Oxidation Behavior of ZrO2 Reinforced MoSi2 Composite Coatings Fabricated by Vacuum Plasma Spraying Technology

Abstract

In this work, MoSi 2 , MoSi 2 -20 vol.% ZrO 2 , MoSi 2 -40 vol.% ZrO 2 (denoted, respectively, as MZ0, MZ2, and MZ4) coatings were fabricated by vacuum plasma spraying technology. The oxidation behavior of the coatings was examined at 500, 1200, and 1500°C, respectively. Some basic properties of the coatings, including microhardness, porosity, and surface roughness were characterized. The tests at 500°C showed that the pest oxidation phenomenon of MoSi 2 coatings was restrained by the addition of ZrO 2 . The MZ2 coating exhibited excellent oxidation-resistant behavior both at 1200 and 1500°C. However, the MZ4 coating presented the impaired oxidation-resistant behavior at 1500°C, though the comparable oxidation property at 1200°C was still obtained.

Stability and electrical properties of MoSi2‐ and WSi2‐oxide electroconductive composites

“…It was reported in studies that their mechanical strength, fracture toughness and high‐temperature creep resistance could be substantially increased by reinforcing with Al 2 O 3 , ZrO 2 , SiC, and TiC . The refractory oxide addition of choice are typically Al 2 O 3 and ZrO 2 in these composite systems (mostly MoSi 2 –Al 2 O 3 and MoSi 2 –ZrO 2 ), since these materials have a close match of their thermal expansion coefficients (~8.0×10 −6 K −1 for Al 2 O 3 ; 9.6×10 −6 K −1 for ZrO 2 ) with MoSi 2 (8.2×10 −6 K −1 ) and WSi 2 (7.9×10 −6 K −1 ) in a wide temperature range from 20°C to 1400°C . This is very beneficial in composite systems for minimizing thermal stresses and interfacial cracks, and thus, for improving their thermal shock resistance and stability at high temperatures .…”

“…This is very beneficial in composite systems for minimizing thermal stresses and interfacial cracks, and thus, for improving their thermal shock resistance and stability at high temperatures . In addition, it is anticipated that oxygen diffusion pathways may be blocked by reinforcing with these oxidation‐resistant refractory oxides, and therefore, the high‐temperature oxidation resistance could be enhanced, while eliminating the problematic pest oxide formation . Zmii et al.…”

Magnesiothermal synthesis and consolidation of multicomponent powder ceramics in the Zr–Si–Mo–B system

“…Высокотемпературное окисление силицидов сопровождается образованием различных защитных пленок, состоящих из оксидов различного состава. Так, при окислении MoSi 2 на поверхности формируется защитный слой SiO 2 [17], который в условиях экстремально высоких температур (свыше 1800 °С) сильно утоняется за счет испарения кремния в виде монооксида SiО, что приводит к увеличению степени его дефектности и снижению эффективности защиты от окисления [18,19]. Окисление ZrSi 2 сопровождается образованием стекловидной фазы ZrSiO 4 /SiO 2 [20], которая выступает в качестве диффузионного барьера, эффективно препятствуя проникновению кислорода в объем керамики.…”