Nanostructured ZrO₂ ceramic PVD coatings on Nd-Fe-B permanent magnets

The results of vacuum-arc deposition (PVD) of thin ZrO2 coatings to protect the surface of Nd-Fe-B permanent magnets used as repelling devices in orthodontics are presented. Magnetic devices are offered as an optimum and biologically safe forcegenerating system for orthodontic tooth movement. The structure, phase composition and mechanical properties of zirconium oxide films have been investigated by means of SEM, XRD, EDX, XRF and nanoindentation methods. The coatings are formed of polycrystalline ZrO2 films of monoclinic modification with average grain size 25 nm. The influence of the ZrO2 coating in terms of its barrier properties for corrosion in quasiphysiological 0.9% NaCl solution has been studied. Electrochemical measurements indicated good barrier properties of the coating on specimens in the physiological solution environment

The Effect of Hydrogen on Martensite Transformations and the State of Hydrogen Atoms in Binary TiNi-Based Alloy with Different Grain Sizes

The analysis presented here shows that in B2-phase of Ti49.1Ni50.9 (at%) alloy, hydrogenation with further aging at room temperature decreases the temperatures of martensite transformations and then causes their suppression, due to hydrogen diffusion from the surface layer of specimens deep into its bulk. When hydrogen is charged, it first suppresses the transformations B2↔B19′ and R↔B19′ in the surface layer, and when its distribution over the volume becomes uniform, such transformations are suppressed throughout the material. The kinetics of hydrogen redistribution is determined by the hydrogen diffusion coefficient DH, which depends on the grain size. In nanocrystalline Ti49.1Ni50.9 (at%) specimens, DH is three times greater than its value in coarse-grained ones, which is likely due to the larger free volume and larger contribution of hydrogen diffusion along grain boundaries in the nanocrystalline material. According to thermal desorption spectroscopy, two states of hydrogen atoms with low and high activation energies of desorption exist in freshly hydrogenated Ti49.1Ni50.9 (at%) alloy irrespective of the grain size. On aging at room temperature, the low-energy states disappear entirely. Estimates by the Kissinger method are presented for the binding energy of hydrogen in the two states, and the nature of these states in binary hydrogenated TiNi-based alloys is discussed

Heterogeneity of fatigue in bulk lead zirconate titanate

The spatial heterogeneity of fatigue in commercial ferroelectric lead zirconate titanate ceramics was experimentally investigated. All parameters measured on fatigued samples are spatially highly heterogeneous including large signal polarisation and strain hysteresis loops (remnant polarisation Pr, coercive field Ec, bias field Ebias, and strain asymmetry γ) as well as the small signal parameters determined from field dependent converse piezoelectric measurements (remnant piezoelectric coefficient dr, coercive field Ec, offset piezoelectric coefficient doffset, and bias field Ebias). The local strain asymmetry γ was found to linearly depend on the local bias field Ebias. An analogous relation is established for doffset and Ebias. Switching time retardation is similarly heterogeneous across the sample. The previously determined stretched exponential polarisation relaxation equally well occurs locally. A spatial correlation to the observed microcrack densities could not be found

(Table 3) Chemical composition of phosphatized rocks from the Kammu Seamount

Phosphatized biogenic limestones and phosphorites with initial Fe-Mn mineralization dredged from the summit surface of the Kammu Seamount (Milwaukee Seamounts, northwestern Pacific) are studied. The rocks are largely composed of nannofossils and planktonic foraminifers with an admixture of benthic foraminifers, bryozoans, and other organic remains, presumably including bacterial ones. The nannofosssil and foraminiferal assemblages indicate Quaternary age of sediments, and their phosphatization is consistent with the phosphatization age determined previously based on nonequilibrium uranium (within the limits of 1 My). The age of phosphatization and the Fe-Mn mineralization in the sediments from Pacific seamounts that young implies dependence of these ore-forming processes on oceanic environments favorable for ore accumulation rather than on their age

Chemical composition of rocks from the Kammu Seamount and from low atolls of the Western Indian Ocean

Devoted to studies of phosphatized rocks from the Kammu Seamount

(Table 1) Chemical analyses of rock samples from low atolls of the Western Indian Ocean

Compositions, structures, and microstructures of different types of phosphorites and poorly phosphatized rocks from low atolls in the near-equatorial part of the Western Indian Ocean are described. The rocks were examined under optical and scanning microscopes using microprobe techniques and etching of selected samples with weak solvents as well as with the help of chemical analyses. It is proved that phosphorites have been formed owing to the uneven phosphatization of primary carbonate rocks; degree of their phosphatization ranges from traces to 40% P2O5. In the phosphorites numerous organic remains were encountered; they included fragments of plankton, debris of tortoise shells, and coccoidal and filamentous bacteria-like formations. It is suggested that the phosphorites formed due to high local biological productivity over the outer edges of coral reefs and are not related to guano accumulation or to endoupwelling

Fermantasyon endüstrisi atıksularının yeniden kullanım seçeneklerinin araştırılması

Hızla endüstrileşen dünyamız aynı zamanda hızla su sıkıntıları yaşamaya başlamıştır. Bu sebeple, su kaynaklarının kontrolsüz kullanımı da dahil olmak üzere atıksuların nehirlere, göllere ya da diğer sulak arazilere deşarj edilmesi giderek daha az kabul görmeye başlamıştır. Sonuç olarak da atıksuların yeniden kullanım seçeneklerinin araştırılması ve uygulanması özellikle endüstriyel üretim sahasında büyük önem kazanmıştır. Bu çalışma, araştırmaya uygunluğu açısından seçilen bir bira üretim tesisinden alınan bilgiler doğrultusunda gerçekleştirilmiştir. Öncelikle tesisin üretim kademeleri ve arıtma tesisi hakkında bilgi temin edilmiştir. Daha sonra, arıtma tesisinin giriş ve çıkış bölümlerinden alınan numuneler gerekli analizlere tabi tutulmuştur. Analiz sonuçlarına göre arıtılmış atıksuyun endüstriyel amaçlı kullanıma uygunluğu, tarımsal sulamada kullanıma uygunluğu ve yeraltına deşarjının uygunluğu değerlendirilmiştir. Bu değerlendirme kapsamında pilot endüstrinin mevcut arıtma tesisi için önerilen ilave arıtma kademeleri hakkında bilgi verilmiştir. The world industrializing with a growing pace has scarcity problems of water at the same time. For this reason, disposal of the wastewaters to rivers, lakes or wetlands is becoming more and more unacceptable, including the uncontrolled use of water supplies. As the result, investigations of the reuse options and the implementation of these options have come into consideration. This study has been accomplished in accordance with the information gained from the pilot brewery which had been chosen for its appropriateness for the research. Firstly, information about the production steps and the wastewater treatment plant of the brewery has been achieved. Then, the samples that were taken from the influent and the effluent of the treatment plant were analysed to required parameters. According to the results of the analyses, the compatibility of the treated wastewater for industrial use, agricultural irrigation and the groundwater recharge was evaluated. Within the context of this evaluation, recommendations were given for the additional treatment units for the pilot brewery