Q235钢在海水淡化一级反渗透产水中的腐蚀行为

采用旋转挂片和SEM, EDS及IR分析研究Q235钢在海水淡化一级反渗透产水中(RO)的腐蚀速度和腐蚀产物变化规律,并利用动电位扫描、电化学阻抗法研究腐蚀过程及腐蚀反应控制步骤。结果表明,Q235钢在海水淡化一级反渗透产水中腐蚀速度在48 h内迅速增大至1.4 mm/a,其后保持稳定。锈层初期为γ-FeOOH薄层,随时间延长逐渐转为由Fe₃O₄构成的内锈层及由γ-FeOOH和α-FeOOH构成的外锈层。腐蚀过程受阴极控制,初期腐蚀阻力达到最大,其后由于大量γ-FeOOH在酸性条件下极易转化为对腐蚀反应没有阻滞作用的Fe₃O₄,腐蚀阻力迅速减小,腐蚀速度迅速增大,当Q235钢表面γ-FeOOH生成和转化达到平衡后,腐蚀阻力保持稳定,腐蚀速度也不再发生变化。     

碳钢在海水淡化一级反渗透产水中的腐蚀行为

对碳钢在海水淡化一级反渗透产水中生成的锈层进行SEM、IR和XRD分析,并结合电化学测量,研究其腐蚀行为。结果表明,碳钢在一级反渗透产水中腐蚀过程受氧扩散控制,腐蚀产物包括γ-FeOOH、Fe₃O₄以及少量的α-FeOOH。锈层具有双层结构,外锈层很薄,主要成分为γ-FeOOH;内层占整个锈层比重很大,主要成分为Fe₃O₄。一级反渗透产水的弱酸性促使腐蚀产物γ-FeOOH迅速转化为Fe₃O₄,致使Fe₃O₄在金属表面大量堆积。由于Fe₃O₄层的导电性及不连续性,锈层不能阻碍阴极过程的进行,导致碳钢的腐蚀速度一直维持在高位。     

Q235碳钢在宜宾不同大气环境中的腐蚀行为

通过室外暴露试验和电化学测试,研究了电网设备主要金属材料Q235碳钢在四川宜宾地区不同大气环境中的腐蚀行为。结果表明：在四川宜宾A、B、C三个变电站环境中,Q235碳钢的平均腐蚀速率分别为19.68μm/a、41.40μm/a和28.75μm/a,其表面腐蚀产物主要由α-FeOOH、γ-FeOOH和Fe₃O₄组成,在B和C变电站环境中,Q235碳钢表面腐蚀产物中的α-FeOOH含量较高;在B变电站环境中,Q235碳钢的腐蚀电流密度最大,膜层电阻最小,说明其表面锈层对基体的保护性能较差。     

安徽省内电网设备常用Q235和40Cr钢大气腐蚀特性及其规律

针对在安徽省内代表性变电站站点自然环境下曝露1和3 a后的Q235、40Cr钢试样,开展腐蚀产物、腐蚀层形貌的研究,探讨其大气腐蚀机理。采用失重法获取Q235和40Cr钢试样的腐蚀速率,结合安徽省各相关地市的主要环境因素数据,再采用灰色关联分析方法,研究主要环境因素对1和3 a期Q235、40Cr钢试样大气腐蚀的影响规律。结果表明,Q235和40Cr钢试样大气腐蚀产物为FeOOH、Fe₃O₄、Fe(OH)₃及FeSO₄;腐蚀层表面密布着棉花球状的α-FeOOH,其间分布着片状的γ-FeOOH,腐蚀层结构较致密,但发生层状开裂。安徽省内Q235和40Cr钢试样大气腐蚀等级均在C2和C3等级,两者无明显差别。影响Q235和40Cr钢试样1 a期大气腐蚀的环境因素关联度排序为：NO₂>温度>SO₂>相对湿度>O₃;随着曝露时间延长至3 a,该关联度排序改变为：SO₂、温度>NO_2...     

高温高Cl-环境中含Ni、Cr耐蚀钢的腐蚀行为

冶炼了含Ni和Ni-Cr复合钢,采用室外暴晒试验结合锈层成分分析,腐蚀速率计算等研究了其在热带海洋大气环境中的腐蚀行为。结果表明：普碳钢、含Ni钢、和含Ni-Cr复合钢在试验环境中的腐蚀速率分别为66.84,41.54,38.29μm/a。合金元素Ni、Cr明显提高钢的耐蚀性。试样表面锈层主要由γ-FeOOH、α-FeOOH组成,还包含较小的Fe₃O₄颗粒和FeO片层。普通碳钢的锈层比另外两种试样厚,锈层中α-FeOOH含量更高、更稳定,而加Ni、Ni-Cr的试样经过半年试验后,表面未生成稳定锈层。经过半年室外暴晒试验,Ni元素在锈层中含量较少,但是在锈层下钢材内有富集现象。点蚀坑中存在Cr、Cu元素富集。     

碳钢和耐候钢在南沙海洋大气环境中的初期腐蚀行为

采用腐蚀失重法、宏观形貌观察法、SEM、XRD、白光干涉及拉伸实验等分析手段对碳钢Q235和耐候钢Q450NQR1在南沙大气环境下的初期腐蚀行为进行了研究。结果表明,Q235和Q450NQR1在南沙大气环境中的初期腐蚀比万宁及西沙等海洋大气环境中的腐蚀严重,2种钢的朝天面都比朝地面腐蚀严重,朝地面的锈层更容易脱落。暴晒2个月时,Q235和Q450NQR1的腐蚀失厚相近。暴晒5个月时,Q235的腐蚀失厚明显高于Q450NQR1的腐蚀失厚。2种钢在暴晒2个月时,朝天面和朝地面的腐蚀产物都主要为γ-FeOOH、α-FeOOH和Fe_3O_4;而暴晒5个月时,朝天面产物中出现了β-FeOOH,而朝地面β-FeOOH极少。朝天面的产物中Fe_3O_4相对含量少于朝地面,γ-FeOOH的相对含量多于朝地面。     

低合金钢在模拟酸性土壤中的耐蚀性研究

用硅藻土模拟酸性土壤,对两种接地网材料用的实验钢进行室内加速腐蚀实验。通过实验室埋片腐蚀实验、激光拉曼光谱和电化学方法研究其在模拟酸性土壤中的耐蚀性。结果表明,两者的腐蚀速率呈现先升后降的趋势;Q235钢的腐蚀失重明显大于低合金A钢的,且两者的腐蚀速率相差近一倍,腐蚀形貌由局部腐蚀逐渐发展为全面腐蚀;腐蚀产物均出现分层结构,外锈层成分大致相同,主要为α-FeOOH,Fe₃O₄,Fe₂O₃和γ-FeOOH,内锈层成分差别较大,低合金A钢中保护性锈层α-FeOOH所占比例大。Tafel极化曲线测试表明,低合金A钢的自腐蚀电位更正,腐蚀电流密度更小。     

Q235和Q450钢在吐鲁番干热大气环境中长周期暴晒时的腐蚀行为研究

在吐鲁番干热大气环境中对Q235和Q450钢进行4 a大气暴晒实验。结果表明,两种钢表面均有较为明显的锈层,Q450耐候钢4 a的平均腐蚀速率为12 g·m~(-2)·a~(-1),Q235钢平均腐蚀速率为14 g·m~(-2)·a~(-1),Q450钢腐蚀速率相对较低,腐蚀坑深度较浅。腐蚀产物主要由α-FeOOH,γ-FeOOH和Fe_2O_3·H_2O组成,其中Q450钢腐蚀产物中α-FeOOH比例相对较高,腐蚀产物致密。电化学阻抗测试结果表明:Q450钢腐蚀产物电阻远大于Q235钢的,表面电荷转移电阻也大于Q235钢的,即Q450钢耐蚀性较好,腐蚀产物对基体保护作用相对较好。     

耐酸性土壤腐蚀接地网用钢研究

采用硅藻土模拟法研究了Q235,A1和A2钢在模拟酸性土壤中的腐蚀行为,对比分析了材料的腐蚀失重,利用扫描电镜(SEM)和X射线衍射(XRD)等方法研究了材料的腐蚀形貌及腐蚀产物。结果表明,在模拟酸性土壤中,Q235,A1和A2钢周期360h的腐蚀速率别为0.48,0.14和0.097mm/a。碳层分析表明,降低碳含量有助于减少钢中的微电池腐蚀;Cr的加入可以提高基体的自腐蚀电位;腐蚀后内锈层位置Cr的富集可以提高锈层的致密性,并改变点蚀的扩展方式;3种材料主要腐蚀产物均为α-FeOOH,γ-FeOOH和Fe3O4,其中A1和A2钢内锈层腐蚀产物中α-FeOOH比例增大,其α/γ-FeOOH比值约为Q235的10倍,腐蚀产物保护性更优。     

一种新开发的车体钢S500AW在户外大气环境中的腐蚀行为及寿命预测

通过大气暴晒试验结合室内加速腐蚀试验，研究了新开发的车体钢S500AW和用于对比的传统Q450NQR1钢及Q345B钢的早期腐蚀行为，采用扫描电镜(SEM)、拉曼光谱仪，分析了试验前后试样表面的腐蚀形貌和腐蚀产物成分。结果表明：在北京大气环境暴露初期，S500AW钢表面更为平整光洁，仅有少量尘埃颗粒附着物，耐蚀性更优异；腐蚀产物为Fe₂O₃和一定量的γ-FeOOH,随着腐蚀时间的延长，γ-FeOOH含量逐渐增加，钢的耐蚀性逐渐提高；以腐蚀质量损失数据为参照，建立铁路车辆车体用钢腐蚀试验方法和腐蚀寿命预测模型，通过灰色关联度分析方法，证实了周期浸润试验与户外自然环境大气暴露试验良好的相关性。     

Influence of Rust Layers on the Corrosion Behavior of Ultra-High Strength Steel 300M Subjected to Wet–Dry cyclic Environment with Chloride and Low Humidity

The influence of rust layers on the corrosion behavior of ultra-high strength steel 300 M subjected to a simulated coastal atmosphere was investigated by corrosion weight loss, surface analysis techniques, and electrochemical methods.The results exhibit the presence of a large proportion of c-Fe OOH and a-Fe OOH and a small amount of Fe3O4 in the outer rust layer. During the wet–dry cyclic process, the bonding performance and the density of outer rust layer deteriorate with the thickness of outer rust. The inner rust layer plays a main role on protectiveness, which can be attributed to the formation of an ultra-dense and adherent rust film with major constituent of a-Fe OOH and a-Fe2O3 on the steel.     

Rust formation and corrosion performance of Si- and Al-bearing ultrafine grained weathering steel

A high Si, Al type ultrafine-grained (UFG) weathering steel was produced by the multi-pass warm rolling method, and its corrosion resistance was estimated by a cyclic wet/dry corrosion test using chloride ions. The Si- and Al-bearing UFG steel exhibited excellent corrosion resistance in comparison with Si–Mn carbon steel (SM).

EPMA and TEM analyses showed that Si and Al mainly exist in nano-scale iron complex oxides in the inner rust layer formed on the developed steel. The Al K X-ray spectrum of Al₂O₃ and metallic Al had different peak positions due to chemical shifts, and that of the test sample was the same as that of Al₂O₃ in the EPMA analysis. This result suggested that Al was present in the complex oxides as Al³⁺. In the same way, Si was identified as an intermediate state such as Si²⁺ in the complex oxides of the inner rust.

EIS (electrochemical impedance spectroscopy) measurement of the corrosion test samples revealed that the rust resistance (R_rust) and corrosion reaction resistance (R_t) of the developed steel were much larger than those of SM. It was found that nano-scale complex iron oxides formed in the lower layer of iron rust in the developed steel, resulting in increased R_rust and R_t, and finally suppressing corrosion.     

Characterization of the rust formed on weathering steel exposed to Qinghai salt lake atmosphere

The product formed on weathering steel exposed to salt lake atmosphere for 12 months was investigated by X-ray diffraction (XRD), infrared transmission spectroscopy (IRS), scanning electron microscopy (SEM), electron probe micro analyzer (EPMA) and electrochemical techniques. The rust was mainly composed of β-FeOOH, Fe₈(O,OH)₁₆Cl_1.3 and a little γ-FeOOH. Amorphous δ-FeOOH was only on skyward surface. The rust layer suppressed anodic reaction and facilitated the cathodic reaction. The very small value of rust resistance R_r in this work indicated that the rust had poor protective ability. Cl element was rich in the whole rust layer and played an important role in accelerating the corrosion of weathering steel in salt lake atmosphere.     

周期干湿浸条件下P265GH钢和Q235钢的大气腐蚀行为简

以NaCl+NaHSO3为腐蚀介质,通过浸渍干湿复合循环实验及腐蚀失重分析,并利用SEM,XRD和FTIR技术,研究了Q235碳钢和P265GH低合金钢的大气腐蚀行为。结果表明,两种钢的腐蚀遵从相同的动力学规律,腐蚀产物中均存在大量致密的α-FeOOH和非晶态δ-FeOOH,锈层具有很好的保护性,使得腐蚀速率降低。实验开始阶段两种钢的腐蚀量基本相同,但随着腐蚀的进行两者差距增大,P265GH低合金钢较Q235碳钢的失重小、锈层致密、耐腐蚀性好。     

红壤中变电站接地网金属材料的腐蚀行为分析

采用扫描电镜 (SEM)、能谱 (EDS) 和X 射线衍射 (XRD) 等技术对红壤中变电站接地网服役长达13 a的镀锌扁钢进行了形貌分析和腐蚀产物分析。结果表明,该镀锌扁钢受到严重腐蚀,腐蚀产物主要由FeOOH,Fe₃O₄和Fe₂O₃等组成,腐蚀产物分层的原因是新生成的腐蚀产物沉积在金属/腐蚀产物层界面或腐蚀产物开裂处,同时S和Cl对内层腐蚀产物具有较大的影响。Tafel测试结果表明,在腐蚀电流峰值附近,SO₄^2-与Cl^-的百分比为1∶2时,两者对镀锌Q235碳钢在该红壤中的腐蚀性影响具有等效作用。通过室内加速实验模拟镀锌Q235碳钢在该红壤中的腐蚀发现,镀锌Q235碳钢的腐蚀速率呈现先增大后减小的规律,该加速实验在未改变镀锌Q235碳钢腐蚀机理的同时具有较好的加速效果。     

Cu,P,Cr 和 Ni 对低碳钢耐蚀性的影响简

选择Cu-P-Cr-Ni钢、Cu-P-Cr钢和Q235碳钢,在0.01 mol/L的NaHSO3溶液中进行周期浸润、阻抗谱和极化曲线实验,研究了Cu-P-Cr-Ni系合金钢相比Q235碳钢在模拟工业大气(SO2)环境下的耐腐蚀性能;利用SEM,EPMA面扫描和XRD分析腐蚀锈层的形貌、组成及Cu,Cr和Ni的元素分布情况。结果表明:Cu-P-Cr-Ni系钢的腐蚀诱发敏感性最低,其次为Cu-P-Cr钢,腐蚀速率分别为Q235碳钢的59.5%和52.8%;锈层分为内、外两层,致密的内锈层明显发生Cu的颗粒状、Cr的团聚状富集,外锈层主要有Cr的富集,Ni富集不明显。Cu和Cr等的富集可形成致密的内锈层,提高低碳钢的耐蚀性。     

Effect of Deep Sea Pressures on the Corrosion Behavior of X65 Steel in the Artificial Seawater

The corrosion behaviors of X65 steel in the artificial seawater at different hydrostatic pressures are investigated by potentiodynamic polarization measurements, electrochemical impedance spectroscopy measurements and weight loss measurements.The corroded morphologies and the corrosion products are also investigated by scanning electron microscopy, X-ray diffraction analysis and Raman analysis.The results show that the corrosion current increases as the hydrostatic pressure increases.The charge transfer resistance decreases as the hydrostatic pressure increases.The corrosion products are mainly composed of γ-FeOOH and Fe_3O_4 at the atmospheric pressure, while the main components are γ-FeOOH, Fe_3O_4, and γ-Fe_2O_3 at the high pressure.The hydrostatic pressure accelerates the corrosion of X65 steel due to its effect on the chemical and physical properties of corrosion products, including the promoted reduction of γ-FeOOH and the wider and deeper cracks on the corrosion products layer.     

A study of the evolution of rust on Mo–Cu-bearing fire-resistant steel submitted to simulated atmospheric corrosion

The corrosion evolution of a Mo–Cu-bearing fire-resistant steel in a simulated industrial atmosphere was investigated by corrosion weight gain, XRD, EPMA, XPS, and polarization curves. The results indicate that the corrosion kinetics is closely related to the rust composition and electrochemical properties. As the corrosion proceeds, the relative content of γ-FeOOH and Fe₃O₄ decreases and α-FeOOH increases, and the rust layer becomes compact and adherent to steel substrate. Molybdenum and copper enrich in the inner rust layer, especially at the bottom of the corrosion nest, forming non-soluble molybdate and Cu(I)-bearing compounds responsible for enhanced corrosion resistance of the rust layer.