Coatings

Polycrystalline diamond compact (PDC) bits are widely used in oil, gas, and geological exploration. During rock breaking, most of the work is converted into cutting heat, leading to a rise in cutter temperature and potential damage. However, the influence of formation temperature and rock properties on cutting temperature and thermal stress remains insufficiently understood. This study combined numerical simulation and experimental methods to investigate the temperature rise and thermal stress of a single PDC cutter during rock breaking, focusing on the effects of formation temperature (27–250 °C) and rock strength (sandstone, marble, and granite). The results show that the temperature rise of the PDC cutter adheres to the following three distinct stages: rapid increase, slow increase, and stabilization. Rock strength significantly affects the temperature rise rate and stress; when breaking granite, the cutter temperature reached approximately 131.4 °C, about 2–3 times higher than for marble and sandstone, while the rate of penetration (ROP) decreased by 70.6–75.6%. As formation temperature increased from 27 °C to 250 °C, the internal temperature difference within the cutter decreased from 72.6 °C to 35.6 °C, and the equivalent stress first increased and then decreased, peaking at 2.84 GPa at 50 °C. The ROP initially increased and then decreased with an increase in formation temperature. Numerical simulations and experimental findings are in good agreement. This study provides theoretical and technical guidance for optimizing cutter design and improving the rock-breaking efficiency and service life of PDC bits in deep and high-temperature formations.

Outdoor sportswear increasingly demands multifunctional performance, including waterproofness, breathability, and intelligent thermal regulation. Nanofiber membranes, especially those prepared via electrospinning, offer a promising platform due to their tunable pore structures, high specific surface area, and ease of functionalization. This review outlines progress from fabrication to multifunctional integration, highlighting key quantitative advances: electrospun membranes achieve water vapor transmission rates >10,000 g·m⁻²·day⁻¹ with hydrostatic pressure resistance of 80–150 kPa, and thermal conductivity as low as 0.033–0.040 W·m⁻¹·K⁻¹. We analyze how structural designs enable tailored functionalities for diverse outdoor scenarios. The review’s key contributions include establishing a clear “process-structure-function” framework, critically comparing nanofiber membranes with conventional materials, and identifying industrialization challenges—scalability, durability, cost—while pointing toward smart, sustainable, and customizable future directions.

The escalating global heatwave crisis demands urgent advancements in high-efficiency, energy-saving cooling technologies. Radiative cooling (RC) paints, capable of passively dissipating heat through the atmospheric transparent window (ATW, 8–13 μm) without external energy input, have emerged as a groundbreaking solution for sustainable thermal management. This perspective advocates for a paradigm shift in the field from solely focusing on optical performance optimization to comprehensive system design that simultaneously achieves high cooling power, industrial-scale manufacturability, long-term environmental durability, and customizable aesthetics. We systematically analyzed the fundamental design principles of RC paints, reviewed the construction strategy of the state-of-the-art RC paints, advanced multi-band spectral engineering, synergistic integration with complementary cooling technologies, and robust structural configurations for large-scale deployment. Addressing critical challenges for commercialization, we also proposed targeted solutions, including enhanced application-specific durability, cost-effective production scaling, and multifunctional system integration. This work provides a strategic roadmap to accelerate the transition of RC paints from laboratory prototypes to ubiquitous real-world applications, ultimately contributing to a sustainable future with improved thermal comfort.