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Communication Dans Un Congrès Année : 2019

Sintering of Aluminium Nitride nanopowders synthesized by thermal plasma and commercial micropowders

Résumé

The research for new materials with exceptional properties sets the pace for technological development. Non-oxide ceramics are characterized by high refractoriness, good mechanical properties at high temperatures, and high chemical inertness towards molten salts or liquid metals. More specifically, the AlN has the characteristics of an electrical insulator with high thermal conductivity (320 W.m-1.K-1), and a low thermal expansion coefficient (4x10-6 K-1), which make this ceramic a material of choice for the realization of substrates in the field of microelectronics or optoelectronics. During the last decade, the research field related to the AlN has focused on the use of nanometric powders, either in electronic applications, structural applications or as sintering aids. In this regard, the objective of this research is to study the sintering of AlN nanopowders synthesized by thermal plasma. The low sinterability of AlN can be related to the presence of covalent chemical bonds and to high refractoriness of this ceramic. This observation leads the ceramist to consider several solutions to densify AlN: I) sintering under load, II) adding sintering additives and finally, III) to use fine powders that are at least submicron or even nanometric. Taking into account this latest solution, high-purity AlN nano-powders were synthesized by using a 200kW non-transferred arc plasma, conducted in one-chamber thermal plasma reactor. The experimental assembly incorporated: high temperature gradient between the crucible and reactor´s wall, and high super-saturation of the system by nitrogen and carbon. Nitrogen was the only gas, used as the reagent and plasmogenic gas. Aluminum discs of Al 1100 were used as precursor material. Thermodynamic modelling was conducted in order to achieve the best conditions for AlN formation. The synthesized AlN particles, appears as agglomerates, with diameter between 130 and 180 nanometers, constituted by particles of 10 to 80 nanometers. It is proposed to carry out a comparative study of the sintering process between these AlN nano-powders obtained by plasma, commercial AlN micro-powders and a composite mixture micro-nano powder, by exploiting its physicochemical properties. The addition of nano-powders, can decline the sintering temperature and promote better compaction of the green bodies compared to that observed by using micro-powders, thanks to a significant increase in the specific surface area of the system. In addition, the use of conventional sintering, or HP or less conventional SPS, must allow control densification and granular growth kinetics for obtaining nanostructured objects close to full density with thermomechanical, thermal and electrical exacerbated properties.
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Dates et versions

hal-02163169 , version 1 (24-06-2019)

Identifiants

  • HAL Id : hal-02163169 , version 1

Citer

Norberto Labrador, Nicolas Pradeilles, Hélène Ageorges, Olivier Rapaud, Alexandre Maitre. Sintering of Aluminium Nitride nanopowders synthesized by thermal plasma and commercial micropowders. XVI ECerS Conference, Jun 2019, Torino, Italy. ⟨hal-02163169⟩
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