Mechanism of AlN Formation through the Carbothermal Reduction of Al₂O₃ in a Flowing N₂ Atmosphere

Abstract

Mixtures of Al2O3, and C powders in a molar ratio of 1:3 were reduced in a N2 atmosphere. The effects of time, temperature, particle size of both reactants, and N2 flow rate were investigated. Kinetics show that the rate‐limiting process is the combustion of carbon, which leads to the reaction mechanism through the following basic steps: Al2O3= 2Al + 3/2 O2 3C + 3/2 O2→ 3CO (slow, with or without intermediate formation of CO2) 2Al + N2= 2AlN (fast) All of the experimental results have been discussed on the basis of this model, which allows one to predict the best conditions for preparing AlN powders.

Functional composites with core–shell fillers: I. Particle synthesis and thermal conductivity measurements

“…Examples of AlN and Si 3 N 4 material synthesis by means of CTRN process can be found in the literature [25][26][27][28][29][30]. The core-shell fillers used in our study were prepared according to the below described process which is schematically presented in Fig.…”

Carbothermal synthesis of spherical AlN granules: Effects of synthesis parameters and Y2O3 additive

“…Comparatively, the CRN process is a better choice for industry production, since it results in AlN powders with better properties such as high purity, facile sinterability and resistance against humidity [12]. To date, a lot of researchers have devoted themselves to improving the quality of the AlN powders synthesized by the CRN method [13][14][15][16][17][18]. Unfortunately, most of them just aimed at preparing fine or ultrafine AlN powders in order to meet the requirements of sintering AlN ceramics.…”

Processamento, propriedades e aplicações das cerâmicas de nitreto de alumínio

“…Após a secagem, a mistura homogeneizada é tratada termicamente em forno com fluxo de gás nitrogênio ou amônia (Al 2 O 3 +3C+N 2 gAlN+3CO) entre 1400 e 1700 ºC [27,28]. Uma subsequente calcinação ao ar ou em atmosfera oxidante é realizada entre 400 e 800 ºC para remoção do C não reagido [27].…”

“…A Tabela II mostra algumas características técnicas dos pós de AlN produzidos pelos processos RCN e ND. Os custos de produção do pó de AlN são dispendiosos devido às elevadas temperaturas de síntese [26,28] [29]. Dependendo da temperatura de síntese, os dois processos (RCN ou ND) podem resultar em pós de AlN com significativo residual de segundas fases oriundas das adições de agentes catalizadores.…”