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1

Cermet composite material based on aluminothermy

Penkov I., Petkov V., Valov R.

Prace Instytutu Odlewnictwa

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2017

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Vol. 57, no. 4

293--296

EN

A new method for synthesis of cermet composite materials was developed based on aluminothermy. Employing this method a cermet composite material with a high content of AlN crystal phase was synthesized. Fine powders of aluminum and silica glass were mixed and heated in a corundum crucible for 6 hours at 1100°C in air. The X-ray diffraction analysis showed that the composite material thus synthesized contains a high concentration of AlN particles (about 33 vol. %) embedded in an aluminum silicon alloy. A small amount of Al2O3 particles (about 8 vol. %) was also found. The method proposed can also be used for synthesis of aluminum matrix composite materials containing, besides AlN, other ceramic reinforcement phases. The properties of these composite materials can be tailored by choosing an appropriate composition of the initial powder mixture for aluminothermic synthesis.

2

Epoxy composites filled with boron nitride and aluminum nitride for improved thermal conductivity

Hutchinson J. M., Román F., Cortés P., Calventus Y.

Polimery

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2017

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T. 62, nr 7-8

560--566

EN

Epoxy composites containing boron nitride (BN) or aluminum nitride (AlN or Al2N3) particles have been studied with a view to obtaining increased thermal conductivity. The effect of these fillers on the cure reaction has been investigated by differential scanning calorimetry (DSC) for two systems, epoxy-diamine and epoxy-thiol, and for volume fractions up to about 35 % of these filler particles. For the epoxy-diamine system, the glass transition temperature of the fully cured system, the heat of reaction, and the temperature at which the peak heat flow occurs were all independent of the cure conditions, filler type and content. In contrast, the epoxy-thiol system shows a systematic effect of filler on the peak temperature for both fillers: there is an initial acceleration of the reaction, which diminishes with increasing content, and the reaction is even significantly retarded at high contents for BN. This is interpreted in terms of an improved interface between epoxy matrix and particles, with a consequent enhancement of the thermal conductivity of the epoxy-thiol composites.

PL

Otrzymywano kompozyty epoksydowe napełnione cząstkami azotku boru (BN) lub azotku aluminium (Al2N3, AlN) o polepszonej przewodności cieplnej. Metodą różnicowej kalorymetrii skaningowej (DSC) oceniano wpływ dodatku (do 35 % obj.) napełniacza na przebieg reakcji sieciowania za pomocą systemu zawierającego epoksy-diaminę lub epoksy-tiol. W wypadku sieciowania systemem z udziałem epoksy-diaminy temperatura zeszklenia w pełni utwardzonego układu, ciepło reakcji i temperatura odpowiadająca maksimum przepływu ciepła były niezależne od warunków utwardzania, rodzaju i zawartości napełniacza. W wypadku użycia systemu z udziałem epoksy-tiolu zaobserwowano systematyczny wpływ dodatku obu rodzajów napełniacza na temperaturę maksimum przepływu ciepła. Początkowo następowało przyspieszenie reakcji sieciowania, której szybkość zmniejszała się wraz ze wzrostem zawartości napełniacza, a w wypadku dużego udziału cząstek BN reakcja spektakularnie spowalniała. Zjawisko to można interpretować zmniejszoną odległością (poprawą oddziaływań) między cząstkami matrycy epoksydowej i napełniacza, a w konsekwencji polepszoną przewodnością cieplną kompozytów epoksy-tiolowych.

3

Numerical simulations of epitaxial growth in MOVPE reactor as a tool for aluminum nitride growth optimization

Skibinski J, Caban P., Wejrzanowski T., Grybczuk M., Kurzydlowski K. J.

Journal of Power Technologies

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2016

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Vol. 96, nr 2

110--114

EN

The present study concerns numerical simulations and experimental measurements on the influence of inlet gas mass flow rate on the growth rate of aluminum nitride crystals in Metalorganic Vapor Phase Epitaxy reactor model AIX-200/4RF-S. The aim of this study was to design the optimal process conditions for obtaining the most homogeneous product. Since there are many agents influencing reactions relating to crystal growth such as temperature, pressure, gas composition and reactor geometry, it is difficult to design an optimal process. Variations of process pressure and hydrogen mass flow rates have been considered. Since it is impossible to experimentally determine the exact distribution of heat and mass transfer inside the reactor during crystal growth, detailed 3D modeling has been used to gain insight into the process conditions. Numerical simulations increase the understanding of the epitaxial process by calculating heat and mass transfer distribution during the growth of aluminum nitride crystals. Including chemical reactions in the numerical model enables the growth rate of the substrate to be calculated. The present approach has been applied to optimize homogeneity of AlN film thickness and its growth rate.

4

Properties of AlN thin films deposited by means of magnetron sputtering for ISFET applications

Firek P., Waśkiewicz M., Stonio B., Szmidt J.

Materials Science Poland

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2015

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Vol. 33, No. 4

669--676

EN

This work presents the investigations of AlN thin films deposited on Si substrates by means of magnetron sputtering. Nine different sputtering processes were performed. Based on obtained results, the tenth process was prepared and performed (for future ISFET structures manufacturing). Round aluminum (Al) electrodes were evaporated on the top of deposited layers. The MIS capacitor structures enabled a subsequent electrical characterization of the AlN films by means of current-voltage (I-V) and capacitance-voltage (C-V) measurements. Based on these results, the main parameters of investigated layers were obtained. Moreover, the paper describes the technology of fabrication and electrical characterization of ISFET transistors and possibility of their application as ion sensors.

5

Aluminum Nitride Formation From Aluminum Oxide/Phenol Resin Solid-Gel Mixture By Carbothermal Reduction Nitridation Method

Mylinh D. T., Yoon D. H., Kim C.-Y.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1551--1555

EN

Hexagonal and cubic crystalline aluminum nitride (AlN) particles were successfully synthesized using phenol resin and alpha aluminum oxide (α-Al2O3) as precursors through new solid-gel mixture and carbothermal reduction nitridaton (CRN) process with molar ratio of C/Al2O3 = 3. The effect of reaction temperature on the decomposition of phenol resin and synthesis of hexagonal and cubic AlN were investigated and the reaction mechanism was also discussed. The results showed that α-Al2O3 powder in homogeneous solid-gel precursor was easily nitrided to yield AlN powder during the carbothermal reduction nitridation process. The reaction temperature needed for a complete conversion for the precursor was about 1700°C, which much lower than that when using α-Al2O3 and carbon black as starting materials. To our knowledge, phenol resin is the first time to be used for synthesizing AlN powder via carbothermal reduction and nitridation method, which would be an efficient, economical, cheap assistant reagent for large scale synthesis of AlN powder.

6

Modeling of the formation of AlN precipitates during solidification of steel

Kalisz D., Rzadkosz S.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 1

63--68

EN

The study was carried out computer simulations of the formation process of AlN precipitates in the solidification of steel. The chemical composition of steel and non-metallic inclusions formed was determined using the commercial software FactSage. Calculated amount of precipitates formed during cooling of steel between the liquidus and solidus temperatures under conditions of thermodynamic equilibrium. In parallel, the computations were performed using your own computer program. It was found that aluminum nitride is formed at the final stage of solidification, and the condition of its formation is low oxygen content in steel.

7

Density Functional Study of 27Al and 14N Quadrupole Coupling Constants in the Carbon Doped (4,4) Single-Walled Armchair Aluminum Nitride Nanotube

Farahani M., Seif A., Boshra A.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 1

145-151

EN

Density functional theory (DFT) calculations are carried out to study the influence of carbon doping (C-dop ing) on the aluminum-27 and nitrogen-14 quadrupole coupling constants (CQ) in a representative model of aluminum nitride nanotubes (AlNNTs). The model includes two perfect and C-doped forms of the (4,4) single-walled armchair AlNNT. To this aim, each of two forms of AlNNT is firstly optimized and then the electric field gradient (EFG) tensors are calculated and converted to CQ. Comparison of the calculated CQ values in two perfect and C-doped forms of AlNNT reveals that the influence of C-doping is significant at the sites of the nearest Al and N nuclei while those nuclei far from the C atoms do not show changes.