A method for preparing tungsten functional coating on the surface of niobium or niobium alloy at low temperature

Abstract

The invention discloses a method for preparing a tungsten functional coating on the surface of niobium or a niobium alloy at a low temperature. The method includes the following steps that firstly, the surface of a substrate is polished, and the substrate includes the niobium or the niobium alloy or a combination of the niobium and the niobium alloy; secondly, the polished substrate is buried into an embedding permeating agent to react, wherein the embedding temperature ranges from 200 DEG C to 300 DEG C, the heat insulation time ranges from 1 h to 10 h, the embedding permeating agent includes WCl6 powder, an activating agent and Al2O3 powder, all of which are evenly scattered, and the proportion of the WCl6 powder in the embedding permeating agent ranges from 25 wt.% to 55 wt.%; and thirdly, after heat insulation is over, the embedded substrate is cleaned and subjected to vacuum drying. By means of the embedding method, the substrate is put into the WCl6 embedding permeating agent, the substrate and the embedding permeating agent are subjected to a diffusion reaction at the temperature ranging from 200 DEG C to 300 DEG C, the coating can be obtained without adopting a high temperature or a pressurizing method, the requirement for equipment is lowered, and the method is suitable for scale production.

Description

technical field [0001] The invention relates to the technical field of coating preparation, in particular to a method for preparing a tungsten functional coating on the surface of niobium or niobium alloy at low temperature. Background technique [0002] When aerospace, nuclear industry and gas turbines are working, the blades must withstand high temperatures of 1000°C to 1200°C. Nickel-based high temperature is limited by its own melting point (about 1400°C), and its service temperature limit is only 1100°C. Therefore, it is imperative to develop high-temperature structural materials with higher service temperatures. Niobium belongs to the VB group of refractory metals with a bcc structure, which has a high melting point (2468°C), high strength, good ductility and thermal conductivity, low plastic-brittle transition temperature (-160°C), moderate density (8.6 g / cm 3 ), due to the good physical and chemical properties of niobium and its alloys, it is expected to replace nic...

AI Technical Summary

Problems solved by technology

Heat-resistant alloys and precious metals based on iron, nickel and chromium are often used as alloy coatings, but the bonding force between heat-resistant alloy coatings and niobium alloy substrates is poor, and the service temperature is also low, and it is easy to corrode and peel off under high temperature washing , the porosity of the coating provides a large number of diffusion channels for oxygen atoms. During long-term use, the interdiffusion between the protective layer and the substrate niobium alloy forms a brittle phase, which leads to the failure of the niobium alloy substrate, and there are problems of cumbersome process and high cost.

Images