用于陶瓷加工的金刚石磨具

介绍了金刚石磨具的结构，详细阐述了在陶瓷砖用烧结金属结合剂和树脂结合剂金刚石磨具制备中金刚石磨料的选择和应用，以及结合荆的种类和结合荆对金刚石磨轮性能的影响。     

烧结磨轮用铜基钎料真空预钎焊金刚石的性能研究

采用铜锡钛(Cu-Sn-Ti)合金钎料并选用合适的隔离剂在加热温度930℃的工艺下对金刚石磨粒进行真空预钎焊处理,在烧结工艺条件下使用预钎焊磨粒制作预钎焊金刚石磨轮,并进行常规磨轮、预钎焊磨轮磨削对比试验。通过磨粒力学性能测试分析了预钎焊磨粒性能,借助扫描电镜分析了预钎焊磨粒的界面微结构。试验表明:选用D粉作隔离剂的铜基预钎焊金刚石磨粒表面生成了均匀的预钎焊金属层,隔离效果好,磨粒力学性能损失小;预钎焊磨粒与胎体之间界面处呈Ti元素偏聚富集,Fe、Cu等元素相互扩散状态,界面形成了化学冶金结合;预钎焊磨轮加工性能优于常规磨粒磨轮,铜基预钎焊磨轮锋利度高,综合加工性能最好。     

基于铝热反应的金属结合剂金刚石工具初探

文章探索了一种基于铝热反应的新型金属结合剂金刚石工具的制备方法,分析了铝热反应制备结合剂过程的反应合成机理,研究了热压烧结温度对铝热反应结合剂的相组成、微观结构、力学性能的影响。制备了铝热反应结合剂金刚石磨具,并测试了干、湿磨两种条件下磨削建筑陶瓷砖的加工性能。研究表明, Fe_2O_3-Al复合粉体在1028.8℃开始发生铝热反应,反应产物主要为Fe、Fe_3Al相以及少量Al_2O_3及FeAl_2O_4(铁铝尖晶石)相,随着热压烧结温度的升高, FeAl_2O_4含量有所增加,结合剂的硬度、致密度和抗弯强度都随之升高。初步测试显示铝热反应结合剂金刚石磨具可以对建筑陶瓷砖进行加工,但工具耐磨性还存在不足。     

陶瓷金刚石砂轮结合剂的探讨与研制

陶瓷结合剂金刚石砂轮具有加工效率高，耐用度高，易于修整等优点。本文探讨了陶瓷金刚石砂轮结合剂的原料、化学组成、制造方法及陶瓷金刚石砂轮的烧成条件。试验结果表明：不同的结合剂原料影响结合剂的耐火度及对金刚石磨料的把持力，在埋砂条件下，750℃烧成对金刚石的破坏很小，可以用高温冶炼法生产新型陶瓷结合剂。     

不同因素对金刚石柔性磨轮磨损的影响研究

金刚石柔性磨轮是金刚石砂带的一个衍生产品,主要用于宝石和玻璃加工。通过对金刚石柔性磨轮进行磨削实验,分析了法向压力、磨轮转速、磨料浓度、磨料粒度及加工方式对磨轮磨损的影响。结果表明:增加磨削过程中法向压力,磨轮磨粒脱落数目和磨耗比都逐渐增大;磨轮转速对磨粒脱落数目无明显影响,磨耗比逐渐增加;当磨料浓度增加到13%时,磨粒脱落数目仅增加2颗,磨削玻璃磨耗比达到最大为90;磨料粒度越粗,单位面积脱落的金刚石越少,磨耗比越大;磨轮树脂结合剂耐热性差,在磨削过程中应加水进行冷却。     

超硬磨料砂轮圆弧修整技术综述

超硬磨料砂轮以其优异的磨削性能获得业内普遍认可。但是,由于超硬磨料具有很高的硬度及耐磨性,使其砂轮修整极其困难。对于复杂形面砂轮修整,则更是难上加难。为此,选最简单形面-圆弧砂轮修整为研究对象,梳理了超硬磨料砂轮圆弧修整相关技术,分析了工作原理、修整特点及其应用状况。结果发现：基于金刚石的机械式修整仍是当下超硬磨料砂轮圆弧修整之主流;点轮摆动修整,适于疏松型结合剂砂轮修整;成型修整、插补修整,易损伤工具轮精度,主要用于砂轮精修整、点修整;展成法修整,主要用于精修整。普通磨料磨具,以其脆硬特性以柔克刚,主要用于密实型结合剂超硬磨料砂轮圆弧修整;往复+摆动复合修整,主要用于大圆弧修整;插补修整,用于小众砂轮圆弧修整;往复+插补复合修整,多用于小圆弧修整;电火花成型修整,适于导电性金属结合剂砂轮粗修整;激光修整,寿命超长,但修整技术尚存不足。集非接触与机械式协同之复合修整是工程界期待的超硬磨料砂轮圆弧理想修整方法,尚需深入研究。     

树脂金刚石砂轮内圆磨削硬质合金工件的试验研究

采用树脂结合剂金刚石砂轮,针对圆筒形硬质合金工件进行内圆磨削试验,研究不同修整工具和修整工艺对砂轮磨削性能的影响,同时对硬质合金磨削用砂轮类型和磨削参数进行了优选。试验结果表明:SiC砂轮及45#钢修整的树脂金刚石砂轮磨削效率和耐用度较高;2#锋利型砂轮在砂轮线速度17500r/min、工件转速280r/min、轴向进给速率1000mm/min和径向进刀量0.015mm的工艺条件下,试验砂轮的加工效率较高,加工工件的尺寸精度高且工件表面质量好。     

金刚石修整滚轮技术(上)

上世纪60年代,由于金刚石修整滚轮的出现,为磨加工业的高速、高效、高精度和降低制造成本提供了条件.随着各工业领域的技术进步,金刚石修整滚轮技术也相应获得了发展和完善.文章着重介绍了金刚石修整滚轮的制造和应用技术,并例举了国产人造金刚石修整滚轮在气轮发动机叶片之叶根榫槽加工中的应用实例.     

树脂结合剂金刚石砂轮设计及应用

树脂结合剂金刚石砂轮(resin bond diamond grinding wheel)由于具有自锐性好、胎体柔性和易于修整等特点而广泛用于各种难加工材料精密加工。文章主要就树脂结合剂金刚石砂轮的设计思路、性能影响因素以及加工应用进行简单综述,最后对提高我国树脂结合剂金刚石砂轮性能提出了几点建议。     

两种磨料柔性磨轮加工性能对比分析

通过对比试验,对金刚石磨料柔性磨轮和白刚玉磨料柔性磨轮在宝石加工中的加工效率、磨耗比及加工表面粗糙度等进行了对比分析,得出在宝石加工中金刚石磨料柔性磨轮的加工效率及寿命均高于白刚玉磨料柔性磨轮,同一粒度磨轮加工宝石表面粗糙度金刚石磨料柔性磨轮较低.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。