SEM/TEM investigation of aluminide coating Co-doped with Pt and Hf deposited on Inconel 625

The effect of simultaneous introduction of Hf and Pt into aluminide coating deposited on Inconel 625 alloy was investigated using scanning and transmission electron microscopy (SEM/TEM) methods. The coating consisted of two layers: the additive and the interdiffusion. The additive layer and part of the interdiffusion layer consist of the β-NiAl type phase. The middle part of the interdiffusion layer comprised an interpenetrating finger-like structure formed by the β-NiAl and TCP-σ type phases with numerous fine Cr precipitates in the former and occasional larger precipitates of NbC carbides interspersed in between them. The σ type phase inclusions are situated at the border between the substrate and the interdiffusion layer. The experiment showed that platinum fully dissolves in the β-NiAl-type matrix, while most of the introduced hafnium accumulates in HfO2 dioxide precipitates located close to the additive/interdifusion interface

On the morphological investigation of Pt dispersion and structure of alumina-platinum composites obtained by thermal oxidation of Al-Pt nano thin layers

This article presents the methodology for the Pt/Al and Pt/Al nanolaminates production as well as Pt + Al composites using two magnetrons by preparing the oxide-metal composites through high temperature oxidation of nanofilms deposited by PVD method on a metal substrate. In this article, we described the nanostructures obtained as a result of PVD technology. The applied layers were oxidized at a temperature of 860°C under Ar + O2 for 48 hours. SEM surface analysis of the obtained nanolaminates showed that the base of the oxidized laminates was covered with a fine wafer and whisker structure with an anisotropic growth orientation. Oxidation of composite layers provided the growth of chaotically oriented and mutually penetrable whiskers and small crystals. Analysis of nanolayers by the TEM technique indicated that the growth of oxide crystals leads to the dissipation of Pt particles. The comparison of oxide layers obtained with the Pt/Al system with oxide layers obtained with Pt + Al composite nanofilms indicates that those obtained through the oxidation of nanofilms shows a greater surface development. This is due to the partial covering of Pt particles through the Al layer, which causes a very strong fragmentation of the Pt nanofilms occurring during oxidation. During the oxidation in the entire volume of nanofilms, strong stresses are created that cause numerous nano-cracks, which promotes the expansion of the surface and its high activity

Deposition of Al2O3-TiO2 Nanostructured Powders by Atmospheric Plasma Spraying

Al2O3-13%TiO2 coatings were deposited on stainless steel substrates from conventional and nanostructured powders using atmospheric plasma spraying (APS). A complete characterization of the feedstock confirmed its nanostructured nature. Coating microstructures and phase compositions were characterized using SEM, TEM, and XRD techniques. The microstructure comprised two clearly differentiated regions. One region, completely fused, consisted mainly of nanometer-sized grains of c-Al2O3 with dissolved Ti+4. The other region, partly fused, retained the microstructure of the starting powder and was principally made up of submicrometer-sized grains of a-Al2O3, as confirmed by TEM. Coating microhardness as well as tribological behavior were determined. Vickers microhardness values of conventional coatings were in average slightly lower than the values for nanostructured coating. The wear resistance of conventional coatings was shown to be lower than that of nanostructured coatings as a consequence of Ti segregation. A correlation between the final properties, the coating microstructure, and the feedstock characteristics is give

Systemic sclerosis without antinuclear antibodies or Raynaud's phenomenon: a multicentre study in the prospective EULAR Scleroderma Trials and Research (EUSTAR) database

Objective. To assess patients with SSc who present without circulating ANAs or RP. Methods. Five thousand three hundred and ninety patients who fulfilled the ACR criteria for SSc and were enrolled in the EULAR Scleroderma Trials and Research (EUSTAR) database were screened for the absence of both RP and circulating ANA. To differentiate SSc from its mimics, additional information was gathered using a standardized questionnaire. Results. Five thousand three hundred and seventy-eight (99.8%) of the 5390 SSc patients in the EUSTAR database had either detectable ANA or a history of RP. Twelve (0.2%) patients lacked both circulating ANA and RP. Details of the medical history could be obtained for seven patients. Three cases were compatible with ANA-negative and RP-negative SSc and were not typical of any known SSc mimic. Four patients had a malignancy: two had breast cancer, one had multiple myeloma with possible scleromyxoedema and one had bladder carcinoma. There was no temporal relationship between the onset of skin fibrosis and that of the tumour. Although no patient with confirmed nephrogenic systemic fibrosis was identified among the cases of ANA-negative and RP-negative SSc, the presentation of one patient could be compatible with that of nephrogenic systemic fibrosis other than for the absence of chronic kidney disease or of known prior gadolinium exposure. Conclusion. We have identified a very small subgroup of SSc patients who lack both circulating ANA and RP, none of whom fulfils the diagnostic criteria for any known SSc mimic. Prospective studies are needed to elucidate the clinical presentation, evolution and outcome of such patient

Diamond-max ceramics bonding phase composites – phases and microstructure analysis

The possibility for improving the thermal stability of polycrystalline materials based on diamond (PCD) is to reduce the content of cobalt. Diamond compacts without cobalt phases with Ti3₃iC₂ і Cr₂AlC prepared using the method of self-propagating high-temperature synthesis (SHS). The resulting compacts with 20 wt. % of the above phases were exposed to high pressure and temperature in order to further consolidate the structure by sintering. Sintering was performed at 8±0.2 GPa and 1950±50 °C. Phase composition and microstructural study of the original compacts and the composites made by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Одна з можливостей підвищення термостійкості полікристалічних матеріалів на основі алмазу (PCD) полягає в зменшенні вмісту в них кобальту. Алмазні компакти без кобальту з фазами Ti3₃iC₂ і Cr₂AlC отримували з використанням методу само поширюваного високотемпературного синтезу (SHS). Отримані компакти з 20 мас. % зазначених фаз піддавали дії високого тиску і температури з метою подальшої консолідації структури шляхом спікання. Процес спікання здійснювали при 8 ± 0,2 ГПа и 1950 ± 50 °С. Фазовий склад і мікроструктурні дослідження вихідних компактів і отриманих композитів виконані методами рентгенівської дифрактометрії (XRD) і скануючої електронної мікроскопії (SEM).Одна из возможностей повышения термостойкости поликристаллических материалов на основе алмаза (PCD) заключается в снижении содержания в них кобальта. Алмазные компакты без кобальта с фазами Ti3₃iC₂ и Cr₂AlC получали с использованием метода самораспространяющегося высокотемпературного синтеза (SHS). Полученные компакты с 20 % по мас. указанных фаз подвергали воздействию высокого давления и температуры с целью дальнейшей консолидации структуры путем спекания. Процесс спекания осуществляли при 8 ± 0,2 ГПа и 1950 ± 50 °С. Фазовый состав и микроструктурные исследования исходных компактов и полученных композитов выполнены методами рентгеновской дифрактометрии (XRD) и сканирующей электронной микроскопии (SEM)

Comparison of the physicochemical properties of TiO2 thin films obtained by magnetron sputtering with continuous and pulsed gas flow

In this paper, a comparison of TiO2 thin films prepared by magnetron sputtering with a continuous and pulsed gas flow was presented. Structural, surface, optical, and mechanical properties of deposited titanium dioxide coatings were analyzed with the use of a wide range of measurement techniques. It was found that thin films deposited with a gas impulse had a nanocrystalline rutile structure instead of fibrous-like anatase obtained with a continuous gas flow. TiO2 thin films deposited with both techniques were transparent in the visible wavelength range, however, a much higher refractive index and packing density were observed for coatings deposited by the pulsed gas technique. The application of a gas impulse improved the hardness and scratch resistance of the prepared TiO2 thin films

Accumulation and annealing of radiation donor defects in arsenic-implanted Hg0.7Cd0.3Te films

Processes of accumulation and annealing of radiation-induced donor defects in arsenic-implanted Hg0.7Cd0.3Te films were studied with the use of the Hall-effect measurements with processing the data with mobility spectrum analysis. A substantial difference in the effects of arsenic implantation and post-implantation activation annealing on the properties of implanted layers and photodiode ‘base’ layers in Hg0.7Cd0.3Te and Hg0.8Cd0.2Te films was established and tentatively explained