Yongbin Ma

A wearable microwave absorption cloth

Wearable functional materials and textiles have attracted overwhelming attention in a broad range of industries owing to their exclusive merits for developing smart electronic and energy devices. As they are massively utilized in the telecommunication and aerospace communities, microwave absorption materials also require fascinating properties that enable them to exhibit excellent performance ranging from mechanical features to functionalities. Unfortunately, conventionally developed microwave absorbing fillers are generally limited in practice for the undesirable performance in terms of stability and poor durability, which is out of the scope for exploiting wearable and long-term microwave absorption materials. To overcome such limitations, a wearable microwave absorption cloth was fabricated via in situ employing carbon materials into a nonwoven matrix, showing a range of advantages that meet the criteria of high-performance wearable electromagnetic functional materials. According to the best performance curve as well as radar cross section values from a CST simulation, the as-fabricated cloths can deliver ideal microwave absorption performance based on the unique structural configuration. Practical applications indicate that the effective absorption bandwidth of 8.2–14.5 GHz at a thickness of 4 mm has been achieved in a wearable fashion, manifesting a novel platform for developing advanced wearable functional cloth.

Thermal Shock Resistance of Chemical Vapor Deposited Zinc Sulfide Under Active Cooling

The thermal shock resistance of chemical vapor deposited zinc sulfide (CVD ZnS) infrared side window of high-speed vehicles with convective cooling is studied using finite volume method. The involved factors are the surface heat flux, coolant temperature, convective heat transfer coefficient, and thermal shock initial temperature. All the material properties are temperature-dependent. The study shows that convective cooling can improve the thermal up shock resistance of CVD ZnS caused by aerodynamic heating at the upper surface. On the other hand, it can also lead to thermal down shock failure at the lower surface. The critical failure time corresponding to thermal down shock failure is much less than that corresponding to thermal up shock failure. Thus, thermal down shock failure should be avoided in application. The critical thermal shock initial temperatures, below which convective cooling will not cause thermal down shock failure, for different coolants are calculated.