Though AlTiN coating has been intensively studied, there is still a need to develop AlTiN coating to meet the growing demand of industrial machining. One effective way to improve the performance of AlTiN coating is by adding alloying elements. In this study, AlTiN and AlTiMo coatings were deposited using multi-arc ion plating to investigate the influence of molybdenum addition on the structure, mechanical properties, and cutting performance of AlTiN coatings. Spherical droplets formed on the surfaces of both coatings, with the AlTiMoN coating exhibiting more surface defects than the AlTiN coating. The grazing incidence X-ray diffraction results revealed the formation of an (Al,Ti)N phase formed in the AlTiN and AlTiMoN coatings. Molybdenum doping in the AlTiMoN coating slightly reduced the grain size. Both coatings exhibited excellent adhesion to the substrate. The hardness (H), elastic moduli (E), H/E, and H3/E2 ratios of the AlTiMoN coating were higher than those of the AlTiN coating. The improvement in the mechanical properties was attributed to grain refinement and solution strengthening. Molybdenum doping improved the tribological properties and cutting performance of the AlTiN coatings, which was ascribed to the formation of MoO3 as a solid lubricant. These results show a path to increase the performance of AlTiN coating through molybdenum addition and provide ideas for the application of AlTiMoN coatings for cutting tools.

Magnetron-sputtered WS2 composite thin films are solid lubricants with excellent performances. However, the low hardness of the WS2 thin films necessitates the further improvement of their wear resistance. For this purpose, an effective strategy is to alternately deposit or code posit WS2 and a hard phase, such as TiB2, to form hard lubricant thin films. Herein, a TiB2 thin film was prepared under the same conditions as those used for depositing the WS2 thin film with a dense structure and excellent tribological properties. Because of the high deposition energy of high-power impulse magnetron sputtering (HiPIMS), the TiB2 thin film possesses a dense structure and leather-like flat surface (hardness = 24.17 GPa). The friction coefficient of the film under different loads ranges between 0.6 and 0.8. The wear rate of the thin film increases with load, mainly because of fatigue wear and abrasive wear. Under high loads, obvious furrow-like wear marks are observed. At different sliding frequencies, except 8 Hz, the friction coefficient of the film ranges from 0.6 to 0.8. The main wear mode is fatigue wear, particularly at increasing sliding frequencies. Although the film possesses a relatively high friction coefficient, its wear resistance is excellent (minimum wear rate = 1.96 × 10−6 mm3/(N·m)).

The exploration of unleaded free-cutting Cu40Zn brass with excellent mechanical and tribological properties has always drawn the attention of researchers. Due to its attractive properties combining metals and ceramics, Ti3AlC2 was added to Cu40Zn brass using high-energy milling and hot-pressing sintering. The effects of Ti3AlC2 on the microstructure, mechanical and tribological properties of Cu40Zn-Ti3AlC2 composites were studied. The results showed that Ti3AlC2 could suppress the formation of ZnO by adsorbing oxygen impurity and promote the formation of the β phase by releasing the β-forming element Al to the substrate. The hardness and wear resistance of Cu40Zn-Ti3AlC2 composites increased with increasing Ti3AlC2 content from 0 to 5 wt.%. The proper Ti3AlC2 additive was beneficial to both the strength and plasticity of the composites. The underlying mechanisms were discussed.

In this study, a dense WS2 coating was deposited via high-power impulse magnetron sputtering (HiPIMS) after solving the glow discharge problem, and it was compared with WS2 coating deposited via radio frequency (RF) sputtering. The latter showed a columnar growth, with a loose and porous microstructure. The columnar crystal growth of the former was inhibited, resulting in a more compact coating structure and a more uniform, flatter and smoother surface. Therefore, the structure and tribological properties of WS2 coating prepared via HiPIMS were investigated under different loads and frictional frequencies. Under low loads (up to 15 N), the coefficient of friction (COF) decreased with polishing wear mechanism. Under a high load of 20 N, the COF rapidly increased, the wear rate was the highest, and the wear mechanism changed from polishing to abrasive wear. At low frequencies (5 and 10 Hz), the coating had a low and stable COF, good wear resistance and the wear mechanism was abrasive wear. At high frequencies (≥15 Hz), the COF and wear rates rapidly increased and the wear mechanism changed from abrasive to adhesive wear and plastic fracture. However, the friction and wear rates were similar across different wear mechanisms.

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 degrees 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.

In this work, the Polyurethane/MoS2 composites (PUM) filled with different amount of modified molybdenum disulfide (MoS2) were prepared by solution-blending-casting method. The thermal reversible Diels–Alder (DA) bonds enabled the polymer system recyclable ability. The modified MoS2 were obtained by tannic acid (TA) assistant ultra-sonication exfoliation method were used to improve the gas barrier performance of materials. Compared with the pure PU, about twofold decrease in oxygen gas permeability of PUM composites (from 6719 to 3927 cm3/m2˙d˙Pa) were obtained with 1 wt% MoS2. More important, the samples showed excellent gas barrier and mechanical properties before and after being hygrothermal aged for 100 h. The PUM composites had good gas barrier and recyclability and had great potential application prospects in packing materials.

The development of polymer-based composites with self-healing and recyclable capability has attracted the attention of several researchers for resource recycling and environment protection. In this work, Halloysite nanotubes (HNTs) reinforced polyurethane materials (PU) with self-healing and recyclable ability were constructed by in situ polymerization method. The mechanical, thermal amd morphological properties of PU and related composites were studied. The morphology of samples fracture surface ensured the homogeneous dispersion of HNTs in the polymer matrix. Moreover, thermal stability was improved with the incorporation of the HNTs. The tensile test showed strength increased with HNTs content increased. The tensile strength of composites increases from 23.38 to 34.92 MPa at 2 wt% HNTs. Therefore, the designed strategy provides a simple approach for preparing high mechanical properties, reprocessing and self-healing ability polyurethane composites.

The realization of recyclable materials is an urgent problem to be solved for extending practical applications in industry. Herein, a simple method was proposed to prepared the recyclable materials thorough dynamic reversible chemistry. In this work, we design the recyclable and self-healing polyurethane based on the thermoreversible dynamic Diels-Alder reaction. In addition, the Halloysite nanotubes (HNTs) were introduced into the system to improve the thermal properties, mechanical properties of polyurethane nanocomposites (PUDM/ HNTs). The tensile tests showed that the HNTs can significantly improved the mechanical properties of nano composites. The healing efficiency above 90% on average was achieved which was determined by the recovery of breaking strength. Besides, the composites exhibited outstanding reprocessability via thermally induced. Therefore, Such excellent recyclable performance and self-healing ability give the polyurethane materials an opportunity to have great potential in the fields of save-energy, friendly-environment materials.