磷酸一氢钠对AZ91镁合金的缓蚀作用

采用电化学阻抗谱(EIS)、动电位极化曲线、失重法和扫描电镜研究了磷酸一氢钠对AZ91镁合金在0.05%NaCl溶液中的缓蚀行为,及其与部分有机物的协同作用。结果表明,因为磷酸一氢根离子与镁离子反应产生了镁盐沉淀物,磷酸一氢钠对镁合金有一定的缓蚀作用;有机磺酸盐、羧酸盐或氨酸盐单独使用时,这些缓蚀剂的阴离子可以部分吸附在镁合金表面上,从而起到一定程度的保护作用;磷酸一氢钠与磺酸盐复配使用时缓蚀效率最高。     

Na_3PO_4对模拟汽车冷却液中AM60镁合金的缓蚀作用

通过极化曲线、电化学阻抗谱等电化学方法研究了Na_3PO_4对AM60镁合金在模拟汽车冷却液中的缓蚀性能,考察了缓蚀剂浓度、腐蚀介质温度和浸泡时间对缓蚀效率的影响,并探讨了缓蚀机理。结果表明:当Na_3PO_4的浓度为0.6 mmol/L时,AM60镁合金的缓蚀效率高达84.58%,长时间浸泡和高温时缓蚀效果不明显,更适合于在汽车模拟冷却液中对AM60镁合金进行短时间的缓蚀保护。     

硅酸钠对模拟汽车冷却液中AM60镁合金的缓蚀作用研究

目的了解在模拟汽车冷却液介质中,Na_2SiO_3对AM60镁合金的缓蚀作用和缓蚀机理。方法通过极化曲线、电化学阻抗谱方法等电化学方法研究了Na_2SiO_3对AM60镁合金在模拟汽车冷却液中的缓蚀性能,考察了Na_2SiO_3浓度、模拟冷却液温度和浸泡时间对缓蚀效率的影响,并对缓蚀机理进行了探讨。结果 Na_2SiO_3浓度对其缓蚀效率影响较大,其最佳浓度为0.8 mmol/L,此时缓蚀效率为95.87%。冷却液在高温(80℃)时,Na_2SiO_3的缓蚀效率为36.08%,也能对AM60镁合金提供一定的缓蚀保护作用。浸泡初期,Na_2SiO_3对AM60镁合金电极的缓蚀效率为17.47%,浸泡10 h后可达72.38%。结论在模拟汽车冷却液中,当Na_2SiO_3的浓度为0.8 mmol/L时其缓蚀效率最高,且其缓蚀效率随介质温度的升高而降低,随浸泡时间的增加而增大。Na_2SiO_3表现为阳极型缓蚀剂的特征,缓蚀机理可解释为Si O32-能与腐蚀产生的Mg2+生成难溶性的Mg Si O3化合物,生成的Mg Si O3沉积于合金表面形成一层保护膜,从而阻滞了金属的进一步离子化。     

AZ91镁合金在冷却系统中的耐腐蚀性

运用电化学方法研究一种水杨酸Schift 碱化合物(Salcn)对AZ91镁合金在30%乙二醇水溶液(30%EG/W)中的腐蚀行为的抑制作用。用扫描电镜观察合金在30%乙二醇水溶液(30% EG/W)中的腐蚀前、后的形貌。在室温下,添加这种水杨酸Schift碱化合物对AZ91镁合金的腐蚀抑制作用不明显,但在高温下,由于合金表面化学吸附了抑制剂而使其耐腐蚀性得到增强;随着抑制剂浓度的增加,镁合金表面吸附更多的抑制剂,从而使抑制作用的增强。     

NaOH溶液中表面活性剂对工业纯铝的缓蚀作用

采用失重法研究了阴离子表面活性剂油酸钠(SO)和阳离子表面活性剂溴化十四烷基吡啶(TDPB)在0.1mol/LNaOH溶液(20~50℃)中对工业纯铝的缓蚀作用。结果表明:SO在20~50℃时对铝基本无缓蚀作用。TDPB对铝在20℃和30℃时缓蚀效果较差;但在40℃和50℃时TDPB对铝具有良好的缓蚀作用,50℃时1.0×10-3mol/LTDPB对铝的最大缓蚀率为81.2%。TDPB在铝表面的吸附符合校正的Langmuir吸附模型,根据热力学公式求出了吸附热力参数(吸附自由能ΔG0,吸附焓ΔH0,吸附熵ΔS0),并用吸附观点讨论了缓蚀作用机理。     

MoO42-与 Zn2+对镁合金在 NaCl 溶液中的协同缓蚀作用

采用动电位极化曲线法,结合腐蚀后的表面微观形貌及EDS能谱分析,研究了MoO42-与Zn2+对AZ31镁合金在3.5%NaCl溶液中的协同缓蚀性能。结果表明:0.005 mol/L Zn2+与0.05 mol/L钼酸钠联合作用,可有效抑制镁合金在NaCl溶液中的腐蚀,Zn2+促进MoO42-在合金表面的吸附,缓蚀效果优于单一的钼酸盐缓蚀剂。缓蚀机制是:钼酸盐与Zn2+协同作用,使镁合金表面形成更为致密的钝化膜,从而抑制镁合金的腐蚀。     

添加Gd对AM60镁合金耐腐蚀性能的影响

采用区域凝固法制备AM60和AM60Gd1.0镁合金。采用析氢实验和电化学实验研究了添加Gd对AM60合金的显微结构和在0.9%(质量分数) NaCl溶液和模拟人体体液中的耐腐蚀性能的影响。结果表明,AM60合金由α-Mg相和β-Mg_(17)Al_(12)相组成,Gd的添加促进了Al_2Gd相的生成;同时提高了合金的腐蚀电位,降低了腐蚀电流密度。在0.9%NaCl溶液中,AM60合金和AM60Gd1.0合金的阻抗谱均由一个高频容抗弧和一个低频感抗弧组成;在模拟人体体液中,两种合金的阻抗谱由两个高频容抗弧组成;在同一浸泡时间下,AM60Gd1.0合金阻抗谱的半径大于AM60合金的。Gd的添加提高了AM60合金的耐蚀性。     

稀土、锶复合添加对AM60镁合金组织和性能的影响

稀土、锶复合添加对AM60镁合金组织、力学性能和抗热裂性能的影响的研究结果表明,往AM60镁合金中添加稀土后,稀土与合金中的异质形核核心Al9Mn11相或Al(8Fe,Mn)5相反应生成Al-RE-Mn三元相,减少了合金熔体中异质形核核心的数目,从而引起了合金晶粒粗化。往AM60镁合金中复合添加稀土和锶后,锶能够消除稀土引起的晶粒粗化作用,减少晶粒粗化对合金力学性能和抗热裂性能的不利影响,从而提高合金的高温屈服强度,并消除稀土对合金抗热裂性能的恶化作用。     

高氯油田水溶液中咪唑类缓蚀剂的性能

采用失重试验和电化学方法研究了苯并咪唑及6-硝基苯并咪唑两种缓蚀剂在含氯油田水溶液中对Q235钢的缓蚀作用,并探讨其缓蚀机理,研究了两种缓蚀剂添加量对缓蚀效率的影响。结果表明,苯并咪唑及6-硝基苯并咪唑缓蚀剂都具对Q235钢有明显的缓蚀作用,苯并咪唑缓蚀率随着浓度增大呈现增大趋势,浓度为1.0g/L时缓蚀效果最好,缓蚀率达90.41%;6-硝基苯并咪唑的缓蚀率随着浓度的增大具有极值效应,当浓度为0.5g/L时,最大缓蚀率为84.78%。极化曲线和电化学阻抗谱试验结果与失重法的结果一致,都表明在油田水溶液中苯并咪唑的缓蚀率较6-硝基苯并咪唑高。苯并咪唑的缓蚀效果较6-硝基苯并咪唑更好,且两种缓蚀剂在Q235钢表面的吸附都为自发过程,符合Langmuir吸附等温式。     

油酸钠作用下金红石的浮选行为及作用机理

通过纯矿物试验,研究金红石在油酸钠为捕收剂体系中的浮选行为。当油酸钠用量为20 mg/L、pH值为6~8时,金红石浮选回收率均在80%以上;当pH=7.5时,金红石浮选回收率最高,为85.27%。Zeta电位及红外光谱测试结果表明,油酸钠在金红石表面主要发生了化学吸附,同时也可能存在物理吸附。根据油酸钠溶液化学计算,当pH值为6~8时,油酸钠溶液的优势组分为C17H33COO-和(C17H33COO)22-;而金红石表面Ti4+的羟基化合物主要以[Ti(OH)2]2+和[Ti(OH)3]+形式存在。结合金红石在油酸钠捕收剂体系中的浮选行为,油酸钠在金红石表面的相互作用原理是,金红石表面解离的Ti4+在水溶液中形成羟基化合物[Ti(OH)2]2+和[Ti(OH)3]+络合在金红石表面成为浮选的活性质点,再与C17H33COO-和(C17 H33COO)22-作用形成Ti(C17H33COO)4,从而使金红石疏水上浮;油酸(C17H33COOH(aq))分子和离子-分子缔合物(C17H33COOH·C17H33COO-)的物理吸附也可能存在。     

Comparison of corrosion behaviors of AZ31, AZ91, AM60 and ZK60 magnesium alloys

The corrosion behaviours of four kinds of rolled magnesium alloys of AZ31, AZ91, AM60 and ZK60 were studied in 1 mol/L sodium chloride solution. The results of EIS and potentiodynamic polarization show that the corrosion resistance of the four materials is ranked as ZK60＞AM60＞AZ31＞AZ91. The corrosion processes of the four magnesium alloys were also analyzed by SEM and energy dispersive spectroscopy(EDS). The results show that the corrosion patterns of the four alloys are localized corrosion and the galvanic couples formed by the second phase particles and the matrix are the main source of the localized corrosion of magnesium alloys. The corrosion resistance of the different magnesium alloys has direct relationship with the concentration of alloying elements and microstructure of magnesium alloys. The ratio of the β phase in AZ91 is higher than that in AZ31 and the β phase can form micro-galvanic cell with the alloy matrix, as a result, the corrosion resistance of AZ31 will be higher than AZ91. The manganese element in AM60 magnesium alloy can form the second phase particle of AlMnFe, which can reduce the Fe content in magnesium alloy matrix, purifying the microstructure of alloy, as a result, the corrosion resistance of AM60 is improved. However, due to the more noble galvanic couples of AlMnFe and matrix, the microscopic corrosion morphology of AM60 is more localized. The zirconium element in ZK60 magnesium alloy can refine grain, form stable compounds with Fe and Si, and purify the composition of alloy, which results in the good corrosion resistance of ZK60 magnesium alloy.     

Inhibition of steel corrosion by calcium benzoate adsorption in nitrate solutions

The inhibitive properties of calcium benzoate for steel corrosion were studied in sodium nitrate solutions at room temperature. Corrosion parameters of the steel/nitrate and steel/benzoate + nitrate interfaces were obtained from polarisation curves. Adsorption parameters of benzoate on steel in sodium nitrate solutions were determined through changes in the degree of surface coverage by the inhibitor, as a function of concentration, time and adsorption potential. The effect of chloride on the corrosion inhibition of benzoate was analysed exposing the metal in different chloride solution concentrations.     

Inhibition of corrosion of AZ91 magnesium alloy in ethylene glycol solution in presence of chloride anions

The influence of chloride ions on the corrosion of AZ91 magnesium alloy in water/ethylene glycol solutions and the inhibiting effect of lactobiono‐tallowamide (LTA) were investigated using electrochemical and surface analysis methods. Potentiodynamic polarization curves in aqueous solution of ethylene glycol (50:50w%) containing 0.1 g.L⁻¹ chloride and up to 0.5 g.L⁻¹ LBT were obtained at room and at elevated temperatures. The chloride anions showed a distinct deteriorating effect as they caused pit initiation and accelerated the dissolution of the tested alloy. The selected organic compound demonstrated good protective properties against corrosion of AZ91 magnesium alloy and behaved as inhibitor of mixed type hindering both the cathodic and the anodic partial reactions. It showed inhibition efficiency of 77% at relatively low concentration of 0.2 g.L⁻¹ and was considered as a promising corrosion inhibitor. The mechanism of inhibition was discussed on the basis of the electrochemical impedance spectroscopy (EIS) and XRD analysis of the surface.     

稀土元素Ce和La合金化对AM60镁合金腐蚀行为的影响

采用电子探针-能谱分析,场发射扫描电镜X射线衍射等方法研究了稀土元素Ce和La合金化对AM60镁合金结构和耐蚀性能的影响.结果表明,Ce和La的加入可在AM60镁合金中形成了富含稀土元素的γ相（MgAlRE）;能有效抑制析氢,提高镁合金的耐蚀性能;改善镁合金在含Cl-溶液中的耐蚀性能;腐蚀产物膜的晶态主要成分为铝和锰的氧化物,并含有少量的稀土氧化物和氢氧化物.     

Corrosion behaviour of magnesium in ethylene glycol

Corrosion of magnesium engine components by coolant is an important issue in the automotive industry where magnesium alloys may be used. It is of significance to understand the corrosion behaviour of pure magnesium in ethylene glycol solutions, as this can provide a basis for developing new coolants for magnesium alloy engine blocks. In this paper, through corrosion and electrochemical tests, it was found that the corrosion rate of magnesium decreased with increasing concentration of ethylene glycol. Individual contaminants, such as NaCl, NaHCO₃, Na₂SO₄ and NaCl can make aqueous ethylene glycol solution more corrosive to magnesium. However, in NaCl contaminated ethylene glycol, NaHCO₃ and Na₂SO₄ showed some inhibition effect. The solution resistivity played an important role in the corrosion of magnesium in ethylene glycol solutions, and the competitive adsorption of ethylene glycol and the contaminants on the magnesium surface was also responsible for the observed corrosion behaviours. The corrosion of magnesium in ethylene glycol can be effectively inhibited by addition of fluorides that react with magnesium and form a protective film on the surface.     

Synergistic inhibition effect of rare earth cerium(IV) ion and anionic surfactant on the corrosion of cold rolled steel in H2SO4 solution

The synergistic inhibition effect of rare earth cerium(IV) ion and anionic surfactant of sodium oleate (C₁₇H₃₃-COONa, SO) on the corrosion of cold rolled steel (CRS) in H₂SO₄ solution was first investigated by weight loss and potentiodynamic polarization methods. The results revealed that SO had a moderate inhibitive effect, and the adsorption of SO obeyed the Freundlich adsorption isotherm. For the cerium(IV) ion, it had a negligible effect. However, incorporation of Ce⁴⁺ with SO significantly improved the inhibition performance, and produced strong synergistic inhibition effect. Depending on the results, the synergism mechanism was proposed.     

AZ91镁合金表面电化学沉积羟基磷灰石涂层的制备及其耐蚀性

采用电化学沉积方法在AZ91镁合金表面制备了羟基磷灰石(HA)涂层,研究了电沉积工艺参数对羟基磷灰石涂层形貌和相组成的影响,并通过腐蚀浸泡试验、极化曲线测试等方法对该涂层的耐蚀性进行了研究。结果表明:当溶液pH为4.5,温度为60℃时,涂层的致密性最好,呈放射状的结构,主要成分为HA相,涂层的厚度约为60~70μm,与基体结合较好;HA涂层对镁合金基体具有较好的保护作用,显著提高了基体合金在生理溶液中的耐蚀性。     

巴比妥钠对铝合金在NaCl溶液中缓蚀作用的研究

通过极化曲线及扫描电镜（ＳＥＭ）研究了巴比妥钠对硬铝合金（ＬＹ１２ＣＺ）在３．５％ＮａＣｌ中的缓蚀作用机制。结果表明,巴比妥钠对铝合金具有较好的缓蚀作用并且能提高铝合金在ＮａＣｌ溶液中抗点蚀的能力,这种能力主要是通过在铝合金的表面形成不溶怀盐转化膜来实现的。