Al_(2)O_(3)–SiO_(2)sols were synthesized by using aluminum chloride hex hydrate and tetraethoxysilane(TEOS)as precursors,deionized water and ethanol mixture as the solvent,and propylene oxide as the coagulant aids.Al...Al_(2)O_(3)–SiO_(2)sols were synthesized by using aluminum chloride hex hydrate and tetraethoxysilane(TEOS)as precursors,deionized water and ethanol mixture as the solvent,and propylene oxide as the coagulant aids.Alumina coatings were prepared on the surfaces of hollow quartz filament fiber,then a new lightweight and thermal insulating material were successfully prepared by impregnatingAl_(2)O_(3)–SiO_(2)sol into a needle fabric made by coated hollow quartz filament fiber.The coated quartz fiber,aerogels and composites were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),nitrogen adsorption-desorption(BET),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile tests.The effects of different fiber and calcination temperatures on the microstructures and properties ofAl_(2)O_(3)–SiO_(2)composite aerogels were investigated.The test results indicate that the mechanical properties of the aerogels are improved by introducing quartz filament fabrics and the introduction of alumina coating improves the thermal stability of the material.Compared to other fibers,Al_(2)O_(3)-coated hollow quartz fiber has significant advantages as reinforcement for composite,and their tensile strength is well retained after high temperature heat treatment.展开更多
Al_(2)O_(3)-ZrO_(2)-TiO_(2)coatings were successfully prepared by plasma spraying Al_(2)O_(3)-ZrO_(2)composite powders with and without TiO_(2)addition.The effects of TiO_(2)on the phase composition,microstructure and...Al_(2)O_(3)-ZrO_(2)-TiO_(2)coatings were successfully prepared by plasma spraying Al_(2)O_(3)-ZrO_(2)composite powders with and without TiO_(2)addition.The effects of TiO_(2)on the phase composition,microstructure and properties of the Al_(2)O_(3)-ZrO_(2)coating were studied.The results show that the Al_(2)O_(3)-ZrO_(2)-TiO_(2)composite powder was composed of t-ZrO_(2),a-Al_(2)O_(3),m-ZrO_(2)and rutile,while the Al_(2)O_(3)-ZrO_(2)-TiO_(2)composite coating consisted of t-ZrO_(2),a-Al_(2)O_(3)and c-Al_(2)O_(3).The diffraction peaks of TiO_(2)could not be detected in the Al_(2)O_(3)-ZrO_(2)-TiO_(2)coating even up to10 wt%TiO_(2)addition.The reason may be that TiO_(2)was dissolved in the amorphous phase or formed solid solution with c-Al_(2)O_(3)phase in the coating during cooling.Compared with the Al_(2)O_(3)-ZrO_(2)coating,the as-prepared Al_(2)O_(3)-ZrO_(2)-TiO_(2)coating had denser microstructure,less microcracks and more amorphous phases.The density of the Al_(2)O_(3)-ZrO_(2)-TiO_(2)coating increased with the increase of TiO_(2)content.The Al_(2)O_(3)-ZrO_(2)-10 wt%TiO_(2)coating had the most uniform and dense microstructure,possessed higher toughness,adhesive strength and wear resistance compared with the Al_(2)O_(3)-ZrO_(2)coating,which was due to its lower porosity and more uniform microstructure.展开更多
文摘Al_(2)O_(3)–SiO_(2)sols were synthesized by using aluminum chloride hex hydrate and tetraethoxysilane(TEOS)as precursors,deionized water and ethanol mixture as the solvent,and propylene oxide as the coagulant aids.Alumina coatings were prepared on the surfaces of hollow quartz filament fiber,then a new lightweight and thermal insulating material were successfully prepared by impregnatingAl_(2)O_(3)–SiO_(2)sol into a needle fabric made by coated hollow quartz filament fiber.The coated quartz fiber,aerogels and composites were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS),nitrogen adsorption-desorption(BET),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and tensile tests.The effects of different fiber and calcination temperatures on the microstructures and properties ofAl_(2)O_(3)–SiO_(2)composite aerogels were investigated.The test results indicate that the mechanical properties of the aerogels are improved by introducing quartz filament fabrics and the introduction of alumina coating improves the thermal stability of the material.Compared to other fibers,Al_(2)O_(3)-coated hollow quartz fiber has significant advantages as reinforcement for composite,and their tensile strength is well retained after high temperature heat treatment.
基金the National Natural Science Foundation of China(Nos.51672067,51541208 and 51102074)the Natural Science Foundation of Hebei Province(Nos.E2018202034 and E2015202070)+1 种基金the Talent Training Project in Hebei Province(No.A2016002026)the Top Talents in Universities in Hebei Province(No.SLRC2017027)。
文摘Al_(2)O_(3)-ZrO_(2)-TiO_(2)coatings were successfully prepared by plasma spraying Al_(2)O_(3)-ZrO_(2)composite powders with and without TiO_(2)addition.The effects of TiO_(2)on the phase composition,microstructure and properties of the Al_(2)O_(3)-ZrO_(2)coating were studied.The results show that the Al_(2)O_(3)-ZrO_(2)-TiO_(2)composite powder was composed of t-ZrO_(2),a-Al_(2)O_(3),m-ZrO_(2)and rutile,while the Al_(2)O_(3)-ZrO_(2)-TiO_(2)composite coating consisted of t-ZrO_(2),a-Al_(2)O_(3)and c-Al_(2)O_(3).The diffraction peaks of TiO_(2)could not be detected in the Al_(2)O_(3)-ZrO_(2)-TiO_(2)coating even up to10 wt%TiO_(2)addition.The reason may be that TiO_(2)was dissolved in the amorphous phase or formed solid solution with c-Al_(2)O_(3)phase in the coating during cooling.Compared with the Al_(2)O_(3)-ZrO_(2)coating,the as-prepared Al_(2)O_(3)-ZrO_(2)-TiO_(2)coating had denser microstructure,less microcracks and more amorphous phases.The density of the Al_(2)O_(3)-ZrO_(2)-TiO_(2)coating increased with the increase of TiO_(2)content.The Al_(2)O_(3)-ZrO_(2)-10 wt%TiO_(2)coating had the most uniform and dense microstructure,possessed higher toughness,adhesive strength and wear resistance compared with the Al_(2)O_(3)-ZrO_(2)coating,which was due to its lower porosity and more uniform microstructure.
