| Pipeline scaling is very common in the petroleum industry.The formation of scale is due to the precipitation of inorganic salts such as calcium carbonate,calcium sulfate and magnesium hydroxide.The scale of the pipeline can lead to narrow the area of cross-section conduits,increase the flow resistance of fluid and reduce the transportation efficiency.The pipeline will be completely blocked in serious cases,which may affect the normal production of the oilfield.Therefore,people pay more attention to the antiscaling technology.By preparing or coating low surface free energy materials on the surface of metal equipment,the difficulty of adhesion of scale to the surface is increased.Due to its low surface free energy and micro rough structure,polymer based superhydrophobic coating has shown its unique advantages in self-cleaning,anti-corrosion,fluid drag reduction,anti-icing and anti-fouling,and has become a research hotspot in this field.In order to improve the antiscaling performance and durability of polymer based coating,we report the polymer based superhydrophobic composite coatings with excellent antiscaling performance,which are fabricated by incorporating various inorganic nanofillers,carbon nanofillers and organic chelating agents into the polymer.The effects of nanofillers on the surface morphology,surface free energy,surface roughness and antiscaling performance of coatings were systematically studied by the calcium carbonate scaling test.The mechanism of inorganic nanofillers,carbon nanofillers and organic chelating agents to improve the antiscaling performance of the coating was revealed.The main researches are as follows:?1?The superhydrophobic PPS/PTFE/SiO2 composite coating was fabricated by adding nano-SiO2into high temperature-resistant thermoplastic polymers PPS and PTFE.The surface free energy was 0.90 m J/m2,and the static water contact angle?WCA?of superhydrophobic PPS/PTFE/SiO2composite coating was 151.30°.The superhydrophobic PPS/PTFE/SiO2composite coating formed a micro-nano multilevel-structure,which was similar to the surface of lotus leaf,so that it could maintain a high hydrophobicity and had good antiscaling performance.The CaCO3scaling rate on the superhydrophobic PPS/PTFE/SiO2composite coating was 38.6%of that on the hydrophobic epoxy coating.Nano-SiO2plays a dual role in the construction of coating microstructure and roughness,which provides a basis for the discussion of the scale prevention mechanism of superhydrophobic coatings.?2?PVDF/FEP/inorganic nanofiller composite coating was fabricated by adding four different inorganic nanofillers?nano-Zn O,Al2O3,Cu O and SiO2?into PVDF and FEP.The effect of inorganic nanofiller on the antiscaling performance of superhydrophobic coating with different resin matrix was studied.The surface free energy of PVDF/FEP/SiO2composite coating was 5.7 m J/m2,and the WCA was 150.65°.The surface of superhydrophobic PVDF/FEP/SiO2composite coating had a micro-nano multilevel-structure.The microstructure formed SiO2wrapped around with CNTs could well wrap the air to a thick film,which could effectively prevent the nucleation and growth of calcium carbonate crystals.Compared with the commercial hydrophobic epoxy coating,the scaling amount of CaCO3on the surface of superhydrophobic PVDF/FEP/SiO2composite coating was 71.2%of the former.The results show that nano-SiO2is suitable for superhydrophobic coating with thermoplastic resin as the film-forming material.?3?The superhydrophobic PVDF/FEP/SiO2 composite coatings incorporating various carbon nanofillers,such as carbon nanotubes?CNTs?,carbon nanofibers?CNFs?,graphene nanoplates?Gn Ps?and carbon black?CB?respectively,were successfully fabricated by spraying.The effect of carbon nanofillers on the antiscaling performance of superhydrophobic composite coating was investigated.It was found that the special hollow structure and high strength of CNTs can maintain the stability and durability of air film.In addition,the low surface free energy and tackling effect of CNTs can effectively prevent the adhesion of CaCO3on the surface of coatings,and further enhance the antiscaling performance of the superhydrophobic PVDF/FEP/SiO2/CNTs composite coating.The surface roughness of PVDF/FEP/SiO2/CNTs composite coating was relatively large?17.568?m?,but the surface free energy was only 0.40 m J/m2,and the static WCA was 152.30°.The scaling amount of superhydrophobic PVDF/FEP/SiO2/CNTs composite coating was 36.8%and44.0%of that of epoxy coating and PVDF/FEP/SiO2composite coating,respectively.After the addition of CNTs,the superhydrophobic PVDF/FEP/SiO2/CNTs composite coating formed a porous nanonetwork structured composed of CNTs,polymer and nano-SiO2.This kind of special structure could keep thick air film on the surface of coating and enhanced the hydrophobicity.?4?On the basis of the microstructure of PVDF/FEP/SiO2/CNTs composite coating,superhydrophobic PVDF/FEP/SiO2/CNTs-EDTA composite coatings were successfully fabricated by adding organic chelating agent ethylenediamine tetraacetic acid?EDTA?.The purpose of this study is to explore the antiscaling performance of superhydrophobic coatings.It was found that Ca2+could be firstly chelated by EDTA,and slow down the scaling reaction of inorganic salts,thus greatly improving the antiscaling performance of the coating.When CNTs was dipping with EDTA for 12 h,the surface free energy of PVDF/FEP/SiO2/CNTs-EDTA composite coating was 0.95 m J/m2,and the WCA was 150.63°.After the addition of EDTA,a micro-nano multilevel-structure centered on SiO2and surrounded by CNTs-EDTA was formed in the superhydrophobic PVDF/FEP/SiO2/CNTs-EDTA composite coating,which played an important role in maintaining the air film under the water and the stability of the superhydrophobic surfaces.After 192 h,the CaCO3scaling rate of the superhydrophobic PVDF/FEP/SiO2/CNTs-EDTA composite coating was 1.7%,5.4%and 13.1%of the hydrophobic epoxy coating,superhydrophobic PVDF/FEP/SiO2and PVDF/FEP/SiO2/CNTs composite coating,respectively.The research on the antiscaling performance of the organic chelating agent enhanced superhydrophobic coating will play an important role in the development and application of the superhydrophobic coating. |
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