The preparation and performance analysis of zirconium-modified aluminum phosphate-based high-temperature(RT-1500℃)resistant adhesive for joining alumina in extreme environment

High-temperature-resistant adhesives are critical materials in the aerospace field.The zirconium-modified aluminum phosphate-based adhesives developed in this work had the advantage of adjustable thermal expansibility,achieving a high matching of coefficient of thermal expansion(CTE)with alumina.The introduction of zirconium can significantly improve the thermal stability of the adhesive matrix,and the Zr/Al ratio substantially affects the various reaction processes inside the adhesive,especially the types of zirconium-containing compounds.Most of the zirconium-containing compounds in the A7Z3 adhesive were ZrO_(2) only when the mass ratio of zirconium hydroxide to aluminum hydroxide was 3:7,which was the key reason why it had the highest CTE.The room-temperature bonding strength of A7Z3 after heat treatment at 1500℃reached 67.2 MPa.After pretreatment at 1500℃,the high-temperature bonding strength of A7Z3 was greater than 50 MPa in the range of(room temperature)RT-1000℃.After 40 thermal cycles between RT and 1500℃,the bonding strength still reached 10 MPa.Physical bonding occurred at temperatures below 1000℃,while chemical bonding dominated above 1000℃based on the generation of Al5BO9 and mullite at the interfaces.

Poly(arylene ether nitrile)Dielectric Film Modified by Bi_(2)S_(3)/rGO-CN Fillers for High Temperature Resistant Electronics Fields

High-quality film capacitors are widely used in many fields such as new energy vehicles,electronic communications,etc.,due to their advantages in wide frequency response and low dielectric loss.The dielectric film is a crucial part of the film capacitor,and its properties have an important impact on the performance and use conditions of the film capacitor.In this work,a novel high-temperature-resistant dielectric film was prepared.Firstly,the Bi_(2)S_(3)/rGO-CN fillers were prepared by hydrothermal method combined with cyanation treatment,and then added to the poly(arylene ether nitrile)(PEN)matrix to prepare the dielectric film materials(PEN/Bi_(2)S_(3)/rGO-CN).After high temperature treatment,the fillers Bi_(2)S_(3)/rGO-CN reacted with the PEN matrix,and the composites materials transformed into a thermosetting hybrid film(PEN-Bi_(2)S_(3)/rGO)with gel content of 97.88%.The prepared hybrid dielectric films did not decompose significantly before 400℃,and showed a glass transition temperature(Tg)of up to 252.4℃,which could increase the effective use temperature of the materials.Compared with the composite films without heat treatment,they exhibit better mechanical properties,with further improvement in tensile strength and elastic modulus,and a decrease in elongation at break.The dielectric constant of the hybrid films can be up to 6.8 while the dielectric loss is only about 0.02 at 1 kHz.Moreover,the hybrid films showed excellent dielectric stability during temperature changes,and remain relatively stable before 250℃,which is suitable as a high-temperature-resistant high-dielectric material and is more advantageous for practical applications.

Difunctionalization of Alkynes： Synthesis of Novel Fluoropolymer Materials

A Pd-catalyzed multi-component carbonylative difluoroalkylation/perfluoroalkylation through the alkyne difunctionalization process has been developed. Besides, new functional fluoropolymer materials have been successfully synthesized. Owing to the presence of the fluorine element, the materials present excellent chemical resistance, high-temperature-resistance and outstanding hydrophobicity simultaneously, which may significantly make them great appealing in the industrial production and life science as well.