A preparation method of infiltrated layer for improving high temperature oxidation resistance of k444 alloy

Abstract

The invention belongs to the field of thermal treatment and particularly relates to a method for manufacturing a penetration layer for improving the high-temperature-oxidation resistance of K444 alloy. The method includes the steps that silicon powder, nickel-aluminum alloy powder, ammonium chloride, ammonium bifluoride, a bonder and a diluting agent are mixed into paste and the surface of a part made of the K444 alloy is sprayed with the paste; secondly, a well type thermal treatment furnace protected through argon gas is adopted, a sample is arranged in a clamp and protected through the argon gas, and an aluminum-silicon coating is obtained after heat is preserved; and thirdly, in order to achieve the purposes that the fragility of the surface of the aluminum-silicon penetration layer is reduced and by weight, aluminum on the outer surface of the penetration layer is larger than 10% and the silicon is smaller than 8%, the part made of the K444 alloy subjected to aluminum-silicon penetration is placed in a vacuum furnace for diffusion treatment. By the adoption of the penetration layer, the high-temperature-oxidation resistance of the K444 alloy can be remarkably improved and the penetration layer is suitable for being used for parts working in a severe environment for a long time and especially suitable for turbine blades of a gas turbine, and the service life of the blades can be prolonged.

Description

technical field [0001] The invention belongs to the field of heat treatment, in particular to a method for preparing an infiltrated layer for improving the high-temperature oxidation resistance of K444 alloy. Background technique [0002] The blades of the gas engine are made of K444 alloy. K444 alloy is a hafnium-containing nickel-based cast superalloy with excellent thermal corrosion resistance, moderate high-temperature strength and good structural stability. The blade is an important hot-end part of the engine. In addition to bearing complex alternating stress, it also suffers from high-temperature oxidation and severe gas corrosion. For this reason, many high-temperature protective seepage layers have been developed at home and abroad to improve the oxidation resistance of the blade surface, so as to improve the reliability of the turbine blade and prolong its service life. Although the protective seepage layer can make the blade obtain good protection performance, it ...

AI Technical Summary

Problems solved by technology

At high temperature, the activated aluminum and iron blocks react to decompose active aluminum atoms, and the argon carrier gas absorbs and infiltrates the surface of the workpiece to form an aluminized layer, which improves the ability to resist high temperature oxidation and gas corrosion. The process stability is not enough, and the concentration of aluminum in the permeated layer is low

Both of these two processes form an aluminide coating mainly composed of NiAl phase on the surface after high-temperature diffusion treatment. The NiAl phase will decompose and degrade due to the diffusion of aluminum to the inside and outside, and the oxidation resistance will decrease with the prolongation of the service time of the compound coating at high temperature.

Images