Influence of MoSi2 on oxidation protective ability of TaB2-SiC coating in oxygen-containing environments within a broad temperature range

Abstract

TaB 2-SiC coating modified by different content of MoSi 2 was fabricated on graphite substrate with SiC inner coating by liquid phase sintering to elevate the anti-oxidation capability of the TaB 2-SiC coatings. As compared to the sample with the TaB 2-40wt%SiC coating, the coating sample modified with MoSi 2 exhibited a weight gain trend at lower temperatures, the fastest weight loss rate went down by 76%, and the relative oxygen permeability value reduced from about 1% to near 0. More importantly, the large amount of SiO 2 glass phase produced over the coating during oxidation was in contact with the modification of MoSi 2 , which was proved to be beneficial to the dispersion of Ta-oxides. A concomitantly formed continuous Ta-Si-O-B compound glass layer showed excellent capacity to prevent oxygen penetration. However, when the TaB 2 content was sacrificed to increase the MoSi 2 content, the relative oxygen permeability of the coating increased instead of decreased. Thus, on the basis of ample TaB 2 content, increasing the MoSi 2 content of the coating is conducive to reducing the relative oxygen permeability of the coatings in a broad temperature region.

Oxidation inhibition behaviors of HfB2‐MoSi2‐SiC oxygen blocking coating prepared by spark plasma sintering

“…19,20 In our previous work, we have found that the MoSi 2 phase has a great influence on the enhancement of the oxidation inhibition ability of the generated compound glass layer. 21 Furthermore, we have prepared the HfB 2 -MoSi 2 -SiC coating by in situ synthesis method, which could protect the C/C composites from oxidation at 1773 K in air for 408 h, exhibiting good application potential. 22 Since the defects in the coating itself and the selfgenerated glass layer are the main oxygen diffusion channels, the dynamic stability of the coating to inhibit the generation of defeats greatly affects the oxygen blocking effect of the coatings.…”

“…Among the silicides, MoSi 2 is not only an excellent glass‐forming substance, but also an outstanding sintering additive 19,20 . In our previous work, we have found that the MoSi 2 phase has a great influence on the enhancement of the oxidation inhibition ability of the generated compound glass layer 21 . Furthermore, we have prepared the HfB 2 ‐MoSi 2 ‐SiC coating by in situ synthesis method, which could protect the C/C composites from oxidation at 1773 K in air for 408 h, exhibiting good application potential 22 …”

Fabrication and microstructure evolution of Csf/ZrB2-SiC composites via direct ink writing and reactive melt infiltration

“…Generally, C sf /UHTCs are prepared by ceramic processing, such as hot pressing [11][12][13], spark plasma sintering [14][15][16], pressureless sintering, and reactive melt infiltration (RMI). For the C sf /UHTCs composites fabricated by these conventional methods, there are two main bottlenecks.…”

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

“…However, ZrB 2 is challenging to achieve densification due to its strong covalent bond and low diffusion coefficient [11,12], which would also become porous during the oxidation process [13]. To suppress such defects, MoSi 2 , the most commonly used sintering additive, was generally used to increase the compactness of ZrB 2 [14,15]. Moreover, the excellent film-forming properties of MoSi 2 can effectively reduce the oxidation consumption of ZrB 2 , thus making the ZrB 2 -MoSi 2 coating present great potential [16][17][18].…”