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Synthesis of AlN Powder by Carbothermal Reduction‐Nitridation of Various Al2O3 Powders with CaF2
Author(s) -
Ide Takayuki,
Komeya Katsutoshi,
Meguro Takeshi,
Tatami Junichi
Publication year - 1999
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1999.tb02193.x
Subject(s) - carbothermic reaction , materials science , particle size , raw material , particle (ecology) , particle size distribution , molar ratio , chemical engineering , catalysis , mineralogy , metallurgy , chemistry , organic chemistry , carbide , oceanography , engineering , geology
We investigated the effect of characteristics of raw Al 2 O 3 powder on the synthesis of AlN by the carbothermal reduction‐nitridation method, in which CaF 2 was added as a catalytic material. Four types of Al 2 O 3 powders were selected. An Al 2 O 3 /C molar ratio of 0.29 was fixed, and the amount of CaF 2 was varied from 3 to 30 wt%. The carbothermal reduction‐nitridation was conducted from 1350° to 1450°C in N 2 flow. The nitridation rate tended to increase with decreasing particle size of raw Al 2 O 3 and was found to depend on the Al 2 O 3 synthesizing method. The particle sizes of the synthesized AlN increased somewhat with increasing reaction temperatures. However, even though different particle sizes of Al 2 O 3 powders were used, AlN powders synthesized under the same conditions exhibited almost the same particle size, round shape, and narrow size distribution. From XRD analysis, CaO·6Al 2 O 3 and CaO·2Al 2 O 3 were identified as intermediate compounds during these reactions. The above phenomena suggest that the synthesis mechanism of AlN powder by carbothermal reduction‐nitridation of Al 2 O 3 with CaF 2 addition was the nitridation of the intermediate compounds through the liquid phase of the system CaF 2 ‐CaO·6Al 2 O 3 ‐CaO·2Al 2 O 3 .