Silicon carbide ceramics SHS-produced from mechanoactivated Si–C–B mixtures

Abstract

We investigated the influence of mechanical activation (MA) and initial temperature T 0 on combustion temperature T c and burning velocity U c for 90% (Si + C) -10% (4B + C) mixtures as well as on product morphology. Mechanical activation was found to strongly change the size and morphology of Si and graphite particles (by a factor of 6-8), lead to accumulation of micro strains, and increase the reactivity of green mixture. An increase in T 0 was found to proportionally increase the values of T c and U c but produce little or no influence on the phase composition of product. The SiC powder consisting of 50-100 nm crystal lites was obtained by diminution of combustion product and then used to prepare, by hot pressing, a ceramic PVD target for magnetron sputtering.

SHS of Silicon‐Based Ceramics for the High‐Temperature Applications

“…For example, SHS of compositions TaSi 2 –50%SiC and TaSi 2 –70%SiC was characterized by the E eff of 380 and 240 kJ mol −1 , correspondingly. These values of E eff signify the increase of the amount of Si melt during the combustion and formation of larger amounts of β‐SiC in the combustion products . The crystallization of β‐SiC from Si melt is not hindered by the diffusion of reagents through the layers of already‐formed reaction products.…”

“…TaSi 2 , TaC, Ta 5 Si 3 , and SiC are formed as the primary products in the combustion zone. In the post‐combustion zone, TaC and Ta 5 Si 3 interact with leftover Si and C, producing secondary nanosized grains of TaSi 2 and SiC …”

Structure, Properties, and Oxidation Resistance of Prospective HfB2–SiC Based Ceramics

“…Кроме того, учитывая масштаб гетерогенности 4-компонентной порошковой системы, кристаллизация зерен HfB 2 возможна из пересыщенного бором расплава бинарной эвтектики Hf-Si (t пл = 1330 °С). Карбид кремния SiC образуется по механизму реакционной диффузии из пересыщенного углеродом кремниевого расплава [25,38].…”

Self-propagating high-temperature synthesis of advanced materials and coatings

“…and provides a highly dense, uniform structure that exhibits the required mechanical, thermal, and electrical properties needed for composite PVD target materials. During the last decades various SHS-composite targets have been developed and synthesised for deposition of hard tribological and heat resistant coatings (TiC x , TiB x , TiSi x , CrB 2 , TiCB, TiBN, TiSiN, TiSiC, TiSiB, TiCrB, TiCrC, TiAlC, TiAlB, TiMoC, TiZrC, SiCB, TiTaMoC, TiAlBN, TiAlSiB, TiAlBO, TiAlSiCN, TiCrSiCN, TiSiBCN) [320,[333][334][335][336][337][338]. More recently, the studies of chemical reactions and structure formation during CS of Cr-Al-Si-B [339] and Mo-Si-B [129,130] were carried out to design high-temperature targets and electrodes for coating deposition.…”