Thermal barrier coatings on niobium-based alloys structural materials

V P Babak,O V Kharchenko,T T Suprun,S D Kharchenko,V V Shchepetov

doi:10.20535/2521-1943.2019.86.189071

Abstract

During thermocyclic creep, the properties of a niobium alloy with a two-layer combined coating were studied at a temperature of 1400 ºС in air. A comparison of the data obtained with other coatings is made. The role of the shape and distribution of cracks in the mechanism of strength degradation of coatings is investigated. Consideration of many factors in the formation of the combined coating ensured an increase in its durability of 1.9...8.5 folds depending on the temperature mode of creep.The applied structural materials do not provide the relevant requirements for the development of modern technology, the need to increase their functionality. Thus, the operational capabilities of nickel alloys, which for decades have provided the aerospace complex, have almost reached the upper limit. One of the actually directions for solving the existing situation is the alternative use of new generation heat-resistant materials for modern highly reliable equipment. For example, the use of niobium-based alloys, the prospect of which is due to their physicomechanical properties than excellent similar products.

Highlights

The development of coatings on niobium alloys has been the subject of many theoretical and applied studies, in particular, common reference [1,2,3,4,5]
The aim of the article is to generalize the experimental data on determining the properties of coatings under thermocyclic creep and long-term strength of a niobium alloy (Nb-Zr-С type) with a two-layer combined coating at temperatures of 1400°C in air and analyze the obtained experimental values with the properties of diffusion silicide coatings, as well as compare their degradation results under conditions creep
Three coatings were tested: I – silicide composition of Si-Fe-Cr-Ti slip method; in the borosilicidal coating (II) – borosilicidal composition of Si-B-Ti slip method; in samples with coating (III) – a complex coating with a plasma sublayer of molybdenum disilicide (MoSi2) with an outer diffusion alloying of the surface layer with elements, the main ones being silicon and boron

Summary

Introduction

The development of coatings on niobium alloys has been the subject of many theoretical and applied studies, in particular, common reference [1,2,3,4,5]. It should be noted that the most effective results on the protection of niobium alloys were obtained by the method of vacuum activated diffusion alloying [8]. This method provides a complex coating on niobium. The application of coatings on niobium alloys in liquid metal melts is widely used [9]. Fusible metals with alloying elements are used as transport melts

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