Treatment In Temperature Range Research Articles

Structure and phase composition transformation in Cr20Ni80 + Ni2Al3 + CrAl7 layered coating under thermal effect

The thermal stability of the Cr20Ni80 / (Ni2A13 + CrAl7) layered coating on Ml copper substrate was studied. It is found, that the sequence of phase transformations in layered coating during the heat treatment in temperature range of 700-1000 °C is Ni2Al3 + CrAl7 → Ni2Al3(Cr) + NiAl(Cr) → NiAl(Cr). It is shown, that an increase in temperature and duration of thermal effect leads to the alignment of Al, Ni and Cr content over the coating thickness due to the diffusion redistribution of elements and to the formation of a secondary reaction zone with a high chromium content.

Mechanism and degradation kinetics of zinc complex containing isophthalato and 2,2′-dipyridylamine ligands under different atmospheres

The design of mixed-ligand complexes are of increasing interest from fundamental as well as technological and curative aspects. Having that in mind, we studied zinc complex containing 2,2′-dipyridylamine (dipya) and dianion of isophthalic acid (ipht), [Zn(dipya)(ipht)]n, as promising precursor for synthesis of nanostructured metal oxide. In that sense, the mechanism and degradation kinetics of [Zn(dipya)(ipht)]n was analyzed under non-isothermal conditions in nitrogen and in air atmospheres. Peak deconvolution of the [Zn(dipya)(ipht)]n decomposition profile, in the form of a derivative thermogram (DTG), in nitrogen atmosphere, revealed the presence of three decomposition steps, while in air five single steps were isolated. In both cases ZnO is formed as residue at 530 °C: pure (in air) or in amorphous matrix (nitrogen). In air we obtained well crystalized ZnO nanospheres (∼25 nm), by thermal treatment in temperature range 370–530 °C showing that this complex could be considered as good precursor for production of nanosized ZnO.

Grain character and mechanical properties of Fe-21Cr-15Ni-6Mn-Nb non-magnetic stainless steel after solution treatment

A systematic investigation on grain growth behavior, grain boundary character distribution and mechanical properties of Fe-21Cr-15Ni-6Mn-Nb non-magnetic stainless steel was performed after solution treatment in temperature range of 1100–1200 °C with various durations. The results showed the hot-rolled plate still maintained fine microstructure with the grain size range of 11.5–19.6 µm after solution treatment. A Nb(C, N) drag mechanism concurrent with a restraining effect of Σ3n boundaries during solution treatment resulted in a slow kinetics with grain growth exponent n of ~ 4. The proliferation mechanism of Σ3n boundaries mainly varied from Σ3 regeneration to new twinning accompanied by grain growth. Twin boundary has an effective strengthening role like a grain boundary. The YS, UTS and elongation of solution-treated plate was above 634.0 MPa, 838.9 MPa, 45.3％, respectively, which were superior to the conventional austenitic stainless steel. The Hall-Petch relationship was determined well between the grain size under the condition of either including or excluding twin boundaries and tensile results. An inherent relationship between k′ and k (k′ and k correspond to the circumstance of including and excluding twin boundaries, respectively), was expressed by k′=1.52037+1.67168k.

Impact of hot water pretreatment temperature on the pyrolysis of birch wood

Hydrothermal treatment of wood is an integral part of a modern biorefinery concept. Our research is devoted to the study of properties of birch wood and lignocelluloses at its base after hydrothermal treatment at various temperatures using TG and Py-GC/FID/MS. It was found that treatment in temperature range 150–200°C led to increase of the content of pyrolysis volatiles due to the increase of the content of the main cellulose product—levoglucosan, while the content of the phenolic products was practically constant. Due to hydrolytic processes and condensation reactions in the temperature range 200–250°C the content of all carbohydrate derived volatiles decreased and the content of lignin destruction products increased mainly at the expense of dimethoxylated derivatives.

Thermal post-deposition treatment effects on nanocrystalline hydrogenated silicon prepared by PECVD under different hydrogen flow rates

In this paper, hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited on mono-crystalline silicon substrate by plasma enhanced chemical vapor deposition (PECVD) under different hydrogen flow rates followed by a thermal treatment in an infrared furnace at different temperature ranging from 300 to 900°C. The investigated structural, morphological and optoelectronic properties of samples were found to be strongly dependent on the annealing temperature. Raman spectroscopy revealed that nc-Si:H films contain crystalline, amorphous and mixed structures as well. We find that post-deposition thermal treatment may lead to a tendency for structural improvement and a decrease of the disorder in the film network at moderate temperature under 500°C. As for annealing at higher temperature up to 900°C induces the recrystallization of the film which is correlated with the grain size and volume fraction in the layer. We demonstrate that high annealing temperature can lead to a decrease of silicon⿿hydrogen bonds corresponding to a reduction of the amorphous matrix in the layer promoting the formation of covalent Si⿿Si bonds. The effusion of the hydrogen from the grown film leads to increase its density and therefore induces a decrease in the thickness of the layer. For post-deposition thermal treatment in temperature range under 700°C, the post-deposition anneal seems to be crucial for obtaining good passivation quality as expressed by a minority carrier lifetime of 17μs, as it allows a significant reduction in defect states at the layer/substrate interface. While for a temperature higher than 900°C, the lifetime reduction is obtained because of hydrogen effusion phenomenon, thus a tendency for crystallization in the grown film.

Effect of thermal treatment on reactivity and mechanical properties of alkali activated shale–slag binder

This paper is aimed at investigating the properties of calcined shale–slag as an alternative alkali-activated constructional binder hardened by geopolymerization reaction with sodium silicate solution. Focus is put on possibilities of thermal treatment in temperature range of 500–1000°C and investigation of structural changes. These investigations were done by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (FTIR), measurement of specific surface area, pozzolanic activity and mechanical strength of prepared geopolymer mixtures. Reaction rates were measured by small amplitude dynamic rheometry as a relatively new method for investigation of geopolymerization process. The best compression strength of 82.52MPa and highest reactivity, according to the pozzolanic activity and dynamic rheometry, was achieved by thermal treatment at 600°C for duration of 4h.

Selected problems of formability of aluminised steel plates

The paper presents the results testing of the influence of heat treatment on formability of aluminised steel sheets. Tests have been conducted on samples of DX52D+AS120 aluminised steel sheet with the surface coating thickness of ca. 20μm, before and after heat treatment in temperature range 300–1000°C within 3–150min and after deep drawing. Tests of thickness, roughness, structure and plasticity of coating before and after heat treatment and deep drawing have been conducted. Special equipment for non-destructive and destructive measurements has been used in these tests. A digital camera, an optical microscope and a scanning electron microscope have been used to show changes of coating surface and structure at the cross-section after tests.

Effect of Thermal Treatment on Coercivity of SmCo<sub>5</sub> Sintered Magnets

Permanent magnet materials composed of transition and rare earth metals exhibit high energy products. Samarium cobalt magnets are developed and research is done to have high coercivity. Chemistry is varied from 34 to 36 weight percent of samarium in Sm1Co5 compound. Effect of chemistry and sintering treatment temperatures on final properties has been studied. Magnets are manufactured by powder metallurgical technique involving isostatic pressing and sintering in inert atmosphere at temperatures range of 1140-1170°C. Then the magnets are subject to post sintering aging treatment in temperature range of 800-900°C. It is observed that coercivity of Sm1Co5 magnet varies with aging temperature and can be improved by post sintering aging treatment.

Characterization of RF magnetron sputtered Se-doped Ge2Sb2.3Te5 thin films

ABSTRACTRF magnetron sputtering technique has been used to deposit new films potentially applicable in phase-change memories. Ge2Sb2Te5 seems to be promising material, but it is not clear whether it is optimum composition for such application. We studied different deposition condition and deposition of films doped by excess of Sb and doped also by Se, which equally replaces Te atoms compare to Ge2Sb2Te5. The sputtering target composition for our study was Ge2Sb2.3Te4Se1. Sputtered films contained less Se than target. Deposited films were characterized as-deposited and after thermal treatment in temperature range 30 − 300 °C.

Correlation of phase transition with the change in TL characteristics in CaSO4:Dy phosphor—effect of thermal treatment

The study is aimed at optimising the glow curve structure of CaSO4:Dy phosphor for dosimetric purpose and also to understand the observed changes owing to thermal treatment in the thermoluminescence (TL) sensitivity and glow curve structure. The reversible changes in the intensities of the lower temperature satellite peak and the main dosimetric glow peak with temperature of thermal treatment in the temperature range 400-700 degrees C indicates the interconversion of defect complexes responsible for the glow peaks in CaSO4:Dy. Phosphor samples subjected to thermal treatment in temperature range beyond 800 degrees C, showed irreversible changes in the intensities of the lower temperature and dosimetric peaks. The changes in TL characteristics of the phosphor for thermal treatments >800 degrees C are attributed to the partial phase transition in the phosphor as confirmed by the XRD and TG/DTA analysis of the phosphor.