免清洗水性助焊剂主要组分的选择及其缓蚀性能研究

通过实验优选了环保型水性免清洗助焊剂所用的活化剂、成膜剂和表面活性剂等组分。采用交流阻抗法确定了缓蚀剂苯并三氮唑(BTA)的最佳配比,探究了体系中各组分对助焊剂缓蚀性能的影响。结果表明,酸–胺复配可以降低助焊剂的腐蚀性,而缓蚀剂BTA能显著提高助焊剂体系的缓蚀性能。当苹果酸和己二酸以1∶5的物质的量之比与三乙醇胺复配,n复配酸∶n三乙醇胺=11∶1,且酸–胺复合液的质量分数为3.15%、表面活性剂聚乙二醇2000的质量分数为0.2%、缓蚀剂BTA的质量分数为0.05%,助溶剂异丙醇和乙二醇丁醚的质量分数均为1.5%,成膜剂聚乙烯醇的质量分数为0.2%时,所制备的助焊剂体系的缓蚀性能最佳,膜电阻最大,为6.2×105Ω·cm2。该助焊剂体系对基底金属铜板的腐蚀性较弱。     

环保型免清洗助焊剂组分对其腐蚀性能的影响及其机理

主要研究活化剂、表面活性剂和缓蚀剂3种组分对环保型免清洗助焊剂腐蚀性能的影响。采用交流阻抗法研究了各组分对铜电极缓蚀性能的影响;通过扫描电镜观察测试了各组分对梳形试件的腐蚀;借助热分析研究了组分残留及相互作用。结果表明,随活化剂酸性的减弱,助焊剂体系的腐蚀性逐渐减弱;壬基酚聚氧乙烯醚系列的非离子表面活性剂有助于降低体系的腐蚀性能;缓蚀剂苯并三氮唑（BTA）的添加能显著改善助焊剂体系的缓蚀性能。用壬基酚聚氧乙烯(50)醚（w=0.2%）作表面活性剂、丁二酸和苹果酸复配（w=1.6%）作活化剂,BTA作缓蚀剂（w=0.06%）制备的助焊剂体系的膜电阻最大,在湿热条件下助焊剂对梳形试件的腐蚀明显降低,缓蚀性能最佳。热分析结果表明,体系缓蚀性能的改善可能是有机酸与丙三醇发生的酯化反应所致。     

一种环境友好复配酸洗缓蚀剂的研制及性能研究

以2-巯基苯骈咪唑作为EDTA酸洗缓蚀剂的主体药剂,通过正交试验筛选出了高效、环境友好型缓蚀剂。采用失重法研究了其缓蚀性能,讨论了酸洗介质浓度、缓蚀剂浓度、温度、Fe3+对缓蚀性能的影响。Tafel极化曲线表明缓蚀剂为混合型缓蚀剂;交流阻抗谱法(EIS)阻抗谱出现"退化"现象,只表现出一个高频容抗弧,与空白溶液对比,容抗弧的形状几乎一致;在缓蚀效率方面,电化学实验结果与失重法实验结论基本一致。     

缓蚀剂作用机理研究进展

对常用的钝化膜型缓蚀剂、沉淀膜型缓蚀剂和吸附膜型缓蚀剂进行了概述,重点阐述了目前关于缓蚀剂作用机理的三种主要理论,即成膜理论、吸附理论和电极过程抑制理论,分析了钨酸盐、钼酸盐、有机膦酸盐、杂环类及复合型缓蚀剂作用机理的研究进展情况。     

镀锌板有机-无机复合钝化膜的研究

以水性硅丙树脂为主成膜剂,以有机硅烷为辅助成膜剂,以钼酸钠和偏钒酸铵为无机缓蚀剂,在镀锌板表面制备了有机-无机复合钝化膜。通过极化曲线、电化学交流阻抗谱、盐雾实验、扫描电镜和能谱仪对钝化膜的耐蚀性、表面形貌及成分进行了表征与分析。结果表明:所得钝化膜表面平整、均匀,阻止了氧气和水分的进入,抑制了阴、阳极腐蚀,提高了镀锌层的极化电阻及耐蚀性。     

交流阻抗法研究膜层的形成和破损(I)——缓蚀剂膜层的EIS变化

ＹＫＩ５海水介质缓蚀剂主要成分为多元醇磷酸酯、多元醇聚磷酸酯、聚磷酸盐、正磷酸盐等。本文运用电化学阻抗谱（ＥＩＳ）研究了在９０７Ａ钢表面缓蚀剂膜的形成、破坏的缓蚀机理，结果表明缓蚀剂膜的形成和破坏，所对应的阻抗谱均有明显的变化，因此，ＥＩＳ是评价缓蚀剂膜持久性和监测膜完整性的有效方法。分析表明，ＹＫＩ５在９０７Ａ钢表面形成复合型缓蚀剂膜，具有很强的自修复能力和良好的持久性     

交流阻抗法对凝汽器铜管镀膜效果评价研究

采用交流阻抗法来评价凝汽器铜管镀膜的耐蚀性能及添加缓蚀剂的缓蚀效率,并与经典摇床挂片法实验结果进行比较。研究发现,随着BTA浓度增加,未镀膜电极缓蚀效果增强。当BTA浓度C_(BTA)≥0.45 mg/L时,BTA可覆盖电极表面具有缓蚀效果;对于镀膜电极,交流阻抗法显示镀膜可以起到防腐效果,且缓蚀剂的添加对其Nyquist图影响不明显。摇床挂片法验证了交流阻抗法的试验结论,可通过交流阻抗法快速评价镀膜电极或缓蚀剂防腐和缓蚀效果及机理。     

交流阻抗法研究膜层的形成和破损（Ⅰ）：缓蚀剂膜层的EIS变化

ＹＫＩ－５海水介质缓蚀剂主要成分为多元醇磷酸酯、多元醇聚磷酸酯、聚磷酸盐、正磷酸盐等。本文运用电化学阻抗谱（ＥＩＳ）研究了在９０７Ａ钢表面缓蚀剂模的形成、破坏的缓蚀机理,结果表明缓蚀剂膜的形成和破坏,所对应的阻抗谱均有明显的变化,因此,ＥＩＳ是评价缓蚀剂膜持久性和监测膜完整性的有效方法。分析表明,ＹＫＩ－５在９０７Ａ钢表面形成复合型缓蚀剂膜,具有很强的自修复能力和良好的持久性。     

AZ91D镁合金用复合缓蚀剂缓蚀行为的研究

采用腐蚀试验、电化学极化曲线和交流阻抗谱对自主研发的用于抑制镁合金在3.5%NaCl溶液中腐蚀的有机-无机复合缓蚀剂的缓蚀性能和缓蚀机理进行了研究。实验结果表明,在3.5%NaCl溶液中添加复合缓蚀剂的质量分数为3%时,其缓蚀效果最好,缓蚀效率高达91%,此时AZ91D镁合金的静态腐蚀速度小于0.06 g/(m2.h);复合缓蚀剂同时抑制了镁合金腐蚀的阴极和阳极过程,且以阳极抑制作用为主。     

一种复合缓蚀剂对铸铁材料带锈缓蚀保护作用研究

通过浸泡实验检验了单宁酸、环己胺和钼酸钠复合缓蚀剂对带锈铁币的缓蚀效果,采用动电位极化曲线、交流阻抗法研究了铸铁电极在缓蚀剂作用下的电化学行为,并用X射线衍射技术分析了缓蚀作用对试样表面锈层的组成的影响。结果表明,由单宁酸、环己胺和钼酸钠组成的三元复合缓蚀剂对带锈铸铁具有良好的协同缓蚀效果,铸铁电极腐蚀电位正移,且出现了有明显的钝化现象。带锈铁币经缓蚀处理后,表面锈层生成含有Fe_2O_3、α-FeOOH的稳定沉积膜,提高了锈层的耐蚀性能,且锈层颜色变化小,能满足铁质文物保护要求。     

304L不锈钢钢筋在模拟混凝土孔溶液中的钝化行为

利用恒电位极化法以及Mott-Schottky测试研究了304不锈钢钢筋与Q235钢筋在模拟混凝土孔溶液中的致密性以及生成的钝化膜的半导体特性.研究结果表明：304不锈钢钢筋在模拟混凝土孔溶液中表面形成的p型半导体钝化膜远比普通钢筋形成的n型半导体钝化膜的耐蚀性更高.     

The use of migrating corrosion inhibitors to repair motorways' concrete structures contaminated by chlorides

The effectiveness of migrating corrosion inhibitors (MCIs) and repair mortars against rebar corrosion was studied in concrete specimens made by ordinary Portland cement with w/c ratio equal to 0.6 and containing 1 wt.% of chlorides. An alkanolamine-based inhibitor was tested in addition with a common mortar and two repair mortars. Electrochemical techniques, measurements of corrosion potential and electrochemical impedance spectroscopy (EIS) were used to determine the corrosion behaviour of the specimens when a cell containing a 3.5% NaCl solution was applied on the rehabilitation mortar. Mercury intrusion porosimetry (MIP) was also used for the characterisation of repair mortars' total porosity and a chemical analysis was made to determine the amount of chlorides penetrated in the mortar layers and in the concrete substrate. Results demonstrate that the simultaneous use of the alkanolamine-based inhibitor with a good barrier coating offers protection against rebar corrosion and allows rehabilitation of deteriorated concrete structures.     

胶砂比和集料级配对ASR膨胀的影响

为建立快速鉴定硅质集料碱活性的方法 ,以沸石化珍珠岩和硅质砾石为集料研究了胶砂比和集料级配对砂浆试体ASR膨胀的影响。结果表明 :对检测集料ASR活性而言 ,快速砂浆棒法 (ASTMC12 6 0和CSAA2 3 2 - 2 5A)所建立的集料级配和胶砂比不是最敏感条件。采用单级配集料和多胶砂比砂浆试体可以更快速、可靠地鉴定集料ASR活性     

氨基醇类阻锈剂的阻锈机理

在分析氨基醇类阻锈剂对混凝土和钢筋作用行为的基础上,给出了氨基醇类阻锈剂的阻锈机理,即一方面阻锈剂通过在钢筋表面形成保护膜,隔离侵蚀性离子到达钢筋表面,另一方面通过和混凝土中的水化产物反应生成沉淀,提高混凝土密实度。两者相辅相成,共同起到延缓钢筋腐蚀或降低钢筋腐蚀速率的作用。氨基醇类阻锈剂在碳化混凝土中的阻锈效果微乎其微,在氯盐环境中依然有效,但当混凝土中氯离子浓度或腐蚀速率较高时,其阻锈作用大幅降低。由于阻锈剂的成分较为复杂,其成膜机制等还需进一步的研究。     

Corrosion of steel bars in OPC mortar exposed to NaCl, MgCl2 and CaCl2: Macro- and micro-cell corrosion perspective

In North America, corrosion of the steel rebar commonly occurs due to chloride attack from deicing salts. In Canada, based on the severity and temperature of the ambient environment, three different deicing salts, or combination of them, are used: NaCl, MgCl₂ and CaCl₂. In this paper, the effect of each of these salts on the corrosion of steel rebar and their impact on the durability of the mortar have been investigated. The results show that CaCl₂ has the most negative effect on the steel and, in high concentrations, on the integrity of the mortar. MgCl₂ also deteriorates the mortar if used in high concentration, while NaCl has no apparent effect on mortar durability even in high concentration.     

Effects of alkaline conditioning and temperature on the properties of glass fiber polymer composite rebar

This article investigated long term alkaline conditioning and temperature on the physical and mechanical properties of glass fiber‐reinforced polymer (GFRP) composite rebar for structural applications. The GFRP rebar was immersed in alkaline solution (pH ≈ 13) for 23 months at 23°C, and for 24 months at 60°C. The moisture absorption was found to be 0.34% at 23°C after 23 months, and 0.76% at 60°C after 24 months. At both temperatures, moisture absorption did not reach equilibrium which was attributed to two stages non‐Fickian behavior. Glass transition temperature (T_g) of the polymer matrix of rebar that conditioned at 23°C was found to be decreased because of plasticization, whereas T_g of the rebar that conditioned at 60°C was remained greater than the T_g of control rebar due to nonplasticization effect. Shear strength was retained by 83.5% at 23°C and 80.5% at 60°C, flexural strength was retained by 81% at 23°C and 69% at 60°C, and tensile strength was retained by 91.2% at 23°C and 74.3% at 60°C. It was revealed that durability of GFRP rebar in alkaline environment was controlled by the absorbed moisture; this was because the load transfer efficiency of fiber/matrix interface is vulnerable to moisture. POLYM. COMPOS., 37:3181–3190, 2016. © 2015 Society of Plastics Engineers     

Study on the corrosion behavior of reinforcing steel in cement mortar by electrochemical noise measurements

The corrosion behavior of reinforcing steel in cement mortar has been studied by electrochemical noise (EN) compared with the electrochemical impedance spectroscopy (EIS). The wavelet transform, as well as the statistical methods including the standard deviation of current noise (σ_I) and noise resistance (R_n), has been employed to analyze the EN data of reinforcing steel in mortar. It is revealed that there exist three different corrosion stages of reinforcing steel in cement mortar, including a competition process between breakdown and repassivation of passive film, a pitting development and an active corrosion during the 20 cyclic immersion and drying tests. The energy distribution plot (EDP) is able to provide useful information about the dominant process for the different corrosion stages.     

A study on the corrosion of reinforcing bars in alkali-activated fly ash mortars under wet and dry exposures to chloride solutions

This research investigates the corrosion protection afforded to the embedded rebars by room temperature-cured alkali-activated mortars, based on class F fly ash (FA), during wet and dry (w/d) exposures to 0.1 M NaCl solution. The results were compared to those obtained in a traditional cement-based mortar (REF). The rebar corrosion behaviour was characterized by corrosion potentials (E_cor) and potentiostatic polarization resistance (R_p) measurements, polarization curve recording and electrochemical impedance spectroscopy (EIS). The information collected suggested that FA mortars afforded a lower corrosion protection to the rebars and the reason was investigated by microstructural, physical–mechanical and chemical analyses of the mortars. FA mortars were found to undergo a fast carbonation, so that depassivation of the rebars occurred concurrently, in spite of a limited total chloride content inside these mortars. REF mortar was much less susceptible to carbonation and rebar corrosion started when a sufficiently high chloride concentration was built up.     

激发剂对含复合掺合料普通硅酸盐水泥体系 的改性研究

本文通过应用激发剂对含复合掺合料普通硅酸盐水泥体系进行改性,参照工程常用的混凝土配合比,设计配制了水泥砂浆及混凝土,并对水泥砂浆的力学性能及膨胀性能和混凝土力学性能的进行了研究。结果表明,激发剂对含复合掺合料普通硅酸盐水泥砂浆具有显著的增强减缩效果;对比工程常用C30混凝土配合比,能够明显降低C30混凝土中的水泥用量,增加复合掺合料的掺量,并提高混凝土的强度,这有利于商品混凝土企业的节能降本。     

Corrosion of a 3D-C/SiC composite in salt vapor environments

Corrosion behavior of the three-dimensional C/SiC composite was investigated in a Na₂SO₄ vapor environment at temperatures from 1000 to 1500°C. The degradation mechanisms for the C/SiC composite could be determined by dividing a complicated function describing the weight change of the composite with temperature into several monotone functions describing the mechanisms, and then identified by the strength change of the composite with temperature. There were three reactions between the C/SiC composite and the Na₂SO₄ vapor. The first one was the passive oxidation of the CND SiC, leading a small weight gain. The second one was the oxidation of the carbon phases, leading a small weight loss. The third one was the active oxidation of the CVD SiC, leading a large weight loss. The threshold temperature for these reactions was, respectively, 1080, 1100 and 1300°C. The transition temperature from passive to active was 1200°C. The activation energy for these reactions was, respectively, calculated by the weight change with temperature to be 114, 105 and 112 kcal/mol. The flexural strength loss of the composite reached its minimum value when the weight gain of the composite reached its maximum value at 1200°C. Below 1200°C, the C/SiC composite had a higher corrosion resistance to the Na₂SO₄ vapor. Above 1300°C, the poor corrosion resistance of the CVD SiC made the composite having a poor corrosion resistance to the Na₂SO₄ vapor.