Toward Superamphiphobic Coatings By Electrochemical Techniques And Their Realization Inside The Pipes

The design of superhydrophobic/superamphiphobic coatings open up a new way for efficient protection of iron and steel material under aggressive environment.By forming a thin air film at the solid-liquid interface when such coatings are immersed into chemical mediums,aggressive ions such as chloride ions,hydroxyl ions and oxygen more difficult to infiltrate through the barrier and damage the underlying metal material,and therefore,corrosion rate would slow down significantly.As well as that,previous studies revealed that the presence of an air film on a superhydrophobic surface can not only prevent crystalline scale like CaCO₃ from approaching the solid surface,which contributed to their anti-scaling function,but also reduce flow drag by decreasing the friction shear stress at the interface,which offered them drag reduction function.It is therefore of great importance to investigate the corrosion resistance,anti-scaling and drag reduction performances of superhydrophobic/superamphiphobic coatings,especially under circumstances that are similar to ones we usually deal with in the real industrial production processes.Nevertheless,for the superhydrophobic/superamphiphobic coatings appeared up till now,it is still a problem to realize the advantages of both physical/chemical durability and tenability?e.g.,tunable film thickness and morphology?.Meeting the requirements of scaling-up production by inexpensively fabricating superhydrophobic/superamphiphobic coatings is a major target in the near future.Nickel-based alloy coatings are a type of ideal protecting material widely used in the fields of petroleum and chemical engineering industry and marine equipment,due to their high strength,low interior stress and durable features.In this paper,a one-step electro-chemical deposition technique assisted by low-frequency ultrasonic irradiation had been introduced to fabricate a superhydrophobic nanocrystalline nickel-copper alloy film.By changing experimental parameters,the micro-scale morphology of the film was able to be facially tuned.In the further experiment,the nanocrystalline alloy film was successfully deposited on the inner wall of a long-distance narrow pipe,which realized superamphiphobicity after subsequent treatments of anodization and modification of fluorosiloxane monomers.In the following experiments,the drag reduction and anti-scaling abilities of the fabricated inner superamphiphobic coating were evaluated.The main contents of this paper are divided into the following three parts:1.Inspired by the high efficient of sonochemical reaction as well as the crystal refiningeffect of ultrasounic field,we developed a low-frequency ultrasound irradiated electrochemical deposition technique to prepare scalable superhydrophobic nanocrystalline nickel-copper alloy film on Q235B-type carbon steel,which can be achieved in very short time duration.Under the optimal experimental condition,a static contact angle?WCA?of156.1° while a slighting angle?SA?as small as 1.1° can be obtained.In addition,the morphological features of the deposited film were able to be precisely tuned by changing the concentration of NiSO₄,the main salt in the electrolyte,or additives such as micron-scale SiO₂ sphere and lauric acid.In addition,the unique effect of ultrasonic irradiation and the mechanism of deposition procedure had been studied.Furthermore,the corrosion inhibition performance of the superhydrophobic film had been evaluated based on electrochemical impedance spectroscopy?EIS?and potential dynamic polarization curve.2.It has been discovered that the low-frequency ultrasound can propagate for a long distance with little energy lost.Here in our experiment,a electrodeposition technique with the presence of axially propagated ultrasound was developed and the nanocrystalline alloy film was successfully deposited onto the inner wall a 1.2-meter-long narrow transporting pipe.After treated by anodization and sequentially modification of fluorosiloxane monomers,the superamphiphobicity of such inner coating can be realized.In a typical case,the superamphiphobic film was obtained through a 15-minute-long electrodeposition process under ultrasound irradiation with a frequency of 4.0 × 104 Hz and a power of 3.03 × 103 Wcm^-2,followed by a 3-minute-long anodization process and finally the modification treatment.After such treatments,the static contact angles reached 154.8° for water,150.4° for lubrication oil-water mixture,150.8° for glycerol and 150.3° for ethanediol.Additionally,it had been demonstrated that the film thickness and morphological properties were able to be conveniently tuned by changing electrochemical deposition duration and ultrasound power.The roughness parameter?Ra and Rq?measured by a roughness profile meter revealed that the growth rate of film roughness with increase of deposition duration in the ultrasound irradiation case was much slower in comparison with that in the conventional electrodeposition case,which can be explained by the significant crystal refining effect induced by the ultrasound.Profitably,the functional film exhibited stable superamphiphobic property under various deposition durations,demonstrating the possibility of producing thickness-controllable superamphiphobic coatings inside long transporting pipes.3.The CaCO₃ scale formation test was conducted under thermalstatical and flowing conditions,aiming to evaluate the anti-scaling property of the inner wall superamphiphobic film.The results indicated that the superamphiphobic film can not only efficiently reduce the deposited amount of CaCO₃,but also induce the formation of needle-like aragonite crystals,which was easy to be cleaned up by fluid.Furthermore,the drag reduction property of thesuperamphiphobic film was tested via a home-made circulating equipment.By measuring the pressure difference of pipes with bare and superamphiphobic inner surfaces,it was demonstrated that the superamphiphobic surface possessed obvious drag reduction performance in turbulent region.