys based on Co–Al–Mo–Nb and Co–Ni–Al–Mo–Nb systems was performed. The analysis was performed at different stages of heat treatment process. The differential thermal analysis (DTA) was utilized for the determination of characteristic temperatures related to microstructural changes. First of all, the DTA analysis was carried out for discussing as-cast alloys in the temperature range of 40–1500 °C. The results showed thermal effects connected with melting and important order–disorder transition. The temperature range of 1200–1250 °C was chosen for performance of a first heat treatment operation for the investigated alloys. Specimens were annealed at selected temperature for 5 h. The microstructure of alloys after solution heat treatment was analyzed as well. Afterward, the solutionized specimens were subjected to the further thermal analysis in order to select the aging temperature according to the order–disorder transformation related to formation of γ′ phase with overall formula Co3(Al,X). Five aging variants were performed in the temperature range of 800–1000 with a step of 50 °C. After each stage of heat treatment, SEM/EDS analysis and hardness measurements were performed.

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 GdAlO3 type.

Novel siliconized Mo-Re coatings dedicated to applications in the glass industry are shown in this paper. The study aims at the characterization of morphology, phase composition, and oxidation behavior of siliconized Mo-based coatings deposited on a ceramic–metal substrate. Two coatings with different contents of rhenium were prepared using a hybrid process that includes atmospheric plasma spraying and pack siliconizing. The microstructure, chemical, and phase composition of the obtained coatings were characterized and compared to Mo coating. Moreover, a characterization of starting powders was performed. After the description of the coatings’ microstructure, oxidation tests were carried out at 1000, 1100, and 1200 °C. The surface condition of oxidized coatings was investigated. The structure of Re-containing coatings after the siliconizing process was comparable. Both were composed of Mo and (Mo,Re)Si2-ReSi1.75 layers. However, in the case of Mo-44Re (wt.%) coating, a higher concentration of rhenium silicide was observed compared to that of coating containing 15% Re. The Re-containing silicide layers were characterized by a presence of lower content of hexagonal MoSi2 compared to that of non-alloyed MoSi2. The oxidation resistance of both coatings containing rhenium was comparable; however, the one with a higher amount of Re exhibited slightly higher durability in high-temperature oxidation.

The following paper presents study on synthesis and thermal diffusivity of europium zirconate, cerate and hafnate as a new types of materials with pyrochlore or fluorite type of lattice, dedicated to replacement of conventional 8YSZ ( yttria stabilized zirconia ) in TBC ( thermal barrier coatings ) systems for aircraft gas turbines. All materials were synthesized via solid-state reaction ( SSR ) preceded preparation of powder mixtures (mechanical milling in ethanol). The feedstock powders were characterized by analysis of crystallite size, particle size distribution and phase composition. On the base of DSC measurements, the parameters of high temperature sintering were selected (1350 °C/2 h/15 MPa). Structural characterization of obtained materials inclusive analysis of morphology, chemical and phase composition of sinters was performed. Thermal diffusivity was measured in temperature range 25÷1400 °C by laser flash analysis ( LFA ). The obtained materials with pyrochlore and fluorite type of lattice exhibit lower thermal diffusivity compared to that of yttria-stabilized zirconia at high temperatures. In particular, the most promising material in view of insulating properties is Eu 2 Ce 2 O 7 , which exhibit much lower thermal diffusivity than Eu 2 Zr 2 O 7 and Eu 2 Hf 2 O 7 , especially at temperature higher than 1000 °C. However, in temperature range 25–700 °C, europium hafnate and zirconate exhibit lower thermal diffusivity compared to that of europium cerate and 8YSZ.

The degradation process of thermal barrier coatings (TBCs) such as monolayered La2Zr2O7, composite 50% La2Zr2O7 + 50% 8YSZ, and double-ceramic layer (DCL) La2Zr2O7/50% La2Zr2O7 + 50% 8YSZ/8YSZ was investigated. Coatings were deposited using the atmospheric plasma spraying (APS) process (ceramic layer and bond-coat) on the Ni-based superalloy substrate with Ni-22Cr-10Al-1Y bond-coat. The thickness of the ceramic top-coats in all cases were 300&micro, m. In the case of La2Zr2O7/8YSZ, the internal sublayer was built from 8YSZ powder whereas the outer from La2Zr2O7. Between both sublayers&rsquo, &ldquo, composite&rdquo, a 50% La2Zr2O7 + 50% 8YSZ zone was present. The &ldquo, 50% La2Zr2O7 + 50% 8YSZ TBC system was sprayed from two different feedstock powders with equal weight ratios. In the first part of the investigation, the microstructural characterization of the TBCs was presented. The main goals were related to the characterization of the degradation processes in different TBC systems with special emphasis on the phenomenon in the thermally grown oxide (TGO) zone related to oxidation, and the phenomenon related to phase stability in ceramic top-coats as related to temperature influence. The oxidation test was carried out in air at 1100 &deg, C for 500 hours. In the second step of the investigation, the numerical simulation of the monolayered TBC 8YSZ and La2Zr2O7 systems was analyzed from the stress distribution point of view. Additionally, the two-layered TBC coating of the DCL type was also analyzed.

This work was supported by the National Science Centre, Poland, under grant number 11/030/PBU17/0176.

The basic direction of the development of thermal barrier coatings (TBC) systems is connected with new materials solutions dedicated for bond-coats and ceramic insulating layers. The present article shows the synthesis and thermal properties of different types of insulating ceramic materials based on zirconia, hafnia and ceria. The analyzed materials were synthesized via solid state reaction (SSR) of the mixtures of nanocrystalline feedstock powders of zirconia, hafnia, ceria and samaria. The synthesized materials were analyzed in view of chemical and phase composition. The morphological characterization of the utilized feedstock powders was showed as well. The basic range of the investigation was related to the analysis of thermal parameters such as a thermal diffusivity and coefficient of thermal expansion in temperature range 25 ÷ 1100 °C. The P-type samarium zirconate and hafnate were synthesized as well as F-type non-stoichiometric samarium cerate. The chemical homogeneity of obtained solid materials was satisfactory. The dilatometric measurements showed that Sm2Zr2O7 and Sm2Hf2O7 may be beneficial materials for TBC insulating layer due to the thermal expansion coefficient close to metallic substrate. These materials were also beneficial taking into account the results of thermal diffusivity measurements. In the temperature range 25–1100 °C, samarium hafnate and zirconate were characterized by substantially lower thermal diffusivity compared to that of 8YSZ. In the case of cerate of samarium with fluorite type of structure, the more beneficial thermal properties compared to that of YSZ were observed, however, were considerably less promising related to pyrochlore ceramic materials based on zirconia and hafnia.

The aim of the study is characterization of high-temperature oxidation behavior of new Co-based superalloys by thermogravimetry (TG). The following alloys have been taken into account: Co–9Al–9W, Co–20–Ni–7Al–7W, Co–10Al–5Mo–2Nb and Co–20Ni–10Al–5Mo–2Nb (at.%). The thermogravimetric analysis was carried out in the temperature range 40–1200 °C of heating rate 5° min−1. The investigation was performed using the thermal analyzer NETZSCH STA 449 F3 Jupiter. TG–DTG plots showed oxidation behavior up to 1200 °C and indicated the temperatures of further isothermal oxidation examinations. The oxidation behavior of basic Co–9Al–9W (at.%) alloy was compared to W-free Co–10Al–5Mo–2Nb and Co–20Ni–10Al–5Mo–2Nb (at.%) alloys. The obtained data showed different oxidation behavior dependably on the type of alloying elements. Moreover, the effect of Ni addition on oxidation performance was determined. The scales grown on Co-base superalloys after thermogravimetry were evaluated by means of scanning electron microscopy and energy dispersive spectroscopy.

Present paper concerns primary structure of new type of tungsten-free cobalt-based superalloys with formula Co-Al-Mo-Nb. Due to replacement of W by addition of Mo and Nb, the desirable dual phase structure of γ/γʹ should be formed after heat treatment of this alloy. In analyzed case, the alloy in as cast state was described. The Co-10Al-5Mo-2Nb (at%) alloy was casted via induction melting process. The specimens were cut from “foot“ area of the rod and analyzed from phases and chemical point of view by XRD and EDS analysis. Detailed analysis of primary microstructure by light and scanning microscopy observations were performed. Obtained data revealed that in as cast state, the main phases detected in the alloy were solid solution of Co(Al,Mo,Nb) and Mo with Nb reach precipitations, probably with formula of Co3(Mo,Nb). The morphology of observed interdendritic precipitations is typical for eutectic reaction.

A new type γ–γ′ Co-Al-Mo-Nb Co-based superalloys were developed due to limitations of basic Co-Al-W superalloys, related to tungsten alloying. The present study aims to characterization of new γ–γ′ Co-10Al-5Mo-2Nb (at.%) cobalt-based superalloy performance in terms of the high-temperature exposure under cyclic conditions, with particular regard to surface condition. Specimens were tested in cycles of high-temperature exposition (25, 50, 75, 100 and 150 h) in air environment at 800 °C. Detailed analysis of oxidized surfaces by scanning electron microscopy, energy-dispersive spectroscopy and x-ray diffraction was made at various intervals during testing. The cyclic oxidation behavior of new alloy was compared to the basic Co-9Al-9W (at.%) Co-based superalloy.

The characterization of high temperature cyclic oxidation behavior of as-cast and as-aged Co-(Ni)-Al-W alloys, and the influence of alloying elements on oxide spallation resistance have been investigated in this study. The cyclic oxidation and oxide scale morphology of the alloys are analyzed from 700° to 900°C. It has been observed that the ternary Co-Al-W alloys are prone of oxide scale spallation and increasing the Al, W and Ni contents improves the cyclic oxidation resistance of the alloys. The structural effect of Ni on oxidation performance is related to its introduction to single and complex oxides present in a scale.

In the presented study, different Ti-Al-Si coatings were deposited on Ti-48Al-2Cr-2Nb (at. %) alloy via the slurry method. Al and Si's nominal content in coatings was varied (100 at. % Al, Al-5Si, Al-12.5 Si, Al-20Si, Al-40Si, Al-60Si, Al80Si, 100 at. % Si) to find an optimal coating resistant to high-temperature oxidation. The deposited materials were analyzed because of the microstructure and phase composition. Afterwards, the obtained modified aluminide coatings were subjected to the isothermal oxidation at 900 °C for 500 h. After the oxidation experiment, the oxidized coatings were evaluated, taking into account the microstructure, chemical and phase composition of the oxidation products. The most favourable oxidation behaviour was noticed for the aluminide coatings with Si's small content (respectively 5 and 12.5 at.% Si). In these cases, on the surfaces, the protective α-alumina scale was formed. Moreover, the Ti5Si3 phase was detected for the oxidized Al-12.5Si (at. %) coating. In the case of other coatings, the formation of TiO2 oxide on the surface was observed.

The molybdenum-based alloy powder materials containing 15 and 44 wt.% of rhenium were produced with application of powder metallurgy techniques including reduction and annealing operations. The alloys were synthesized from a mixture of ammonium perrhenate and metallic molybdenum. The powders were reduced at 900 °C and subsequently annealed at 1150 °C for 6 or 24 h. The obtained powders were used for production of protective coatings on the cermetallic surface by plasma spraying technique. Two types of coatings were prepared - from powders before and after annealing. The effects of plasma spraying parameters and powder processing on properties of the obtained powders and coatings, especially phase composition and microstructure, have been investigated. Annealing process influences the qualitative and quantitative phase composition of the powders, but has no significant effect on the microstructure of obtained coatings, as observed.

Thermally sprayed hardmetal WC-Co-based coatings are widely applied in order to provide good wear resistance to mechanical components working in demanding environment. The WC-Co coatings are obtained by various spraying methods such as High Velocity Oxygen Fuel (HVOF) or High Velocity Air Fuel (HVAF) techniques. Additional improvement of coatings' properties can be achieved by adding very fine carbides to the WC-Co powder feedstock. The usual approach is the agglomeration and sintering of submicron-sized carbides without or with micro-sized carbides (bimodal distribution). In this work, WC-Co powders were modified by blending them with 5 wt% nano-sized TiC ( 0.9 W 0.1 by selected area electronic diffraction, was detected. W dissolution effect was observed to be lower in the case of nano-sized TiC-added coatings. Microstructural investigation by STEM indirectly indicates that nano-sized WC completely dissolved in the cobalt matrix, inducing solid solution of tungsten in cobalt formation in the 5 wt% WC-added coating. The formation of new phases containing Ti, except TiC, was not found in the coating. Obtained results suggest that nano-sized TiC may increase the stability of metallic matrix microstructure in a WC-Co-based coating.

Cobalt-based γ–γ′ superalloys are novel heat-resistant materials suitable for high-temperature applications, such as components of the turbine engine. These alloys exhibit favorable strength and corrosion resistance at high temperatures owing to the γ–γ′ microstructure, analogous to that of Ni-based superalloys. The aim of this paper is to evaluate the oxidation behavior of basic Co-9Al-9W (at%) and new tungsten-free Co-10Al-5Mo-2Nb (at%) alloys at elevated temperatures. The investigation is concerned with thermogravimetric studies in the temperature range of 40–1200 °C. The oxidized surfaces after high temperature oxidation have been characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction analysis (XRD).

The paper presents results of investigation on synthesis and characterization of cerium-dysprosium oxide. The input powders - dysprosium oxide Dy2O3 and cerium oxide CeO2 - were mixed so as to obtain equimolar ratio of cations, milled in alcohol and synthesized via solid state reaction process at 1350°C under 15MPa in vacuum for 2h. The microstructure, phase composition and thermal properties were analyzed. The obtained material was multiphase. Non-stoichiometric compounds were identified. Thermal diffusivity of investigated material decreased in the temperature range of 25-1000°C from 0,71 to 0,45 mm2/s.

A2B2O7 oxides with pyrochlore or defected fluorite structure are among the most promising candidates for insulation layer material in thermal barrier coatings. The present paper presents the procedure of synthesis of holmium zirconate Ho2Zr2O7 and praseodymium zirconate Pr2Zr2O7 via Polymerized-Complex Method (PCM). Thermal analysis of precursor revealed that after calcination at relatively low temperature (700°C) fine-crystalline, single-phase material is obtained. Thermal diffusivity was measured in temperature range 25-200°C, Ho2Zr2O7 exhibits lower thermal diffusivity than Pr2Zr2O7. Additionally, PrHoZr2O7 was synthesized. The powder in as-calcined condition is single-phase, but during the sintering decomposition of solid solution took place and Ho-rich phase precipitated. This material exhibited the best insulating properties among the tested ones.

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 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.

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.

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 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 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.

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-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.

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.

Results of morphology and electrical properties evaluation of Y2O3 powders were presented in this article. The tests were made on the two different types of powders. First of them was a powder of the "microsize" type with the particle sizes not crossing10 µm, however the size of particles of the second powder was located in range 30 - 50 nm. Totally different was a morphology of both powders as well. In the first case the form of dense polyhedrons about the smooth surface was observed. However the powder of the type nano was characterized by spongy conglomeration of nano particles type of morphology. The range of investigations included the evaluation of the phase composition of powders (X-ray and electrons diffraction), characteristics of their morphology (SEM, STEM) and evaluation of electric properties by impedance spectroscopy. The obtained results showed that nano powders of oxide Y2O3 is different in the morphology of individual particles, but he is also better ionic conductor in the temperature of 20°C comparing to powder the micro type.

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.

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).

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.

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 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 alloys based on the intermetallic phases from Ti-Al system are materials which, on the grounds of their resistance characteristics, could be widely used in automotive and aerospace applications. The insufficient oxidation resistance of this alloys could be increased by the coating silicon modification. The technology used in this investigation was the immersion in water-based slurry containing metal powders. MHI high-Nb (14 wt %) alloy has been used as the research material for the coatings produced. The water-based slurries containing Al and Si powders have been prepared with 0-80 wt % Si content. The diffusion treatment has been done at 950oC in 4h in the Ar atmosphere. The investigation has showed that the thickness of the coatings ranged from 30 to 40 m. The structure of the Si-modified aluminide coatings is as follows: (a) outer zone consisting of TiAl3 phase and titanium silicides, (b) middle zone consisting of columnar titanium silicides in phase TiAl3 matrix (c) the inner zone consisting of TiAl2 phase. The XRD phase analysis has confirmed Ti5Si3 creation and, in case of the high silicon content (above 20 wt %), also other silicides: types Ti5Si4,TiSi2,TiSi

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.

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 article presents research results of long-time cyclic oxidation of TiAlCrNb intermetallic alloy with and without an Al–Si coating. The coating was deposited by the Arc-PVD method in two steps. First the AlSi layer was deposited, and then the samples were heated in a vacuum chamber to form a diffusion TiAlSi coating. After coating deposition, the samples were heat treated in vacuum at 950 °C for 2 h. Cyclic oxidation tests were carried out at 950 °C. Heating time was 23 h and cooling was made in static air. Mass changes of the specimens were recorded after each cycle. A total of 60 cycles were performed. An analysis of the results achieved during cyclic oxidation was performed. Phase composition, morphology and distribution of elements in AlSi layers as well as in the scale were investigated using EDX, XRD and SEM. The results showed that Al–Si coatings were very effective in reducing the oxidation rate of γ-TiAl especially during the first 40 cycles. The oxide formed on the coating after oxidation is composed of a mixture of a large portion of Al2O3 and a small portion of TiO2. After 40 cycles of oxidation the main component of the scale was rutile. Kirkendall voids were found in the coating.

Ti46Al7Nb alloy has been used as the research substrate material for the deposition of water-based slurries containing Al and Si powders. The diffusion treatment has been carried out at 950 °C for 4 h in Ar atmosphere. The structure of the silicon-modified aluminide coatings 40 μm thick is as follows: (a) an outer zone consisting of TiAl 3 phase and titanium silicides formed on the matrix grain boundaries composed of TiAl 3 –type Ti 5 Si 3 ; (b) a middle zone containing the same phase components with the matrix TiAl 3 and the silicides Ti 5 Si 3 , which formed columnar grains; (c) an inner zone, 2 μm thick, consisting of TiAl 2 phase. Cyclic oxidation tests were conducted in 30 cycles (690 h at high temperature) and showed a remarkably higher oxidation resistance of the Ti46Al7Nb alloy with the protective coating in comparison with the uncoated sample.