Ni-P/Si3N4复合镀层在醋酸溶液中腐蚀行为的研究

通过阳极极化曲线、交流阻抗谱和腐蚀失重实验研究了化学镀N i-P/S i3N4复合镀层在20%醋酸溶液中的腐蚀行为,并用SEM观察腐蚀前后镀层的形貌。实验结果表明:镀态N i-P/S i3N4复合镀层的耐蚀性能略高于N i-P合金;镀层中P质量分数升高,镀层的耐蚀性能增强;400℃热处理后复合镀层耐蚀性能明显降低。交流阻抗谱显示,N i-P/S i3N4镀层在醋酸溶液中的电极过程是受电荷转移和扩散步骤混合控制的。     

热处理对镍—磷化学镀层在饱和CO2盐水中腐蚀行为的影响

采用扫描电镜、能谱、X射线衍射、塔菲尔曲线和电化学阻抗谱,研究了热处理对P110钢上化学镀高磷镍-磷合金层在饱和CO,盐水溶液中腐蚀行为的影响.结果表明,热处理使镀层的表面形貌,成分和结构发生了显著变化,但对镀层在饱和CO2盐水中的腐蚀电位影响不大.经200℃热处理后,镀层的腐蚀电流略有下降,而后随热处理温度的升高,腐蚀电流迅速增大.镀态及经200 ℃热处理的镀层以均匀腐蚀为主;而经400 ℃和600 ℃热处理的镀层阻抗谱呈现2个时间常数,有坑蚀发生.     

镁合金化学镀Ni-P合金和脉冲电镀Zn-Ni合金组合镀层

在镁合金表面制备了化学镀镍-磷合金和脉冲电镀锌-镍合金组合镀层。采用扫描电镜、能谱仪考察了镁合金化学镀N i-P合金和电镀锌-镍合金组合镀层的形貌和成分。结果表明,组合镀层表面均匀、致密、无明显缺陷。采用电化学测试系统对组合镀层进行了动电位扫描极化曲线测试。研究了镀层腐蚀后的表面形貌和成分。结果表明,在腐蚀介质中,电镀锌-镍合金层首先发生腐蚀,之后发生化学镀镍层的腐蚀,电镀锌-镍合金层不仅对化学镀镍底层的腐蚀起到机械保护作用,还作为牺牲阳极起到电化学保护作用,因此延缓了腐蚀介质对镁合金基体的腐蚀。     

金刚石表面化学镀Ni-P

研究了金刚石表面化学镀N i-P,给出了化学镀镍溶液的配方及工艺流程。试验结果表明,金刚石经N i-P化学镀后,表面呈银白色,有金属光泽,镀层致密而且均匀,结合力好。未经热处理的金刚石表面N i-P镀层为非晶态;经热处理后,N i-P镀层的结构为晶体结构,镀层物相组成为N i3P和N i。     

木材单板表面化学镀镍

以杨木单板为原料,利用化学镀法在其表面镀覆N i-P合金镀层,以此来制备具有电磁屏蔽功能的木材-金属复合材料。用扫描电镜(SEM)、能谱分析仪(EDS)和X射线衍射仪(XRD)分析了镀层形貌、成分和镀层结构,研究了经表面化学镀N i-P合金后杨木单板的电磁屏蔽性能和表面导电性能。SEM分析表明,杨木单板经表面化学镀N i-P合金后,表面完全被镀层覆盖,金属感增强。EDS分析表明,镀层为N i-P合金镀层,其中磷含量较低,主要成分为镍。XRD分析结果表明,镀层为晶态结构。镀后杨木单板的表面电阻率很低,而电磁屏蔽效能较高,在9 kHz~1.5 GHz,可达到60 dB左右。     

镍基非晶合金镀层性能研究

采用化学镀及化学复合镀方法,得到了N i-P、N i-M o-P、(N i-M o-P)-A l2O3及(N i-M o-P)-PPS四种镀层;对各种镀层的形貌进行分析,并研究了随热处理温度升高各种镀层耐蚀性能的变化机理。结果表明:N i-M o-P基镀层的耐蚀性优于N i-P镀层;在85℃的10%H2SO4溶液中(N i-M o-P)-PPS镀层的腐蚀速率约是N i-M o-P镀层的1/3。     

电镀Ni-Sn镀层在人工汗液中的腐蚀行为

采用环保络合剂体系制备Ni-Sn合金镀层。通过Tafel曲线测试、交流阻抗测试、扫描电镜、X射线衍射研究了Ni-Sn合金在人工汗液中的腐蚀行为。结果表明,镀态镀层为Ni相晶态结构,Ni-Sn合金镀层的耐腐蚀性随镀层中Sn含量的增加先升高后下降,Sn含量为8.88%的镀层在人工汗液中的耐蚀性最佳。交流阻抗测试及浸泡挂片实验结果与Tafel曲线测试结果一致。热处理实验表明,镀层耐腐蚀性能随热处理温度的升高先提高后降低,200℃热处理后镀层耐腐蚀性能最好,热处理温度高于400℃后镀层开始有新相Ni_4Sn析出,镀层耐腐蚀性能随之降低。     

ZM5镁合金化学镀Ni-P合金镀层的电化学腐蚀行为

在ZM5镁合金表面制备了化学镀Ni-P合金镀层,并对其微观形貌、成分、相结构及电化学腐蚀行为进行了分析。结果表明:化学镀Ni-P合金镀层的厚度约为25μm,表面均匀、平整,内部致密无缺陷,与基体结合紧密,其结构为非晶态。与ZM5镁合金基体相比,化学镀Ni-P合金镀层的自腐蚀电位正移了1.171 V,自腐蚀电流密度减小了近3个数量级,表现出良好的耐蚀性。化学镀Ni-P合金镀层在阴极极化电位和自腐蚀电位下的阻抗谱均由两个容抗弧半圆组成,表现为均匀腐蚀。而阳极电位下化学镀Ni-P合金镀层的阻抗谱由容抗弧和Warburg阻抗组成,表现为局部腐蚀。化学镀Ni-P合金镀层在自腐蚀电位和阴极极化电位下工作能显著提高耐蚀性,并且在自腐蚀电位下的耐蚀性更好。而化学镀Ni-P合金镀层在阳极极化电位下的耐蚀性较差,不利于镀镍镁合金的长期使用。     

缓冲镍层对轧辊毛化铬镀层耐蚀性的影响

在轧辊用9Cr2Mo钢表面电沉积凸包状毛化铬层,并在毛化铬层与钢基体之间引入缓冲镍层。采用扫描电镜表征了镀铬钢和镀镍/铬钢表面镀层的表面形貌和截面形貌。通过电化学测量和中性盐雾(NSS)试验研究了缓冲镍层的引入对毛化铬镀层腐蚀行为的影响。结果表明,镀镍/铬钢的电化学腐蚀倾向更小。NSS试验后,镀铬钢表面有大量腐蚀产物堆积,其主要成分为FeO和少量铬的氧化物。铬镀层中贯穿性裂纹的存在使得腐蚀介质可以渗透其内部并侵蚀钢基体,产生的腐蚀产物可通过裂纹扩散至镀层表面。相对而言,镀镍/铬钢中生成的腐蚀产物较少,主要为铬的氧化物。由此可见,缓冲镍层的引入通过隔绝腐蚀介质通道,有效抑制了腐蚀产物的形成,进而改善凸包状毛化铬镀层的耐蚀性。     

ZrO2颗粒浓度对钕铁硼Ni-P/ZrO2复合镀层耐蚀性的影响

采用化学镀技术在钕铁硼表面制备出Ni-P/ZrO2复合镀层,并研究了ZrO2颗粒浓度对复合镀层中ZrO2颗粒含量、复合镀层的形貌、孔隙率和耐蚀性的影响.结果表明,ZrO2颗粒浓度在0.5～4.0 g/L范围内时,复合镀层的耐蚀性随着ZrO2颗粒浓度增加逐步改善,在不同腐蚀介质中的平均腐蚀速率都呈现减小的趋势,主要归因于复合镀层中ZrO2颗粒含量升高以及复合镀层表面趋于光滑平整,且孔隙率明显降低.但ZrO2颗粒浓度超过一定限度后,复合镀层中ZrO2颗粒含量下降,加之孔隙率升高和表面平整度有所下降,导致耐蚀性变差.ZrO2颗粒浓度为4.0 g/L制备的复合镀层具有良好的耐蚀性,但在不同腐蚀介质中其耐蚀性存在一定的差异.该复合镀层腐蚀前后的形貌差异不太明显,而钕铁硼腐蚀前后的形貌有明显的差异,表明该复合镀层在不同腐蚀介质中的耐蚀性明显好于钕铁硼.     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。