Nature is a school for scientists and engineers. Inherent multiscale structures of biological materials exhibit multifunctional integration. In nature, the lotus, the water strider, and the flying bird evolved different and optimized biological solutions to survive. In this contribution, inspired by the optimized solutions from the lotus leaf with superhydrophobic self‐cleaning, the water strider leg with durable and robust superhydrophobicity, and the lightweight bird bone with hollow structures, multifunctional metallic foams with multiscale structures are fabricated, demonstrating low adhesive superhydrophobic ­self‐cleaning, striking loading capacity, and superior repellency towards different corrosive solutions. This approach provides an effective avenue to the development of water strider robots and other aquatic smart devices floating on water. Furthermore, the resultant multifunctional metallic foam can be used to construct an oil/water separation apparatus, exhibiting a high separation efficiency and long‐term repeatability. The presented approach should provide a promising solution for the design and construction of other multifunctional metallic foams in a large scale for practical applications in the petro‐chemical field. Optimized biological solutions continue to inspire and to provide design idea for the construction of multiscale structures with multifunctional integration.

The bubbles electrochemically generated by gas evolution reactions are commonly driven off the electrode by buoyancy, a weak force used to overcome bubble adhesion barriers, leading to low gas transporting efficiency. Herein, a Janus electrode with asymmetric wettability has been prepared by modifying two sides of a porous stainless-steel mesh electrode, with superhydrophobic polytetrafluoroethylene (PTFE) and Pt/C (or Ir/C) catalyst with well-balanced hydrophobicity, respectively; affording unidirectional transportation of as-formed gaseous hydrogen and oxygen from the catalyst side to the gas-collecting side during water splitting. "Bubble-free" electrolysis was realized when "floating" the Janus electrode on the electrolyte. Anti-buoyancy through-mesh bubble transportation was observed when immersing the electrode with PTFE side downward. The wettability gradient within the electrode endowed sticky states of bubbles on the catalyst side, resulting in efficient "bubble-free" gas transportation with 15 folds higher current density than submerged states.

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Metal foam is recently being applied in down-hole sand control. The open pore substrate has a very permeable structure, the porosity and the pore size of the metal foam can be varied in a large range to meet the sand control demand. The three dimension open pore of metal foam results a very permeable structure to prevent plugging risks. The open pore metal foam is wrapped around a cylindrical geometry perforated base pipe. The number of foam layers and the pore sizes can be varied in order to achieve optimum flexibility for different sand control applications. The effects of pore size and relative density on the metal foam mechanical properties and the relationship between the pore size and the sand control size have been studied. This paper compares the sand control characteristics of metal foam with two different conventional mechanical sand control screens supplied by manufactory, under similar conditions, loads, and formation sand. The metal foam based sand control screen improves the sand retention, and reduces the flow resistance by 16.6%. The metal foam based sand control screen was successfully used in the Liaohe Oilfield in China.

Understanding of dynamic behaviors of gas bubbles on solid surfaces has significant impacts on gas-involving electrochemical reactions, mineral flotation and so on in industry. Contact angle (θ) is widely employed to characterize the wetting behaviors of bubbles on solid surfaces; however, it usually fluctuates within the bubble's advancing (θ a ) and receding (θ r ) range. Although the term of most-stable contact angle (θ ms ) was defined previously as the closest valuable approximation for thermodynamically meaningful contact angle for a droplet on solid surface, it has not been widely appreciated; and the precise θ ms measurement methods are inadequate to describe bubbles' wetting behaviors on solid surfaces. Herein, we proposed to take θ ms as the mean value of θ a and θ r , as a more accurate descriptor of gas bubbles' dynamic behaviors on non-ideal solid surface, as similar to the definition of droplets' θ ms on solid surfaces. The feasibility and accuracy of the proposed θ ms have been evidenced by recording the bubbles' contacting behaviors on solid surfaces with varied wettabilities. In addition, it was found that the contact angle hysteresis (δ), as the difference between θ a and θ r, reached its maximum value when θ ms approached to 90°, regardless of the roughness (r) of substrates. Finally, built on the above concept, lateral adhesion force (ƒ) of gas bubble on solid interface, which worked on the three-phase contact line (TPCL) of individual bubble on a solid surface against its lateral motion during the bubble advancing or receding process, was described quantitatively by combining θ a , θ r and liquid-gas interfacial tension (γ lg ). Experimental and theoretical data jointly confirmed that ƒ reached its maximum value at θ ms~9 0°, namely the "super-sticky" state, which described the dynamically most sluggish movement of bubble along the solid surface.

Plunger pumps are widely used in oil pumping units around the world. The water content of the wellbore is increasing along with the development progress, so the lubricating capacity of the well fluids between the plunger and barrel is decreasing correspondingly. Commonly, the substrate material of the plunger and barrel are stainless steel, and the plunger surface is usually covered with nickel-based coating. Therefore, the performance of the plunger and barrel has been affected due to poor lubrication and eccentric wear. Non-smooth surfaces have been proven to improve the tribology performance in many cases. A surface texturing plunger covered with specific dimples has been prepared by using laser surface texturing technology. The morphology of the surface texturing plunger was characterized and analyzed. The tribology performance of surface texturing plunger samples was tested using standard friction and wear test machines with oil and water lubrication, respectively. The results indicated that surface texturing could effectively reduce the coefficient of friction, and the wear resistance of the surface textured samples has been improved to some extent.