Gradient Laser Coating on Graphite in the Zrb₂–MoSi₂ System

Abstract

A high-temperature coating on graphite in the Zrb₂–MoSi₂ system is obtained by pulsed laser melting (in air) of a graphite sample with powder layers pre-deposited on the working surface. It is demonstrated that the laser melting is accompanied with an intensive phase formation in the layers and on the interface boundary. The main phases of the surface are: ZrB₂, MoSi₂, Mo₅Si₃, and ZrC. It is demonstrated that the coating forms with the liquid phase reinforced with ~1 μm thick fibers. It is characterized by a gradient change of the composition towards the base: the content of ZrC increases and the content of а ZrB₂ decreases towards the graphite substrate. Such a change in the composition supposes an enhanced adhesive strength of the coating.