Ni-纳米WC复合镀层结构与性能研究

通过恒流电沉积制备Ni镀层和Ni-纳米WC复合镀层,利用扫描电镜和X射线衍射仪,并通过浸泡腐蚀实验和高温氧化实验,研究纳米WC颗粒对Ni镀层的微观形貌、物相结构、耐蚀性能和抗高温氧化性能的影响。结果表明,纳米WC颗粒使Ni镀层表面平整性明显改善,组织结构趋于完整且致密,镀层的耐蚀性能和抗高温氧化性能得到了提高;与Ni镀层相比,Ni-纳米WC复合镀层表面平整、结构致密,同等条件下的腐蚀速率和氧化增量均较低,表现出良好的耐蚀性能和抗高温氧化性能。     

电化学沉积法制备Cu-纳米SiO_2复合镀层及其性能的研究

利用电化学沉积法制备以纳米SiO_2微粒为增强相的Cu-纳米SiO_2复合镀层。研究发现:Cu-纳米SiO_2复合镀层的形貌特征不同于纯铜镀层的,其性能较好。增强相纳米SiO_2微粒引起形核增殖、结晶细化,同时形成弥散强化,致使Cu-纳米SiO_2复合镀层的形貌特征不同,性能得以改善。随着镀液中纳米SiO_2微粒的质量浓度的增加,Cu-纳米SiO_2复合镀层的显微硬度先升高后降低,体积磨损率先减小后增大。当镀液中纳米SiO_2微粒的质量浓度为35g/L时,Cu-纳米SiO_2复合镀层的显微硬度最高,接近1 500 MPa,约为纯铜镀层的1.46倍;体积磨损率最低,为6.59×10-5 mm3/(N·m),比纯铜镀层的降低约35.4%。     

新型抗菌Ni-PTFE纳米复合镀层的制备

为提高单金属镍镀层材料的抗菌性能,采用电镀镍工艺添加抗菌性能优越的聚四氟乙烯(PTFE)纳米颗粒,制备Ni-PTFE纳米复合镀层。通过考察纳米复合镀层的接触角和表面能,考察了纳米复合材料的抗菌性能。结果表明:纳米复合镀层中镍与PTFE纳米颗粒结合紧密,形成均匀,致密的表观形貌;PTFE纳米颗粒的加入大幅度地提高了镍镀层的抗菌性能。     

(Zn-Co)-TiO_2纳米复合镀层的制备及耐蚀性能的研究

利用纳米复合电沉积方法在低碳钢基体上制备了(Zn-Co)-TiO2纳米复合镀层。分析了镀液中纳米TiO2含量、表面活性剂十六烷基三甲基溴化铵质量浓度、电流密度以及温度对镀层中Co、纳米TiO2含量的影响,得出制备(Zn-Co)-TiO2纳米复合镀层的最优工艺条件:60g/L纳米TiO2、1.0 g/L表面活性剂十六烷基三甲基溴化铵、Jκ为4A/dm2、θ为55~60℃。通过扫描电镜、极化曲线对镀层的形貌特征及耐蚀性能进行了分析。结果表明,纳米复合镀层表面完整,没有明显的缺陷;TiO2均匀地分布在Zn-Co合金镀层中,进一步提高了镀层的耐蚀性能。     

基于纳米二氧化硅的防冰疏水涂层的制备及性能研究

采用HTPS(端羟基聚二甲基硅氧烷)和APTES(氨基丙基三乙氧基硅烷)改性纳米SiO_2,并制备了改性纳米SiO_2/氟硅树脂-环氧树脂(M-SR)复合涂料。采用傅里叶变换红外光谱仪和扫描电镜对改性前后纳米SiO_2颗粒,以及M-SR复合涂料的结构和表面微观形貌进行了表征,并通过水接触角、水滴结冰时间和覆冰层的剪切附着强度评估了M-SR复合涂层的防覆冰效果。结果表明,经过HTPS和APTES改性后,纳米SiO_2颗粒表面的亲水基团被HTPS和APTES中低表面能的甲基取代,纳米SiO_2表面能更小,疏水性能更佳。随着改性纳米SiO_2颗粒含量的增加,M-SR复合涂层的疏水性增强,纳米SiO_2颗粒含量为50%的M-SR复合涂层综合性能最优,水接触角168.1°,水滴结冰时间279 s,覆冰剪切粘附强度小于5 kPa,是较为理想的防覆冰材料。     

汽车用AZ91D镁合金表面Ni-SiO_2纳米复合镀层的制备与研究

为改善和提高汽车支架类零件常用的AZ91D镁合金表面耐蚀性能,采用两步法在其表面电沉积Ni-SiO_2复合镀层。设计了正交试验,以SiO_2质量分数和表面粗糙度作为评价指标,运用正交试验法确定了施镀工艺参数的影响主次顺序,并得到最优施镀工艺参数为:镀液中SiO_2颗粒质量浓度20 g/L、电流密度8 A/dm~2、超声波功率300 W、镀液温度55℃。结果表明:采用最优施镀工艺制备出Ni-SiO_2纳米复合镀层,其表面平整、致密,腐蚀均匀,腐蚀速率为65 g/(m~2·d),明显低于镁合金基体的96 g/(m~2·d)。Ni-SiO_2纳米复合镀层能够提供有效的表面防护,改善和提高镁合金耐蚀性能。     

镁合金表面羟基磷灰石/介孔SiO_2自修复耐蚀涂层的研究

通过旋涂法,在AZ31镁合金表面制备了聚多巴胺/羟基磷灰石复合涂层,并将负载有缓蚀剂2-巯基苯并咪唑(MBI)的介孔SiO_2纳米颗粒掺杂到复合涂层中,以改善镁合金的耐腐蚀性能。使用SEM、TEM、XRD和BET等手段表征介孔SiO_2纳米颗粒的形貌、结构及缓蚀剂的负载情况;通过傅里叶红外光谱(FTIR)和扫描电子显微镜(SEM)对涂层的成分和形貌进行表征;使用电化学阻抗谱(EIS)研究了不同涂层的耐蚀性能和自修复性能。结果表明,制备的二氧化硅为介孔纳米颗粒,可负载缓蚀剂。将负载有缓蚀剂MBI的介孔SiO_2纳米颗粒掺杂到聚多巴胺/羟基磷灰石复合涂层中,能够改善涂层的耐蚀性能,使涂层具有自修复性能。     

镁合金表面羟基磷灰石/介孔SiO_2自修复耐蚀涂层的研究

通过旋涂法,在AZ31镁合金表面制备了聚多巴胺/羟基磷灰石复合涂层,并将负载有缓蚀剂2-巯基苯并咪唑(MBI)的介孔SiO_2纳米颗粒掺杂到复合涂层中,以改善镁合金的耐腐蚀性能。使用SEM、TEM、XRD和BET等手段表征介孔SiO_2纳米颗粒的形貌、结构及缓蚀剂的负载情况;通过傅里叶红外光谱(FTIR)和扫描电子显微镜(SEM)对涂层的成分和形貌进行表征;使用电化学阻抗谱(EIS)研究了不同涂层的耐蚀性能和自修复性能。结果表明,制备的二氧化硅为介孔纳米颗粒,可负载缓蚀剂。将负载有缓蚀剂MBI的介孔SiO_2纳米颗粒掺杂到聚多巴胺/羟基磷灰石复合涂层中,能够改善涂层的耐蚀性能,使涂层具有自修复性能。     

Ni-AlN纳米复合镀层的制备及耐蚀性能研究

采用电沉积的方法在低碳钢表面成功制备了Ni-AlN纳米复合镀层,通过称量法计算出沉积速率,采用X-射线衍射、扫描电镜和电化学测量技术探究了镀液中不同AlN浓度对镀层的组织结构、微观形貌和耐蚀性能的影响。结果表明,在电沉积过程中,沉积速率随镀液中AlN浓度的增大呈先增大后减小的趋势;镀液中AlN的加入,使镀层表面产生了米粒状的多晶单元,提高了镀层的耐蚀性能,随着镀液中AlN浓度的增加耐蚀性能先提高后降低。当镀液中纳米AlN质量浓度为1 g/L时,复合镀层中的AlN质量分数约为4.5%,表面致密性最好,与纯Ni镀层相比,腐蚀电流密度降低了2个数量级,耐蚀性能最佳。     

纳米SiO_2微粒对Ni-P-纳米SiO_2复合镀层组织和性能的影响

采用化学镀方法在Q235钢表面制备了Ni-P-纳米SiO_2复合镀层,并研究了纳米SiO_2微粒的质量浓度对Ni-P-纳米SiO_2复合镀层组织和性能的影响。结果表明:在0~4.0g/L范围内,随着纳米SiO_2微粒的质量浓度的增加,Ni-P-纳米SiO_2复合镀层表面胞状结构的尺寸逐渐减小,镀层更加致密,硬度逐渐提高。在10%的H2SO4溶液和10%的NaCl溶液中腐蚀后,Ni-P-纳米SiO_2复合镀层的腐蚀速率比Ni-P合金镀层的腐蚀速率低,耐蚀性更好。     

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.     

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.