Long-term forecast of corrosion mass losses of technically important metals in various world regions using a power function

An analysis of the results of corrosion tests on flat and helix specimens made of technically important metals carried out within the ISO CORRAG program is given. Stochastic relationships between coefficient n in the power function, which characterizes the protective properties of the corrosion products, and the limiting corrosion rate α, with the corrosivity of each type of atmosphere were found. A forecast of corrosion losses for a period of up to 50 years was given using the linear function in the stationary stage, a power function, and limiting corrosion rate values α. The reliability of the forecasts was estimated.     

Microstructural influence on the electrochemical corrosion behaviour of dual-phase steels in 3.5% NaCl solution

Galvanostatic corrosion behavior of five different dual-phase (DP) steels with varying morphologies and martensite content has been assessed in comparison to a ferrite–pearlite steel in 3.5% NaCl solution. It has been observed that both the amount of martensite and the morphology of the phase constituents have definite influence on the corrosion behaviour of DP steel. Higher corrosion tendency has been observed with increased amount of martensite and increased refinement of phase constituents.     

合金调控对钢筋耐蚀性能的影响北大核心CSCD

采用通过微合金调控技术,合理控制钢中C、Cu、Cr和P等元素的含量,研发了一种比普通HRB400aE具有更高耐工业大气和含Cl^(-)污染物综合内陆自然环境腐蚀的400 MPa级低合金耐蚀抗震钢筋(NS-HRB400aE)。通过周浸试验、电化学极化曲线和电化学阻抗谱测试试验,对2种钢筋的耐蚀性进行了评价,结果表明合金化后的NS-HRB400AE低合金耐蚀抗震钢筋表面的腐蚀形貌为均匀腐蚀,而普通HRB400AE钢筋的腐蚀形貌主要为点蚀,NS-HRB400aE钢筋相比HRB400aE钢筋具有更低的腐蚀速率、更高的点蚀电位、更低的维钝电流密度和更高的临界Cl^(-)含量,表明微合金调控后钢筋的耐蚀性能显著提升。     

Effect of hydrogen on pitting susceptibility of 2507 duplex stainless steel

The effect of hydrogen on pitting corrosion susceptibility of duplex stainless steel was investigated. Pits are observed on the hydrogen-charged specimen after 6 days of immersion in 6% FeCl₃ solution, while no pits on the uncharged specimen even after more than 30 days of immersion, which indicates that hydrogen promotes pitting initiation and pit growth. Moreover, pitting susceptibility increases with hydrogen charging current density. The pitting tends to nucleate initially inside the austenite or at ferrite/austenite boundaries, and then appears in the ferrite, because of different behaviors of hydrogen in two phases, such as solubility and diffusivity of hydrogen.     

三种电弧喷涂涂层在大庆地区土壤中的腐蚀性

采用电弧喷涂方法在球墨铸铁管表面上分别制备纯Zn涂层、Zn-Al合金涂层、Zn-Al伪合金涂层,通过对三种涂层在大庆土壤中进行埋样试验,研究了三种涂层在大庆土壤环境下的耐腐蚀性能,观察了试样表面的腐蚀产物的宏观和微观形貌,并通过电子能谱(EDS)和X射线衍射试验(XRD)对腐蚀产物进行了分析。结果表明,在大庆土壤环境下,三种涂层的耐腐蚀性能按Zn-Al合金涂层、Zn-Al伪合金涂层、Zn涂层的顺序依次减小。     

Preparation of SOFC anode composites by spray pyrolysis

Lowering the SOFC working temperature would also be greatly attractive, but low temperature working SOFCs require high-performance anodes. The cermet SOFC anodes, which are composed of nickel and samarium doped ceria, were prepared by spray pyrolysis (SP), because SP produces spherical particles with small size distributions. SP-derived particles of NiO, SDC, and NiO/SDC composite had a round shape and comprised nanometer-sized primary grains. The cermet anodes were prepared by using SP-derived NiO/SDC composite particles or mixing SP-derived NiO and SDC particles. The anode prepared with the composite particles showed higher SOFC cell performance than that with the mixed ones. The composite particles had high surface areas and a capsule-type form. The outer shell would be composed of SDC and the inner core was NiO. The capsule-type composite particles would depress aggregation of Ni or NiO during reduction from NiO to Ni metals, and this depression would enhance SOFC anode performance.     

Experiments and first principles calculations on the effects of hydrogen on the optical properties of ferroelectric materials

The effects of hydrogen on the optical properties of lead zirconate titanate (PZT) ceramics and BaTiO₃ single crystals have been investigated. The experimental results showed that the color of BaTiO₃ single crystals changed from light to dark after charging of hydrogen in NaOH solution at room temperature and in H₂ gas at high temperature, and then, restored to light color after outgassing in the air, which were the same as PZT-5H ceramics reported earlier. Measurement of the absorbance indicated that hydrogen increased the absorbance within the visible spectrum for both PZT ceramics and BaTiO₃ single crystals. The first principles calculations for Pb(Zr_0.5Ti_0.5)O₃ and BaTiO₃ showed that hydrogen increased the absorbance within the infrared and visible spectral region and the absorbance increased with the rise of hydrogen concentration. Density of states (DOS) researches indicated that hydrogen changed the DOS of the outer shell electrons, which caused the change of absorbance spectrum.     

Analysis of fracture failure of fir-tree serrations of stage II turbine disks

This paper presents an analysis of fracture failure of fir-tree serrations in stage II turbine disks in a certain type of engine. On the basis of statistical analysis, basic fracture features and fracture mechanisms of stage II turbine disk serrations have been summarized. The reasons for the serration fracture failure are: (a) the first order bending resonance k=5 in the turbine blade occurring at the speed of 9700 rpm; (b) the unreasonable design of the five-serration structure, which causes each serration to bear non-uniform stresses; (c) the disk being made of the alloy GH2036 having a low fatigue resistance; (d) the high intergranular corrosion sensitivity of GH2036. Finally, measures, i.e. the change of the five-serration structure into a three-serration structure and the replacement of GH2036 with GH2132, have been given to prevent the fracture failures, and the application has indicated that these measures are effective.     

1-羟基苯并三氮唑和钼酸钠对铜的缓蚀协同作用

采用电化学、扫描电子显微镜、X射线光电子能谱等实验方法研究了1-羟基苯并三氮唑（BTAOH）和钼酸钠（Na₂MoO₄）复配后对铜在ASTM D 1384模拟大气腐蚀溶液中的缓蚀协同作用.电化学实验结果表明:BTAOH与Na₂MoO₄在50mg·L-1的质量浓度条件下,以2:1复配使用能够显著提高铜在模拟大气腐蚀溶液中的电荷转移电阻,降低腐蚀电流密度,缓蚀率达到90.7%;铜在模拟大气腐蚀溶液中的腐蚀产物呈聚集柱状堆砌在表面,而在含有缓蚀剂的溶液中表面平整致密,且疏水性增强,接触角显著增大至91.8°.X射线光电子能谱结果显示Na₂MoO₄与铜表面作用后形成MoO₃和MoO₂,两种氧化物填充在BTAOH形成的表面膜的缝隙中,提高了膜的致密性,对铜产生良好的保护作用.