松香对锌基钎料助焊剂物理性能及Zn20Sn钎料铺展性能的影响

锌基合金钎料是一种比较理想的高温无铅软钎料,但是Zn20Sn钎秤润湿性差.本文开发一种新型Zn基舍金专用松香基钎剂,研究了不同含量的松香添加量对钎剂的物理性能和其对Zn20Sn钎料的铺展性能影响.结果表明,当助焊剂中的w(松香)55％时,对Zn20Sn钎料的铺展率有明显提升,且该助焊剂的黏性、腐蚀性、不挥发物含量等均符合标准要求.     

松香ZnCl2基钎剂对Sn-Zn基无铅钎料润湿性的影响

以松香为载体,ZnCl2为活性剂,酒精为溶剂,乙二醇为添加剂,设计了不同钎剂配方,通过铺展性试验研究了钎剂成分对Sn-Zn基无铅钎料在铜上的润湿性的影响.研究结果表明:松香-ZnCl2-酒精-乙二醇钎剂的去膜作用是松香和ZnCl2共同作用的结果,随着钎剂中ZnCl2和松香配比的增加,钎料的铺展面积先增大后减小.钎剂中的酒精具有降低钎剂黏度的作用,酒精中的水分具有增强ZnCl2去除金属氧化膜能力的作用,从而使钎剂具有促进钎料在铜上铺展的能力,但是钎焊过程中钎剂飞溅大.钎剂中的乙二醇具有增大钎剂黏度,减少钎剂飞溅的作用,但具有降低钎料润湿性的作用.ZnCl2、天然松香、酒精和乙二醇进行适当配比配制的钎剂能明显改善Sn-Zn钎料的润湿性.     

铜-铝异种金属钎焊材料的研究现状

从钎剂和钎料两方面对国内外有关铜-铝异种接头钎焊材料的研究成果进行了综述,重点介绍了铜-铝异种接头钎焊连接过程中无腐蚀性钎剂和钎料成分对钎焊接头结合机理、界面反应、金属间化合物的微观结构及生长规律等的影响。然而,铜-铝异种接头钎焊材料的应用过程中仍存在以下问题:无腐蚀性钎剂熔化温度和价格均较高,适用范围较窄;铝硅系钎料熔化温度较高,铝合金容易过烧熔蚀;钎料洁净度低,钎缝处容易出现氧化夹杂,影响钎焊接头的力学性能。     

药芯锌钎料的润湿性及显微组织研究

介绍了一种铜铝钎焊用药芯锌钎料,探讨了钎焊温度、保温时间、钎剂、钎料成分和钎剂添加方式对钎料在纯铝上润湿性能的影响,分析了钎料在不同加工状态的显微组织变化。试验结果表明,药芯锌钎料在铝上具有很好的润湿性,润湿面积随钎焊温度和保温时间的增加而增加;QJ201保护下的无药芯锌钎料在较低温度时就能在铝上很好润湿,且铺展面积和润湿速率均比无腐蚀性钎剂保护下的铺展面积大,但其腐蚀性强;药芯锌钎料中添加0.2%～10%(质量分数)的元素银,熔融钎料的表面张力降低,钎料润湿性得到明显改善,同时钎料晶粒细化,钎料强度提高;加工状态对药芯锌钎料显微组织的影响较大,由铸态的粗大树枝晶,变为挤压态织构,最后为拉丝态丝状织构。     

活性元素对Sn-2.5Ag-0.7Cu-xGe钎料润湿性能的影响

采用铺展试验法研究了Sn-2.5Ag-0.7Cu-xGe无铅钎料在铜基板上的润湿性能;对比了在钎料中添加活性元素锗前后的铺展润湿面积;研究了钎剂中SnCl2的含量对Sn-2.5Ag-0.7Cu-xGe无铅钎料润湿性能的影响规律;分析了锗与SnCl2的交互作用对焊接性能的影响。结果表明:在钎料中加入锗元素后,钎料的润湿性能会逐渐升高,当Ge含量超过0.5%时铺展面积会逐渐下降。SnCl2对钎剂的活性有很大程度的改善,在含量为4.5%时效果较好,当继续增加其含量时虽然会加大润湿面积,但同时也会出现大量的腐蚀性残留物,并且基板出现轻微溶蚀现象。综合分析得出,钎料与助焊剂的最佳组合是Sn-2.5Ag-0.7Cu-0.5Ge钎料与乙醇-30%松香-4.5%氯化亚锡溶液钎剂匹配。     

不同钎剂对Sn-Zn系无铅钎料润湿特性的影响

采用润湿平衡法研究了在znC12一NH4C1、中等活性松香(RMA)和免清洗三种不同钎剂作用下,Sn-Zn无铅钎料在Cu基板上的润湿特点.结果表明,使用ZnC12-NH4C1钎剂时,Sn-Zn钎料具有良好的润湿性能;研究了不同钎剂下,Sn-9Zn钎料在Cu基板上的铺展情况,并分析比较了焊点界面金属间化合物层的特征.Sn-Zn钎料与Cu基板界面形成的金属间化合物在靠近Cu基板一侧较为平坦,而在钎料一侧呈扇贝状,而且,不同钎剂能影响钎料在Cu基板上的润湿、铺展性能,界面金属间化合物特征及焊点外观;Sn-Zn钎料表面存在大量ZnO,去除钎料表面ZnO是开发针对Sn-Zn系无铅钎料专用钎剂的关键.     

Sn-3.5Ag0.6Cu合金对铜引线的钎焊性研究

研究了Sn-3.5Ag0.6Cu无铅钎料的制备工艺、助钎剂系统和活性剂含量以及钎焊工艺参数等对铜引线钎焊性的影响.试验结果表明,通过材料改性可提高钎焊性,而松香-乙醇或异丙醇溶液是其优良的助钎剂;当添加的活性剂为松香质量的0.4%或溶液质量的0.1%时,可分别将润湿速率提高5倍,润湿力提高1.5倍;其最佳工艺参数熔融钎料温度≤270℃,浸渍时间2～3 s.     

Al-Cu接头钎焊研究

通过时工艺性能、钎焊接头的力学性能及抗腐蚀性能等方面的研究，探讨了Al-Cu接头的钎焊。研究结果表明，Zn-40Sn-2Cu及Zn-55Sn-2.5Ag钎料配合铝反应钎剂可获得钎焊Al-Cu接头理想的效果，在钎料中添加微量的稀土有提高Al-Cu钎焊接头强度和抗腐蚀性的作用。     

低腐蚀钎剂在散热器生产中的应用

无机软钎剂ZnCl_2水熔液的助焊性虽能满足散热器软钎焊的要求,但鉴于它较强的腐蚀性,90年代初,国内研究者借鉴国外的经验,开发出残留物少、腐蚀性较弱的软钎剂（低腐蚀钎剂）,并在全国多家散热器厂进行推广应用。本文介绍东风汽车公司散热器厂对低腐蚀钎剂的应用情况。1 助焊性试验用低腐蚀钎剂与现生产使用的ZnCl_2饱和水溶液在相同焊接条件下按GB11364一89标准规定进行对比试验,每个试样做三次,取其平均值作为试验数据。     

KF-AlF_3-KBr低熔点铝基钎剂研制

氟铝酸钾钎剂不吸潮、无腐蚀,广泛应用于铝及其合金的钎焊,但由于该钎剂熔点较高,限制了其使用范围。在KF-AlF3钎剂基础上,添加第三组元KBr降低了熔点,获得了低熔点的无腐蚀性钎剂。通过DSC、XRD和一系列钎焊性能实验表明,当w(KBr)=20%时钎剂熔点最低,液相线温度522.1℃。钎剂由KAlF4、K3AlF6和KAlBr4组成,KAlF4-K3AlF6-KAlBr4组成的三元共晶是钎剂熔点降低的主要原因。通过性能测试表明,此钎剂具有良好的铺展性、填缝性,去膜能力也有较大程度的提高,可以应用于低熔点铝合金钎焊。     

我国海域海水对防锈铝合金的腐蚀性及材料因素影响的规律

通过铝镁合金在我国青岛、厦门、榆林各海域海水经16a及短期海水的腐蚀实验结果，分析了我国海域海水腐蚀行为的主要规律：厦门海域的海水对铝镁系防锈铝合金构成相对苛刻的腐蚀环境。不同防锈铝合金的耐蚀性能不同，且其腐蚀行为与不同的海水环境因素密切相关，使用不同的防锈铝合金来评定各海域海水腐蚀性，所得的排序不同。合金不同表面状态对海水腐蚀行为的影响依海域及合金而异，在腐蚀性较强的海水中，不同浓度酸洗状态带来的腐蚀行为差异可被逐步加大，但对不同海域海水腐蚀性的评定未构成大的影响。原始出厂态的耐蚀性能受合金类型及其原始表面膜质量的影响，其用于评定海水腐蚀性会比酸洗态带来更多不确定因素。杂质等缺陷的存在增大了点蚀发生的随机性，也给腐蚀性的评定带来一定的干扰。     

Effect of wood species on corrosion behavior of carbon steel and stainless steels in black liquors

Black liquors produced by pulping different wood species can have different corrosivity towards carbon steel equipment in pulp mills. Inorganic constituents of black liquor alone do not correlate well with the corrosivity of different black liquors. Organic constituents of the black liquor have significant effect on determining its corrosivity. However, understanding of the role of individual organic constituents or group of constituents of black liquors in overall black liquor corrosivity is generally lacking. The objective of this study was to determine the effect selected wood species on the corrosivity of their black liquors which contained similar inorganic constituents. The role of black liquor constituent, pyrocatechols, whose presence in the black liquor has been associated with an increase in corrosion of carbon steel, was also studied. Results from electrochemical tests point to the mechanisms by which the catechols may participate in the accelerated corrosion of carbon steels. This study demonstrates the role of organic constituents of the black liquor in determining its corrosivity.     

Physicochemical studies of mild steel corrosion and atmospheric corrosivity mapping of Karachi: An important harbor city of modern Maritime Silk Route

This paper has reported physicochemical features of mild steel's corrosion products and provided atmospheric corrosivity maps of Karachi harbor city, drafted on the basis of spatial distribution of corrosion data from July 2018 to June 2019 at 10 different urban, industrial, and marine test sites. Exposure tests have been performed to study atmospheric corrosivity, corrosion products, and corrodants including chloride, sulfur dioxide, time of wetness (TOW), and corrosion rate as per ISO and ASTM standards. Scanning electron microscope, Fourier-transform infrared spectroscopy, and X-ray diffraction have corroborated the presence of lepidocrocite, goethite, magnetite, and quartz phases at almost all the test sites, with slight variations in their morphologies and quantities. The data analysis has revealed that TOW is a major detrimental factor to accelerate corrosion of mild steel at Karachi city. The corrosivity category of all urban and marine test sites is found in C₄–C₅ range, whereas for industrial test sites, it is found in C₃–C₅ range. Resultant corrosivity maps have shown that the prevailing atmosphere is significantly corrosive at Karachi harbor city. This study has furnished a novel product of atmospheric corrosivity map, which is the first-ever corrosivity map for Pakistan.     

Corrosion of copper by food acids containing colourants and sweetening agents – Part II: Corrosion by tartaric acid

The corrosion of copper in tartaric acid solutions containing various food colourants and/or sweetening agents has been studied with respect to the concentration of the acid and the colourant, and temperature. At constant acid concentration the corrosion increases with the concentration of the colourant whereas at constant colourant concentration it increases with acid concentration. In acid solutions the corrosivity of the colourant increases in the order: tartrazine < ponceau 4 R < carmoisine < amaranth < fast red E < sunset yellow. The addition of sweetening agent also increases the corrosion of copper, the corrosion increasing in the order: saccharin < fructose < glycerol < sucrose < glucose. In acid containing the colourant as well as the sweetening agent the order of corrosivity is: sucrose < glucose < fructose < saccharin < glycerol. Copper in 0.05 M tartaric acid develops a corrosion potential of ?40 V (vs SCE). The addition of colourants or sucrose do not appear to have any effect on the corrosion potential. Galvanostatic polarisation curves show very little anodic but appreciable cathodic polarisation. Additives like sodium benzoate, raspberry essence, gum tragacanth, dextrin, and potato starch appear to confer some protection to copper in tartaric acid containing colourants like carmoisine.     

Phasenumwandlungen in Korrosionsschichten auf Eisen: Mößbauerspektroskopische Untersuchungen

Phase transformations in corrosion layers on iron: Mössbauer spectroscopic studies The corrosion of steel surfaces was studied by Mössbauer spectroscopic phase analysis in scattering and transmission geometry. In atmospheres of low corrosivity, long exposure times result mainly in the relatively stable β-phases among the possible iron corrosion products. An increase in corrosivity by addition of hydrochloric acid leads to a pronounced formation of β-FeOOH, whereas the α-phases are absent. The influence of different coatings on the phase composition was also studied. The formation and transformation of the different iron containing phases in rust can be understood in terms of a stability diagram. Furthermore, the effect of so-called “rust transformers” was studied. None of these products showed the desired effect of phase transformations towards the formation of protective compounds such as Fe₃O⁴. In some cases it was found that the rust transformers even caused a destruction of an already existing protective layer.     

我国典型地区大气腐蚀性的综合评价

运用模糊综合评价方法,选择合适的隶属函数,根据国际标准化组织ISO9223大气腐蚀性评价分级标准和我国大气腐蚀网站的腐蚀数据,对我国典型地区的大气腐蚀性进行了综合评价,其结果与单因素评价进行了对比。综合评价结果能较好地反映我国典型地区大气环境的腐蚀性。     

Corrosion in alkanolamine used for acid gas removal: From natural gas processing to CO2 capture

The aim of this paper is to review some of the parameters influencing the corrosivity of alkanolamine solvents used for natural gas purification or for CO₂ capture. In the light of literature data and of new experimental results, the influences of temperature and of acid gas loading are discussed. These two parameters appear to have a strong impact on corrosion rates of carbon steel, with extrapolated corrosion rates of several tens of mm/year for the highest temperature and acid gas loading condition. It is then proposed to discuss about similarities and differences between natural gas processing and CO₂ capture from flue gas. For both applications, alkanolamine processes are used. Still, differences can be found in operating parameters. The most significant gap concerns the lean amine sections. In acid gas treatment, the regeneration of the solvent is often performed down to zero loading. Under these conditions, an extremely low corrosivity of the lean solvent is expected. On the contrary, CO₂ capture from flue gas requires only a partial stripping of the CO₂ in the regeneration section, due to energy efficiency reasons. Then, the lean solvent still contains some acid gas, and subsequently a higher corrosivity. Finally, the general principles for material selection for the different parts of acid gas removal units are discussed, considering both cases of natural gas processing or CO₂ capture.     

Abgasseitige Korrosion bei Öl- und Gasfeuerung

Flue gas side corrosion in oil and gas fired heating systems Corrosion of metallic material of heaters of chimneys in contact with flue gas is guided by the amount and composition of condensate occurring on the surface when the temperature of the surface lies below the dew point of the flue gas. The corrosivity of the condensate depends on its content of sulfuric acid which results mainly from the sulfur content of the fuel. In some cases a special corrosivity against stainless steel may arise from a chloride-ion content of the condensate due to pollution of fuel or air by organic chlorine compounds. As a result of experiences with corrosion damages of heaters and chimneys a corrosion test methode for prefabricated stainless steel chimney elements was developed. Acceleration of corrosion is reached by simulation of only those phases in which condensation may occur and by addition of sulfur dioxide to the combustion air.     

碳钢和不锈钢在高温环烷酸介质中的腐蚀行为

采用失重法和表面分析研究了碳钢和不锈钢在高温环烷酸油介质中的腐蚀行为规律。结果表明：酸值和温度是影响金属环烷酸腐蚀行为的主要因素,其反应动力学遵循Arrhenius公式。腐蚀速度随着温度的上升而增加,同一温度下酸值影响气相腐蚀速度与液相腐蚀速度之间的关系。腐蚀速度与酸值的平方根成线性关系。随着腐蚀时间的增加,腐蚀速度迅速降低,最后趋于稳定的腐蚀速度。     

Effect of preparation method on the anti‐corrosive properties of nanocrystalline Zn–CoO ceramic pigments

Zn–CoO green ceramic pigments were synthesized by two different methods; high energy ball milling and solution combustion, with two different fuels; citric acid and glycine. Products were characterized by X‐ray diffraction and scanning–transmission electron microscopy (TEM). The anti‐corrosive properties of the obtained pigments were investigated by electrochemical impedance spectroscopy (EIS) techniques. Results have shown that either by solid state reaction or combustion by citric acid, a calcination step was needed to obtain the desired phase whereas by glycine fuel, pure ZnO phase was obtained directly. TEM showed particles with mean particle size of about 70, 150, and 180 nm for glycine, citric acid, and solid state reaction samples, respectively. The corrosion performance of the coating in 3% w/v NaCl solution was evaluated by EIS and polarization measurements. According to the measurements of EIS and electrochemical polarization, the coatings with glycine‐based pigment showed the highest corrosion resistance among the prepared coatings.