基于表面成分和微观结构防结蜡的膜层研究

针对石油开采过程中管道存在着严重的结蜡问题,在油管内部涂上一层光滑的低表面能涂层仍然结蜡严重,表明这类涂层并不能表现出很好的防结蜡效果;因此在油管内部热喷涂含有催化成分的合金涂层.并经过无机盐封闭处理获得特殊的表面结构以解决采油管道表面的防结蜡问题.试验结果表明,该种方法具有很好的防结蜡效果,重复试验表明其防蜡率在90%以上.通过对防结蜡机制的探讨得出,合金表面的催化元素和特殊微观结构是导致防结蜡效果明显提高的原因,即催化元素改变油管采油过程中的流体静电位,从而防止了原油中蜡在油管壁上的沉积.     

表面刻蚀粉末冶金黄铜的微观结构和防结蜡性能研究

目的原油运输中管道结蜡问题严重影响正常的生产运输,通过表面刻蚀的方法,获得具有超亲水性的粉末冶金黄铜表面,从而达到良好的防结蜡性能。方法结合不同刻蚀时间下的表面微观结构、粗糙特性和润湿特性,对防结蜡性能进行系统研究。采用Fe Cl3溶液,刻蚀粉末冶金黄铜试样不同时间,通过X射线衍射仪和扫描电子显微镜对刻蚀表面的成分和形貌进行分析,利用接触角测量仪测量样品表面润湿性,最后对刻蚀后的黄铜进行防结蜡测试。结果表面刻蚀过程实为"脱锌",在试样表面形成了微纳米级颗粒粗糙结构。随着刻蚀时间的延长,最大轮廓高度Rz相应增大。与未刻蚀试样相比,刻蚀后的试样表面水接触角大幅降低,防结蜡性能显著提升。当刻蚀时间为120 min时,水接触角远小于30°,粉末冶金黄铜表面达到超亲水状态,防结蜡测试后,约80%表面为干净的原始表面,几乎没有石蜡吸附。结论刻蚀表面的亲水成分和棱锥状铜单质颗粒组成的微细粗糙结构,使得其在水相中形成稳定的"水膜",这层水膜可以有效阻止油相中石蜡的析出与沉积,达到良好的防结蜡效果。     

清防蜡技术的研究及应用

介绍了国内外清防蜡工艺的研究进展,总结了结蜡机理及结蜡影响因素,并对比分析了已被各油田广泛使用的四种防蜡技术(机械清蜡、表面能防蜡、化学清防蜡和微生物清防蜡)的防蜡机理、特点、适用性及现场应用效果,以便能为各油田在生产实践中,有针对性地选择合适的清防蜡技术提供理论依据,为清防蜡技术的未来发展奠定一定的基础。提出改进现有技术和开发高效、稳定、多功能的清防蜡剂是清防蜡技术的未来发展方向。     

黄铜表面多层化学转化膜特性研究

黄铜经苯并三氮唑(BTA)和络合钝化剂PVA溶液钝化处理后,表面耐蚀性明显提高,椭圆偏振法和X射线光电子能谱法(XPS)研究表明,PVA能在Cu(I)BAT薄膜上继续外延生长成膜,BTA—PVA混合液钝化处理效果与先用BTA、后用PVA溶液钝化处理效果基本相同、钝化处理后的化学转化膜大体上为三层结构,即Cu_2O/Cu(I)BTA/PVA膜     

铝合金表面无铬化学转化膜的研究

采用钼酸盐、高锰酸盐作为成膜氧化剂,研究了铝合金化学转化膜的处理溶液,优化了溶液配方与工艺参数,在铝合金表面制备出有良好耐蚀性的转化膜.利用各种测试手段与分析方法,对转化膜的综合性能进行分析,对转化膜的微观形貌与元素组成进行表征.提出了钼酸盐化学转化膜成膜机理.     

镁合金表面化学转化膜研究进展

总结镁合金表面化学转化膜的研究现状,介绍铬酸盐转化膜、锡酸盐转化膜、磷酸盐/高锰酸盐转化膜、稀土转化膜、植酸转化膜和钼酸转化膜的处理工艺,讨论磷酸盐/高锰酸盐转化膜的成膜机理,分析各种化学转化膜的优缺点,展望今后镁合金表面化学转化膜的发展方向。     

AZ91D镁合金表面无铬化学转化膜的研究

在AZ91D镁合金表面利用无铬的KMnO4-Mn(H2PO4)2-pH值调整剂转化液进行化学转化,分析了转化膜的形成机理.经XRD分析结果显示,转化膜为非晶态结构,SEM观察发现,转化膜表面均匀,存在有利于增强涂装层附着力的网状裂纹.转化膜经EDS和XPS分析表明,主要元素为Mg、Al、Mn、O,由MgO、Mg(OH)2、MgAl2O4、Al2O3、Al(OH)3、MnO2组成.转化后的AZ91D镁合金在3.5%的NaCl溶液中全浸试验结果表明,其腐蚀速率低于其他化学转化膜.     

镁合金化学转化膜上化学镀镍的研究

将化学转化和化学镀镍结合在一起,先对AZ91D镁合金进行化学转化处理,然后在转化膜上进行化学镀镍.并用扫描电镜(SEM)、X射线衍射技术(XRD)研究了镀层表面形貌和组织结构及处理后镁合金的耐蚀性能.结果表明:两种工艺结合得到的镀层使腐蚀电位正移0.83 V,腐蚀电流降低,有效的提高了镁合金耐腐蚀性能.     

镁合金表面化学转化膜的研究进展

综述镁合金化学转化膜:铬酸盐转化膜、磷酸盐转化膜、磷酸盐-高锰酸盐转化膜、锡酸盐转化膜、稀土转化膜、植酸转化膜等处理方法的工艺特点.讨论磷酸盐转化膜的成膜原理及工艺,分析这些化学转化工艺存在的不足,并展望镁合金化学转化膜的研究前景.     

Characteristics of blueing as an alternative chemical conversion treatment on carbon steel

Alternative pretreatments are proposed in order to avoid the environmental aggressive impact produced by using surface finishing processes based on Cr(VI) compounds. In this work, blueing method is proposed as chemical conversion treatments (CCTs) in AISI 1010 commercial steel. CCTs were carried out by the so-called “Swiss blueing” method using a solution with 20 g HNO₃ + 5 g CH₃CH₂OH + 5 g CuSO₄·5H₂O + 160 g FeCl₃ dissolved in water (1:1). This solution was added onto steel sheets using spray impregnation technique. Anticorrosion protection and adhesion properties were evaluated using polarization resistance (Rp), ac impedance and pull-off test, respectively. The thickness, morphology and microstructure of the protective films have been examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Although, no-treated specimens showed the highest polarization resistance (Rp) and impedance values, the oxide compounds are porous and unstable, while samples with the CCTs increased anticorrosive protection and favoured a strong adhesion between substrate and top coating. Continuous immersion values obtained by ac impedance showed remarkable variations in the coating resistance. SEM micrographs indicate that chemical treatment increased the surface porosity-roughness. XRD patterns showed some iron oxide compounds: mainly magnetite, and a small quantity of hematite, which have influenced the electrochemical behavior and adhesion. Pull-off tests showed good adhesion in the previously treated samples. These results indicate that obtained roughness with one CCTs using “Swiss blueing” method increased anticorrosion protection and adhesion properties.     

AZ31镁合金表面磷酸盐-高锰酸盐化学转化膜性能的试验研究

用磷酸盐-高锰酸盐在AZ31镁合金表面制备出无铬化学转化膜,并采用金相显微分析、扫描电镜分析、能谱分析、X-射线衍射分析、电化学方法、中性盐雾试验分别对化学转化膜封孔处理前后的表面形貌、成分、相结构和耐蚀性进行检测和评价.研究结果表明,无铬化学转化处理可以显著提高镁合金的耐蚀性,封孔后处理可以有效地封闭化学转化膜中存在的孔隙,并进一步提高镁合金的耐蚀性.     

ZK60镁合金磷酸盐及锡酸盐化学转化膜

为了提高ZK60镁合金的耐腐蚀性能,利用磷酸盐溶液或锡酸盐溶液,考察了在ZK60镁合金上形成磷酸盐或锡酸盐化学转换膜的工艺条件及膜层的耐蚀性能。通过改变处理时间和温度,可以得到性能不同的转换膜。通过电化学阻抗谱技术和极化曲线技术研究转化膜的耐腐蚀性能,利用扫描电镜研究其微观结构。结果表明:在磷酸盐溶液中,当处理温度为50℃时,磷化30min后试样的电荷转移电阻(Rct)为224.03Ω·cm2;当温度为80℃,反应时间为45min时,所得转换膜的Rct为377.67Ω·cm2,阻值最大,耐腐蚀性能最好;对于锡酸盐化学转化膜,90℃下,处理60min的膜层耐蚀性能最好,其Rct为388.32Ω·cm2,与磷酸盐化学转化膜相比,两种膜的保护性能相差不大。     

Surface characteristics of chemical conversion coating for Mg-Al alloy

The chemical conversion coating was formed on Mg alloy for low cost and harmlessness in environment by using the colloidal silica as the main component. The film formed at 298 K was thick, which was thought to be the combination of Si and O. In salt spray test, the ratio of black rust on the specimen that did not conducted chemical conversion treatment was five times or more than those of the chemical conversion treated specimen. The film of chemical conversion coating produced by alkali treatment process was thinner than the specimen produced in basic chemical conversion treatment solution.     

化学转化膜上沉积镍对镁合金耐腐蚀性能的影响

将化学转化和化学镀镍结合在一起,先对铸态AZ91D合金进行锡酸盐转化处理,然后在转化膜上进行化学镀镍.研究了转化膜及化学镀镍涂层的成分、结构和耐腐蚀性能.结果表明:锡酸盐转化处理后合金表面形成了以MgSnO3*H2O为主要成分的转化膜,可对合金起到一定的防护作用; 转化膜由细小的球形颗粒密积而成,颗粒之间存在间隙,它可以为化学镀镍的前处理过程提供良好的吸附条件; 转化膜上的化学镀镍层组织致密、无缺陷,MgSnO3*H2O转化膜在镀镍层与基体之间起到过渡作用,镀层的磷含量达到9%,与基体结合良好; 在3.5% NaCl (pH=7)溶液中的动电位极化测试表明,镀镍以后的合金在阳极极化过程中发生了明显的钝化,耐腐蚀性能进一步提高,对基体起到了较好的防护作用.     

Electrochemical properties and structure of vanadium-based conversion coatings on electro-galvanised steel

The corrosion resistance of vanadium-based conversion coatings on electro-galvanised steel (EG) was examined in terms of the different valence species V⁵⁺ and V⁴⁺ as the raw material in the treatment solution. The effects of mixing phosphoric acid with the vanadium-based conversion coating have also been investigated. Corrosion performance was tested by neutral salt spray test and the mechanism of corrosion resistance was analysed by electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. It was found that conversion coatings formed from V⁵⁺ or V⁴⁺ did not clearly show different corrosion behaviour, but that the addition of phosphoric acid to the solution including V⁵⁺ improved corrosion protection. These results indicate that mixing phosphoric acid lowers the pH of the solution and improves corrosion resistance. The role of phosphoric acid is also explained by the formation of hydrogen bonds at the interface between the vanadium species and EG substrate.     

Corrosion properties ofAZ31 magnesium alloy and protective effects of chemical conversion layers and anodized-coatings

The corrosion properties of AZ31 magnesium alloys were studied by potentiodynamic polarization curves and electrochemical impedance spectroscopy（E1S） techniques, meanwhile, the protective properties of two environmentally protective types of chemical conversion layers and anodized coatings of AZ31 magnesium alloys were also discussed. The component of chemical conversion bath is NaH2PO4·12H2O 20 g/L, H3PO4 7.4 mL/L, NaNO2 3 g/L, Zn（NO3）2·6H2O 5 g/L and NaF 1 g/L, and components of the anodization bath is Na2SiO3 60 g/L, C6H5Na3O7·2H2O 50 g/L, KOH 100 g/L and Na2B4O7·2H2O 20 g/L. The results show that the corrosion resistance of AZ31 magnesium increases with the increase of pH value of the corrosive medium. For the chemical conversion layer acquired at 80 ℃, 10 min is the best processing time and the charge transfer resistance of the chemical conversion layer is enhanced nearly by 10 times. The optimum processing time for the anodization of AZ31 is 60 min, the charge transfer resistance value of the anodized sample at the early immersion stage is nearly 26 times of that of the blank sample and the corrosion type of the anodized samples is pitting.     

化学转化膜对镁合金抗腐蚀性的影响

利用扫描电镜、X射线衍射和质量损失等手段,研究预处理前后的表面形貌及质量变化和锡酸盐化学转化膜层表面形貌及其相组成,采用盐雾和湿热实验箱检验膜层的抗腐蚀性能。结果表明:预处理前后镁合金表面相组成基本不变,质量减少主要发生在酸洗阶段,但变化不大;由于发生化学腐蚀和电化学腐蚀,预处理后表面在相界处出现较深的狭缝。化学转化膜层主要由Mg、Al12Mg17和MgSnO3.3H2O组成,表面由细小近球形颗粒密积而成,颗粒之间存在缝隙。经盐雾和湿热检测,化学转化膜层可以大大提高镁合金基体的抗腐蚀性。     

定向碳纳米管薄膜的制备及可控浸润性

利用热化学气相沉积系统(CVD),用乙炔为碳源,氮气为载气,氢气为还原气体,氨气为刻蚀气体,在单晶硅上制备定向碳纳米管薄膜.通过扫描电镜(SEM)观察不同反应温度对碳纳米管薄膜的形貌影响,并通过接触角测量仪评估薄膜的浸润性.结果表明,生长温度对碳纳米管薄膜的定向性程度及其尺度有很大的影响,温度太低不利于定向碳纳米管的形成,太高也会阻碍定向生长,适合定向碳纳米管生长的温度在850℃左右;通过生长温度改变碳纳米管薄膜的表面微观形貌就可以大幅度地调控其表面的浸润性能,从亲水79.9°到超疏水155.4°.碳纳米管的定向程度、尺寸和浸润性等特性可以用生长温度来加以调控.