金刚石工具用Ni-Co合金粉末的制备及表征

在金刚石工具领域,纯钴基以及钴基金刚石工具具有优良的使用性能,但钴价格很高,使纯钴基以及钴基金刚石工具的使用受到了限制,所以代钴研究具有重大的实际意义.镍和钴同属于过渡族元素,两者物理和化学性质非常接近,故镍代钴有一定的可行性.采用草酸盐共沉淀法得到前驱体,然后将前驱体煅烧还原的工艺制得Ni-Co预合金粉末;对前驱体进行了X射线、热(差热和热重)分析,结果表明,通过共沉淀法得到的前驱体是固溶体;对预合金粉末进行了性能表征,所制得的Ni-Co预合金粉末氧含量低,形貌近似球形,粒度均匀;通过共沉淀反应前的成分设计,可制备出成分含量连续变化的预合金粉末;通过改变制备工艺参数,可制取不同粒径的粉末.本实验的粉末成分设计是70Ni-30Co(wt%).     

50Mn2V金刚石锯片激光焊接过渡层粉末的研制(下)

介绍了自主研发的A激光焊接过渡层粉末的设计性能指标、制备方法和基本参数,测试了A粉末烧结试样块的机械性能,检测了A过渡层、国外某公司过渡层与50M n2V钢基体的激光焊接强度。焊接强度测试结果表明:在780℃~880℃常用烧结温度范围内,A过渡层可以与不同的工作层配合使用,比国外某公司过渡层具有更高的安全性和稳定性,焊接强度达到并超过BS En13236:2001安全标准。A激光焊接过渡层粉末可以替代国外进口的激光焊接过渡层粉末。     

50Mn2V金刚石锯片激光焊接过渡层粉末的研制(上)

介绍了自主研发的A激光焊接过渡层粉末的设计性能指标、制备方法和基本参数,测试了A粉末烧结试样块的机械性能,检测了A过渡层、国外某公司过渡层与50M n2V钢基体的激光焊接强度。焊接强度测试结果表明:在780℃~880℃常用烧结温度范围内,A过渡层可以与不同的工作层配合使用,比国外某公司过渡层具有更高的安全性和稳定性,焊接强度达到并超过BS En13236:2001安全标准。A激光焊接过渡层粉末可以替代国外进口的激光焊接过渡层粉末。     

技术创新在金刚石制品业中的重大作用(上)

通过对国内外近两年来金刚石工具工业技术创新的发展与作用的考察与分析，作者认为必须重视金刚石的镀覆和预合金粉末的应用，容积式冷压机与各种烧结工艺与设备的开发，加快激光焊接锯片，金刚石绳锯与金刚石表面金属化及单层金刚石高温钎焊的开发与应用，重视半导体工业中金刚石工具的应用，特别是CMP的研制与生产。     

技术创新在金刚石制品业中的重大作用(下)

通过对国内外近两年来金刚石工具工业技术创新的发展与作用的考察与分析．作者认为必须重视金刚石的镀覆和预合金粉末的应用、容积式冷压机与各种烧结工艺与设备的开发．加快激光焊接锯片，金刚石绳锯与金刚石表面金属化及单层金刚石高温钎焊的开发与应用．重视半导体工业中金刚石工具的应用，特别是CMP的研制与生产。     

不断完善预合金粉末的性能,满足金刚石工具的应用(上)

随着预合金粉末在金刚石工具中使用量的增加,使用范围的不断扩大,不断完善预合金粉末的性能,进一步满足金刚石工具应用的需求,具有重大作用与意义。在预合金粉末生产方法中:湿法冶金方法生产的预合金粉,广泛并成功地应用在国外,但成本高,在国内市场应用较少。机械合金化方法多用于科研中,批量生产能耗大。在国内主要采用气雾化、水雾化、多金属化学共沉积法等生产预合金粉末。文章探讨了氧含量对金刚石工具性能的影响;介绍了国内不同生产设备条件下的还原工艺,进一步提出不断完善预合金粉性能的各种途径,以满足金刚石工具应用的需求。     

国外超硬材料工具的最新应用与进展（下）

为促进我国超硬材料工具的发展,对国外超硬材料工具的最新应用与发展进行了调查与分析,其中包括:金刚石与刀具的镀覆与应用,代钴预合金粉末的研制,金刚石均匀有序排列在刀头中的应用与进展,板条式CO2激光器激光焊接金刚石工具的快速发展,金刚石绳锯的创新与应用,金刚石与cBN单层钎焊在切削与磨削中的应用,环保型精密自动控制电镀工艺与装备的发展,以及金刚石工具在半导体工业中的应用.     

国外超硬材料工具的最新应用与进展（上）

为促进我国超硬材料工具的发展,对国外超硬材料工具的最新应用与发展进行了调查与分析,其中包括:金刚石与刀具的镀覆与应用,代钴预合金粉末的研制,金刚石均匀有序排列在刀头中的应用与进展,板条式CO2激光器激光焊接金刚石工具的快速发展,金刚石绳锯的创新与应用,金刚石与cBN单层钎焊在切削与磨削中的应用,环保型精密自动控制电镀工艺与装备的发展,以及金刚石工具在半导体工业中的应用.     

激光焊接金刚石工具过渡层配方设计初步研究

采用预合金焊接层粉NEXT300替代工作层粉A中难烧结成分的方式设计过渡层粉G1~G4,以预合金焊接层粉NEXT300、单质Cu粉及预合金粉B混合的方式设计过渡层粉G5、G6,通过分层试样抗弯强度试验进行层间结合影响因素研究。试验结果表明:工作层强度与整体分层结构设计对于整体强度起决定性作用,过渡层仅起辅助改善作用。     

反应温度对超细铜基前驱体的影响

采用共沉淀法在不同反应温度下,制备了超细铜基前驱体粉末,使用XRD、SEM和激光粒度分析仪对超细预合金粉末进行了表征。结果表明:当反应温度为50℃时,制备的前驱体粉末粒度最细且尺寸均匀,在3~5μm左右。     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.