The Preparation And Degradation Behavior Of Oxide Doped Aluminide Coating System

With the progress of the modern power industry,especially the continuous development in the aviation,automobile and other industrial fields,hot parts such as the gas turbine and the engine are getting higher and higher operating temperature,so applying a high temperature protective coating on the surface of the superalloy can effectively solve the problem of degeneration of hot-end components in a high-temperature environment.The aluminide coating is widely used because it can form metallurgical bond with the matrix material due to its reaction with the matrix material and because of a good adhesion performance,simple coating preparation process and low cost.However,the aluminide coating is brittle and easy to peel,its degradation rate is high,and diffusion easily occurs between the coating and the substrate.Therefore,it is desired to design and prepare a new aluminide coating system with a new structure,which can hinder the mutual diffusion between the coating and the substrate,and also has excellent high temperature oxidation resistance,slow down the spalling and degradation rate,and prolong the service life of the high temperature alloy.Using a composite electrodeposition process,the nickel-based matrix material was placed into doped oxides of nano-Ce O₂?concentrations of 2g/L,10g/L,20g/L?,micro-Ce O₂?concentration of 10g/L?,Al₂O₃?concentration of 20g/L?,nano-Ce O₂ gradient?with a concentration distribution of 2 g/L and 20 g/L from outside to inside?and a plating solution without any oxide added.Then through the powder embedding aluminizing method,the plating part is placed in a self-designed vessel,and the aluminizing is carried out with the furnace heating up to 650°C for 5 hours to prepare a series of oxide-doped aluminide coatings with different types,compositions and contents.Through the atmosphere furnace,the prepared infiltrated parts were respectively annealed at 1000°C for 10 minutes/1 hour and isothermally oxidized for 20 hours.The cross-section thickness and the cross-section structure of the plated part were observed with an ultra-deep-depth microscope.The morphology,phase composition and the distribution of Al,Ni and other elements in the coating were analyzed by SEM,XRD and EDS.The surface,cross-sectional morphology,microstructure and structural characteristics of the aluminide coatings doped with different types,different particle sizes,and different contents of oxides after vacuum annealing and high temperature oxidation were investigated to the degradation and oxidation behavior of the coating system.The effects of the type,particle size and concentration of doped oxides on their degradation behavior were analyzed and summarized,which provided references for the preparation of rare earth oxide doped aluminide coatings and their degradation behaviors.