Influence of Lead Melts on the Embrittlement of Chromium Steels of Ferritic and Austenitic Classes

Materials Science - We study the influence of liquid-metal media of lead and the eutectic lead–bismuth mixture on the mechanical properties of chromium and chromium–nickel steels of...     

Ni-Cu-P钢耐点蚀性能的机理研究

选择Ni-Cu-P钢和碳钢各两种,在pH=10的3%(质量分数)NaCl溶液中进行极化实验,比较钢的点蚀诱发敏感性;在3%海盐水中进行间浸挂片实验,评价钢的点蚀扩展速率;利用扫描电镜(SEM)、电子探针(EPMA)、X射线衍射(XRD)分析钢中夹杂物、腐蚀形貌和锈层的特征。结果表明:Ni-Cu-P钢比碳钢表现出更弱的点蚀诱发敏感性和更小的点蚀扩展速率。较弱的脱氧可降低碳钢的耐点蚀性能,但对Ni-Cu-P钢不产生明显影响。锈层分析结果发现,Ni-Cu-P钢和碳钢内锈层的主要成分接近,但Ni-Cu-P钢的内锈层明显比碳钢致密。Ni-Cu-P钢中Ni和P能有效降低酸化蚀坑内钢基体的腐蚀速率;Cu则有助于致密锈层的形成。     

Oxidation Resistance of the Aluminide Coating Formed on Carbon Steels

Low and medium carbon steels were aluminized by the pack aluminizing technique using halideactivated pure-Al and Fe-Al packs. The effect of mixture composition, aluminizing temperatureand time and C content of the steel substrate on the structure and thickness of the aluminidelayer, and on the oxidation resistance was investigated. The optimum oxidation resistance canbe achieved with a low carbon steel substrate when the intermetallic phases Fe3Al and FeAlform the surface of the aluminide layer. In this case, the Al concentration at the surface of thealuminide coating is at least ≥15 wt pct. Formation of high Al concentration phases (FeAl3 andFe2Al5) during aluminizing should be avoided as they tend to embrittle the aluminide layer andreduce its oxidation resistance.     

Kinetics of Selective Oxidation of Chromium Steels in Oxygen-Containing Lead

Within the framework of the Wagner model, we determine the thickness of oxide layers formed on chromium steel in lead melts with low concentrations of oxygen. The diffusion processes running in the coexisting phases are taken into account. It is shown that, in the quasiequilibrium stage of growth, the thickness of the oxide layer in a melt changes not so rapidly as in the case of oxidation in a gaseous atmosphere due to the dissolution of chromium in lead. The time dependence of the diffusion coefficient is analyzed. It is demonstrated that the process of growth of the oxide layer is accelerated due to the intensification of accumulation of defects in this layer.     

模拟海洋大气环境下Cu和Cr对耐候钢耐腐蚀性能的影响

过去,合金元素对耐候钢海洋环境中的耐蚀性影响缺乏详细的论讨.选取Q235和5种不同Cu和Cr含量的耐候钢,在0.5%的NaCl溶液中模拟海洋大气环境进行周期浸润试验.研究结果表明:在Cl-存在的环境中,在碳钢的基础上单独添加Cr(0～3.0%)或单独添加Cu(0.25%～0.50%)都不能使钢的耐蚀性有显著的提高.单独提高耐候钢中Cr的含量,有助于抑制其在腐蚀初期的腐蚀速度,但对后期的腐蚀发展趋势不利;单独提高Cu的含量,有助于延缓腐蚀后期的发展趋势.当同时提高耐候钢中的Cu和Cr含量时,可使耐候钢得到较佳的耐大气腐蚀性能.XRD分析结果表明,合金元素对外锈层的成分影响不大,其主要大气腐蚀产物为γ-FeOOH,Fe3O4,γ-Fe2O3和少量α-FeOOH.     

Surface Alloying of Nitrogen to Improve Corrosion Resistance of Steels and Stainless Steels

It is well known that the addition of nitrogen to steels and stainless steels enhances the passivity and localized corrosion resistance, in addition to improving the mechanical properties. Selective alloying of surfaces of steels and stainless steels with nitrogen could also enhance the corrosion resistance and improve the mechanical properties without affecting the bulk properties. Techniques like ion implantation, laser alloying, nitriding, etc. can be effectively used to introduce very high levels of nitrogen. In addition, these techniques can also produce modified surfaces with novel microstructures to further improve the properties. The surface alloying methods also provide an opportunity to selectively nitrogenate the surface of finished components in order to obtain better properties. The review highlights the techniques, modifications and the properties obtained further.     

微弧氧化处理对多孔Ti-15Mo合金显微结构、耐磨性和耐蚀性的影响

在铝酸盐电解液中对多孔Ti-15Mo舍金进行微弧氧化表面改性.利用SEM和XRD研究多孔舍金微弧氧化涂层的显微结构和相组成.采用显微硬度计、动电位极化曲线和球-盘摩擦磨损仪分析微弧氧化处理对多孔Ti-15Mo合金硬度、耐蚀性和耐磨性的影响.结果表明,微弧氧化处理未改变多孔Ti-15Mo合金原有的孔隙率和孔径,在合金表面和孔隙内壁呈现典型的粗糙多孔微弧氧化形貌.微弧氧化涂层主要由金红石TiO2和Al2TiO5相组成.经微弧氧化处理后,多孔Ti-15Mo合金的表面显微硬度提高了32％,摩擦系数降低了近50％,磨损率大幅度下降,磨损机制由磨粒磨损转变为粘着磨损.微弧氧化处理后多孔Ti-15Mo合金的耐蚀性较基体提高了近1个数量级,微弧氧化陶瓷涂层的保护效率高达90.78％.     

微弧氧化处理对多孔Ti-15Mo合金显微结构、耐磨性和耐蚀性的影响

在铝酸盐电解液中对多孔Ti-15Mo合金进行微弧氧化表面改性。利用SEM和XRD研究多孔合金微弧氧化涂层的显微结构和相组成。采用显微硬度计、动电位极化曲线和球-盘摩擦磨损仪分析微弧氧化处理对多孔Ti-15Mo合金硬度、耐蚀性和耐磨性的影响。结果表明,微弧氧化处理未改变多孔Ti-15Mo合金原有的孔隙率和孔径,在合金表面和孔隙内壁呈现典型的粗糙多孔微弧氧化形貌。微弧氧化涂层主要由金红石TiO_2和Al_2TiO_5相组成。经微弧氧化处理后,多孔Ti-15Mo合金的表面显微硬度提高了32%,摩擦系数降低了近50%,磨损率大幅度下降,磨损机制由磨粒磨损转变为粘着磨损。微弧氧化处理后多孔Ti-15Mo合金的耐蚀性较基体提高了近1个数量级,微弧氧化陶瓷涂层的保护效率高达90.78%。     

晶粒尺寸对耐候钢抗大气腐蚀性能的影响

细化晶粒能有效提高耐候钢的力学性能,但是,随着晶粒尺寸的减小,晶粒尺寸对耐候钢的耐腐蚀性能的影响是怎样的,有必要进一步研究.因此,对不同晶粒尺寸耐候钢进行了模拟工业大气周期浸润实验室加速试验,并通过金相扫描、X射线衍射、交流阻抗谱等手段对锈层进行了分析.结果发现,在腐蚀初期还没有形成致密内锈层前,细晶粒比大晶粒的腐蚀更快一些,形膜要快.在腐蚀后期形成致密的内锈层后,细晶粒和大晶粒的腐蚀速率基本一致;耐候钢晶粒尺寸不影响其耐蚀性能.     

Cu对低合金钢耐海水腐蚀的影响

为研究Cu对低合金钢耐海水腐蚀性能的影响,选择含Cu低合金钢和碳钢各两种进行对比实验.利用室内间浸挂片、实海潮差区挂片和模拟闭塞腐蚀电池实验比较钢的耐全面腐蚀和点蚀能力;利用扫描电镜(SEM)、能谱分析(EDAX)、电子探针(EPMA)和X射线衍射(XRD)分析钢中夹杂物和锈层的特征.结果表明:Cu的添加不仅可提高钢的...     

镀锌层表面KH-560硅烷膜耐蚀性能研究

利用正交实验研究了硅烷偶联剂在镀锌板上的钝化工艺,采用KH-560对热镀锌板进行钝化处理.比较钝化膜与空白试样在5%NaCl溶液中的极化曲线、电化学交流阻抗谱,并通过盐水浸泡实验进一步验证了硅烷膜的耐蚀性能.结果表明:经硅烷钝化处理后的镀锌板,其腐蚀电流密度下降,极化电阻升高,硅烷膜抑制了镀锌板的腐蚀过程,其耐蚀性能优于空白试样,接近铬酸盐钝化膜的耐蚀性.     

两种船体钢耐海水腐蚀性能对比

针对10MnNiCr钢、新型440 MPa船体钢,开展了钢的自然腐蚀电位测试、室内加速腐蚀试验,1年期北海海域裸钢海港挂片试验。试验结果表明,由于钢的合金成分不同,10MnNiCr钢表现出较好的耐海水腐蚀性能。     

Influence of the Structure of Carbon Steels on the Corrosion,Hydrogenation, and Corrosion Cracking in Hydrogen-Sulfide Media

Materials Science - We study the influence of the structure of carbon steels on corrosion, hydrogenation, and corrosion cracking in NACE solution. The corrosion and hydrogenation rates of U8 steel...     

船用E36钢和10CrNiCu钢耐海水腐蚀性能研究

针对船用E36钢、10CrNiCu钢,开展了钢的自然腐蚀电位测试、室内全浸加速腐蚀试验。结果表明,10CrNiCu钢具有较高的电位值及较低的平均腐蚀速率,表现出较好的耐海水腐蚀性能;其与E36钢连接时作为阴极受到E36钢的阳极保护,减慢了其腐蚀速率。     

添加P和RE对碳钢耐腐蚀性能的影响

主要研究P和RE复合对碳钢耐腐蚀性能的影响;通过模拟工业大气环境的周期浸润实验室加速试验,对试验钢进行了腐蚀失重分析;并通过X射线衍射等手段对锈层进行了分析.结果发现:通过添加P及少量RE,可以使碳钢获得很好的耐候性.P和RE的复合作用机理主要是促进锈层中α-FeOOH的形成,同时抑制γ-Fe2O3生成,改变锈层结构,从而使锈层更为致密.