Solid state reactions between SiC and Ir

Abstract

Reactivity between SiC and Ir as a function of SiC-crystallinity was investigated by diffusion bonding technique under a vacuum and over the temperature range of 1200-1450°C. As reaction products, various Irsilicides and free unreacted-C were detected. Reactivity is strongly affected by the temperature and SiCcrystallinity involving a series of interactions, from "no reaction" to "massive exothermic reactions". In particular, interfacial phenomena are more pronounced by the presence of defects and grain boundaries.Solid state reactions result in formation of fine C-precipitates rearranged in a quasi-periodic microstructure.On the contrary, clustering of highly ordered C-precipitates (C-graphitized) occurs after "massive reactions" take place.A relationship between the degree of graphitization (from 1 to multi-layers of graphene), temperature and SiC crystallinity was found by Raman spectroscopy. 2D-layering phenomenon is enhanced in polycrystalline SiC at high temperature.

Toward understanding the reaction between silicon carbide and iridium in a broad temperature range

“…The aforementioned studies mainly focused on the phase composition of the products. Camarano et al 25,26 have recently reported more details about the behavior of the Ir/SiC diffusion couple. No reaction between iridium and SiC was revealed in the 1200°C-1350°C temperature range; the first evidence of the reaction between hot-pressed SiC and Ir was detected only at 1375°C.…”

“…Another important finding was the formation of silicides with silicon content more than 50 at% (namely, Ir 4 Si 5 , Ir 3 Si 5 , and Ir 3 Si 4 ) in the immediate vicinity of SiC at 1450°C. 25,26 It was proposed that the formation of these silicide phases was possible due to silicon supersaturation at the boundary with SiC grains. It should be emphasized that Ir 2 Si silicide has never been detected as a product of the reaction between SiC and iridium.…”

“…No references were found on modeling of the PIP process for CMCs, though experimental studies on this manufacturing process have been reported. Studies on polycarbosilanederived SiC ceramic 25 and SiC/SiC composite 26,27 have shown that porosity decreases and mechanical properties improve with the increasing number of PIP cycles. Zhu et al 28 show that increasing pyrolysis temperature and the concentration of SiC fillers in polycarbosilane polymer result in improved mechanical properties in two-dimensional Carbon/ SiC (C/SiC) composites fabricated using the PIP process.…”

SiC-IrSi3 for High Oxidation Resistance

“…Therefore, it is logical to think that a SiC-IrSi X composite material will be a material with high resistance to oxidation. Previous studies by the authors have analyzed the compatibility of SiC with Ir [28] and the process of reactive infiltration of Si-Ir alloys in SiC-C porous preforms [29], where the infiltration process has been optimized, and SiC-IrSi 3 composite has been manufactured.…”

SiC-IrSi₃ for High Oxidation Resistance

“…Therefore it is logical to think that a SiC / IrSiX composite material will be a material with a high resistance to oxidation. Previous studies of the authors have analyzed the compatibility of SiC with Ir [28] and the process of reactive infiltration of Si-Ir alloys in SiC-C porous preforms [29], where the infiltration process has been optimized, and SiC/IrSi3 composite has been manufactured.…”