热浸镀Zn-6Al-3Mg合金镀层组织结构与性能研究

对Zn-6Al-3Mg镀层的物相组成、组织结构及耐腐蚀性能进行研究。Zn-6Al-3Mg合金镀层组织为Zn/Mg Zn2二元共晶组织、块状富Al相和近似六边形单相Mg Zn2组织。Na Cl中性盐雾腐蚀试验结果表明,镀层的耐蚀性优于Zn-5Al和纯Zn镀层。主要原因是由于Mg的加入促进Zn(OH)2向结构更为致密、粘连性更好、导电性更低的腐蚀产物Zn5(OH)8Cl2·2H2O和Zn6Al(OH)16CO3·H2O转变,并且生成的腐蚀产物牢牢附着在镀层表面,从而形成了结构致密的保护膜,有效隔断镀层和外部环境物质的传输,降低腐蚀反应向镀层内部进行的速率。     

各种耐大气腐蚀金属热镀层综述

<正> 为了适应近年来环境的改变、工业污染、沿海地区等严重腐蚀气氛,传统镀锌层的防蚀性能已不适应客观形势的需要。为此,国外研制并发展了各种金属镀层,先后有镀铝层、55% Al—Zn 合金层、4—7%Al—Zn 合金层、5%Al—Zn+稀土合金层、15%Al—0.5Sn—Zn 合金层、Al—Zn—Mg 等合金层。现将它们的耐蚀性能及发展概况综述于下。     

热镀锌铝合金镀层钢丝助镀工艺的研究

介绍锌铝合金镀层钢丝耐腐蚀机制、单镀法的基本原理,重点研究热镀锌铝合金镀层钢丝的助镀工艺,给出适合热镀Zn-5%Al和Zn-10%Al-Re合金钢丝的工艺参数:ρ(ZnCl2)为100⁴00 g/L,ρ(KCl)为10400 g/L,ρ(KCl)为10⁴0 g/L,ρ(添加剂)为2040 g/L,ρ(添加剂)为20⁸0 g/L;温度≥80℃,操作时间不超过3 s。采用单镀法生产的锌铝合金镀层钢丝表面质量稳定,钢丝各项理化技术指标稳定。产品达到GB/T 20492—2006《锌-5%铝-混合稀土合金镀层钢丝、钢绞线》规定的相关表面质量要求。     

镀层显微组织对Zn—Al合金镀层钢丝耐蚀性的影响

<正> 近年来,为了改进热镀钢丝的耐蚀性,研制了多种 Zn—Al 合金镀层,有些已经在钢丝生产中实际应用。钢丝的热镀通常都要采用熔剂,但 Zn—Al 合金镀层采用熔剂会碰到许多问题。由于镀液中存在有 Al,采用传统的 NH_4Cl-ZnCl_2熔剂,镀层表面往往     

桥梁缆索用钢丝锌铝镁合金镀层的开发进展

热镀锌铝镁镀层以Zn、Al、Mg三元合金为主,具有比纯锌和锌铝镀层更优的耐腐蚀性能。目前桥梁主缆热镀锌钢丝耐腐蚀寿命不足20年,从性能和性价比角度看,锌铝镁合金镀层是解决桥梁缆索钢丝耐腐蚀寿命不足的最佳方案。锌铝镁合金镀层钢丝性能优于市场上现有的纯锌和锌铝镀层产品。     

如何正确评判Zn-5%Al-MM合金镀层钢丝

<金属制品>2001年第5期刊登的"Zn-5%Al-MM合金镀层钢丝的生产与评判"一文推荐用加热法识别Zn5%Al-MM合金镀层钢丝,并把该钢丝按合金层占总镀层厚度的比值分成优良级、普通级、低劣级、伪劣级4个级别.对此,我们认为有所不妥,今提出来与作者商榷.     

钢丝双镀镀层的显微组织研究

本文应用镀纯锌后进行镀层热处理,然后再镀Galfan合金的工艺,得到了外层为Galfan合金的厚镀层。研究了纯锌镀层热处理后的显微组织结构与热处理条件的关系,给出了四种类型的双镀镀层结构及其在Fe—Al—Zn三元相图中对应的扩散通道,并对各种类型的缠绕性进行了分析,提出了双镀Zn—Galfan合金工艺中较理想的初镀镀层结构和再镀镀层结构。     

钢丝热镀Zn—5Al—Re合金工艺研究

<正>研究了 Zn—5Al—Re 合金的熔配工艺、性能及工艺参数对镀层质量的影响规律,并进行了小批量热镀钢丝生产。Zn一SAI一Re镀层(Galfan合金镀层)以其良好的耐蚀性、可加工性及其生产设备可利用原镀锌设备改建等特点而获得迅速发展。1953~1985年短短三年,国外已有32家钢铁公司、镀锌公司、钢丝厂、钢管厂等取得了生产许可证,雄出现了26家合金生产厂,现已遍及五大洲14个国家,产品夭量用于建筑、牟辆、船舶、机电等领域。我国对发展合金镀层也丧现了极大的兴趣.近     

蒸发器结垢物的金属元素组成和晶格分析

本文对烧碱法麦草浆黑液四效蒸发系统中,各效蒸发器结垢物的金属元素(K、Na、Ca、Mg、Fe、Al、Cu、Zn)组成和晶格结构进行了对比分析,发现各效垢物在性质和金属元素组成上有较大的差异;钙是除硅以外最主要的结垢金属元素;垢物的晶格组成主要是复杂的晶体物质纤硅碱钙石[(Ca,Na_2,K_2)_8·Si_(16)·O_(40)·[IH_2O],还有少量的紫硅铝镁石[(Mg,Al)_8Si_4(O,OH)_(20)]和雪硅钙石[CaO·SiO_z·YH_2O]。     

胎圈钢丝电化学镀镍和铜的可行性研究

1　研究与成果1.1　研究目的(1)在 2 .8mm钢丝表面预镀镍,在硫酸盐溶液中镀铜;(2 )选择镀镍和镀铜的最佳工艺参数;(3)评价 2 .8mm钢丝拉拔到 0 .94mm的镀层质量。在研究中,通过试验选择合理的镀镍和镀铜胎圈钢丝生产技术。1.2　原料及工艺技术选用 5 .5mmD6 5盘条,其化学成分见表1。表1　D6 5钢材化学成分w/ %CMnSi Pmax Smax (P +S) max Crmax Nimax Cumax Momax0 .6 5 0 .35 0 .10 0 .0 35 0 .0 35 0 .0 6 0 .2 0 .2 0 .2 0 .0 8　　拉丝机型号为UDZSA—2 5 0 0 ,拉拔速度V =6m/s(最后一道) ,用DECAL6 0 0型润滑剂,拉丝模角2α=…     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the