Preparation of Niobium Disilicide Coating by Heating Niobium in a Sodium–Silicon Melt

Abstract

A Niobium disilicide (NbSi2) layer was formed at the surface of Nb plates by heating those plates with Si powder and a piece of Na at 1000­1200K for 1­48 h. The thickness of the NbSi2 layer increased to 129μm with increasing temperature and in proportion to the square root of the heating time. The activation energy of the NbSi2 layer formation evaluated from the Arrhenius plot of parabolic growth constants was 160 kJmol11. NbSi2-coated Nb plates retained their shapes after heating at 1100­1700K for 10 h in air. Oxidation of the inner Nb of the plates was prevented. [doi:10.2320/matertrans.MAW201213]