Wyniki wyszukiwania - Biblioteka Nauki

1

The use of waste materials as fillers in polymer composites-synthesis and thermal properties

100%

Gargol M. , Podkościelna B.

Physicochemical Problems of Mineral Processing

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2019

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tom Vol. 55, iss. 6

1549--1556

EN

This paper presents the synthesis and characterization of new polymeric materials in form of composites. As a fillers, waste materials of inorganic origin (ash and silica gel), were used. In the synthesis of composites, two derivatives of bisphenol A (glycerolate diacrylate, and epoxy resin, Epidian® 5), were applied. The compositions were prepared with an increasing amount of fillers 0-40% w/w in both tested systems. Composites were analyzed using the thermogravimetric analysis (TG/DTG), which showed the influence of different fillers on their thermal properties. Moreover, the proper course of the polymerization reaction was confirmed by spectroscopic analysis (ATR/FT-IR). It has been shown that new resistant materials can be obtained, using cheap and waste materials, by simple synthesis which does not require monitoring of the reaction course or expensive polymerization initiators.

2

Experimental and theoretical approaches on thermal and structural properties of Zn doped BSCCO glass ceramics

100%

Koralay H. , Hicyilmaz O. , Cavdar S. , Ozturk O. , Tasci A. T.

Materials Science Poland

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2016

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tom Vol. 34, No. 1

25--32

EN

Thermal properties of Cu–Zn partially substituted Bi1.8Sr2Ca2Cu3.2-xZnx10+δ (x = 0, 0.1 and 0.5) glass-ceramic systems have been investigated with the help of a differential thermal analyzer (DTA) by using Johnson-Mehl-Avrami-Kolmogorov (JMAK) approximation. Non-isothermal crystallization kinetics of the samples has been tested. The calculated values of activation energy of crystallization (E) and Avrami parameter (n) ranged between 306.1 and 338.3 kJ.mol-1 and 1.29 and 3.59, respectively. Crystallization kinetics was compared following the partial substitution, before and after Zn doping of the sample. In addition, by using a scanning electron microscope (SEM) and X-ray powder diffractometer (XRD), structural properties of Zn doped BSCCO glass-ceramic samples were determined. Surface morphology of the samples was studied by SEM measurements. Lattice parameters and volume of the samples were calculated from the XRD measurements.

3

Structure and magnetic properties of Fe36Co36B19Si5Nb4 bulk metallic glasses

100%

Nowosielski R. , Babilas R.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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tom Vol. 30, nr 2

135-140

EN

Purpose: The work presents a microstructure characterization, thermal stability and soft magnetic properties analysis of Fe-based bulk metallic glasses. Design/methodology/approach: The studies were performed on bulk amorphous ribbons and rods. The amorphous structure of tested materials was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods. The thermal properties associated with crystallization temperature of the glassy samples were measured using differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The magnetic properties were determined by the Maxwell-Wien bridge and VSM methods. Findings: The X-ray diffraction and transmission electron microscopy investigations have revealed that the studied as-cast bulk metallic glasses were amorphous. Based from the XRD analysis and TEM investigations of the Fe₃₆ Co₃₆B₁₉Si₅Nb₄ rod samples, it was believed that the tested alloy can be fabricated into a bulk glassy rod with the diameter of up to 4 mm. A two stage crystallization process was observed for studied bulk amorphous alloy. The changes of Curie temperatures, crystallization temperatures and magnetic properties as a function of glassy ribbons thickness (time of solidification) were stated. The investigated magnetic properties allow to classify the studied metallic glasses as soft magnetic materials. Practical implications: The studied bulk metallic glasses are suitable materials for many electrical application in different elements of magnetic circuits and for manufacturing of sensors and precise current transformers. Originality/value: The obtained examination results confirm the utility of applied investigation methods in the microstructure, thermal and soft magnetic properties analysis of examined bulk amorphous alloys.

4

Synthesis and proton conductivity of anhydrous dendritic electrolytes

100%

Şenel M. , Tülü M. , Bozkurt A.

Open Chemistry

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2007

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tom 5

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nr 2

546-556

EN

Water soluble PEG cored dendritic hexa-acid which comprises peripheral carboxylic acidic groups were prepared via nucleophilic substitution reactions. Novel anhydrous proton conducting electrolytes were prepared by incorporation of the heterocyclic protogenic solvent imidazole (Im) into PEG cored dendritic hexa acid, (PEG-HA), at several molar ratios of Im to-COOH units of PEG-HA. The complexation of PEG-HA and Im was illustrated by infrared spectroscopy (FT-IR). The materials are thermally stable up to 150 °C as evidenced by thermogravimetry analysis (TGA). Differential scanning calorimetry (DSC) results verified that the organic electrolytes are homogeneous and amorphous. The proton conductivities were characterized by means of AC impedance spectroscopy and a maximum conductivity of 1 × 10−3 S/cm was measured at 120 °C in the anhydrous state. [...]

5

Wybrane właściwości użytkowe i termiczne mieszanin poliamid/polipropylen

100%

Koszkul J. , Gnatowski A.

Prace Naukowe Instytutu Technologii Organicznej i Tworzyw Sztucznych Politechniki Wrocławskiej. Konferencje

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2001

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tom Vol. 50, nr 23

124-127

PL

Przedstawiono wyniki badań właściwości użytkowych i termicznych mieszanin PA/PP. Wyznaczono charakterystykę trzech wybranych mieszanin o następującym składzie: PA30%PP70%, PA50%PP50%, PA70%PP30%. Badane polimery są termodynamicznie niemieszalne, dlatego do wytworzenia mieszanin użyto środka proadhezyjnego w postaci Polibondu 3150. Mieszaniny wytworzono za pomocą wytłaczarki dwuślimakowej sterowanej komputerowo, a próbki do badań formowano za pomocą wtryskarki ślimakowej również sterowanej komputerowo. Stwierdzono, iż skład mieszaniny ma istotny wpływ na masowy wskaźnik szybkości płynięcia, absorbcję, chłonność wocy oraz właściwości pvT. Masowy wskaźnik szybkości płynięcia wzrasta w miarę zwiększaniazawartości poliamidu w mieszaninie. Mniejsza zmiana masy pod wpływem absorbcji i mniejsza chłonność wody zauważalna jest dla mieszanin o większej zawartości polipropylenu. W badaniach pvT dla mieszanin przy ochładzaniu izobarycznym stwierdzono szerszy zakres temperatury krystalizacji w stosunku do poliamidu, przy czym zauważono przedziały krystalizacji charakterystyczne dla PA i PP.

EN

The results of investigations of consumption and thermal properties of PA/PP blends where presented. The investigations allowed to calculate characteristic of three chosen blends composed of: PA30%PP70% of total weight, PA50%PP50% of total weight, PA70%PP30% of total weight. Components of blends belong to materials partly immiscible, because to producing of blends one used of centre proadhesion in from Polibond 3150. Blends produced on extruder machine two worms computer controlled and samples to researches on injection moulding machine also computer controlled. The composition of blends has essential influence on melt flow rate index, absorption of water and pvT properties was ascertained. Melt flow rate index grows up in due measure of enlarging contens polyamide in blends. Smaller change of pulp under influence absorption of water perceptible is for mixtures about greater contens polypropylene. In researches pvT for blends at cooling isobaric wider range of temperature of crystallisation in relation to polyamide, at what noticed sections of crystallisation characteristic for PP was ascertained.

6

Theoretical Evaluation of Thermal Properties of TiO₂ Anatase and Rutile by using Einstein-Debye Approximation

100%

Mehmetoglu T.

Acta Physica Polonica A

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2018

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tom 133

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nr 1

126-128

EN

In this work, we propose a new approach to accurate calculation of heat capacities at constant volume and pressure of TiO₂ anatase and rutile. The evaluation model is based on the Einstein-Debye approximation which has been extensively used in solid state physics. The application of proposed approach to anatase and rutile titanium dioxide computations results is shown to be well numerically satisfactory. This approach is valid in wide temperature ranges and can be suggested for accurate evaluation of thermal properties of solids. The calculation results are in well agreement with the literature values reported by other studies.

7

Core/Clad Phosphate Glass Fibres Containing Iron and/or Titanium

100%

Ahmed I. , Shaharuddin S. S. , Sharmin N. , Furniss D. , Rudd C.

Biomedical glasses

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2015

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tom 1

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nr 1

EN

Phosphate glasses are novel amorphous biomaterials due to their fully resorbable characteristics, with controllable degradation profiles. In this study, phosphate glasses containing titanium and/or iron were identified to exhibit sufficiently matched thermal properties (glass transition temperature, thermal expansion coefficient and viscosity) which enabled successful co-extrusion of glass billets to form a core/clad preform. The cladding composition for the core/clad preforms were also reversed. Fe clad and Ti clad fibres were successfully drawn with an average diameter of between 30~50 μm. The average cladding annular thickness was estimated to be less than 2 μm. Annealed core/clad fibres were degraded in PBS for a period of 27 days. The strength of the Fe clad fibres appeared to increase from 303 ± 73 MPa to 386 ± 45 MPa after nearly 2 weeks in the dissolution medium (phosphate buffered solution) before decreasing by day 27. The strength of the Ti clad fibres revealed an increase from 236 ± 53 MPa to 295 ± 61 MPa when compared at week 3. The tensile modulus measured for both core/clad fibres ranged between 51 GPa to 60 GPa. During the dissolution study, Fe clad fibres showed a peeling mechanism compared to the Ti clad fibres.

8

Microstructure and thermal properties of quasi-equal rare earth substitution Y0.5Gd0.5Ba2Cu3O6.94 superconductor

100%

Terzieva S. , Stoyanova-Ivanova A. , Shivachev B. , Terzijska B. , Zaleski A. , Misiorek H. , Mikli V.

Open Physics

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2009

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tom 7

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nr 1

84-88

EN

Sintering effects in YBa2Cu3Oz samples with quasi-equal rare earth substitution have been investigated. It has been shown that the Y-123 type compound can be formed when gadolinium is partially substituted (in this case 50% atomic substitution) for yttrium. The superconducting compound was obtained by the optimized ceramic method, including solid-state reaction, melting and sintering, controlled by X-ray diffraction. The microstructure was investigated by SEM and energy dispersive X-ray analyses. An AC susceptibility measurement has shown that T c =93 K. Temperature-dependece of the thermal conductivity (4.5–300 K) of the polycrystalline Y0.5Gd0.5Ba2Cu3O6.94 sample was also measured.

9

Synthesis and Thermal Properties of Europium-Cerium Oxide as a New Fluorite-Type Ceramic Material for Thermal Barrier Coatings Applications

100%

Mikuśkiewicz M. , Stopyra M. , Moskal G.

Archives of Metallurgy and Materials

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2018

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tom Vol. 63, iss. 4

2089--2093

EN

In the present paper the structure and thermal properties of europium cerium oxides were investigated. The material for the research was obtained via solid state synthesis. The initial powders: ceria CeO2 and europia Eu2O3 were mixed in 1:1 mass ratio (non-stoichiometric proportion with the excess of CeO2) and milled. The sintering process was performed using high temperature vacuum press at 1350°C. Calorimetric analysis was conducted both for initial powders and milled mixture. The structure, phase composition and thermal diffusivity of obtained material were investigated in as-sintered condition. It was revealed that the obtained material was multi-phase. Non-stoichiometric phases including Ce0.5Eu0.5O1.75 with fluorite type structure and different lattice parameters were present. Thermal diffusivity decreased in the range from 25 to 900°C from 1.49 to 0.57 mm2 /s and then increased to 0.70 mm2 /s at 1400°C.

10

Development of the modelling and numerical simulation of the thermal properties of machine tools

100%

Jędrzejewski J. , Kwaśny W. , Kowal Z. , Winiarski Z.

Journal of Machine Engineering

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2014

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tom Vol. 14, No. 3

5--20

EN

This paper highlights the need for the holistic modelling of the thermal properties of machine tools to provide a good basis for the effective aiding of machine tool design and optimization. A brief history of this modelling and the idea of accurate modelling and its experimental verification are presented. Examples of the holistic modelling of drive units both isolated from the machine tool and interconnected with its structure are provided.

11

Mechanical and thermal properties of commercial multilayer flexible plastic packaging materials irradiated with electron beam

100%

Oliveira V. M. , Nogueira B. R. , Ortiz A. V. , Moura E. A. B.

Nukleonika

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2008

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tom Vol. 53, suppl. 2

141--144

EN

The effects of electron-beam irradiation on mechanical and thermal properties were studied for two commercial multilayer structures of flexible food packaging. Both the laminated poly(ethylene terephthalate) (PET)/ low-density polyethylene (LDPE) and the coextruded LDPE/polyamide(PA)/LDPE structures were irradiated up to 120 kGy using a 1.5 MeV electron beam accelerator, at room temperature in the presence of air. Mechanical properties showed significant changes (p < 0.05), specially in sealability that was severely affected. Changes in mechanical properties were discussed in relation to the eight day and the six month period after irradiation. In addition, the DSC analysis six months after treatment showed that the fusion enthalpy of the PET/LDPE structure components increase for the LDPE from 10 kGy and decrease for the PET up to 120 kGy (p < 0.05). On the other hand, the LDPE/PA6/ LDPE presented increase in the LDPE and PA up to 120 kGy, except for LDPE at 10 and 15 kGy and PA at 5 kGy doses (p < 0.05). The effects of irradiation were less severe for the LDPE/PA6/LDPE than for the PET/LDPE. The electron-beam irradiation did not show advantageous results that could be of interest for commercial applications for the film industry, but brings important information about the packaging behavior for food producers who may decide to use irradiation as a form of cold pasteurization of their packed products.

12

Thermal properties of nanoliquids in the aspects of their used in the insulation system of high voltage power transformer

100%

Dombek G. , Nadolny Z. , Przybyłek P.

Computer Applications in Electrical Engineering

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2014

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tom Vol. 12

217--226

EN

The article presents information concerning the electrical and thermal properties of nanoliquids in the context of their use in the insulating system of high voltage power transformers. It consists of six chapters. The first chapter is an introduction. The second chapter describes properties of the modern insulating nanoliquids created on the basis of mineral oil and nanoparticles. The third chapter is devoted to the measurement systems to the measure of the viscosity, thermal conductivity and density. The fourth chapter presents the methods of preparation of nanoliquids. In the fifth chapter the viscosity, thermal conductivity and density of mineral oil and nanoliquids were compared. Article ends with a summary.

13

Thermal stability and GFA parameters of Fe-Co-based bulk metallic glasses

100%

Nowosielski R. , Januszka A.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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tom Vol. 48, nr 2

161--168

EN

Purpose: The paper present fabrication process, structure characterization and selected thermal properties of Fe-Co-based bulk metallic glasses in form of rods. Additionally selected GFA parameters were determined. Design/methodology/approach: The studies were realized on Fe36Co36B19.2Si4.8Nb4 metallic glasses in form of rods with diameter of 0=1.5, ø=2 and ø=3 mm. Samples were performed by the pressure die casting method. An amorphous structure was confirmed by the X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The thermal properties of the studied samples were examined by differential scanning calorimetry (DSC). GFA parameters were calculated based on thermal properties. Findings: The X-ray analysis and scanning microscopy observation revealed that the studies as-cast rods were amorphous. For each sample broad diffraction halo could be observed. That diffraction pattern confirm formation of glassy phase in studied samples. Practical implications: Fe-Co-based bulk metallic glasses could be used in many practical application. For the sake of great mechanical, thermal and magnetic properties they may be used as a structural material and in many electric and magnetic applications (for example soft electro-magnetic cores). Knowledge about thermal properties could be useful in computer simulation of metallic glasses casting process. Originality/value: The obtained examination results allow to confirm the utility of investigation methods, which has used in this work. Thermal analysis allow to determinate selected GFA parameters for selected Fe-Co-based alloy.

14

Synthesis, Characterization and Thermal Decomposition of a New Energetic Salt of 1H,1′H-5,5′-Bistetrazole-1,1′-diol

100%

Xiao L. , Jin B. , Shang Y. , Liu Q. , Guo Z. , Peng R.

Central European Journal of Energetic Materials

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2018

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tom Vol. 15, no. 3

405--419

EN

1,1-Dimethylbiguanidium 1H,1′H-5,5′-bistetrazole-1,1′-diolate (MGBTO), a novel nitrogen-rich energetic salt, was synthesized by cation exchange. Its structure was characterized by elemental analysis, FTIR, NMR, DTA and TG-DTG. Single crystal X-ray diffraction analysis revealed that MGBTO was crystallized in the monoclinic space group C2/c. Thermal analysis demonstrated that its thermal stability extended up to 531.1 K. The nonisothermal kinetic and apparent thermodynamic parameters of the exothermic decomposition of MGBTO were determined by the Kissinger and Ozawa methods. Its detonation velocity and detonation pressure were calculated on the basis of the Kamlet-Jacobs equation and were 6342 m·s–1 and 15.78 GPa, respectively. The impact and friction sensitivities of MGBTO were quantified using standard BAM (10 kg drop hammer) procedures. The results revealed that the salt has good mechanical sensitivity (FS > 120 N, IS > 40 J), thus indicating its potential applications as an energetic material.

15

Photothermal methods for determination of thermal properties of bulk materials and thin films

100%

Bodzenta J. , Kaźmierczak-Bałata A. , Mazur J.

Open Physics

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2010

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tom 8

|

nr 2

207-220

EN

Information on the thermal properties of materials is very important both in fundamental physical research and in engineering applications. The development of materials with desirable heat transport properties requires methods for their experimental determination. In this paper basic concepts of the measurement of parameters describing the heat transport in solids are discussed. Attention is paid to methods utilizing nonstationary temperature fields, especially to photothermal methods in which the temperature disturbance in the investigated sample is generated through light absorption. Exemplary photothermal measuring techniques, which can be realized using common experimental equipment, are described in detail. It is shown that using these techniques it is possible to determine the thermal diffusivity of bulk transparent samples, opaque and semi-transparent plate-form samples, and the thermal conductivity of thin films deposited on thick substrates. Results of the investigation of thermal diffusivity of the ground in the polar region, which is based on the analysis of the propagation of the thermal wave generated by sun-light, are also presented. Based on chosen examples one can state that photothermal techniques can be used for determination of the thermal properties of very different materials.

16

Wpływ pigmentów ftalocyjaninowych na właściwości kauczuku butadienowego

100%

Pająk A. , Janowska G. , Czajkowski W. , Kucharska-Jastrząbek A.

Przemysł Chemiczny

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2010

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tom T. 89, nr 12

1689-1692

17

Comparison of experimental and modelling results of thermal properties in Cu-AlN composite materials

100%

Chmielewski M. , Weglewski W.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2013

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tom Vol. 61, nr 2

507--514

EN

Copper-based composites could be widely used in automotive, electronic or electrical industry due to their very promising thermal properties. In the present paper, Cu-AlN metal matrix composites with ceramic volume fractions between 0.1 and 0.4 were fabricated by hot pressing method in vacuum. Dependence of the coefficient of thermal expansion (CTE) and the thermal conductivity (TC) on the chemical composition of composites has been investigated. The measured values of the thermal expansion coefficient have been compared with the analytical models’ predictions. A numerical model based on FEAP 7.5 in 3D space has been used to evaluate the influence of the porosity on the thermal properties (thermal conductivity) of the composite. A fairly good correlation between the FEM results and the experimental measurements has been obtained.

18

The Influence of Silica Fume on the Mechanical and Thermal Parameters of Portland Cement Concretes

88%

Strzałkowski J. , Garbalińska H.

Journal of Ecological Engineering

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2019

|

tom Vol. 20, nr 9

95--102

EN

The influence of the silica fume (SF) addition on the basic mechanical and thermal parameters of cement concrete was presented in this paper. Numerous studies show that the specific properties of silica fume allow producing concretes with increased strength and durability properties. However, the results of the authors' own studies demonstrated that under specific circumstances, the SF addition can negatively affect the strength of cement concrete. In this paper, the concretes made from two types of coarse aggregate, 4–8 mm fraction: reference ordinary gravel aggregate (Ref) and broken basalt aggregate (Bas) were tested. Comprehensive tests (microstructural, strength and thermal) were carried out on three formulas: the first one (Ref-0) did not contain any additives or admixtures. Silica fume and superplasticizer were used in the second formula (Ref-8), introduced in the amount of 8% and 0.75% of the cement’s weight, respectively. The third formula, based on basalt aggregate (Bas-8), also contained silica fume and a superplasticizer, dosed in the same amount as in the second formula. Porosimetric studies showed that the use of silica fume in the Ref-8 formula resulted in a decrease in the number of pores smaller than 0.15 μm in comparison to the Ref-0 reference concrete without the silica fume. On the other hand, numerous additional pores with diameters ranging from 0.05 to 300 μm were found in the Bas-8 concrete. In turn, optical porosimetry proved that the basalt-based concrete had numerous pores in the range above 70 μm, which were not observed in the case of the concretes with ordinary pebble aggregate. In the case of the normal concrete, the addition of silica fume resulted in an increase in the compressive strength. However, the basalt-based concrete, due to its much higher porosity, achieved significantly lower strength values. The results showed that the observed changes in porosity, caused by the presence of silica fume, resulted in lower values of thermal conductivity and specific heat of mature composites that it had been added to. This was particularly evident for the basalt-based concrete.

19

Właściwości termokinetyczne spawanych laserowo wyprowadzeń wewnętrznych w półprzewodnikowych przyrządach mocy.

88%

Tomczyk M.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

|

2006

|

tom Vol. 44, nr 18

208-212

PL

W artykule przedstawiono wyniki badań właściwości laserowych połączeń spawanych w odniesieniu do testowych połączeń drutowych oraz wyprowadzeń ze struktur półprzewodnikowych. Badania przeprowadzono z punktu widzenia analizy zjawisk cieplnych zachodzących podczas przepływu prądu. Dokonano pomiaru rezystancji połączenia oraz przedstawiono wyniki badań termograficznych. Dokonano analizy czynników wpływających na ilość ciepła wydzielanego w połączeniu.

EN

This paper presents an experimental investigations of physical and electrical properties of laser weld bonding. It analyzes reasons of generation of technological narrowings and growth of resistivity of connection. It presents results of technical methods of measurements of resistivity and results of thermography investigations. There is performed analysis of influence of change of selected properties of connections on distribution of temperature in semiconductor devices.

20

Thermal Properties of Carbon Nanotube (CNT) Reinforced Polyvinyl Alcohol (PVA) Composites

88%

Hasan M. , Das S. K. , Islam J. M. M. , Gafur M. A. , Hoque E. , Khan M. A.

International Letters of Chemistry, Physics and Astronomy

|

2013

|

tom Vol. 12

59--66

EN

Homogeneous Polyvinyl alcohol (PVA)/Carbon nanotube (CNT) composite has been prepared by solution casting method using gum acacia as a surfactant. CNT content in the composite was varied from 5-10 % by weight. The thermal properties of PVA/CNT composites were investigated by Thermo Gravimetric/Differential Thermal Analyzer (TG/DTA) and Thermo Mechanical Analyzer (TMA). TG/DTA results showed that higher thermal stability in higher percentage of CNT in the composites. The 10 % CNT containing PVA composite exhibit highest onset of melting, glass transition point and offset of melting temperature and the recoded values are 330.4K, 379K and 421.3K respectively. All of the result indicates that the developed PVA/CNT composite might be promising for use in solar cell application.