Static oxidation behaviour of silicide coating onniobium alloy at high temperature
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering,
Ministry of Education, Central South University, Changsha 410083, China)
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering,
Ministry of Education, Central South University, Changsha 410083, China)
Abstract: A silicide coating was prepared on the surface of the Nb521 alloy by the complex pack cemented method. The oxidation resistance properties of the present coating were examined by the static oxidation tests at 1 700 ℃ in air. The compositions and the microstructures of the coating before and after test were characterised and analysed through scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), energy dispersive X-ray spectrometry (EDS) and electron probe microanalysis (EPMA), respectively. The present silicide coating can provide an effective protection for the Nb alloy for 25 h at 1 700 ℃ in air. The results show that the oxidation kinetics of the present silicide coating is parabolic. The diffusion of Si leads to the phase transformation and evolution during the oxidation.
Key words: niobium alloy; silicide coating; static oxidation; diffusion; phase transformation