利用扫描电镜 (SEM)、X射线光电子谱技术 (XPS)、和X射线衍射 (XRD) 技术,分析了国产锻造态316LNSS在加氢高温高压水中浸泡480 h后表面氧化膜的形貌和化学成分。结果表明,氧化膜最外层主要分布两种不同尺寸的氧化物颗粒,大尺寸氧化物 (~1 mm) 分布较为稀疏,而小尺寸氧化物 (200~300 nm) 分布非常紧密；锻造态316LNSS表面形成外层富Fe、内层富Cr的双层结构氧化膜,外层氧化膜主要由Fe3O4和少量氢氧化物 (Ni(OH)2 和CrOOH等) 组成,内层氧化膜主要由富Cr尖晶石结构氧化物组成。同时讨论了316LNSS在模拟压水堆一回路水中的氧化机制。
Forged 316LNSS has been selected as the main pipe line material used in the third generation nuclear power plants. The oxide scale formed on the forged 316LNSS after immersion in high temperature pressurized water with 2.3 mg/L of dissolved hydrogen (DH) was studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Results showed that a double-layer oxide scale was grown on 316LNSS. The outer Fe-rich layer was composed of Fe3O4 and hydroxides (mainly Ni(OH)2 and CrOOH) and the inner layer was composed of Cr-enriched spinel oxides. The mechanism of oxide scale formation was also discussed.
采用极化曲线、电化学阻抗谱 (EIS)、莫特-肖脱基曲线和X射线光电子能谱 (XPS) 研究了MoO42-和NO2-对碳钢小孔腐蚀的协同抑制作用。结果表明,MoO42-和NO2-联合应用使碳钢的亚稳态孔蚀电位 (Em) 和孔蚀击穿电位 (Eb) 发生明显正移,并且显著提高了两者的差值,对抑制亚稳态小孔形核以及亚稳态小孔向稳态小孔转变的效果明显；MoO42-和NO2-联合应用可以在碳钢表面形成一层Fe2O3+Fe2(MoO4)3复合钝化膜,这层复合钝化膜的阻抗较大、缺陷较少,对碳钢的保护作用明显加强。
The synergistic inhibition effect of MoO42- and NO2- on pitting corrosion of mild steel was studied by polarization curve, electrochemical impedance spectroscopy (EIS), Mott-Schottky plot, and X-ray photoelectron spectroscopy (XPS). The results showed that the metastable pitting potential (Em) and the pitting breakdown potential (Eb) of the mild steel shift significantly to much positive and the value of (Eb-Em) increased markedly when MoO42- and NO2- were applied at the same time, indicating that the combined application of MoO42- and NO2- not only restrained the initiation of metastable pits but also prevented the transition from metastable pits to stable pits, correspondingly where a composite passive film Fe2O3+Fe2(MoO4)3 could form on the mild steel surface. The impedance of the composite passive film Fe2O3+Fe2(MoO4)3 formed in the solution containing MoO42- and NO2- was larger than that of the single passive films formed in the solutions with individual MoO42- or NO2-, while the defects of the former was less than that of the later one, therefore, the composite passive film could provide better protectiveness for the mild steel.
Corrosion behavior of 16MnR low alloy steel in KOH solutions was studied by means of electrochemical measurement. Results show that with the increase of KOH concentration, the corrosion potential and polarization resistance (Rp) decreased, while the corrosion current density and the passivation current density increased, thus the corrosion rate of 16MnR increased correspondingly. After immersion test the steel exhibited surface morphology with severe corrosion characters and its main corrosion product was Fe2O3.
通过电化学阻抗 (EIS)、极化曲线、扫描电镜 (SEM)、能谱分析 (EDS) 和X射线衍射 (XRD) 等技术对接地极Q235碳钢材料在含不同盐分的上海地区土壤中的腐蚀行为进行了研究。结果表明,在不同盐分土壤条件下,Q235碳钢的阻抗均随着浸泡时间的延长出现先升高后平稳的趋势,腐蚀速率随盐分含量增大而增大。由于沿海土壤的侵蚀性阴离子含量较高,使得所产生的锈层失去保护性。Q235碳钢腐蚀主要以全面腐蚀为主,还伴有微生物腐蚀现象,腐蚀产物膜主要由Fe2O3组成。根据耐腐蚀性能评价标准,接地极碳钢材料在上海土壤环境中的耐腐蚀性能为良。
The corrosion behavior of Q235 carbon steel for grounding grids in artificial soils was studied by EIS, polarization curve measurement, SEM, EDS and XRD. These artificial soils were admixture of typical soil from the Shanghai free trade zone with different amount of salt, aiming to simulate the corrosivity of various soils of the entire Shanghai area. It is shown that with the increasing time, the corrosion impedance of the buried Q235 carbon steel increases firstly and then tends to be stable in soils with different salinity, its corrosion rates increases with the increasing salt content. The Q235 carbon steel suffered mainly from uniform corrosion accompanied with microbial corrosion, its corrosion products consisted mainly of Fe2O3. According to the evaluation criteria for corrosion resistance, the corrosion resistance of Q235 carbon steel for grounding grids in Shanghai soils can be ranked as fine.
利用原位表面增强型拉曼光谱 (SERS) 研究了Inconel 600合金和Inconel 690合金在高温高压水环境中生成的氧化膜特征。结果表明,Inconel 600合金氧化膜的内层为薄且连续的Cr2O3,外层为非连续分布的FeCr2O4/NiFe2O4晶粒。Inconel 690合金腐蚀氧化膜由单一连续的Cr2O3构成。从两个方面分析了本文SERS结果与他人研究成果之间的差异。一是合金在腐蚀的早期阶段形成Cr2O3内层,随着时间增加,转变成热力学稳定的富铬尖晶石；二是由不锈钢材料制成的高压釜和回路管道,溶液中含有大量的Fe2+和Ni2+,导致氧化膜中尖晶石相的生成。提出了合金氧化膜与腐蚀时间以及高压釜 (含管道回路) 材质都存在一定的关联性。
In this paper, we have investigated the surface films formed on Inconel 600 and Inconel 690 in high-temperature and high-pressure water by using surface enhanced Raman spectroscopy. The inner layer of the surface film on Inconel 600 is a thin continuous Cr2O3 layer, and the outer layer is composed of discrete FeCr2O4/NiFe2O4 particles. The surface film on Inconel 690 is consisted of Cr2O3 solely. There are at least two possible explanations for the discrepancies in the identities of the surface oxides as found in the present SERS study versus those reported by other researchers. First, there is a significant difference in the time of corrosion. Second,it might also be explained by differences in the concentrations of aqueous metal cations. In this paper, the correlation between surface films with the corrosion time, materials of construction for the autoclaves and water loops is discussed.
A leakages related failure occurred of an electric water heater tank after 8 a service. The material of the specific area of that failed tanker was examined by means of macroscopic and the enamel coating of the inner side of the tanker and the Mg alloy sacrificial anode were also examined by electrochemical methods. The results indicated that the performance of enamel film decreased and the Mg sacrificial anode was significantly degraded after several years' service; while the open circuit potential of twisted area of steel substrate is much negative in comparison with that of ordinary area, so it is more likely that corrosion may preferentially occur at the twisted area and then the corrosion develops till leaking.
研究了X80管线钢在3.5%NaCl溶液中的电化学腐蚀行为。结果表明：经离子渗氮的样品,表面硬度显著提高,且随渗氮温度的升高而增加；渗氮层的耐蚀性明显优于基体材料,腐蚀电流密度降低一个数量级；腐蚀电位明显正移。当渗氮温度为450 ℃时,样品渗氮层由ε相和少量的γ '相构成,表面硬度约为810 HV,耐蚀性最好,腐蚀电流最小,约为0.56 μA/cm2,腐蚀电位最高,约为-214 mV。当渗氮温度为570 ℃时,样品渗氮层全部为γ '相,表面硬度约为930 HV,耐蚀性明显降低。离子渗氮温度显著影响X80钢表面渗氮层的相组成,引起表面硬度和耐蚀性不同。
X80 pipeline steel was nitridated by plasma nitriding and then its electrochemical corrosion behavior in 3.5%NaCl solution was studied by means of polarization curves and impedance spectroscopy. As compared to the bare X80 steel, the nitriding steels exhibit a remarkable increment in hardness, which increases with the rising nitriding temperature; the nitriding steels possess higher corrosion resistance with a lower corrosion current density by about one order of magnitude. The formation of ε phase (Fe3N) with a small amount of γ ' phase (Fe4N) dominates on the surface of the steel nitridated at 450 ℃, resulting in a maximium in corrosion potential about -214 mV and a minimum in corrosion current density about 0.56 μA/cm2, respectively, togeter with the hardness increase to about 810 HV. Only the γ 'phase forms on the surface of the steel nitridated at 570 ℃, which contributes to the hardness increase to 930 HV and a obvious decrease of corrosion resistance. The plasma nitriding temperature determines the phase constitutes of the surface nitriding layer and affects greatly its hardness and corrosion resistance.
利用XRD研究了化学镀Ni-P合金镀层经不同温度热处理后的结构变化。结果表明,镀态Ni-P呈非晶态；350 ℃时镀层由非晶态向晶态转化；热处理温度为400 ℃时,析出Ni3P稳定相。镀态及热处理条件下的阻垢和耐蚀性实验结果表明,随着热处理温度的升高,CaCO3中Ca的原子分数先降低后升高,300 ℃热处理降低了镀层的内应力及氢脆,使镀层的组织更加致密,镀层的阻垢和耐蚀性得到改善。
The effect of heat treatment temperature on the microstructural evolution of electroless plated Ni-P coatings was investigated using X-ray diffraction (XRD) analysis. The results showed that the as plated electroless Ni-P coating is amorphous. After heat treatment at 350 ℃, Ni-P coatings turn into crystalline state, while Ni3P phase appeared at 400 ℃. With the increasing heat treatment temperature, the Ca2+ atomic percentage of the formed fouling scales reduced firstly at 300 ℃, and then increased at 350 and 400 ℃. After heat treatment at 300 ℃, the internal stress and hydrogen embrittleness of the coating was eliminated, thereby, the anti-fouling performance and corrosion resistance of the coating was enhanced.
利用改变脉冲频率,采用脉冲电镀法在黄铜片基体上制备出纳米晶Fe-Ni-Cr合金镀层。采用SEM和EDS对镀层的表面形貌和成分进行表征,采用XRD对镀层的结构进行表征,采用电化学工作站对镀层的极化曲线和电化学阻抗进行表征。结果表明：当脉冲频率为5000 Hz时,镀层的表面较为平整,成分稳定,晶粒尺寸约为12 nm,镀层在3.5%NaCl溶液的自腐蚀电位约为-200 mV,自腐蚀电流密度约为0.12 μA/cm2,电荷转移电阻约为2500 Ω/cm2。频率的改变能引起镀层晶粒尺寸的改变,合适的频率有利于合金的形核,显著改善了镀层的耐蚀性能。
Nanocrystalline Fe-Ni-Cr alloy coatings were deposited on brass substrate by pulse electroplating with variant pulse frequencies, which then were characterized by SEM and EDS, as well as by XRD. The polarization curve and AC impedance of the coating were examined by electrochemical workstation. The results show that the coating prepared by pulse frequency 5000 Hz is nanocrystalline with mean grain size ca 12 nm, as well as a much smooth and uniform surface morphology, of which the corrosion current density, corrosion potential and the charge transfer resistance in 3.5%NaCl solution were -200 mV, 0.12 μA/cm2, 2500 Ω/cm2 respectively. It is believed that proper pulse frequencies may be beneficial to increase the number of nucleation sites of the deposits resulting in a coating with fine grain sized nanocrystallites, and better corrosion resistance.
研究了喹啉季铵盐对超级13Cr 不锈钢在1 mol/L 盐酸溶液中电化学行为的影响，并分析了温度、卤族阴离子类型和浓度对于喹啉季铵盐缓蚀效率的影响及机理。研究表明，喹啉季铵盐属于抑制阳极反应为主的混合型缓蚀剂，温度的升高会促进喹啉季铵盐的脱附过程，使其保护作用降低。卤族阴离子协同作用效果的顺序为：I-＞BrI-＞ClI-。随着I -浓度的升高，其协同作用效果提高。加入0.005 mol/L 以上浓度的KI，喹啉季铵盐的缓蚀率可达99%以上。
The electrochemical corrosion behavior of super 13Cr stainless steel in 1 mol/L HCl aqueous solution with quinoline quaternary ammonium salt was studied. The influence of temperature,anions type and concentration of halides on the inhibition efficiency were also investigated.The results showed that the inhibitor was a mixed type inhibitor which mainly suppressed the anodic reaction. The desorption of inhibitor could be facilitated with the increasing of temperature; correspondingly its inhibition efficiency was lowered. The synergistic effect of inhibitors with different halides showed a ranking as follows: I-＞Br-＞Cl-. The synergistic effect of inhibitor with I- could be enhanced with the increase of the I- concentration. The inhibition efficiency of quinoline quaternary ammonium salt exceeded 99%, when the concentration of KI was higher than 0.005 mol/L.
利用双辉等离子表面冶金技术在Ti2AlNb合金表面制备渗铝层,测定渗铝样品和空白样品在650,750和850 ℃下空气中的氧化增重动力学数据,通过线性拟合获取试样在不同温度下的氧化速率常数。采用SEM和XRD分析氧化膜的组成与结构。探讨高温下渗铝层提高Ti2AlNb合金抗高温氧化性能的机理。结果表明：双辉等离子渗Al后,在Ti2AlNb合金表面形成梯度渗铝层,显著地提高了Ti2AlNb合金在高温下的抗氧化性能。在各实验温度下,渗铝样品的氧化曲线近似呈抛物线规律,其平均氧化速率都低于所对照的空白样品。在850 ℃氧化100 h后,渗铝样品表面形成致密的保护性富Al2O3膜,有效地阻止膜层内部进一步氧化。中间的扩散层也起到保护基体、改善晶间脆性的作用。
Surface aluminized layer was prepared on a Ti2AlNb alloy by double-glow discharge plasma surface technique. The kinetic data of oxidation mass gain were measured for the alloys with and without aluminized layer at 650, 750 and 850 ℃ respectively, and the oxidation rate constants at different temperatures were determined by the relevant linear fitting. The microstructure and phase composition of the formed oxide scale were analyzed by XRD and SEM. It was found that aluminized layer consisted of compact deposited layer and Al-Ti-Nb diffusion layer. At each temperature, the aluminized alloy exhibited parabolic oxidation kinetics and the oxidation rate constant was lower than that of the blank ones. The aluminized layer significantly improved oxidation resistance of Ti2AlNb alloy due to the formation of a dense and continuous Al2O3-rich scale. The inter-diffusion layer provided protection for the substrate from high temperature oxidation and intergranular embrittlement.
采用电化学测试和浸泡失重实验,对比分析了0.1 mg/g Na2S、1%Na3PO4、5000 mg/L Na2MoO4、及其复配0.1 mg/g Na2S+1%Na3PO4、1%Na3PO4+5000 mg/L Na2MoO4几种缓蚀剂的添加对10CrSiNiCu (907) 钢-ZL102铝合金偶合体 (后称钢-铝偶合体) 的缓蚀效果。结果表明：几种缓蚀剂的加入均能在一定程度上减弱钢-铝偶合体的电偶腐蚀,并减缓了钢、Al各自在3%NaCl溶液中的腐蚀,其中复配体系 (1%Na3PO4+5000 mg/L Na2MoO4) 对钢-铝电偶对的综合缓蚀效果最好。
The corrosion inhibition effect of several inhibitors on a galvanic couple of 907 steel-ZL102 Al alloy in 3%NaCl solution was investigated by using electrochemical tests and mass-loss experiment. The inhibitors include 0.1 mg/g Na2S, 1%Na3PO4 and 5000 mg/L Na2MoO4 as well as their compounds of 0.1 mg/g Na2S+1%Na3PO4 and 1%Na3PO4+5000 mg/L Na2MoO4. The results showed that, all the inhibitors can reduce the galvanic corrosion of 907 steel-ZL102 Al alloy coupling to a certain extent, and slow the corrosion of steel and aluminum in 3%NaCl solution; among others the integrated inhibition effect of the compound 1%Na3PO4+5000 mg/L Na2MoO4 is the best for the 907 steel-ZL102 Al alloy coupling.
针对铁基牺牲阳极在工业生产中的应用,分析了铁基牺牲阳极对电位较正金属 (如Cu、不锈钢和钛合金) 阴极保护的可行性。综述了几种铁基材料作为牺牲阳极的性能,以及作为牺牲阳极在保护Cu、不锈钢和钛合金中的实际应用。提出了铁基牺牲阳极未来的研究重点和发展方向。
火电厂湿法脱硫烟囱腐蚀问题严重,目前国内外并无可靠、经济的解决方法。耐酸胶泥与阴极保护联合保护法 (简称ACCP法) 作为新技术,可以有效解决这一难题,还可实时监测钢内筒或钢筋混凝土筒的腐蚀状况,定量评估腐蚀防护效果,且经济性好,适用性强,前景十分广阔。