Effect of TiO_2 content on properties of Al_2O_3 thermal barrier coatings by plasma spraying

Al2O3 thermal barrier coatings with different TiO2 contents were deposited on 6061 aluminum alloy by plasma spraying. The corrosion resistance, thermal insulation property and phase composition of these coatings were investigated. The results indicate that all the feedstock powders exhibit phase transformation during the spray process. With the increase of the TiO2 content in the powder, the corrosion resistance of the coating is enhanced but the thermal insulation property is decreased. This can be attributed to the higher thermal conductivity but lower melting point and brittleness of TiO2 than those of Al2O3, so it is easy for TiO2 to disperse in the brittle Al2O3 substrate during spraying, in which these dispersively distributed TiO2 play the role of hole sealing, releasing stress and reducing cracks.

Preparation and Characterization of Alumina-coated Hollow Quartz Fiber Reinforced Al_(2)O_(3)-SiO_(2) Aerogel Composite

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.

Large‑scale Fabrication of Snake‑skin‑inspired Protective Composite Textiles

Inspired by the overlapping structure of snake scales,a reinforced scale-like knitted fabric(R-SLKF)was created in this work.To achieve this,short carbon fibers in an epoxy resin(ER)matrix were incorporated into the scales of an SLKF.The resulting textile is a highly stable protective composite that is flexible,warm,and thermally insulated.In addition,supe-rior stab-resistance is ensured through rigid protective blocks in the R-SLKF,making up a hard overlapping scale region,besides satisfactory flexibility via soft twisted ultra-high-molecular-weight polyethylene yarn-based textiles.The R-SLKF achieves high stab resistance(peak load of approximately 600 N for a single scale thickness of 2 mm),good flexibility(~290 mN cm),and breathability(100 MPa,423 mm/s),coupled with good warmth retention and thermal insulation prop-erties(0.28℃/s),which are superior to previously reported protective composite textiles.From the results,the combination of desirable individual protection,excellent wearability and comfort enables human beings to survive in extremely danger-ous environments.Finite element simulations provided valuable insights into the factors influencing the stab resistance of R-SLKF and elucidated the underlying anti-puncture mechanism in accordance with the experimental findings.This study presents a novel strategy for the facile industrial fabrication of flexible and lightweight protective composite textiles,which is expected to enhance the structure and material design for future innovations and provide advantages for personal protec-tive equipment in various industrial fields.