热压金刚石地质钻头用石墨模具

近四十年来,我国热压金刚石地质钻头用石墨模具有了长足的进步,但是,与欧美日等发达国家的水平相比,尚有较大的差距。文章通过对国内外石墨模具样品的试验分析,并对碳素材料的氧化机理及其影响因素进行深入地研究,提出要提高热压金刚石地质钻头用石墨模具的尺寸精度、表面光洁度,减少胎体或镶块中金属结合剂的流失量,减缓石墨模具的氧化烧损速度,宜采用超细碳素原料颗粒来制作高电阻率、高石墨化程度、高强度、低灰分、微气孔率的石墨模具。这是赶超世界先进水平的发展方向,也是制取高精度,高使用寿命的热压金刚石地质钻头用石墨模具的有效途径。     

对优质金刚石切边锯片的分析研究

提高锯片寿命和切割效率是金属结合剂金刚石锯片制造研究的关键问题。文章通过实验探讨了用不同金刚石、结合剂制备“三明治”式刀头的相关工艺,研究分析了刀头的性能,如硬度、抗弯强度等。实验结果表明:用Cu作黏结相,同时添加少量的Fe、Sn、Ni、Cr作黏结添加相进一步改善性能,经过780℃保温3min的烧结后,“三明治”刀头合金显微组织在6 5 Mn的金属基体上分布着5 0 / 6 0目的金刚石硬质相,这种柔韧性的基体与适当的分散硬质相结合起来,提高了锯片刀头的硬度、切割性能、强度、抗磨损能力及韧性,达到了预期的目的。     

新型金刚石分齿烧结锯片的半自动成型模具

文章介绍了新型金刚石分齿烧结锯片半自动成型模具的研发及应用,对金刚石工具制造行业在效率、成本上的影响作了说明,对未来烧结锯片成型方式的发展趋势进行了展望。     

不断完善预合金粉末的性能,满足金刚石工具的应用（下）

为此欧泰克金刚石工具公司采用图9a所示的还原炉对冷压后生坯刀头还原,新途金刚石工具公司则采用图9b型还原炉还原[12、13]。2.6激光焊接锯片的脱脂、抽真空和氮气保护下的烧结我国引进的激光焊接锯片的生产工艺中,多采用制粒和全自动冷压机压制刀头,烧结时多采用DSP475,510/515烧结机进行烧结,此时采用脱蜡,抽真空,充入保护气氛（N2）进行烧结,既提高了石墨模具的寿命,又充分保证了刀头的烧结质量,其典型的烧结工艺曲线见图10。     

提高金刚石强化柱齿性能的研究

针对牙轮钻头制造行业对边楔形金刚石强化柱齿的需求及锥球形金刚石强化柱齿在耐磨性、外观、结合强度等方面的不足进行研究。采用烧结法合成边楔形金刚石强化柱齿,使用焙烧石墨模具,合理设计硬质合金基体,选用合适的工艺配方,研制成功了边楔形金刚石强化柱齿,为国内首创,平均磨耗比≥10万,满足了牙轮钻头厂家的要求。采用混合烧结法制作D-D结合的锥球形金刚石强化柱齿,平均磨耗比≥20万,比用烧结法制作的同类产品的耐磨性提高了一倍,外观质量得到明显改善。应用本研究成果生产的产品国内市场占有率达70%以上。     

新一代金刚石工具及其性能分析

新一代金刚石工具以金刚石颗粒有序排列为主要特征,其性能比金刚石颗粒随意分布的传统金刚石工具优越。ARIX工艺制造的金刚石有序排列的锯片消除了传统金刚石锯片使用中提高锯切速率而导致寿命降低的问题。钎焊单层金刚石磨具由于其中的金刚石颗粒以一定间距有序排列成一定形式而且金刚石出刃较高,与其它结合剂金刚石磨具相比,可达到较高的加工效率和表面光洁度。     

干切混凝土时金刚石锯片振动及噪声的研究

干切混凝土时,金刚石锯片在实际工作过程中产生的振动和噪声是非常严重的。文章从理论上分析了混凝土锯切过程中的强振动、高噪音的原因。通过改变锯切速度、进给速度、切深以及通过采用两种不同的基体结构的锯片,研究了不同的切削参数以及锯片的结构对锯片振动和噪声的影响。在不同的锯切工艺参数和锯片结构下,测量了噪声值、噪声功率、噪声电压、振动功率和振动幅值,并对其进行频谱分析。可以从锯片的基体结构、金刚石节块的结构、锯切工艺以及锯机的整体性能等方面来进行改进,从而达到降低噪声与振动的目的。本文在理论分析和实验的基础上提出了一些降低噪声和振动的方法。     

人造金刚石用石墨性能的研究

用于合成金刚石的石墨具有三个功用——碳源、热源和受压介质,其性能直接关系着金刚石的质量。文章针对人造金刚石用石墨材料主要性能的研究进行了综述,包括石墨化度、气孔率(体积密度)、灰分(纯度)、电阻率以及晶体结构等等。提出在选择合成金刚石用石墨材料时,应综合考虑其满足不同功用的各项性能,同时还要结合具体的生产条件。认为满足合成设备大型化和粉末工艺的粉状石墨和辅助加热用的石墨材料将是人造金刚石用石墨材料发展的新亮点。     

浅析中频热压烧结过程中影响金刚石钻头性能的因素

通过试验和分析，说明在中频热压烧结金刚石钻头过程中，钻头性能受各种因素综合影响，其主要因素是电磁场影响到胎体粉料和金刚石分布，模具配合间隙引起胎体的流失而导致金刚石浓度发生变化。文中分析了电磁场对钻头性能的影响与胎体中铁磁物质含量及金刚石浓度的关系，也分析了模具配合间隙对胎体流失而引起金刚石浓度变化的关系。在中频热压烧结，高铁磁质含量胎体和低金刚石浓度的前题下，采用新工艺制作钻头，金刚石分布得到改善，钻头在使用中取得了良好的效果。     

薄型金刚石圆锯片结构设计探讨

使用薄型金刚石圆锯片的意义在于减小切缝宽度,从而降低石材资源浪费。薄型金刚石圆锯片的结构设计主要包括锯片基体与金刚石刀头的设计,在文章中对两者均作了论述。通过薄型金刚石圆锯片与普通金刚石圆锯片的性能对比,证实了前者的性能优于后者。     

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