Seyed Farshid Chini

Ice accumulation severely threatens the reliable operation of outdoor optical windows. Existing research has primarily developed two strategies: slippery coatings for passive ice removal by reducing ice adhesion, and photothermal coatings for active ice melting via photothermal conversion. However, the former mostly rely on slippery liquid-infused porous surfaces (SLIPS), which are prone to failure due to lubricant depletion; the latter (such as carbon-based materials and MXenes) sacrifice optical clarity because of their broad-spectrum absorption and opacity. To address these bottlenecks, this paper reports a novel coating technology that integrates three functions: solid-state sliding, high transparency, and highly efficient photothermal properties. By designing a phenyl/methylsiloxane cross-linked network and free PDMS segments, a solid slippery property (sliding angle of 16°) without liquid lubrication is achieved. Distinct from the broad-spectrum absorption of carbon-based and MXene materials, this study introduces cesium tungsten bronze (CsxWO3) nanoparticles, whose localized surface plasmon resonance peak is situated in the near-infrared region with almost no absorption of visible light, thereby achieving efficient photothermal conversion (heating up to 86.5 °C under 1 sun illumination) while maintaining a visible light transmittance higher than 83%. The coating synergistically integrates passive anti-icing and active de-icing, achieving a low ice adhesion strength of 56.8 kPa, an icing delay time of 121 s at -20 °C, and a 46.4% increase in ice-melting efficiency compared to conditions without photothermal effects. Moreover, the coating exhibits excellent mechanical durability (stable performance after 1000 friction cycles) and long-term chemical stability. Notably, benefiting from the selective absorption characteristics of CsxWO3, the coating can effectively block near-infrared thermal radiation in summer (reducing the temperature inside a model house by 19.9 °C), demonstrating its potential for year-round thermal management. This work achieves the first integration of solid-state sliding, high transparency, and highly efficient photothermal characteristics, realizing a synergistic effect of passive and active anti-icing/de-icing. It provides an all-weather solution for outdoor optical windows that require both high transparency and anti-icing performance, such as automotive autonomous driving optical sensors, UAV optoelectronic pods, and BIPV photovoltaic curtain walls.

Superhydrophobic photothermal anti-icing coatings represent a crucial strategy for addressing outdoor icing challenges. However, they still face significant challenges regarding long-term durability and large-scale production. In this study, a facile and cost-effective one-step spraying strategy is proposed to construct a robust photothermal superhydrophobic composite coating based on a modified epoxy resin system. By introducing an epoxy oligomer grafted with perfluorodecyltrimethoxysilane and precisely regulating the synergistic ratio of 14 nm nanoscale silicon dioxide (SiO2) and carbon black, a dual-scale hierarchical superhydrophobic structure was successfully fabricated. The SiO2 nanoparticles act as physical spacers to effectively suppress carbon black agglomeration, which not only induces a light-trapping effect with an optical absorptance exceeding 96% to enhance solar energy harvesting, but also endows the coating with excellent superhydrophobicity (water contact angle of 169.2°, sliding angle of 1.7°). Owing to the overall homogeneity and structural self-similarity of the composite coating, it exhibits exceptional mechanical robustness and weatherability, maintaining its anti-icing and liquid-repellent functions even after 180 tape peeling cycles, 45 sandpaper abrasion cycles, and 288 hours of intense UV aging. Notably, the coating demonstrates superior thermal stability, retaining excellent superhydrophobic characteristics after continuous annealing in a muffle furnace at 200 °C for 7 days, thereby effectively overcoming the industrial bottleneck of performance degradation in photothermal coatings under severe summer sun exposure. In extreme anti-icing tests at -30 °C, The coating significantly reduced the adhesion strength of ice on the aluminum substrate from 80.4 kPa to 21.5 kPa; concurrently, the complete freezing time of water droplets was extended from 27 s on aluminum to 93 s. Under xenon lamp irradiation at 25 mW/cm2, its freezing delay time was prolonged from 46 s on aluminum to 214 s. Under an irradiation intensity of 50 mW/cm2, the coating relies on an efficient interfacial melting mechanism to shed a large 1.5 cm3 ice block in merely 73.3 s. This research provides a novel perspective for the fabrication of low-cost, long-lifespan coatings with active-passive synergistic anti-icing performance for harsh extreme environments.

Corrosion prevention techniques such as cathodic protection (CP) are commonly applied to extend the useful lifetime of buried steel tanks in corrosive environments. Sacrificial anodes effectively supplement CP systems through controlled galvanic corrosion. For buried steel tanks, magnesium-based anodes are regularly used due to suitable current output over extended deployment periods. However, field conditions such as temperature fluctuations and proximity effects between adjacent tanks can influence CP performance. This study numerically simulates the CP of a 3.8 m diameter, 12 m long steel tank which the upper section of the tank is located at a depth of 1 m, protected by uniformly distributed magnesium anodes. To understand the importance of the current output of extended anodes, conventional anodes (i.e., 7.7 kg, 38.7 mA) and extended anodes (i.e., 9 kg, 62.7 mA) were studied. Proximity effects on anodes placed between adjacent buried tanks were also examined. In addition, the influence of temperature and concentration parameters was investigated along with a time-dependent analysis of the protected structure. Under the hottest and coldest conditions, the bottom temperature of the computational domain (in height of 6.8 m) reached 8.7°C and 11.3°C, respectively, with noticeable concentration gradients. The temperature rise necessitated increased protective current, leading to the need for additional sacrificial anodes to meet the demand. The simulation results indicated that the anodes positioned between the two tanks experienced the highest corrosion rate. After 21.5 y, approximately 85% of the mass of these anodes will be lost, with full depletion occurring shortly thereafter. This modeling approach offers valuable insights for selecting the optimal type and placement of anodes, ensuring the long-term integrity of underground infrastructure under varying thermal conditions.

Cathodic protection (CP) is widely used to mitigate corrosion and protect the substrate. However, sacrificial anodes are often undersized or improperly positioned. This study systematically investigates how anode design factors affect the CP effectiveness through computational modelling and double-objective optimisation techniques around the optimum location and dimension of anodes. State-of-the-art algorithms including the Monte-Carlo, Nelder–Mead, co-ordinate search, constrained optimisation by linear approximation (COBYLA) and bound optimisation by quadratic approximation (BOBYQA) are employed to optimise anode locations and genetic algorithm is utilised for optimising anode dimension and the objective is maximising the current output and minimising the cost. In the current study, the BOBYQA technique proved efficient in reaching the optimal response at the appropriate time. The findings indicate that in double-objective (cost and potential) optimisation of 14.5 kg anode, minimising anode radius (from 6.5 cm to 5.4 cm) and optimising the position boosts the current output by up to 15.5%. Refined anode geometries increase the average structure potentials (806 → 822 mV) by over 15 mV, translating to extended service lifetimes. In the comparison of single (cost) and double (cost and potential)-objective optimisation, about 15% more current reaches the structure and causes about 2% less anode mass loss for the same anode dimensions. Also, the results show the 7.7 kg anode performs better than the 14.5 kg anode and so output current and the percentage of current that reaches the structure of the 7.7 kg and 14.5 kg are 0.66 A and 0.46 A and 66% and 60%, respectively.

Cathodic protection as a complementary technique is widely considered in the industry along with the selection of suitable materials as well as efficient coating considerations. In cathodic protection (CP), anode produces a current output to protect the structure (cathode) and part of the current output is wasted by the grounding system. We developed a 3D, and time-dependent numerical model to simulate the anode corrosion (using arbitrary Lagrangian-Eulerian method), find the deposit formation (by interface tracking level set method), anode mass loss and current wasted by the grounding system. We also defined a CP efficiency as anode mass loss times the current percentage received by the structure. The CP efficiency can be utilized for anode quantity and placement pattern. The results showed when the conductivity of corrosion products (deposit) is lower than that of soil, the current output from the anode decreases over time. When the deposit conductivity is higher than that of soil, the current output from the anode increases in time, reaches a peak, then decreases. This is due to the competition among three factors: anode surface increase, medium conductivity change, and inhibition effect of the deposition layer. For the studied case, almost 54% of the current from the anode is wasted by the grounding system. To illustrate the significance of CP efficiency, this study compares three alternative anode configurations with the original design. It is observed that for a 14.5 kg anode, burying the anodes 2 m deeper enhances the mean potential distribution on the structure by 4%. Additionally, the configuration featuring the 7.7 kg anode, owing to its superior dimensional design, demonstrates improved performance compared to other configurations.