Influence of Anticorrosion Pigments on Protective Properties of Epoxy Coatings

We investigated the impedance characteristics of epoxy coatings which contain chromate pigment or a mixture of phosphate and calcium-containing pigments in their primer layer. The coatings were applied on low-carbon and zinc-coated steels. The studies were performed in a corrosive medium which simulated the acidic atmospheric precipitation. We found that chromate pigment provides a greater passivation effect without significant improvement of the insulating properties of the epoxy coating. The introduction of a chromate-free pigment mixture increases the barrier characteristics of the epoxy coating. As can be concluded from the impedance dependences, the combination of two chromate-free pigments can be regarded as a promising alternative to toxic chromates in epoxy protective coatings, their use being more efficient on a normal steel as compared with a zinc-coated steel.     

Analysis of Surface Oxide Films Formed in Hydrogenated Primary Water on Alloy 690TT Samples With Different Surface States

Oxidation of Alloy 690 TT samples either manually ground to 400 and 1500 grit, mechanically polished, or electropolished was performed in a solution of 1500 10 6B and 2.3 10 6Li with 2.5 10 6dissolved H2, at 325℃ and 15.6 MPa for 60 days. The oxide films grown on samples with different surface states were analyzed using various techniques. Results show that a triple-layered structure was formed after immersion： an outermost layer with large scattered oxide particles rich in Fe and Ni, an intermediate layer with small compact oxide particles rich in Cr and Fe for the ground surfaces and loose needle-like oxides rich in Ni for the polished surfaces, and an inner layer with continuous Cr-rich oxides. The surface state was found to affect not only the surface morphology, but also the corrosion rate. Grinding accelerated the growth of protective oxide films such that the ground samples showed a lower oxidation rate than the polished ones.Samples of ground Alloy 690 TT showed superior resistance to intergranular attack（IGA）.     

An Aluminide Surface Layer Containing Lower-Al on Ferritic-Martensitic Steel Formed by Lower-Temperature Aluminization

An aluminide(AlFe and α-(FeAl)) surface layer containing lower-Al was formed on ferritic-martensitic steel P92 by means of surface mechanical attrition treatment(SMAT) combined with a duplex aluminization process at lower temperatures,i.e.a packed aluminization followed by a diffusion annealing treatment below its tempering temperature.Indentation tests indicated that the lower-Al surface layer formed on the SMAT sample is more resistant to cracking and has better adhesion to the substrate in comparison with the Al_5Fe_2 layer formed on the as-received sample after the duplex aluminization process.Isothermal steam oxidation measurements showed that the oxidation resistance is increased significantly by the lower-Al surface layer due to the formation of a protective(Fe,Cr)Al_2O_4 layer.The rate constant of oxidation was estimated to decrease from-0.849 mg~2 cm~(-4)h~(-1) of the as-received material to~0.011 mg~2 cm~(-4) h~(-1) of the AlFe layer at 700 ℃.     

Effect of Cl- on the Properties of the Passive Films Formed on 316L Stainless Steel in Acidic Solution

The corrosion behavior of 316L stainless steel （31 6L SS） has been investigated in solutions containing various concentrations of chloride ions by using potentiodynamic polarization, capacitance measurement and Mott- Schottky relationship analysis （M-S）. The result indicates that passive currents change slightly with the addition of chloride ions. The pitting potential （Epit） decreases linearly with Iog[CI-]. Correspondingly, the point defect diffusion coefficient （Do） of the passive film increases linearly with increasing Iog[CI-]. The results also indicate that the pitting corrosion of 316L SS follows the adsorption mechanism in NaCI solution.     

熔态Mg在Air/SF6保护气氛中形成的表面膜特征

研究了熔态Mg在Air/SF6保护气氛中形成的表面膜特征.随着镁液在保护气氛中暴露时间的增加,表面膜中F原子分数逐渐增加,而O的原子分数基本不变.因此认为保护性表面膜形成后,主要为F和Mg发生反应.部分近表面区域场发射SEM断面图中有多个不连续的白亮富F(约为74%原子分数)小半圆区域,而富F的小半圆亮区之间F含量显著降低(约为4.98%);部分为一条厚度不均匀的白亮带,其中F原子分数也很不均匀.随着暴露时间的增加,表面的结晶粒度逐渐增加.冷却凝固后的表面有很多裂纹,这些裂纹的形成可能是由于表面MgO膜疏松,晶粒不断长大收缩,快速凝固过程中,MgO膜下面的镁液凝固收缩而形成.     

低碳钢液相等离子体电解硼碳共渗层生长特性研究

在含有硼砂和甘油的电解液中对Q235低碳钢表面进行液相等离子体电解硼碳二元共渗(PEB/C)处理,研究不同时间条件下PEB/C共渗层的组织形貌,着重探讨了PEB/C二元共渗过程中电解质的分解反应和渗硼层快速生长机理。结果表明,在330V电压条件下,经过6min PEB/C处理后,在样品表面开始生成不连续的岛状硼化物;而经过30min PEB/C处理后,可以形成主要由Fe2B相组成的均匀致密的渗硼层,渗硼层的硬度可以达到1 800HV,厚度约为20μm。PEB/C共渗样品渗硼层的生长过程主要包括共渗初期阶段、生成岛状硼化物阶段和渗硼层均匀生长阶段。     

Ceramic Films Containing Ca,P and Al Formed on Surface of TC4 Alloy by Micro-Arc Oxidation

Ceramic films containing Ca, P and Al were prepared on surface of TC4 alloy by micro-arc oxidation using direct current supply to enhance its seawater and plankton corrosion resistance. XRD, EDS, SEM and EPMA were employed to characterize the microstructure and the phase composition. The results showed that 15 μm-ceramic films which was uniform and compact were formed on TC4 . The mass proportion of Ca, P and Al is about 2 : 3 : 4. There was AlPO4 crystal but Ca was not crystal. Cyclic Volt-Ampere test showed that the corrosion resistance of theceramic films was much better than that of the TC4 substrate.     

直通型430不锈钢矩形盒拉深中的曲面压边技术

比较传统的压边方式,提出并实现了曲面压边技术,该技术能有效缩小毛坯,节省工序.     

近海大气中耐候钢表面保护锈层残余应力分析

本文观察了锈层/耐候钢界面形貌以及锈层致密情况的变化,建立了锈层/基体界面模型,通过Ansys5.3有限元程序模拟计算,分析了锈层中应力分布情况.在低合金钢大气腐蚀过程中,表面在电化学电位低的地方形成腐蚀坑;在腐蚀坑腰部锈层中存在着应力集中.此外锈层首先开裂,加速此处基体腐蚀,加大了腐蚀坑曲率半径,有利于锈层/基体界面平直化,减弱应力集中程度.促进致密锈层形成.     

Characterization of the Protective Surface Films Formed on Molten AZ91D Magnesium AHoy in SO2/Air Atmospheres in a Sealed Furnace

Surface films that formed on molten AZ91D magnesium alloy in SO_2/air cover gases at 680 ℃ in a sealed furnace were characterized by scanning electron microscopy,energy dispersive spectroscopy,X-ray diffraction and Auger electron spectroscopy.It is revealed that the film formed on molten AZ91 D alloy surface in cover gas with high air content can prevent the molten AZ91 D alloy from oxidation and ignition.The surface film contained three elements,namely magnesium,oxygen and sulfur,and was mainly composed of MgO and MgS.The properties of the film depended on air content in the cover gas and holding time.Thermodynamic calculation showed that MgSO_4 was the stable phase,and it was concluded that the formation of MgSO_4was important for the formation of the protective surface film in SO_2/air atmospheres.     

不锈钢表面处理对Cr2O3薄膜太阳能选择吸收性能的影响

采用Sol-gel法以及浸渍提拉法在不锈钢表面制备了Cr2O3选择性吸收薄膜。分别采用喷砂处理和氧化液腐蚀两种方式对不锈钢进行表面处理,考察不同表面处理方式对Cr2O3太阳能选择吸收薄膜性能的影响。用Lambda 750型UV-Vis-NIR分光光度计和Tensor 27型BRUKER红外光谱仪分别测试薄膜在可见-近红外光谱区和红外光谱区的反射光谱。结果表明,氧化液处理的不锈钢基体,其表面所涂覆薄膜的红外发射率明显降低,发射率由喷砂基体的0.465降低到0.186,具有良好的选择吸收性。     

纳米结构316L不锈钢基掺钽TiO_2薄膜生物活性研究

采用射频磁控溅射技术在表面微结构纳米化316L不锈钢和粗晶粒316L不锈钢基体上制备掺钽TiO2薄膜。采用扫描电镜和X射线衍射仪分析薄膜形貌和晶体结构,用体外模拟人体体液浸泡实验研究薄膜的生物活性。结果表明:表面微结构纳米化的316L不锈钢具有强烈诱导掺钽TiO2薄膜形核效应;316L不锈钢表面微结构纳米化能显著提高自身及其表层掺钽TiO2薄膜的生物活性;316L不锈钢表面纳米化后,其表层掺钽TiO2薄膜诱导的羟基磷灰石形貌由原先的球状变为多孔网状结构。     

Protective Properties of Layers Formed on the Surface of Nickel

The polarization and impedance methods are used to study, in a 3% NaCl solution, the protective properties of films preliminarily formed on the surface of nickel in air, in HCl and H₂SO₄ vapors, and under the conditions of anodic polarization of the electrode in HCl solutions. It is shown that the protective properties of the films depend on the conditions of their formation.     

表面改性剂对碳酸钙基复合白色颜料性能影响研究

本文通过活化一复合两步法制备碳酸钙基复合白色颜料粉体。研究了不同表面改性剂对颜料性能的影响,并且测试了复合粉体的遮盖力、吸油值、白度等性能及微观形貌。结果表明选取三乙醇胺为改性剂时,复合粉体的综合性能最佳,其中遮盖力为19．5g／m2,吸油值24．2g／100g,白度95．8％。     

静电自组装功能性纳米复合膜的研究进展

通过静电相互作用可自组装形成功能性纳米复合膜.近年来,这一技术发展十分迅速,并且得到了广泛的应用.综述了静电自组装成膜的机理、制备、表征的最新研究进展.     

水介质中纳米金刚石表面改性研究

对纳米金刚石在水介质中的分散进行了探讨,利用机械力和化学力共同作用,对纳米金刚石表面进行改性,从而实现纳米金刚石在水介质中的分散和稳定,采用不同的机械化学处理工艺,可以使得体系在酸性和碱性介质条件下均保护良好的分散。对表面改性过程进行了机理分析。     

Cathodoluminescence of TiO2 Films Formed by Molecular Layer Deposition

Technical Physics Letters - Use of the method of local cathodoluminescence in Si–TiO2 and Si–SiO2–TiO2 structures helps to elucidate the nature of centers influencing the...     

不锈钢衬底上沉积类金刚石薄膜的硬度

利用射频辉光放电法在不锈钢衬底上制备了类金刚石薄膜，用显微硬度计测试了薄膜与衬底复合膜度和衬底硬度。并用Ｂ．Ｊｏｎｓｏｎ和Ｂ．Ｈｏｇｍａｒｋ方法将薄硬度分离出来，得到了硬度值与制与制备参数间的关系，确定了在不锈钢衬底上沉积高度和强附丰度类金刚石薄膜的最佳工艺条件范围，并对实验结果进行了理论解释。