Investigation of the SHS mechanisms of titanium nitride by in situ time-resolved diffraction and infrared thermography

The self-propagating high-temperature synthesis (SHS) or combustion synthesis is a promising process to produce advanced ceramics due to the high purity of the elaborated materials and the very short synthesis time. Titanium nitride has been synthesised from pressed titanium powder and a nitrogen gas flow under a 0.1 MPa pressure. The influence of the addition of a TiN diluent was investigated. For the first time, SHS reaction mechanisms were determined from in situ time-resolved X-ray diffraction (TRXRD) experiments using the synchrotron radiation. These experiments were coupled with infrared thermography to study the propagation of the combustion reaction. It appeared that the initiation of the combustion reaction is due to the α-Ti to β-Ti phase transformation. A single δ-TiN phase was then produced from pressed titanium powder. The addition of a TiN diluent resulted in the synthesis of a multiphase material with the presence of the α-Ti, Ti2N and TiN phases. The combustion reaction propagates in a surface mode at a velocity ranging from 6.4 to 7.4 mm/s