化学镀Ni_P合金镀层对铁细菌微生物污垢的影响

针对化学镀Ni-P合金镀层对换热设备表面常见微生物污垢的影响问题,扩大化学镀层应用范围。通过调整化学镀液工艺制备出多种不同特性的镀层表面,计算了试样的表面能,研究乳酸浓度对镀速及表面能带来的影响;将试样置于OD(光密度)值一定的菌悬液中进行为期5~7天的静置实验,分析镀层表面微生物污垢实验前后宏观和微观形貌,以普通碳钢试样作为对照,研究镀层试样表面能和镀层表面失重量的关联。在实验工艺范围内,制备的镀层表面光滑致密,镀速和镀层试样的表面能均随着乳酸含量的增加而减小;在静置实验结束后,普通碳钢试样表面附着微生物污垢较多,在一个微生物生命周期内,碳钢表面受微生物腐蚀质量呈现逐渐下降的趋势;镀层表面则仍呈金属光泽,质量变化不大,且镀层在微生物污垢实验前后微观形貌变化较小,展现了较好的抗垢效果和耐蚀性;在所制备的镀层试样中,低表面能的镀层试样表面腐蚀失重量最小。制备的Ni-P合金镀层表面可以有效抑制或减轻微生物污垢,其低表面能和表面分布Ni-P非晶结构有效抵抗了微生物污垢生长和腐蚀。     

对管式换热器黏液形成菌生物污垢特性的实验研究

为了探讨黏液形成菌在管式换热器中的污垢特性,以某电厂循环冷却塔塔底黏泥中分离纯化后得出的黏液形成菌为研究对象,利用污垢动态模拟实验系统,采用对比实验的研究方法得到了不同入口温度、流速及体积浓度条件下黏液形成菌在不锈钢光管换热器中的污垢特性。结果表明:黏液形成菌的结垢过程存在诱导期。随着入口温度的升高,诱导期缩短,污垢热阻达到渐近值所需时间减少。在实验温度范围内,入口温度为30℃时污垢热阻渐近值最大,35℃时次之,25℃时最小;随着流速的增加,污垢热阻达到渐近值所需时间减少,污垢热阻渐近值减小;随着体积浓度的增加,诱导期会延长,结垢速率加快,污垢热阻渐近值增大。     

板式换热器黏液形成菌生物污垢特性的实验研究

为探讨黏液形成菌在板式换热器里的结垢规律,对不同流速、温度及体积分数下黏液形成菌在板式换热器内的污垢特性进行了实验研究。结果表明：随着流速的增加,黏液形成菌的污垢热阻渐近值逐渐减小;随着温度的升高,黏液形成菌结垢的诱导期缩短,并且达到稳定的时间增加,在实验温度范围内,污垢热阻渐近值在35℃时最大;而随着细菌体积分数的增加,污垢热阻值呈现明显幅度的增长。     

节理三维形貌与抗剪强度相关性研究

岩石节理的表面形貌对其力学特性具有重要影响。运用JAW 1000试验系统开展不同节理试样的剪切试验,得到不同法向应力条件下节理试样的剪切变形曲线和法向变形曲线,并利用KEYENCE_LK G5000激光扫描仪在剪切前后对节理试样表面形貌进行高精度激光扫描测试,得到节理试样表面三维形貌数据。根据改进的节理三维形貌表征参数的算法,分析剪切试验前后节理试样表面三维形貌变化,研究节理三维形貌表征参数与抗剪强度的关系。结果表明,三维平均视倾斜角越大,抗剪强度越大,并提出了三维平均视倾斜角与抗剪强度的经验模型。     

太阳能热发电用熔盐储热材料金属相容性研究

为分析第三代太阳能热发电技术熔盐与低温罐选材的相容性,该文以一种低熔点(142℃)、高分解温度(>700℃)的混合熔盐为腐蚀环境,通过静态腐蚀实验研究碳钢(A515Gr70)和两种低合金钢(Q345R、15CrMoR)在450℃混合熔盐中的腐蚀行为。采用失重法测量不同金属的腐蚀速率。通过扫描电子显微镜(SEM)、X射线衍射(XRD)和能谱仪(EDS)对金属腐蚀表面的微观形貌、相组成和微区成分进行分析。结果表明：碳钢不含有耐腐蚀元素Cr、Ni和Mo,腐蚀速率最大。15CrMoR表面氧化层以疏松多孔的Fe₂O₃为主,不能阻止熔盐浸入金属基体内部,导致氧化程度加重,耐腐蚀性较差。Q345R表面氧化层由致密性好的FeCr₂O₄、NiO和TiO₂组成,对金属基体具有保护性,耐腐蚀性最佳。     

不同金属材料与海水温度对海水结垢影响的实验研究

针对海水换热结垢现象进行了实验研究。对比了镀锌铁片、黄铜、紫铜和不锈钢4种金属在海水中的结垢特征,以及4种金属表面结垢量的变化。实验结果显示,不同金属在海水中的污垢形貌及结垢量不同,镀锌铁片的结垢量最大,紫铜表面腐蚀较为严重,结垢量最小。对海水污垢进行了XRD(X-Ray Diffraction)和EDX(Energy Dispersive XRay)物相分析,结果显示,不同金属材料表面形成的海水污垢的物相组成不同,镀锌铁片表面的污垢成分主要是锌的腐蚀产物,而不锈钢表面的污垢成分主要为氢氧化镁。比较了镀锌铁片和黄铜在80℃和60℃海水中的结垢量变化,镀锌铁片污垢随着海水温度的上升而下降,而黄铜污垢随着海水温度的上升而上升。     

考虑污垢因素的凝汽器传热系数的计算研究

凝汽器冷却水系统运行过程中,由于难溶盐分的沉积和微生物污垢的生成,会在凝汽器的换热表面上形成污垢,使传热系数下降,真空降低。分析了凝汽器水侧污垢的特性,然后给出了考虑污垢因素的凝汽器传热系数的计算方法。     

垃圾焚烧环境中典型材料的腐蚀性研究

模拟垃圾焚烧炉内环境,在550℃条件下,开展了T91、TP347H、TP347HFG、TP310S、UNS 6625等材料的腐蚀实验研究。采用减重法和壁厚法分别计算腐蚀速率,利用光学显微镜和配有能谱仪的扫描电镜对试样件腐蚀后的形貌结构、元素含量进行分析。结果表明:垃圾焚烧炉中积灰腐蚀严重,可采用改善受热面清洁状况及优化受热面材质的方法减轻;在相同条件下,镍基合金材料UNS 6625由于其氧化物在氯化物熔盐中的热稳定性好,腐蚀速率小,耐腐蚀性好,可用于垃圾焚烧炉中的高温部位;不锈钢材料表面的晶粒细化后,能有效改善材料的抗腐蚀性能;在工程现场,壁厚法仅适用于无晶间腐蚀的材料,不适用于不锈钢材料;不锈钢材料的腐蚀情况判断应将晶间腐蚀考虑在内,并结合SEM-EDS分析。     

ZnO:Al绒面透明导电薄膜的制备及分析

利用中频脉冲磁控溅射方法,采用Al掺杂(质量百分比2%)的Zn(纯度99.99%)金属材料为靶材制备平面透明导电ZnO:Al(ZAO)薄膜。利用湿法腐蚀方法,将平面ZAO薄膜在0.5%的稀盐酸中浸泡一定时间后,形成表面凹凸起伏的绒面结构。研究了平面ZAO薄膜的结构特性以及衬底温度、溅射功率和腐蚀时间对绒面ZAO薄膜表面形貌的影响,并对腐蚀前后薄膜的电阻变化进行了分析。结果表明:高温、低功率条件下制备的绒面ZAO薄膜表面形貌较好,在硅薄膜太阳电池中具有潜在的应用前景。     

温度对纳米氧化镁颗粒污垢特性的影响

为了探讨温度对纳米氧化镁颗粒污垢结垢特性的影响,通过改变循环工质入口温度和水浴温度实验研究了温度对纳米颗粒污垢在交叉缩放椭圆管中的结垢特性,并通过静置沉降实验验证了入口温度对循环工质聚沉情况的影响。结果表明,循环工质入口温度和水浴温度对纳米颗粒污垢特性都有显著的影响。随着循环工质入口温度的升高,污垢热阻渐近值明显减小,并且污垢热阻达到渐近值的时间缩短。随着水浴温度的升高,污垢热阻渐近值也随之减小,但是达到渐近值的时间略有增加。     

Investigation of single-layer and multilayer coatings for aluminum bipolar plate in polymer electrolyte membrane fuel cell

Aluminum bipolar plates offer good mechanical performance and availability for mass production while allow up to 65% lighter than stainless steel. To improve the corrosion resistance and surface electrical conductivity of aluminum bipolar plates, several coatings, including TiN, CrN, C, C/TiN and C/CrN, are deposited on aluminum alloy 5052 (AA-5052) by close field unbalanced magnetron sputter ion plating. Scanning electron microscope (SEM) results show that the coatings containing carbon layer are denser than TiN and CrN. Although the potentiodynamic test results show improved corrosion resistance by all the coatings, the potentiostatic test results reveal different stability of these coatings in PEMFC environments. Comparing the SEM images of these coatings after potentiostatic test, C/CrN multilayer coating exhibits the best stability. C/CrN multilayer coated AA-5052 has the lowest metal ion concentration after potentiostatic test, being 11.12 ppm and 1.29 ppm in PEMFC cathodic and anodic environments, respectively. Furthermore, the interfacial contact resistance (ICR) of the bare AA-5052 is decreased from 61.58 mΩ-cm² to 4.08 mΩ-cm² by C/CrN multilayer coating at the compaction force of 150 N-cm⁻². Therefore, C/CrN multilayer coating is a good choice for surface modification of aluminum bipolar plate.     

某种煤压机叶片表面防腐涂层的制备及性能研究

文章介绍了某种燃机的煤气压缩机叶片使用工况,研究了煤压机叶片涂层的制备方案．确定在叶片的叶身表面制备DF-1涂层,在叶柄表面制备Ni—P涂层。研究了涂层的生产制作工艺流程、质量控制要点和涂层的性能．发现叶身表面DF-1涂层具有耐腐蚀性能优异,结合力高,表面光滑等特点;叶柄表面Ni—P涂层具有优异的耐蚀性和耐磨性。最后此种涂层成功应用于新旧燃机机组的压缩机叶片表面防腐生产．     

Synthesis and Ex-Situ characterizations of diamond-like carbon coatings for metallic bipolar plates in PEM fuel cells

Metallic bipolar plates can significantly increase the power density of polymer electrolyte membrane fuel cells; however, they require corrosion-protection coatings with desirable physical and chemical properties. In this study, diamond-like carbon (DLC) film coatings are investigated as such coatings potentially for metallic-based bipolar plates, with the focus on the relation between the processes and properties of the coatings under different coating deposition conditions of Plasma Enhanced Chemical Vapor Depsoition (PECVD) method. Various characterization techniques are applied to study the adhesion, structure, morphology, wettability, corrosion, and electrical resistivity of the film coatings. XPS, EDAX, and SEM analyses are used to identify the ratio of sp³ (diamond-like) and sp² (graphite-like) bonds in the coatings, surface elements, and surface morphology, respectively. Potentiodynamic polarization test is utilized to investigate the corrosion behaviors of substrates with and without DLC coatings. Further, the electrical resistivity of the DLC films is measured by the four-point probe method. The results indicate that higher deposition power along with the absence of argon gas results in more sp³ than sp² bonds in the coating, and the electrical resistivity is increased accordingly. The coating films deposited from methane (CH₄) exhibit superior adhesion to the stainless steel (SS316) substrates over those generated from acetylene (C₂H₂) gas. Coating films deposited on the metallic substrates change the surface wettability appreciably. Further, polarization tests show that coatings generated with a low power of 250 W and higher argon gas percentage of 30% provide better anti-corrosion protection for metallic-based bipolar plates.     

Effect of chemical oxidation of CNFs on the electrochemical carbon corrosion in polymer electrolyte membrane fuel cells

Effect of chemical oxidation of carbon nanofibers (CNFs) on the electrochemical carbon corrosion in polymer electrolyte membrane (PEM) fuel cells is examined. With increasing time of chemical oxidation treatment using an acidic solution, more oxygen functional groups are formed on the surface of CNF resulting in an increasingly hydrophilic carbon surface. This effect contributes to improvements in Pt loading and the distribution of Pt particles on carbon supports. However, the chemical oxidation treatment is found to accelerate electrochemical carbon corrosion. The oxygen functional group and the hydrophilic nature of CNFs after chemical oxidation treatment are believed to encourage the formation of CO₂, which is a product of carbon corrosion. From the observed results, it can be concluded that the chemical oxidation of CNFs is beneficial for catalyst loading and distribution. On the other hand, however, it reduces the durability of the PEM fuel cells caused by the electrochemical carbon corrosion.     

影响化学镀Ni-P合金稳定性因素

通过对化学镀Ni-P 合金络合剂,抑制剂和还原剂等作用进行的分析,对化学镀Ni-P合金工艺条件进行了试验研究,确定了影响镀液稳定性和镀层性能的因素,达到对镀层质量有效控制的目的。     

Corrosion behavior of TiN-coated stainless steel as bipolar plate for proton exchange membrane fuel cell

Stainless steel is a potential material to be used as the bipolar plate for proton exchange membrane fuel cell (PEFC) because of its suitable physical and mechanical properties. Several coating techniques have been applied to improve its corrosion resistance. But seldom study is focused on the microstructure evolution with corrosion. In the present study, the use of TiN-coated stainless steel as the bipolar plate is evaluated. Two surface coating techniques, pulsed bias arc ion plating (PBAIP) and magnetron sputtering (MS), are adoped to prepare the TiN-coated stainless steel. Their corrosion resistances and electrical conductivities of the coated substrates are evaluated. The performance shows strong dependance on microstructural characteristics. The corrosion of SS304/Ti₂N/TiN prepared by MS mainly occurs on the grain boundary. The corrosion of SS304/TiN prepared by PBAIP mainly takes place from the large particles on the coating. The Ti₂N/TiN multilayer coating provides superb corrosion protective layer for stainless steel. Both the TiN and Ti₂N/TiN coatings provide low contact resistance.     

Time-dependent corrosion behavior of electroless Ni–P coating in H2S/Cl− environment

As a mature technology, electroless Ni–P alloy coating is widely applied in the protection of chemical equipment and pipelines owing to its excellent corrosion resistance, but its application and long-term service evaluation in the field of high-sulfur oil and gas are rare. Therefore, the time-dependent corrosion behavior of Ni–P coating, which was plated on the L360 steel surface, was investigated in a saturated H₂S medium by the method of surface analysis. The results indicate that Ni–P coating with a thickness of about 52.6 μm could significantly reduce the corrosion rate compared with uncoated pipeline steel. This is related to the structure of the dense, protective film on the surface. The uncoated pipeline steel suffered local corrosion during the immersion process, and then it developed into uniform corrosion with the formation of a large number of corrosion products. In comparison, Ni–P coatings corroded relatively mildly with only a thin corroded layer. However, during prolonged corrosion testing, the corrosive medium penetrated the coating/substrate interface at inherent defects, leading to severe local corrosion of the substrate.     

Effect of Ni content on the electrical and corrosion properties of CrNiN coating in simulated proton exchange membrane fuel cell

In this paper, CrNiN coatings with various Ni content are deposited on 304ss bipolar plates by closed field unbalanced magnetron sputter ion plating from CrNi alloy targets. Simulative working environment of proton exchange membrane fuel cell (PEMFC) is applied to test the electrical and corrosion properties of uncoated 304ss and CrNiN-coated samples. The influence of Ni content on microstructure, phase structure, contact angle with water and electrochemical performance is investigated. Results show that all the coated samples significantly enhanced the corrosion resistance of the 304ss, and the CrN-coated 304ss sample without Ni has the best corrosion resistance of 153.8 and ?141.9 mV in the simulated anodic and cathodic environments, respectively. Electrochemical impedance spectroscopy (EIS) studies reveal that the resistance of CrN coating is higher than that of other coated samples and 304ss in the cathodic environment. Furthermore, Interfacial contact resistance (ICR) studies revealed that CrN coating has a superior ICR of 11 mΩ cm² at a compaction force of 160 N cm^?2. In addition, the contact angle of the CrNiN coatings with water is approximately 114°, which is beneficial for water management in PEMFC. Analysis result indicates that the enhanced performance of the coated 304ss bipolar plates is related to the high film density determined by closed field unbalanced magnetron sputter ion plating, and the synergistic function of the CrNiN layered structure.     

Evaluation of coated metallic bipolar plates for polymer electrolyte membrane fuel cells

Metallic bipolar plates for polymer electrolyte membrane (PEM) fuel cells typically require coatings for corrosion protection. Other requirements for the corrosion protective coatings include low electrical contact resistance, good mechanical robustness, low material and fabrication cost. The authors have evaluated a number of protective coatings deposited on stainless steel substrates by electroplating and physical vapor deposition (PVD) methods. The coatings are screened with an electrochemical polarization test for corrosion resistance; then the contact resistance test was performed on selected coatings. The coating investigated include Gold with various thicknesses (2 nm, 10 nm, and 1 μm), Titanium, Zirconium, Zirconium Nitride (ZrN), Zirconium Niobium (ZrNb), and Zirconium Nitride with a Gold top layer (ZrNAu). The substrates include three types of stainless steel: 304, 310, and 316. The results show that Zr-coated samples satisfy the DOE target for corrosion resistance at both anode and cathode sides in typical PEM fuel cell environments in the short-term, but they do not meet the DOE contact resistance goal. Very thin gold coating (2 nm) can significantly decrease the electrical contact resistance, however a relatively thick gold coating (>10 nm) with our deposition method is necessary for adequate corrosion resistance, particularly for the cathode side of the bipolar plate.     

35_ CaCO_3溶液中不锈钢304和316表面结垢特性

不锈钢304和316是换热器常用材料,研究CaCO3析晶污垢在这两种金属表面的生长特性是抗垢研究的第一步。在35℃0.05 g/L CaCO3溶液中,通过静态反应法研究CaCO3在两种金属表面的生长特性,采用称重法获得不同时间结垢重量,采用扫描电子显微镜(SEM)获得不同时间污垢的微观形貌。结果表明:在相同条件下,不锈钢304和316表面结垢量很接近;pH升高不仅使结垢量增多而且促进四方形文石和方解石的形成,并且文石不断重结晶形成热力学最稳定晶型(方解石);pH升高使表面产生更多晶核,并且晶体分布没有规律、交叉重叠生长。