Guimin Liu

高太阳光反射率与高中红外发射率的日间辐射制冷材料提供了一种在阳光直射下绿色冷却建筑物的方法。然而，这些材料通常呈现出白色或银色的外观，不仅不能满足对颜色的需求，还会产生光污染，对人眼造成伤害。本文提出一种基于非溶剂诱导相分离法与喷涂法制备双层彩色日间辐射制冷涂层的策略。所得的彩色日间辐射制冷涂层是由彩色顶层和掺杂高折射率纳米粒子的多孔聚合物底层构成，在实现鲜艳色彩的同时，也表现出优异的制冷功能。顶层的无机彩色纳米粒子仅吸收与所显示颜色互补的太阳光，而底层的多孔聚合物涂层则可以强烈反射全波段的太阳光，从而极大减少太阳对物体的热增益。同时，彩色日间辐射制冷涂层的高中红外发射率也使得热量可以高效辐射到外界。因此，与同色度的商业彩色涂料相比，在平均太阳光功率为877.1 W m-2的晴朗天气下，红、黄、蓝三种彩色日间辐射制冷涂层的温度分别可以降低18.2 oC、20.0 oC与14.7 oC，表现出优异的制冷效果。此外，彩色日间辐射制冷涂层可以通过刷涂与喷涂等方式大规模用于建筑物的外立面。本文为兼具美观和冷却功能的绿色建筑材料提供了一条简单有效的解决方案。

C/C–SiC composites are promising candidates for heavy‐duty tracked vehicle brake discs. A third‐body layer (TBL) can be formed on the surface of C/C–SiC self‐mated brake discs, which has an important impact on tribological behavior and wear mechanism of brake discs. Herein, the formation conditions and evolution process of TBL and its effect on friction and wear properties were investigated. An appropriate braking pressure and speed ( P and V ) are beneficial to the cutting of asperities and refinement of wear debris on the contact surface, which are preconditions for the formation of original TBL. The original TBL can be formed under the P·V of 12, 15, and 16, which effectively improve braking stability and reduce the wear rate. During the continuous braking process, the original TBL undergoes growth, stabilization, destruction, and regeneration. Under the frictional heat and compressive stress, wear debris gradually evolves into a uniform and dense TBL. The average coefficient of friction and wear rate reach to the lowest value of .446 and 38.5 × 10 ⁻³ cm ³ /MJ, respectively. A continuous high temperature in the later stages of braking leads to severe oxidative wear. The newly formed TBL covers the original surface to form a multilayered structure, indicating the TBL undergoes destruction and regeneration.