Lubricating oil can effectively reduce friction between mechanical parts, thereby reducing energy consumption and improving service life and reliability. Due to the development of science and technology, it is necessary to improve the performance of lubricating oil to fulfill the higher tribological requirements for countering wear and providing lubrication. Nanolubricant additives have the four lubrication mechanisms of micro-bearing, protective film, polishing, and repair effects. A nanolubricant additive can often demonstrate a variety of lubrication mechanisms at the same time. As lubricating additives, metal and metal oxide nanoparticles have outstanding effects which improve the tribological properties of lubricating oil and have been widely studied in the field of tribology. This paper introduces the lubrication mechanism of nanoadditives and the latest research results for metal and metal-oxide nanoparticle lubrication additives.

Marine engineering equipment operates under extreme conditions such as high salinity, humidity, and flow velocity during marine resource exploration. These harsh environments impose strict requirements on surface performance, especially in terms of wear and corrosion resistance. Wear-resistant coatings are increasingly regarded as a crucial surface engineering approach to mitigate multi-mechanism degradation and improve the long-term reliability of marine equipment. In this review, the typical wear mechanisms in marine environments are systematically analyzed. Corresponding to different service scenarios, the main categories of coating materials, such as metal matrix composite coatings, cermet coatings, functionally graded coatings, and nanolayered coatings are summarized in terms of their structure and performance characteristics. Furthermore, mainstream fabrication techniques, including high-velocity oxy-fuel (HVOF), high-velocity air-fuel (HVAF), laser cladding, cold spray, and physical/chemical vapor deposition (PVD/CVD), are reviewed with respect to their influence on coating micro-structure and properties. Standardized evaluation methods for coating performance are also discussed. Finally, the current research challenges are identified, and future development trends are outlined, with an emphasis on multifunctional, intelligent, and environmentally friendly coating systems. This work aims to provide a systematic reference and theoretical basis for the design and application of wear-resistant coatings in marine environments.

A progressive damage model for aramid honeycomb cutting was proposed to reveal its cutting damage mechanism. It established the relationship between the mesoscale failure modes and the macroscale cutting damage types of the aramid honeycomb. The proposed model addressed the material assignment problem of impregnated honeycomb by developing a material calculation method that simulates the real manufacturing process of the aramid honeycomb. Cutting experiment of aramid honeycomb specimen was conducted concerning on the cutting forces response and cutting damages, which validated that the proposed method was effective for investigating the cutting process and mechanism for the aramid honeycomb. Predicted cutting mechanism results show that: (a) cutting process of the aramid honeycomb can be divided into three stages with four characteristic states—initial state, cut-in state, cut-out state and final state; (b) cell wall bending in the cutting direction relieves the cutting force, and strong plasticity of the aramid fiber makes it hard to break, which lead to uncut fiber and burr damages; (c) using sharp tip cutting tool to reduce cutting force and bonding both top and bottom of the honeycomb to make it stiffer are beneficial to obtain good cutting quality with less damages.

Gray cast iron is widely used for the cylinder bore of marine diesel engine. With the aim to improve the properties of the cylinder liner and maintain the matching ability with piston ring under the harsh working condition, the Fe-based alloy coating is fabricated on the gray cast iron using induction cladding. Owing to the high carbon content in both coating and substrate materials, it is extremely difficult to control the coating process and the coating quality. The additive of welding flux and prolonged heating time is proposed to prepare good quality coating. The coating forming mechanism is investigated, and the electrochemical corrosion and tribological properties of the coating are examined. The results show that the Fe-based coating possess better corrosive and tribological performance than gray cast iron, and it is seemed to be a potential candidate for improving the performance of the cylinder liner.

Deep-sea residual oil has been recognized as a significant environmental hazard due to its poor low-temperature fluidity and complex recovery processes necessitating urgent solutions. A segmented regulated two stage heating transport method is proposed, with a high-precision thermo-fluid coupling model that integrates thermophysical properties to characterize oil thermal coupling characteristics. Dimensional analysis further identifies multi-properties correlations for convective heat transfer coefficient and oil temperature that govern the thermo-fluid dynamics interaction. Numerical simulations reveal that transport distance, heat flux density, and mass flux collectively regulate convective heat transfer efficiency and temperature distribution. It is shown that oil temperatures reduce oil viscosity, thereby enhancing convective heat transfer between the thermal boundary layer oil and the pipe wall; as transport distance increases, accumulated heat and thermophysical properties stabilize simultaneously. A dual-properties regulation mechanism is identified between heat flux density and mass flux: within 180–540 kg/(m²·s), outlet thermal boundary layer oil temperature linearly responds to heat flux density (K = 0.04); exceeding 720 kg/(m²·s), temperature regulation efficiency decreases by 30%, accompanied by a downstream shift of temperature peak region under high mass flux conditions. This method provides reliable theoretical foundations for deep-sea low-temperature residual oil recovery.