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The scope of this work was observing dimensional and heat transfer changes in ZnTiO3 samples during heating in nitrogen and air atmosphere. Interactions of bulk specimens with gaseous surrounding induce microstructure changes duri...
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The scope of this work was observing dimensional and heat transfer changes in ZnTiO3 samples during heating in nitrogen and air atmosphere. Interactions of bulk specimens with gaseous surrounding induce microstructure changes during heating. Sintered ZnTiO3 nanopowder samples were submitted to subsequent heating. Dilatation curves and thermogravimetric with simultaneous differential thermal analysis TGA/DTA curves were recorded. Reheating was performed in air and nitrogen atmospheres. Reheated samples obtained at different characteristic temperatures in air were analyzed by X-ray diffraction (XRD). Microstructures obtained by scanning electron microscopy (SEM) of reheated sintered samples are presented and compared. Reheating in a different atmosphere induced different microstructures. The goal was indicating possible causes leading to the microstructure changes.
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A comparison between the experimentally determined coefficient of thermal expansion (CTE) of two NiAlMo alloys with predictions based on the BFS method for alloys is introduced. An additional pnase characterization of the NiAlMo a...
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A comparison between the experimentally determined coefficient of thermal expansion (CTE) of two NiAlMo alloys with predictions based on the BFS method for alloys is introduced. An additional pnase characterization of the NiAlMo alloys was also carried out for an optimisation of the parameters needed for the atomistic modelling calculations. The BFS method appears to provide a reliable path for the assessment of the NiAlMo CTE trends for the whole ternary diagram, taking NiAl as the reference alloy.
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The influence of network chemical composition and cure conditions in a model epoxy system was investigated.Addition of 1,4-butanediol to a bisphenol-F epoxy resin cured with 4-methyl-2-phenyl imidazole led to a decrease in the mod...
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The influence of network chemical composition and cure conditions in a model epoxy system was investigated.Addition of 1,4-butanediol to a bisphenol-F epoxy resin cured with 4-methyl-2-phenyl imidazole led to a decrease in the modulus and glass transition temperature,which resulted in lower residual stresses.Moisture uptake increased with the addition of 1,4-butanediol and is associated with an increase in the free volume of the epoxy.However,even with greater moisture uptake,the addition of 1,4-butanediol to the epoxy increased its adhesion to quartz,primarily through lower residual stress in the samples and increased energy dissipation on debonding.Differences in residual stress for different cure conditions were not measurable in these systems.However,increasing the cure time increased the adhesion of the epoxy to quartz.
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Cr_(2-x)Ti_xO_(3+δ), where x varies from 0.1, 0.2 and 0.3 has been prepared by glycerol route and characterized by powder X-ray diffraction, dynamic light scattering, BET surface area and scanning electron microscopy. The thermal...
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Cr_(2-x)Ti_xO_(3+δ), where x varies from 0.1, 0.2 and 0.3 has been prepared by glycerol route and characterized by powder X-ray diffraction, dynamic light scattering, BET surface area and scanning electron microscopy. The thermal expansion coefficient of the powder samples was studied using a high-temperature X-ray diffractometer. The bulk thermal expansion was studied by dilatometry. An anomaly in the ‘c’ direction was found initially in the Ti doped samples which manifested in 'a' direction as well at high dopant concentration. The anomalies shown by these compounds could not be manifested in the bulk thermal expansion because of the polycrystalline nature of the samples as revealed by dilatometry.
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Characterization of amorphous materials in terms of mechanical and thermomechanical properties affects significantly the range of their application. In that sense, in the process of thermomechanical examinations of glasses of the ...
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Characterization of amorphous materials in terms of mechanical and thermomechanical properties affects significantly the range of their application. In that sense, in the process of thermomechanical examinations of glasses of the Bi_x(As_2S_3)_(100-x) system, the temperatures of the following processes have been detected: the beginning of brittleness disappearance, glass transition temperature T_g, boundary between visco-plastic and liquid phases, and the beginning of the full glass liquidity. Moreover, using dilatometric analysis, we determined thermal coefficients of expansion of solid phase and visco-plastic phase. Microhardness of the examined glasses was determined by Vicker's method, with progressive increase of the load. Based on the model of elastic/plastic deformation, the correction of experimental values was made. Morphology of the mechanically treated surfaces was investigated using scanning electron microscopy. The results of measurements were discussed and analyzed in the context of the influence of the composition complexity on the values of given parameters.
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High-rate dilatometry is used to study the kinetics of decomposition of undercooled austenite of low-alloy pipe steel 13KhFA obtained upon heating into the single-phase γ field and the intercritical temperature range. The complex...
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High-rate dilatometry is used to study the kinetics of decomposition of undercooled austenite of low-alloy pipe steel 13KhFA obtained upon heating into the single-phase γ field and the intercritical temperature range. The complex effect of the austenitizing in the intercritical temperature range on the decomposition of the undercooled austenite is revealed (the initial temperature of decomposition falls while the temperature of decomposition termination rises).
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Magnetostriction, dilatation and calorimetric measurements were performed on FINEMET type as-quenched and heat treated ribbons. Nb was gradually replaced by Mo in order to study the influence of the refractory elements exchange on...
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Magnetostriction, dilatation and calorimetric measurements were performed on FINEMET type as-quenched and heat treated ribbons. Nb was gradually replaced by Mo in order to study the influence of the refractory elements exchange on several magnetostriction parameters. The results could be correlated with magnetic and structural transformations throughout thermal treatments and assured that the whole series is suitable for technical applications.
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Commercial Mn-Zn powder (Mn0.63Zn0.37Fe2O4, 93 wt. % and Fe2O3 7 wt. %) was milled 0.5, 1, 2 and 4 hours in a planetary ball mill. The goal was to observe intensive milling influences on oxidation and reduction processes that will...
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Commercial Mn-Zn powder (Mn0.63Zn0.37Fe2O4, 93 wt. % and Fe2O3 7 wt. %) was milled 0.5, 1, 2 and 4 hours in a planetary ball mill. The goal was to observe intensive milling influences on oxidation and reduction processes that will happen during subsequent heating. Powders were characterized with XRD, SEM and particle seizer. Subsequent heating was monitored on TGA/DTA in an air atmosphere. After compaction of the milled powders, sintering was also performed in a dilatometric device. Sintered specimens were characterized micro structurally with SEM on a fresh breakage. Obtained differential TGA diagrams suggest intensive changes during prolonged milling of the oxidation kinetics on heating. Ferrite powders changed with milling as well as with second run heating were characterized to enable determination of the potentially best ratio of milling and heating to be applied to obtain the desired microstructure.
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Polymerization volume change (PVC) was measured systematically using mercury dilatometry for 41 epoxide and methacrylate monomers with quartz filler.Quantitative structure-property relationship (QSPR) models were developed based o...
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Polymerization volume change (PVC) was measured systematically using mercury dilatometry for 41 epoxide and methacrylate monomers with quartz filler.Quantitative structure-property relationship (QSPR) models were developed based on this previously unreported data to gain insight into the data collection method for future models.Successful models included only data from those samples which were polymerized to hardness.The most significant descriptors in these models were related to monomer reactivity.In contrast,PVC data collected under experimental conditions which maximized monomer conversion resulted in descriptors describing size and branching,indicating that conversion must be considered for future PVC measurements.A rule of mixtures (ROM) correction term improved the correlations of the dilatometer data with varying quartz content,and an adjustment for conversion may similarly enable inclusion of data which had not polymerize to hardness.
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Eglin steel is a new ultrahigh strength steel that has been developed at Eglin Air Force Base in the early 2000s. This steel could be subjected to a variety of processing steps during fabrication, each with its own thermal history...
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Eglin steel is a new ultrahigh strength steel that has been developed at Eglin Air Force Base in the early 2000s. This steel could be subjected to a variety of processing steps during fabrication, each with its own thermal history. This article presents a continuous cooling transformation diagram developed for Eglin steel to be used as a guideline during processing. Dilatometry techniques performed on a Gleeble thermomechanical simulator were combined with microhardness results and microstructural characterisation to develop the diagram. The results show that four distinct microstructures form within Eglin steel depending on the cooling rate. At cooling rates above, similar to 1 degrees C s(-1), a predominately martensitic microstructure is formed with hardness of similar to 520 HV. Intermediate cooling rates of 1 to 0.2 degrees C s(-1) produce a mixed martensitic/bainitic microstructure with a hardness that ranges from 520 to 420 HV. Slower cooling rates of 0.1 to 0.03 degrees C s(-1) lead to the formation of a bainitic microstructure with a hardness of similar to 420 HV. The slowest cooling rate of 0.01 degrees C s(-1) formed a bainitic microstructure with an apparent carbide constituent at the prior austenite grain boundaries.
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