Cu包裹SiC复合粉体工艺的研究

选用工业生产的SiC粉,利用非均相沉淀法,将Cu均匀地包裹在SiC表面,得到了包裹均匀的Cu／SiC复合粉体。通过调节反应溶液的pH值控制SiC颗粒表面的zeta电位,解决包覆过程中颗粒团聚的问题。X射线衍射分析表明：经过包覆反应能够得到大部分包裹着Cu相的SiC颗粒。SEM形貌观察分析表明：SiC颗粒的大小、形状均对包覆效果有影响,小的SiC颗粒比大的包覆效果好,球形颗粒比其他形貌的包覆效果好。     

以铜锡合金为基质的金属陶瓷镀层形成条件及机理

采用循环上流法在焦磷酸盐镀液中可以电沉积Cu—Sn—Al_2O_3和Cu—Sn—SiC复合镀层。对这种镀层的形成条件进行了研究。通过添加剂、镀液的pH值、电流密度、温度、液流速度及镀液中陶瓷微粒的含量等因素对复合镀层中陶瓷微粒含量的影响,可以证实Cu—Sn—Al_2O_3和Cu—Sn—SiC镀层的形成是电化学机理。     

SiC粉体化学镀铜工艺研究

介绍了SiC粉体的敏化、活化及其碱性化学镀铜的工艺配方。分别对镀液稳定性的影响因素和各工艺条件对镀速的影响进行了研究。结果表明,SiC粉体颗粒越细、镀液pH增大、温度升高,都容易导致镀液分解;增加甲醛含量,可以提高镀速,但是镀液稳定性下降;适宜的络合剂,可以提高镀层质量,保持镀液稳定,但络合剂含量增加,镀速降低。得出了最佳的工艺条件：φ（甲醛）10～20mL／L,ρ（络合剂）50～70g/L,温度15～35℃,pH12．5～13。碱性化学镀铜后的SiC-Cu复合粉体及其于1050℃热处理后的X-射线衍射分析表明,镀层中含Cu、SiC和Cu2O,且Cu呈结晶态;铜镀层在高温下与SiC粉体能够较好共存,无脱落现象。扫描电镜照片显示,SiC-Cu复合粉体分散性良好,镀层表面平滑、均匀,并有细小的金属胞状颗粒随机堆积而成。     

两种Cu包裹SiC颗粒复合粉体工艺的研究

为改善SiC与金属的结合性，分别采用化学镀法和非均相沉淀法制备Cu包裹SiC颗粒复合粉体。通过XRD衍射分析得出以上两种包裹方法都可以得到大部分包裹着Cu相的SiC颗粒，同一组分比例下非均相沉淀法得到的Cu相对于化学镀法得到的Cu多，且非均相沉淀法同样得到相对较多的Cu2O。SEM形貌观察分析得出：化学镀法容易制备Cu包裹粒径较大碳化硅颗粒，非均相沉淀法容易制备Cu包裹粒径较大碳化硅颗粒，其大小、形状均对包覆效果有影响，小颗粒的碳化硅颗粒比大颗粒的包覆效果好，球形颗粒比其他形貌的颗粒包覆效果好。     

pH值对包覆改性SiC料浆分散特性和流变性的影响

通过zeta电位、沉降实验、流变特性、粘度等测试表征pH值对包覆改性SiC料浆分散特性和流变性的影响。研究表明:以偶联剂作为基础层,有机聚电解质作为分散功能层的有机包覆改性SiC粉体主要通过静电空间位阻效应实现稳定分散,调节pH值可以控制接枝聚合物水解产物的解离方式,从而改变了颗粒表面的电荷种类和电荷密度,包覆改性粉体的流动特性也发生变化。调整料浆pH值约11可制备出固相体积分数达56％、表观粘度为568 MPa·s的稳定料浆。     

表面处理对碳化硅浆料流变性的影响

本文通过对SiC粉体洗涤、表面氧化和聚乙二醇(PEG)包覆等处理后制得的SiC浆料的zeta电位和粘度的测试,研究了表面处理对SiC粉体流变性能的影响.研究表明:通过用酸碱洗涤过后再经过在780℃氧化处理或经PEG包覆所得的SiC粉体,都可以使其浆料的zeta电位的等电点向酸性方向偏移,从而使在pH值为11.8时的电位差大幅度增加,改善了浆料的流变性能.而且用PEG包覆过的SiC粉体浆料的电位差增幅达20左右,使其流变性改善的效果更佳.     

纳米碳化硅复合化学镀镍-磷合金工艺

以硫酸镍为主盐,次磷酸钠为还原剂,在铁基体上进行了化学镀Ni-P-纳米SiC.研究了镀液温度、pH及硫酸镍质量浓度对镀速的影响,得到较佳工艺条件如下:硫酸镍24～26 g/L,次磷酸钠20～35g/L,柠檬酸10～20 g/L,醋酸钠10～15 g/L,丁二酸钠2～4 g/L,纳米SiC粉体0.6g/L,pH 4.1～...     

电沉积制备太阳能电池吸收层铜锌锡硫薄膜

以硫酸铜、硫酸锌、硫酸亚锡、硫代硫酸钠、柠檬酸钠为电解质,采用电沉积法在FTO导电玻璃上制备Cu/Zn/Sn/S前驱物,热处理后获得铜锌锡硫(Cu_2ZnSnS_4,CZTS)薄膜。通过单因素试验优化了镀液组成、pH值、沉积电位、沉积时间,得到了最佳的CZTS薄膜,其结晶性好,禁带宽度为1.55eV。它与ZnO缓冲层组装太阳能电池,光电转换效率最高为1.5×10~(-2)%。     

化学复合镀PANI/Cu导电聚合物复合材料

采用化学复合镀技术在尼龙塑料PA66表面沉积PANI/Cu复合镀层。研究了复合镀层与基体的结合力和导电性，采用SEM观察镀层微观结构和表面形貌，并与纯铜、PANI镀层进行了比较；讨论了镀波pH值和温度等施镀工艺条件对镀层导电性能的影响。结果表明，PANI／Cu复合镀层具有良好的导电率且与基体结合紧密；增大镀液pH值和提高施镀温度，则其导电率增大。     

复合镀铜溶液中微粒与镀液间的相互作用

研究了复合镀铜溶液中SiO2、La2O3、BN以及SiC微粒与镀液间的相互作用。通过测定镀液的pH以及微粒表面的Zeta电位,研究了微粒对镀液中氢离子以及铜离子的吸附。结果表明,加入复合镀铜溶液中的SiO2、La2O3、BN以及SiC微粒不仅吸附了镀液中的氢离子,同时还吸附了镀液中的铜离子,致使镀液的pH上升,微粒表面荷正电。纳米粒子对镀液中荷电粒子的吸附能力较微米粒子更强。     

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.     

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.     

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.     

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.     

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.