Effects of Surface Oxide on the Nitridation Behavior of Aluminum Particles
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I.
INTRODUCTION
ALN is used as a basic material for various applications in the electronic devices and structural parts because of its excellent properties including high thermal conductivity, low coefficient of thermal expansion that matches the coefficient of thermal expansion of silicon, considerably high electrical resistivity, low dielectric constant, high dielectric strength, good mechanical strength, and chemical stability.[1–3] Two methods, the carbothermal reduction and nitridation of alumina with a reducing agent (carbon) and the direct nitridation of Al powder in a nitrogen atmosphere, have been widely used for the commercial fabrication of AlN powder.[1–4] Between the two methods, the direct nitridation of Al powder in nitrogen atmosphere offers several advantages owing to its methodological simplicity. In addition, the raw materials are inexpensive, and the method uses low fabrication temperatures.[3] In the presence of nitrogen gas, Al can SUNG-HOON KIM, Master Student, is with the Advanced Analysis Center, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok-dong, Wolsong-gil 5, Seongbuk-gu, Seoul 130-650, Republic of Korea, and also with the Department of Materials Science and Engineering, Korea University, Anam-dong 5-1, Seongbuk-gu, Seoul 136-701, Republic of Korea. JAE-HONG NOH, Research Scientist, and JAE-PYOUNG AHN, Principal Research Scientist, are with the Advanced Analysis Center, Korea Institute of Science and Technology (KIST). JAE-CHUL LEE, Professor, is with the Department of Materials Science and Engineering, Korea University. HOON KWON, JAEGAB LEE, and KON-BAE LEE, Professors, are with the School of Advanced Materials Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Republic of Korea. HEANG RYEAL YANG, Professor, is with the School of Engineering/Department of Vehicle Engineering, University of Incheon, 235, Dowha-dong, Incheon 402-750, Republic of Korea. Contact e-mail: [email protected]; [email protected]; [email protected] Manuscript submitted March 22, 2014. Article published online November 4, 2014 496—VOLUME 46A, JANUARY 2015
readily react according to the following Eq. [1] under the atmosphere of nitrogen gas. From thermodynamic calculations, it is known that Reaction [1] can initiate at room temperature[3,5–7] and during reaction, additionally, generate highly exothermic heat of 319.7 kJ/mol[4,7] AlðlÞ þ 1=2N2 ðgÞ ¼ AlNðsÞ
½1
Although direct nitridation offers many advantages compared to the carbothermal method, the detailed fabrication route is not well known because of the extensive protection of the know-how by fabrication companies.[3] Although the direct nitridation offers many advantages compared with the carbothermal method, the details for the fabrication route are not well known because of the extensive protection of the know-how by fabrication companies.[3] Most studies on direct nitridation have been carried out by both morphological observations of reaction products and thermodynamic calculations.[2–4,8,9] The direct nitr
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