SiC f /SiC composites have emerged as one of the most promising materials for aero-engine hot-end structures. However, their performance is limited by their susceptibility to oxidation and corrosion reactions with oxygen and water vapor. To overcome this challenge, antioxidant-modified phases are introduced into matrices of SiC f /SiC composites which improve their water and oxygen resistance. In this study, the resistance of SiC f /SiC composites modified by yttrium silicate matrix (SiC f /SiC-YS composites) to air at 1000–1400°C and water-oxygen environments at 1200°C was investigated. The diffusion paths of oxygen in SiC f /SiC-YS composites and the antioxidant behavior of the yttrium silicate matrix were discussed. Additionally, the differences in oxygen and water-oxygen corrosion resistance of SiC f /SiC-YS composites at the same temperature were compared. The strength retention of SiC f/ SiC-YS composites after oxidation and water-oxygen corrosion at 1200°C were 138.6% and 108.8%, respectively. This indicates that the addition of water vapor accelerated the degradation of SiC f /SiC-YS composites. By comparing with SiC f /SiC composites, it can be concluded that the modification of the yttrium silicate matrix considerably improved the oxidation resistance of SiC f /SiC composites.
In this study, a reactive hindered phenol antioxidant, 3,5-di- tert -butyl-4-hydroxyphenyl methyl isobutylene ester (DBHMIE), was synthesized and used to improve the antioxidant performance of ABS (acrylonitrile-butadiene-styrene terpolymer) resin. The chemical structure of DBHMIE was determined with Fourier transform infrared spectroscopy, 1 H nuclear magnetic resonance (NMR), and 13 C NMR spectroscopy. Moreover, the effects of the DBHMIE content on the antioxidant capabilities, thermal stabilities, tensile strengths, impact strengths, and morphologies of the ABS/antioxidant systems were investigated. The results indicated that the oxidation induction temperatures of the systems increased from 229.7 to 245.4°C as the DBHMIE content was increased from 0 to 0.5 wt%. The 5% mass loss temperature of the system was increased from 338.4 to 347.8°C by the addition of 0.3 wt% DBHMIE. The impact strengths of the systems increased with increasing DBHMIE content up to 0.1 wt% and then decreased. The addition of DBHMIE did not significantly affect the tensile strength of the ABS resin. SEM images showed that the DBHMIE was uniformly distributed in the ABS resin at low DBHMIE contents and agglomerated at high DBHMIE contents.
Luyu Cao,Si-Min Gu,Bomei Liu,Lin Huang,Jian Zhang,Yiwen Zhu,Jing Wang
Tin-based perovskites are becoming promising alternatives to lead-based perovskites with eco-friendly merit and tantalizing photophysical properties. Unfortunately, the lack of facile, low-cost synthesis approaches associated with extremely poor stability greatly restrict their practical applications. Herein, a facile room-temperature “coprecipitation” method utilizing ethanol (EtOH) solvent and salicylic acid (SA) additive is proposed for synthesizing highly stable cubic phase CsSnBr3 perovskite. Experimental results show that ethanol solvent and SA additive can not only effectively prevent the oxidation of Sn2+ during the synthesis processes but also stabilize the as-synthesized CsSnBr3 perovskite. These are mainly ascribed to the protection effect of ethanol and SA, which are attached on the surface of CsSnBr3 perovskite by coordinating with Br– and Sn2+ ions, respectively. As a result, CsSnBr3 perovskite can be obtained in open air and exhibits exceptional oxygen resistibility under moist air conditions (temperature: 24.2–25.8 °C; relative humidity: 63–78%). Absorption remains unchanged and photoluminescence (PL) intensity is vastly maintained (∼69%) after storage for 10 days, better than bulk CsSnBr3 perovskite film synthesized by spin-coating method whose PL intensity is decreased to 43% after storage for 12 h. This work represents a step toward stable tin-based perovskite by a facile and low-cost strategy.
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