Yoon, JK Kim, GH Han, JH Shon, IJ Doh, JM Hong, KT 2024-01-21T04:08:57Z 2024-01-21T04:08:57Z 2021-09-02 2005-11 0966-9795 https://pubs.kist.re.kr/handle/201004/136030 The microstructure and oxidation property of NbSi2/alpha-Si3N4 nanocomposite coating formed on Nb substrate by a prior nitridation process followed by pack siliconizing process were investigated. The Nb-nitride layers formed by nitridation process at 1300 degrees C consisted of two layers, i.e. the outer layer of mixed nitrides of NbN and Nb4N3 and the inner layer of Nb2N. While the monolithic NbSi2 coating showed the typical columnar microstructure perpendicular to the Nb substrate, the NbSi2/alpha-Si3N4 nanocomposite coating formed by the solid-state displacement reaction of the outer Nb-nitride layer with Si was composed of the equiaxed NbSi2 grains and the alpha-Si3N4 particles with the oblate-spheroidal shape, which were mostly located at the grain boundaries of NbSi2. The average size of equiaxed NbSi2 grains and alpha-Si3N4 particles were about 44-125 and 33-45 nm, respectively. The nanocomposite coating formed by the solid-state displacement reaction of the inner Nb-nitride layer with Si showed the columnar microstructure. The average diameters of NbSi2 grains and the alpha-Si3N4 particles were about 255 and 43 nm, respectively. The volume percentage of alpha-Si3N4 particles ranged from 16.8 to 24.4% with respect to nitrogen concentration in Nb-nitride layers. No cracks were observed in the nanocomposite coating, indicating that its thermal expansion coefficient was close to that of Nb substrate. The isothermal oxidation resistance of NbSi2/alpha-Si3N4 nanocomposite coating in 80% Ar-20% O-2 atmosphere at 1100 degrees C was superior to that of monolithic NbSi2 coating. (c) 2005 Elsevier Ltd. All rights reserved. English ELSEVIER SCI LTD HIGH-TEMPERATURE STRENGTH PROTECTIVE-COATINGS THERMAL-EXPANSION NIOBIUM BEHAVIOR SYSTEM COMPOSITES SILICIDES KINETICS ALLOYS Microstructure and oxidation property of NbSi2/Si3N4 nanocomposite coating formed on Nb substrate by nitridation process followed by pack siliconizing process Article 10.1016/j.intermet.2005.02.012 1 INTERMETALLICS, v.13, no.11, pp.1146 - 1156 INTERMETALLICS 13 11 1146 1156 scie scopus 000230608400003 2-s2.0-21544482877 Chemistry, Physical Materials Science, Multidisciplinary Metallurgy & Metallurgical Engineering Chemistry Materials Science Metallurgy & Metallurgical Engineering Article HIGH-TEMPERATURE STRENGTH PROTECTIVE-COATINGS THERMAL-EXPANSION NIOBIUM BEHAVIOR SYSTEM COMPOSITES SILICIDES KINETICS ALLOYS composites oxidation coatings intermetallic and otherwise vapor deposition aerospace constructional uses