Preparation of ZrB2-MoSi2 high oxygen resistant coating using nonequilibrium state powders by self-propagating high-temperature synthesis

Menglin Zhang,Peizhong Feng,Xuanru Ren,Songsong Wang,Mingcheng Zhang,Qingqing Yang,Hongao Chu,Li Wang

doi:10.1007/s40145-021-0485-y

Abstract

To achieve high oxygen blocking structure of the ZrB2-MoSi2 coating applied on carbon structural material, ZrB2-MoSi2 coating was prepared by spark plasma sintering (SPS) method utilizing ZrB2-MoSi2 composite powders synthesized by self-propagating high-temperature synthesis (SHS) technique as raw materials. The oxygen blocking mechanism of the ZrB2-MoSi2 coatings at 1973 K was investigated. Compared with commercial powders, the coatings prepared by SHS powders exhibited superior density and inferior oxidation activity, which significantly heightened the structural oxygen blocking ability of the coatings in the active oxidation stage, thus characterizing higher oxidation protection efficiency. The rise of MoSi2 content facilitated the dispersion of transition metal oxide nanocrystals (5–20 nm) in the SiO2 glass layer and conduced to the increasing viscosity, thus strengthening the inerting impact of the compound glass layer in the inert oxidation stage. Nevertheless, the ZrB2-40 vol%MoSi2 coating sample prepared by SHS powders presented the lowest oxygen permeability of 0.3% and carbon loss rate of 0.29×10−6 g·cm−2·s−1. Owing to the gradient oxygen partial pressure inside the coatings, the Si-depleted layer was developed under the compound glass layer, which brought about acute oxygen erosion.

Highlights

IntroductionCarbon structural materials are widely exploited in aerospace high-temperature components, as indispensable structural materials in the national defense and civil fields, due to the low density, high specific strength,
Carbon structural materials are widely exploited in aerospace high-temperature components, as indispensable structural materials in the national defense and civil fields, due to the low density, high specific strength, Of the field of oxidation resistance coatings in recent years, ZrB2-based systems have been widely studied owe to their high melting point, low density, high thermal conductivity, and high strength at ultra-high www.springer.com/journal/40145J Adv Ceram 2021, 10(5): 1011–1024 temperature [8,9,10]
We have found that the dispersion of Zr-oxides in the Zr–Si–B–O compound glass layer would strengthen the oxidation protection effect of the coating [21]

Summary

Introduction

Carbon structural materials are widely exploited in aerospace high-temperature components, as indispensable structural materials in the national defense and civil fields, due to the low density, high specific strength,. Little work has been reported about the construction of ZrB2–MoSi2 high oxygen blocking coating structure. To improve the structural oxygen blocking ability of the coating, it is necessary to develop densification sintering technique at a lower temperature [22]. Self-propagating high-temperature synthesis (SHS) method has been widely exploited in the preparation of composites [26,27,28,29,30], which has superior heating and cooling rates, being conducive to generate high activity due to the concentration of defects and non-equilibrium phases in the products. The combination of SPS and SHS methods to prepare ZrB2–MoSi2 high oxygen resistant coating exhibits much potential, little work has been reported. The microstructure and forming mechanism of the self-generated compound glass layer were further analyzed

Experimental

4 Evaluation of oxygen blocking ability

Results and discussion

Conclusions