Preparation technology and anti-corrosion performances of black ceramic coatings formed by micro-arc oxidation on aluminum alloys

In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied. The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings. Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface. There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase. And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.

Investigation of anti-corrosion property of hybrid coatings fabricated by combining PEC with MAO on pure magnesium

Novel hybrid coatings on pure magnesium were prepared by combining plasma electrolytic carburizing(PEC)with micro-arc oxidation(MAO)to further enhance the anti-corrosion property in this paper.Scanning electron microscopy(SEM)was used to observe the microstructure of the coatings,meanwhile,energy dispersive spectrometry(EDS)and X-ray diffraction(XRD)were separately used to investigate the elemental as well as phase compositions of the coatings.The anti-corrosion property of the coatings was evaluated by potentiodynamic polarization curves as well as electrochemical impedance spectroscopy(EIS).The results show that PEC process is closely related with the effects of adsorption as well as diffusion of the activated carbon atoms,and it can provide a favorable pretreatment surface with predesigned chemical composition to obtain a new kind of phase,namely Si C with superior corrosion resistance and chemical stability,in the following PEC+MAO hybrid coatings.Meanwhile,PEC preprocessing also can afford an excellent micro-structure to increase the coating thickness as well as to improve the compactness of the PEC+MAO hybrid coatings.During the fabrication process of the PEC+MAO hybrid coatings,an overlapping phenomenon in regard to coating thickness can be observed instead of heaping up layer by layer.Compared with both single PEC surface modification layers as well as single MAO coatings,the PEC+MAO hybrid coatings exhibit more superior anti-corrosion property.Especially,the EIS data reveal that the PEC+MAO hybrid coatings can act as an effective protection system to provide relatively excellent long-range anti-corrosion protection.Note also that employing same MAO technique for both single MAO treatment as well as PEC+MAO combining procedure is the key to this research.

An electrochemical method for evaluating the resistance to cathodic disbondment of anti-corrosion coatings on buried pipelines

Methods for evaluating the resistance to cathodic disbondment （RCD） of anti-corrosion coatings on buried pipelines were reviewed. It is obvious that these traditional cathodic disbondment tests （CDT） have some disadvantages and the evaluated results are only simple figures and always rely on the subjective experience of the operator. A new electrochemical method for evaluating the RCD of coatings, that is, the potentiostatic evaluation method （PEM）, was developed and studied. During potentiostatic anodic polarization testing, the changes of stable polarization current of specimens before and after cathodic disbonding （CD） were measured, and the degree of cathodic disbondment of the coating was quantitatively evaluated, among which the equivalent cathodic disbonded distance AD was suggested as a parameter for evaluating the RCD. A series of testing parameters of the PEM were determined in these experiments.

Influence of graphene on the anti-corrosion performance of epoxy-based coatings

In this work, graphene-modified epoxy-based anti-corrosion coatings were prepared and the influence of graphene on the anti-corrosion performance of the epoxy-based coatings was investigated with water contact angle test ,chemical solution immersion test, and electrochemical test. The water contact angle and chemical solution resistance of the epoxy-based coatings were improved with an increase in graphene content from 0 to 0.4%. These results prove that addition of graphene can significantly improve the hydrophobicity and impermeability of epoxy- based coatings. However, when the graphene content was increased to 0.5%, the performance of the epoxy-based coatings decreased because of graphene aggregation. Tafel polarization results show that graphene addition can significantly reduce the corrosion current density and corrosion potential of epoxy-based coatings, which enhance their anti-corrosion performance.

The Effect of Cerium Dioxide (CeO_2) in an Anti-corrosion and Self-lubricating Coating

The effect of cerium dioxide(CeO_2)as an additive on the structure and properties of a melting type coating has been studied by means of microhardness measurement,scanning electron microscopy and thermal analysis. The results show that cerium dioxide can modify the microstructure and tribological properties of the coating. Model LIC-23 composite coating which contains CeO_2 performs well as a self-lubricating coating in hydrochloric acid solution.

An Abrasion Resistant TPU/SH-SiO_(2) Superhydrophobic Coating for Anti-Icing and Anti-Corrosion Applications

As a passive anti-icing strategy,properly designed superhydrophobic coatings can demonstrate outstanding performances.However,common preparation strategies for superhydrophobic coatings often lead to environmental pollution,high energy-consumption,high-cost and other undesirable issues.Besides,the durability of superhydrophobic coating also plagues its commercial application.In this paper,we introduced a facile and environment-friendly technique for fabricating abrasion-resistant superhydrophobic surfaces using thermoplastic polyurethane(TPU)and modified SiO_(2)particles(SH-SiO_(2)).Both materials are non-toxicity,low-cost,and commercial available.Our methodology has the following advantages:use of minimal amounts of formulation,take the most streamlined technical route,and no waste material.These advantages make it attractive for industrial applications,and its usage sustainability can be promised.In this study,the mechanical stability of the superhydrophobic surface was evaluated by linear wear test.It is found that the excellent wear resistance of the superhydrophobic coating benefits from the characteristics of raw materials,the preparation strategy,and the special structure.In anti-icing properties test,the TPU/SH-SiO_(2)coating exhibits the repellency to the cold droplets and the ability to extend the freezing time.The electrochemical corrosion measurement shows that the asprepared superhydrophobic surface has excellent corrosion resistance that can provide effective protection for the bare Q235 substrates.These results indicate that the TPU/SH-SiO_(2)coating possesses good abrasion resistance and has great potential in anti-corrosion and anti-icing applications.

A novel anti-corrosion coating for magnesium alloy

A novel enviromental protective water based metallic coating were prepared on the surface of AZ91D magnesium alloy. The properties and structure of the coating were investigated by adhension test, hardness test, heat resisting test, neutral salt spray test and scanning electron microscopy (SEM). The results show that the coating has a stepped structure which can achieve good adhesion of first-grade, heat resistance temperature of 400℃, hardness of HV_ 0.50/30210 and anti-corrosion time of 250h in salt spray test. Meanwhile, the film forming and corrosion mechanism of the coating were also put forward based on the results of the Fourier transform infrared spectroscopy (FTIR) test and electrochemical impedance spectroscopy (EIS) test.

Cerium Methacrylate Assisted Preparation of Highly Thermally Conductive and Anticorrosive Multifunctional Coatings for Heat Conduction Metals Protection

Preparing polymeric coatings with well corrosion resistance and high thermal conductivity(TC)to prolong operational life and ensure service reliability of heat conductive metallic materials has long been a substantive and urgent need while a difficult task.Here we report a multifunctional epoxy composite coating(F-CB/CEP)by synthesizing cerium methacrylate and ingeniously using it as a novel curing agent with corrosion inhibit for epoxy resin and modifier for boron nitride through"cation-π"interaction.The prepared F-CB/CEP coating presents a high TC of 4.29 W m^(−1)K^(−1),which is much higher than other reported anti-corrosion polymer coatings and thereby endowing metal materials coated by this coating with outstanding thermal management performance compared with those coated by pure epoxy coating.Meanwhile,the low-frequency impedance remains at 5.1×10^(11)Ωcm^(2)even after 181 days of immersion in 3.5 wt%NaCl solution.Besides,the coating also exhibits well hydrophobicity,self-cleaning properties,temperature resistance and adhesion.This work provides valuable insights for the preparation of high-performance composite coatings with potential to be used as advanced multifunctional thermal management materials,especially for heat conduction metals protection.

Development of anti-corrosive coating on AZ31 Mg alloy subjected to plasma electrolytic oxidation at sub-zero temperature

Plasma electrolytic oxidation(PEO)is a promising surface treatment to generate adherent and thick anti-corrosive coating on light-weight metals(Al,Mg,Ti,etc.)using an eco-friendly alkaline electrolyte.High energy plasma,however,inevitably generates porous structures that limit their practical performance.The present study proposes a straight-forward simple method by utilizing sub-zero electrolyte(268 K)to alter the plasma characteristics during formation of the protective coating on AZ31 Mg alloy via PEO with a comparison to the electrolyte at room temperature(298 K).In refrigerated electrolyte,the formation of micro-defects is suppressed relatively at the expense of low coating growth,which is measured to be twice lower than that at 298 K due to the temperature-dependent soft plasma discharges contributing to the development of the present coating.As a consequence,corrosion resistance of the sample processed at 268 K is superior to that of 298K,implying that the effect of coating thickness is less dominant than that of compactness.This phenomenon is interpreted in relation to the ionic movement and oxide solidification controlled by soft plasma discharges arising from the temperature gradient between electrolyte and surface of the substrate during PEO.

Bonding strength of graded anti-corrosive coatings of fluoroethylenepropylene (FEP)/polyphenylene sulfide (PPS)

Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found that the poor adhesion of fluororesin coatings to metallic substrates is improved obviously by the graded coating structure of FEP/PPS, and the bonding strength reaches up to 11.8 MPa for the five-layer system. Examination by electron probe microanalysis （EPMA） verifies that the distribution of main components is graded in the five-layer system, which is responsible for the enhancement of the interfacial bonding.

Recent Progress in Superhydrophobic Coatings Using Molecular Dynamics Simulations and Experimental Techniques

Superhydrophobic(SH)coatings are intended to resist a surface from cor­rosion and thereby increases the product life duration.It is also a promising solution to save cleaning costs and time by providing self-clean nature to the surface.This review article provides the most recent updates in design­ing SH surfaces and their characterizations adopted both in experimental and computational techniques.To gain a comprehensive perspective,the SH surfaces present in nature those are inspiring human beings to mimic such surfaces are introduced at the beginning of this article.Subsequently,different fabrication techniques undertaken recently to design artificial SH surfaces are briefly discussed.Recent progress in computations employed in the development of SH surfaces is then discussed.Next,the limitations in SH surfaces are addressed.Finally,perceptiveness of different strategies and their limitations are presented in the concluding remarks and outlook.Overall,this mini review article brings together and highlights the significant advancements in fabrication of superhydrophobic surfaces which may surely help the early-stage researchers/scientists to plan their work accordingly.

高耐水聚合物水泥防水涂料及其应用性能研究

从JS防水涂料的耐水机理出发,针对性地设计了由聚合物中活性官能团(羧基)与交联剂形成的后交联结构,减弱了水分子对聚合物分子间的增塑作用及对聚合物分子与无机填料界面力的破坏作用,研制了一种具有优异耐水性能的JS防水涂料。该涂料在长期浸水后,仍保持较好的物理力学性能,吸水率<9%、拉伸强度>1.6 MPa,且浸水1年后表观无变化。

特种非固化橡胶沥青防水涂料的研制

非固化橡胶沥青防水涂料高温性能较低,无法应用于立面、坡屋面等位置,且130℃时黏度高,需加热到160℃以上才可进行施工,消耗大量能源和废气的排放。开发了特种非固化橡胶沥青防水涂料的配方。并分析SBS、SBR、橡胶粉、沥青和软化油、无机填料、分散助剂和C5石油树脂等原材料对其性能的影响。结果表明:特种非固化橡胶沥青防水涂料相对普通非固化橡胶沥青防水涂料软化点提高35℃,耐热性提高30℃,130℃黏度降低1810 m Pa·s,90℃时与防水卷材不发生滑移,具有高耐热性、低黏度的特点,可用于立面、坡屋面防水,可在130℃施工,降低能源消耗。

乳液粒径对聚合物水泥防水涂料性能的影响研究

探究聚合物水泥防水涂料中苯丙乳液乳胶粒的平均粒径对其涂膜性能的影响及微观结构的差异。采用种子乳液聚合工艺,通过控制阴非离子乳化剂配比,合成一系列具有不同平均粒径的苯丙乳液,加入一定量的助剂并与粉料复配,制得不同平均粒径苯丙乳液的聚合物水泥防水涂料。实验结果证明,在配方既定的情况下,乳液与水泥的相容性与乳胶粒的粒径有关,较好的相容性能够得到物理性能优异的涂膜,其中,乳液粒径为228 nm时微观结构最致密,缺陷、毛细孔较少。乳液粒径为在259 nm时,所得涂膜的综合机械性能(拉伸强度、断裂伸长率和粘接强度)最优。

全球聚氨酯防水密封材料的研究前沿进展

介绍了近年来在建筑防水和密封领域聚氨酯材料的研发和应用新进展,重点聚焦了聚氨酯产品以及相关原材料在阻燃、生物基、水性化、高强度以及与沥青防水卷材复合这5个方面的研究和应用进展,并对聚氨酯在防水密封材料的应用和发展前景进行了展望。

生物质基涂料增强食品包装纸防水防油性研究进展

目的归纳总结目前可增强食品包装纸防水防油性的生物基涂料的最新研究进展,为后续相关领域的研究与应用提供理论参考。方法分类介绍2类生物基涂料(蛋白质和多糖),对不同材料在食品包装领域防水防油改性研究进行详细综述,随后将生物基涂料与传统包装材料性能做对比,并且提出相应的解决办法,最后对目前存在的困难和应用前景进行总结和展望。结论通过与其他生物聚合物复合或添加增塑剂等方式对纤维素、壳聚糖、淀粉和海藻酸盐等疏水性或者疏油性不足的生物聚合物涂料进行改性,可以解决多孔纤维素纸基材料防水防油性不足的问题,并且可以有效避免使用含氟类涂料对人体和周围环境带来的危害,生物涂料在食品包装纸防水防油改性领域具有良好的发展前景。

高强度单组分聚氨酯防水涂料的制备与性能研究

为制备低温固化速度快、强度高的建筑防水用单组分聚氨酯防水涂料,以聚醚多元醇、异氰酸酯为主要原料合成了预聚体,将制得的预聚体与粉体填料、溶剂、助剂等按照一定配比制备了单组分聚氨酯防水涂料;并对其进行了红外表征。结果表明:当聚醚多元醇中330N质量分数为20%、预聚体—NCO含量为5%、粉体填料为绢云母粉、催化剂采用WCAT-WS2与DMDEE复配时,产品具有最佳的综合性能。当潜伏固化剂ALT-402、聚氨酯专用分子筛活化粉JLH-PU的质量分数分别为1%和5%时,产品放置120 d后涂膜细腻无泡。所得产品符合GB/T 19250—2013中Ⅱ型单组分聚氨酯防水涂料的要求,具有良好的稳定性和固化速度,应用前景广阔。

环保型仲胺扩链剂在双组分聚脲防水涂料中的应用

仲胺扩链剂是双组分聚脲防水涂料配方体系中的关键原材料,其分子结构中的位阻基团可有效降低反应活性、改善操作性,提高配方容忍度,同时改善材料性能。本文重点介绍了3类环保型液体仲胺扩链剂在双组分喷涂聚脲防水涂料(芳香族、脂肪族)、双组分涂刷聚脲防水涂料(天冬聚脲、新型、黏弹型)共5个不同配方体系中的应用。

环保型聚氨酯防水涂料的制备及性能研究

以水为固化剂,二苯基甲烷二异氰酸酯(MDI)、聚醚多元醇(DL-2000D、MN-3050D)、磺酸盐接枝聚酯二醇(BY-3306)、二羟甲基丁酸(DMPA)和填料等为原料成功合成了一种环保型的水固化聚氨酯防水涂料。讨论了聚醚多元醇种类、亲水扩链剂、气体吸收剂和水的添加量等对涂料性能的影响。结果表明,当聚醚三醇在聚醚混合物中的质量分数为10%、BY-3306替代聚醚二醇DL-2000D质量的15%或DMBA在体系中的质量分数为0.8%、硅酸盐水泥质量分数为8%、NCO基质量分数为4.5%时,得到的防水涂料在添加15%水固化后,拉伸强度可达4.27 MPa,断裂伸长率为678%,撕裂强度为24.57 N/mm。

快干型聚合物水泥防水涂料的制备

以水性聚氨酯分散体乳液为研究对象,从聚氨酯的分子结构与快干性能的关系出发,合成了一种含有羧基官能团的聚氨酯粒子乳液,并对其进行了全面表征;辅以其他添加剂制成了快干型JS防水涂料,其干燥时间可达1.58 h,快于市售Ⅲ型JS防水涂料;提出了JS防水涂料的快干机理。