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The design and preparation of infrared stealth materials that meet the application in complex environments is urgently demanded in military fields. In this paper, composites with low emissivity and thermal insulation are designed to be used for indoor and outdoor infrared stealth. Thereinto, nanoPE-MXene, yttrium oxide coated hollow glass microspheres (HGMs@Y 2 O 3) and polypropylene nonwoven (PPF) were used as low emission, insulation, and antifouling layers, respectively. The sandwich-structured composite reduce the infrared radiation temperature of the 80 °C heat source object to 33.9 °C , and the average infrared emissivity of 3-15 μm is only 0.17. In addition, the infrared stealth performance of the composite is not affected by environmental changes. More importantly, the composite exhibits excellent anti-fouling and ageing resistance performance, which lays the foundation for the practical application of efficient stealth infrared materials. [ABSTRACT FROM AUTHOR]

An air-coupled acoustic matching layer, based on hollow glass microsphere composite, was developed for air-coupled ultrasonic transducers. The effects of the matrix, powder series, and volume fraction were systematically analyzed by acoustic and rheological characterization. The optimized hollow glass microsphere-epoxy composite showed a superior air-coupling performance, with a characteristics acoustic impedance of 1.08 MRayl and attenuation coefficient of 0.05 dB/mm, respectively. To validate the developed composite, an air-coupled ultrasonic transducer was fabricated with piezoelectric ceramic vibrator, and its feasibility for application in a gas flowmeter was demonstrated. The developed composite exhibits a suitable air-coupling performance for a high-accuracy ultrasonic gas flowmeter. [ABSTRACT FROM AUTHOR]

While the 3D printing technology for cementitious composites has developed rapidly, a combination of 3DP technology and lightweight engineered cementitious composites (LWECCs) could improve many aspects of the construction industry. In this study, a fibre-reinforced high-performance LWECC for extrusion-based printing was proposed. First, six LWECCs were prepared, incorporating two kinds of hollow glass microspheres (HGMs) in varying replacement ratios of fly ash (FA) at 60 wt%, 80 wt%, and 100 wt%. In addition, polyvinyl alcohol (PVA) fibre was introduced given its shrinkage resistance and improvement in printability performance. Thereafter, fresh property (slump loss and setting time), unconfined compression strength (UCS), and flexural strength experiments thoroughly investigated the optimised LWECC design, which was later calibrated for the printing procedure via a printability assessment, including extrudability and buildability. The UCS, flexural strength, and densities of the printed and cast specimens were compared. Lastly, a microstructural investigation using a scanning electron microscope described the reinforcement mechanism of PVA fibre upon the performance of the printed structures and HGMs. The addition of HGMs significantly improve the lightweight property that reaches a value at 1384 kg/m3 but inevitably negates mechanical properties. The printed LWECC obtains 33.6 MPa for UCS and 9.29 MPa for flexural strength. When the printed filament was perpendicular to loading direction, superior toughness was observed, creating a 63% and 40% increase for UCS and flexural strength, respectively. [ABSTRACT FROM AUTHOR]

In order to reduce the urban heat island effect, nonwhite lightweight pigments with high near infrared reflectance were studied. Nickel Antimony Titanium Yellow Rutile pigments (TiNiY) coated hollow glass microspheres (HGM@TiNiY) with core-shell structure were prepared by a novel mixing slurry-sintering method. The Reflective property of HGM@TiNiY/SR composite coating prepared by mixing HGM@TiNiY with silicone resin (SR) was investigated by an UV–Vis–NIR spectrum analyzer. The results showed that the size distribution of TiNiY particles was from 150 to 450 nm with an average size of 230 nm, and the binding mode of TiNiY particles with HGM and the formation mechanism of TiNiY Shell were discussed. The UV–Vis–NIR reflectance of HGM@TiNiY/SR coating was not only better than that of others filled with HGM powders or TiNiY powders alone but also higher than that of the coating filled with the mixture of HGM and TiNiY powders at the same volume ratio. A possible mechanism of HGM@TiNiY/SR coating on thermal reflection was discussed. This clearly indicates that the pigment of HGM@TiNiY with core-shell structure could be applied as a good colour cool pigment. [ABSTRACT FROM AUTHOR]

A temperature resistant buoyant material, namely, fly ash cenospheres-hollow glass microspheres/borosilicate glass (FACs-HGMs/BG) for high temperature application, was prepared through a tert-butyl alcohol-based gelcasting process, with FACs and HGMs as the fillers and BG as the matrix, respectively. The effect of FACs addition on the mechanical and high-temperature performance of the FACs-HGMs/BG composites was studied. The composites containing different amounts of FACs displayed low density (0.44–0.89 g/cm 3 ), low Young's modulus (0.05–1.10 GPa), and relatively high compressive strength (2.78–9.75 MPa). Three stages, namely, elastic, plateau, and fracture stages, could be observed in the stress-strain curves. The compressive strength of the samples at high temperature was lower than the ones at room temperature, and the 10%FACs-HGMs/BG composite tested at 500 °C displayed a compressive strength of 6.03 MPa. The FACs-HGMs/BG composites demonstrating excellent mechanical properties both at room and high temperatures may be used as promising candidates for structural materials or temperature resistant buoyant materials in the near future. [ABSTRACT FROM AUTHOR]

Thermal insulation material made by hollow glass microspheres (HGM) with different content of aluminum–chrome–phosphate solution (ACP) and tetraethyl orthosilicate (TEOS) as binders was formed, dried and sintered at 250 °C, 450 °C or 650 °C for 2 h. Properties such as density, compressive strength, thermal conductivity and microstructure of the specimens were determined. It is found that TEOS improved the distribution of ACP and increased the compressive strength of the specimens. HGM bonded by appropriate amount of ACP and TEOS achieved preferable value of density, compressive strength and thermal conductivity which were significant for thermal insulation materials. The compressive strength of specimens sintered at 450 °C and 650 °C was higher than that of the specimens sintered at 250 °C. [ABSTRACT FROM AUTHOR]