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The performance and applicability of thermal barrier coatings (TBCs) depend strongly on the top coat and bond coat interface integrity. The interlayer in TBC systems is often processed prior to top coat spraying to tailor its material properties or surface topography. Both, the bond coat spraying process and the further post-processing may significantly influence the thermally grown oxide (TGO) build-up which is crucial in terms of enhancing the TBC lifetime. In this work, NiCrAlY bond coats were sprayed by means of atmospheric plasma spraying. The as-sprayed bond coats were subjected to laser microtexturing which resulted in different bond coat topographies. Then, the samples were exposed to isothermal oxidation conditions under various oxidation dwell times to see the TGO evolution. The preliminary assessment of the oxidation mechanisms and oxide distribution was done by confocal laser scanning microscopy (CLSM). Scanning electron microscopy with energy dispersive X-Ray spectrometry (SEM/EDS) was used in order to analyze the evolution of bond coat structure and chemical composition during the high temperature oxidation.

The γ-γ′ Co-based alloys have attracted extensive attention as a new class of materials for high temperature applications. The work is focused on quantitative and qualitative microstructural characterization of selected γ-γ′ type Co-based superalloys obtained by gravity casting. The four Co-based alloys were prepared via vacuum induction melting. The microstructure was analyzed by means of light microscopy and scanning electron microscopy. The microstructural parameters such as porosity and secondary dendrite arm spacing (SDAS) were evaluated by image analysis. The new Co-based superalloys are characterized by proper as-cast microstructure owing to low SDAS and limited microporosity. The values of secondary dendrite arm spacing are comparable for all alloys. The W-free alloys containing Mo and Nb exhibit substantially lower shrinkage porosity compared to those of Co–Al–W and Co–Ni–Al–W. Due to crystallization of Mo and Nb rich phases at lower temperatures, these alloys are characterized by higher solidification range.

In the investigation, crystallization behavior of ternary γ–γ′ alloy based on Co–Al–W system was analyzed. The alloy with nominal composition Co–9Al–9W (at.%) was prepared via vacuum induction melting. Solidification characteristics of the investigated superalloy were obtained by a method of thermal analysis based on temperature measurement of metal solidifying in a mold. After casting, obtained metallic materials were investigated by differential thermal analysis in order to determine characteristic temperatures and compare results with those of obtained in the first thermal analysis. Furthermore, a description of primary microstructure was performed for ingots solidified with two different cooling rates. The analysis was made using X-ray diffraction, optical microscopy and scanning electron microscopy. The crystallization path of alloy was investigated. The solidification range of alloy was narrow. The crystallization in a sand mold resulted in the dendritic microstructure containing γ single phase. The as-cast microstructure after solidification with higher cooling rate was comparable; however, observed crystals were mostly columnar, while sand cast was characterized by equiaxed crystals structure.

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 basic goal of this article was thermal diffusivity characterization of ceramic materials used in thermal barrier coating (TBC) systems for depositions of the insulation layer and characterization of the materials’ morphology and remanufacturing process. The base material was oxide 8YSZ (ZrO2 × 8Y2O3), which is usually dedicated to deposition of an insulating top layer in TBC systems. The data related to thermal properties such as thermal diffusivity and thermal conductivity are widely presented in the literature, but there is lack of information about the morphological form of investigated materials, and the presented results vary widely. Data on thermal properties based on the literature sources are inadequate for the real morphological form of materials used in the experiment (e.g., massive or single crystalline material vs. plasma-sprayed coatings), which consequently gives an unsatisfactory accuracy of the obtained numerical simulations by MES methods. This article presents the characterization of thermal diffusivity of the commercial 8YSZ ceramic material synthesized or remanufactured by different routes, which is investigated in the forms of pressed powder pellet (two commercial nano-sized powders with different morphologies), sintered pellets (one commercial powder, solid-state co-precipitated reacted powder of 8YSZ type), and a two-layered coating system of In625 + NiCrAlY/8YSZ type. The range of analysis included morphological investigations of different types of powders in initial conditions and after remanufacturing (sintering, thermal spraying) as well as the thermal diffusivity analysis by the laser flash method. The obtained data were corrected by porosity factor and compared to each other. The best similarity for obtained thermal diffusivity data was found for commercial powers of HOSPTM type after pressing and sintering processes and calculated (2-layered model) value of thermal diffusivity for two-layered system of In625/8YSZ TBS system. The results showed that there are significant differences in thermal diffusivity values for materials with different morphological forms.

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 γ–γ′ Co-based superalloys are newly developed class of refractory alloys which may replace commercial Ni-based superalloys owing to their favorable properties at high temperature. In case of new Co-based superalloys, the heat treatment aims to obtain microstructure composed of appropriate volume fraction of small cuboidal γ′-Co3(Al,W) precipitates within the γ-Co matrix. However, due to a high tendency to interdendritic segregations of alloying elements, the alloys based on Co–Al–W system should be normally homogenized before further steps of heat treatment (solutionizing and aging). In this study, thermal analysis was applied for determination of temperature range for primary heat treatment of the Co–9Al–9W (at.%). The differential thermal analysis (DTA) measurements were carried out on the thermal analyzer NETZSCH STA 449 F3 Jupiter. On the base of obtained results, respectively, solvus of γ′ phase and solidus temperatures were determined, as well as the thermal range of Co3W (DO19) phase precipitation. As a consequence, the heat treatment without homogenizing (only solution and aging) was proposed as a most suitable way to obtain beneficial microstructure.

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.

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.

A non-destructive technique for measuring effective thermal conductivity of thermal barrier coatings (TBCs) was developed. The heat conduction problem in the sample is solved numerically, making this technique applicable to bodies of elements shape covered by TBCs. The principle of the experiment relies on locally heating the sample by a laser flash and recording the time and space variation of the so generated temperature field on the heated surface by an IR camera. Both laser and camera are located on the same side of the heated surface. The thermal conductivity is retrieved by an inverse method where the Finite Element solver is invoked iteratively minimizing the discrepancy between the measured and simulated results. The geometry of the sample is captured by a laser scanner twice: before and after the TBC is deposited. Results are compared with measurements conducted by a commercial Laser Flash Apparatus (LFA) achieving good agreements.

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.

In this article, the electrochemical behavior of HVAF WC-17Co coatings modified with TiC deposited on low alloyed steel substrates was investigated. As a reference for coating material a commercial WC-17Co powder was used. The WC-17Co feedstock powder modification process was based on the addition of nano-sized TiC (weight ratio from 1 to 7%) by mechanical mixing. The aim of the research is comparing the microstructure and some selected properties of HVAF coatings with different amounts of TiC. The preliminary characterizations concerned the coating porosity, phase composition and microstructure. Then a corrosion resistance for all variant of coatings was evaluated by electrochemical polarization tests at room temperature in 3.5% NaCl and 0.5 M H 2 SO 4 solutions. The results showed an evident influence of nano-sized TiC addition on both on the corrosion resistance and the electrochemical properties of WC-17Co coatings. In the case of investigation in 3.5% NaCl, addition of nano-sized TiC caused shifting polarization curves in more noble range, however in 0.5 M H 2 SO 4 solution no significant changes in corrosion behavior were observed. Addition of nano-sized TiC significantly decreases corrosion resistance of WC-17Co + TiC coatings.

The different concepts of WC-Co thermally sprayed coatings improvement may be considered and the application of nanoparticles, as the mechanical strengthening addition, is one of them. Nanostructured WC-Co coatings are characterized by higher hardness than the coatings formed from micrometric WC grains; whereas coatings with bimodal distribution of particles reveal greater wear resistance than the coatings obtained exclusively from nano-sized powders. Mixed effect of the matrix reinforcement by nanoparticles and strong fix of the micron-sized WC grains was proposed as a possible reason for enhanced wear resistance of bimodal coatings. In order to obtain a bimodal distribution of particles in the material standard WC-Co (83-17) powder was mixed with nanometric TiC powder (40-100 nm). The amount of TiC in powder mixtures was in the range from 1 to 7 wt.%. The mixtures were deposited on steel substrate using HVAF method and also hot pressed in vacuum. The microstructure of obtained coatings and sinters was quantitatively evaluated. Sinters revealed more homogenous distribution of the nano-sized TiC particles than the coatings. The addition of nano-sized TiC in the case of coatings has led to the decrease of its porosity. The agglomeration of nano-sized TiC particles in the coatings results in the decrease of material’s hardness.

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 method of improving the properties of WC-Co thermally sprayed coatings by addition of nanostructured reinforcement for mechanical strengthening was explored in this research. Nanostructured WC-Co coatings were characterized by higher hardness than commercial counterparts, but wear tests in the literature have shown contrasting results, whereas bimodal coatings, where nanostructured components are mixed with conventional, micrometer-sized WC grains, exhibited enhanced abrasive and friction wear resistance, in comparison to coatings obtained exclusively from nano-sized powders. A mixed effect of matrix reinforcement by nanoparticles and strong fixing of the micron-sized WC grains was proposed as a possible reason for the enhanced wear resistance of bimodal coatings. A conventional, agglomerated and sintered WC-Co (83-17) feedstock powder was therefore blended with nano-sized TiC (40–100 nm) particles to obtain multimodal coatings containing a nanostructured reinforcement. The amount of TiC added into the powder mixture was in the range of 1–7 wt%. Powder mixtures were deposited onto carbon steel substrate using a High Velocity Air Fuel (HVAF) process. The dry sliding tribological behavior of the coatings was evaluated via ball-on-disk tests against Al2O3 counterparts. The tests were performed at room temperature as well as at 400 °C, with a sliding speed of 0.1 m/s, a sliding distance of 5000 m and a normal force of 10 N. The wear rates of the coatings and of the Al2O3 counterparts were measured separately, and friction coefficients were recorded during each test. The influence of TiC nano-particles on the sliding wear mechanisms was discussed in this work, based on an analysis of wear scars and wear debris through SEM + EDX and micro-Raman spectroscopy.

Thermal barrier coatings (TBC) are the system build from ceramic insulation top-coat with internal bond-coat as an interlayer between ceramic and Ni-based superalloys substrate materials. The basic role of bond-coat is reduction of thermal strain between ceramic top-coat and metallic substrates. The second role is related to improving the oxidation resistance of metallic substrate. From thermal conductivity point of view, TBC’s system is characterized by three different materials. Usually, bond-coats and Ni-based superalloys were treated as materials with similar thermal properties such as specific heat, thermal diffusivity and thermal conductivity. Actually those materials can exhibit much higher divergences than expected. The aim of this article was the characterization of thermal diffusivity of bond-coats material of NiCrAlY type in the form of powders, massive alloy (obtained during sintering in an actual pressure of 15 MPa, in vacuum of 3 × 10−6 MPa, and at temperature 1050 °C with 2 h of exposure in press), and coating after air plasma spraying. Those studies should get the answer on the question how different morphology and processes impact on thermal diffusivity level of the same material.

The oxides with pyrochlore or defected fluorite structure are a potential alternative ceramic materials for now widely used yttria-stabilized zirconia 8YSZ in the application for the insulation layer of thermal barrier coatings systems. This paper presents a procedure of synthesis of europium zirconate of Eu2Zr2O7 type, by the method of high temperature sintering under pressure. The analysis of the effect of the powders` homogenization methods on homogeneity of final sintered material showed that the highest homogeneity can be obtained after mechanical mixing in alcohol. Moreover, the DSC investigation carried out on a mixture of powders before the sintering process and on the material after high temperature sintering under pressure, suggest the synthesis of a new phase an europium zirconate Eu2Zr2O7 with the pyrochlore structure. Obtained phase was characterized by stability over the entire range of tested temperature, i.e. to 1450°C. The resulting material based on europium zirconate has a lower coefficient of thermal diffusivity than the now widely used 8YSZ.

The article presents results of research relating to the impact of laser treatment done to the surface of plasma sprayed coatings NiCrAlY. Analysis consisted microstructure and oxidation resistance of coatings subjected to two different laser melting surfaces. The test were performed at a temperature 1000°C 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 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.