Study of the nitridation process of TiSi2 powder

Abstract

This paper reports on the nitriding process of TiSi 2 micro/submicrometer-sized powders. TiSi 2 powders were treated under nitrogen flow, at 1100°C, during various durations. The composition and morphology of the nitride powders are characterized by X-ray diffraction and observed on cross-section, prepared using ion polishing system by scanning electron microscopy whereas the chemical composition is analyzed by energy dispersive X-ray spectroscopy. All these analyses revealed that under nitrogen flow, TiSi 2 grains are first transformed into a core-shell structure composed of TiN, surrounding by Si. Long nitriding treatments result in the complete transformation of Si 3 N 4. These results are discussed in terms of various diffusion limitation phenomena.

Manufacturing of ceramic matrix composite using a hybrid process combining TiSi2 active filler infiltration and preceramic impregnation and pyrolysis

“…It is attributed to the transformation of TiSi 2 into free silicon and TiN according the Equation 1 (partial nitridation), into the surface and inside the grains. The mass gain corresponds to around 14 % that is expected [22] .…”

“…Under nitrogen atmosphere, the nitridation of TiSi 2 starts around 1000°C, and leads to the formation of TiN (d = 5.43 g/cm 3 ) and Si 3 N 4 (d = 3.19 g/cm 3 ) with a 57 volume percent increase when the reaction is complete. It is well-known that the powder size can influence the reaction rate; therefore several studies were performed to prepare ceramic composites with a small size powder obtained by ball-milling [20][21][22] . To control the process, the nitridation of TiSi 2 must be well understood.…”

Ceramic Matrix Composites Manufactured by Multistep Densification of Si‐O‐C Fibre Preform

“…This observation shows that the powder is impregnated into the inter-bundle macropores. The TiSi 2 nitridation created TiN, Si 3 N 4 and free Si phases [23] . Preforms used were consolidated with the resin A, therefore it is not always possible to determine if the observed ceramic residue is the results of the consolidation by the final PIP cycle.…”

“…As it has been suggested by P. Greil in the case of ceramic preparation, this problem could be overcome with the use of active fillers, which react during pyrolysis under reactive atmosphere to form oxides, carbides or nitrides leading to a significant volume expansion that can decrease the matrix porosity [11][12][13][14][15][16][17][18][19][20] . Among various expansion agents, titanium disilicide powder (TiSi 2 ) is identified as an interesting active filler [20][21][22][23] . Under nitrogen atmosphere, the nitridation of sub-micronic TiSi 2 powder starts around 1000°C, and leads to the formation of TiN (d = 5.43 g/cm 3 ) and Si 3 N 4 (d = 3.19 g/cm 3 ) with a large volume increase even if the reaction is incomplete.…”

Isothermal nitridation kinetics of TiSi2 powders

“…This kind of composite can be easily obtained by self-propagating high temperature synthesis (SHS) under nitrogen atmosphere [17]. Previous studies undertaken on the nitridation of TiSi 2 powders demonstrated that the nitridation of this compound is a two stepped mechanism [18][19][20]. The influence of the temperature factor was also reported with a noticeable acceleration of the kinetics above 1100°C.…”