No abstract

MoS2–TiL/MoS2–TiH coating (L and H are low and high power of the sputtered Ti target) possesses excellent tribological properties owing to its nano-multilayer structure. In this study, the tribological properties of MoS2–TiL/MoS2–TiH coating were extensively analyzed at different loads. Relative to the MoS2–Ti monolayer coating, the nano-multilayer structure not only improved the wear resistance but also increased the critical load at which the coating began to peel off. The MoS2–Ti coating maintained its lubrication only in the early stage of the test even at a load of 2 N. In contrast, the friction coefficient and wear rate of the multilayer coating were small and stable until the load reached 20 N. The critical load of the optimized MoS2–TiL/MoS2–TiH coating was 10 times that of the MoS2–Ti coating. At excessive loads, the multilayer coating lost its lubrication in the early stage of the test because the coating was completely worn off under such loading.

The permanently chemically cross-linking solid-solid phase change materials (SSPCMs) were designed to solve the problem of leakage and poor shape stability during the whole process of phase transformation. However, these materials lead to environment pollution and resources waste because of the non-recyclability. Therefore, a SSPCMs was fabricated using dynamic thermal reversible Diels-Alder bonds. The prepared SSPCMs exhibited excellent shape, heat storage stability, and reliability and reprocessed ability, resulting from dynamic Diels-Alder bonds. Moreover, the Halloysite nanotubes decorated with Fe 3 O 4 nanoparticles (HNTs@Fe 3 O 4 ) were used to enhance the thermal conductivity of SSPCMs. When the filler content was 0.5 wt%, the best integrated properties (phase change properties and thermal conductivity) of the SSPCMs were obtained, it had the highest melting and freezing phase change enthalpies about 116.8 and 127.2 J/g, and thermal conductivity value, 0.223 W/m K, which was 101% higher than pure SSPCMs. Hence, the prepared SSPCMs can be considered as promising save-energy, friendly-environment thermal management materials.

No abstract

Phase change materials (PCMs) can absorb and release energy while keeping the temperature constant; hence, they play a crucial role in the thermal management field. Shape-stable phase change materials (SSPCMs) were synthesized by chemical crosslinking to address the liquid leakage problem of solid−liquid phase change materials (SLPCMs) during the phase change process. However, the abandoned SSPCMs cannot be reused and recycled, which seriously restricts their practical application. Herein, a polyurethane network containing Diels−Alder bonds was used as the enclosure compound to obtain the encapsulation of polyethylene glycol (PEG), and then, the chemical structure, crystallization behavior, and phase transition ability of SSPCMs were systematically investigated. The results showed that the SSPCMs-3 sample (300 wt % PEG) had the best comprehensive performance, an enthalpy value of 171.7 J/g, and no leakage at 80 °C for 1 h. Moreover, the structure, crystallization behavior, and phase transition ability of SSPCMs could also basically remain unchanged after multiple thermal cycling and reprocessing.