title: Densification Kinetics and Structural Evolution During Microwave and Pressureless Sintering of 15 nm Titanium Nitride Powder.
abstract: Microwave sintering (MWS) of commercially available 15-nm-size nanocrystalline TiN powder was studied. Densification kinetics and grain growth mechanisms of nano-TiN were evaluated using non-isothermal heating up to 1500 °C with variable heating rates. A true nanocrystalline ceramic with ~80-nm-size grains and 94.5 % theoretical density was obtained via MWS consolidation at 1400 °C. At higher temperatures, however, an uncontrolled grain growth and a formation of bimodal microstructure were noticed. A temperature dependence of grain growth suggested grain boundary sliding as a primary mechanism of densification below 1100-1200 °C. An activation energy of nano-TiN densification under MWS varied from 26 ± 3 kJ/mol at the initial stage of sintering (900-1200 °C) to 162 ± 22 kJ/mol at higher temperatures. In addition, a relationship coupling microstructural characteristics (grain size, grain boundary) with mechanical properties of titanium nitride ceramics obtained via both microwave and pressureless sintering techniques was discussed.
authors.affiliation: Frantsevich Institute for Problems of Materials Science, 3, Krzhizhanovsky str., 03680, Kiev, Ukraine. ostap@materials.kiev.ua.
authors.forename: Ostap
authors.initials: O
authors.lastname: Zgalat-Lozynskyy
authors.affiliation: Frantsevich Institute for Problems of Materials Science, 3, Krzhizhanovsky str., 03680, Kiev, Ukraine.
authors.forename: Andrey
authors.initials: A
authors.lastname: Ragulya
keywords: Activation energy; Grain boundary; Grain growth; Microwave sintering; Nanoparticles; TiN