镁合金直接化学镀镍工艺及镀层性能

AZ31D镁合金上直接化学镀镍的较佳工艺条件为:硫酸镍14～22g/L,次磷酸钠20～28 g/L,柠檬酸5～7 g/L,乙酸钠9～17 g/L,氟化氢铵8 g/L,40%(体积分数)的氢氟酸12 mL/L,硫脲2 mg/L,pH(用氨水调节)6.2～6.4,温度75～85℃,时间10～60 min.在此条件下获得的化...     

AZ91D镁合金磷化工艺的研究

通过浸泡式磷化处理在AZ91D镁合金表面沉积一层致密、均匀、结合力好的磷化膜。采用单因素试验法,得到磷化液的最佳配方和工艺条件为:ZnO 2g/L,H_3PO_420g/L,NaF 1g/L,Na_2C_4H_4O_64g/L,NaNO_36g/L,柠檬酸0.25g/L,pH值3.0,磷化温度45℃,磷化时间20min。同时,确定添加剂为焦磷酸钠(TSPP),并且当其质量浓度为0.5g/L时,磷化膜的耐蚀性最好。     

稀土镧对化学镀镍-磷工艺及性能的影响

研究了稀土元素镧对Q235碳钢上化学镀Ni-P工艺及性能的影响.镀液配方及工艺条件为:硫酸镍25～30g/L,次磷酸钠25-30G/L,醋酸钠12～25g/L,柠檬酸5～10g/L,乳酸15～20g/L,丁二酸3 g/L,氧化镧10～20 mg/L,硫脲1～2 mg/L,氢化钠适量,温度84～88℃,pH 4.5～5....     

pH对化学复合镀镍–磷–聚四氟乙烯性能的影响

考察了pH对45钢上化学复合镀Ni–P–聚四氟乙烯(PTFE)沉积速率和镀层孔隙率、磷含量、表面形貌、耐蚀性、显微硬度和摩擦因数的影响。镀液组成和工艺条件为:NiSO_4·6H_2O 25 g/L,NaH_2PO_2·H_2O 30 g/L,无水乙酸钠20 g/L,柠檬酸20 g/L,硫脲2 mg/L,氟碳型表面活性剂18 mg/L,PTFE 1.0 g/L,温度85℃,时间1 h。pH为5.0时,沉积速率为15.93μm/h,所得为高磷(质量分数8.34%)复合镀层,其显微硬度为163.3 HV,摩擦因数0.25,能耐中性盐雾腐蚀24.5 h。     

电沉积方法制备镍硫析氢电极及其电化学性能

采用恒电流电沉积方法制备Ni-S电极,通过极化曲线研究了硫脲质量浓度、电流密度、镀液温度、电沉积时间等对Ni-S电极析氢性能的影响,获得了较佳的制备工艺:NiSO4·6H2O187.2g/L,硫脲100g/L,H3BO340g/L,NaCl 20g/L,pH=4,电流密度30 mA/cm2,镀液温度55℃和电沉积时间1...     

金黄色磷化膜常温制备与耐蚀性能研究

为提高磷化膜的装饰效果以满足特殊场合的需要,通过正交试验优化了一种能在常温下获得金黄色磷化膜的磷化液配方,用正交试验极差分析法、目测法和硫酸铜溶液点滴试验分别研究了溶液主要成分、pH、温度及磷化时间等因素对磷化膜外观和耐蚀性的影响。其磷化液组成为:3.0 g/LHO-R-COOH、3.5 g/L促进剂、3.0 g/LNa3PO4.12H2O、4.8 g/LZn2+、1.2 g/LMn(H2PO4)2.2H2O、13.6 mL/L H3PO4。最佳磷化工艺参数:θ=25~31℃,pH=2.34~2.84,t=15~20min。     

臭氧在铝材磷化中的应用研究

采用SEM、动电位极化曲线及磷化膜重等测试手段,确定了磷化液中各组分的配比及磷化工艺条件.D(臭氧)=(0.6～0.9)mg/L,磷化温度约40℃,pH值控制在3.5～3.7,磷化时间为5 min.在此条件下,加入复合促进剂,制得磷化膜重每平米可达4.92 g.在质量分数3%NaCl溶液中测定磷化膜的电极化曲线,腐蚀电流密度为2.9μA/cm2,说明磷化膜的耐腐蚀性能好.     

柠檬酸体系复合化学镀镍-磷-纳米二氧化钛稳定剂的研究

以镀液稳定性、纳米TiO_2在镀液中的分散性、沉积速率、镀层孔隙率和显微硬度为评价指标,研究了硫脲、碘酸钾以及苯并三氮唑对Ni-P-纳米TiO_2复合化学镀的影响。镀液配方和工艺为:NaH_2PO_2·H_2O 32g/L,NiSO_4·6H_2O26g/L,一水合柠檬酸20g/L,CH_3COONa·3H_2O 15 g/L,表面活性剂20~40 mg/L,纳米TiO_2 1~2 g/L,温度(88±1)℃,pH 4.8±0.2,时间1 h。结果表明:苯并三氮唑不适合作为本体系的稳定剂;硫脲作为稳定剂时的最佳用量为2.5~3.0 mg/L,碘酸钾作为稳定剂时的最佳用量为75~90 mg/L。     

钢铁高温锰系含钙磷化工艺

以极化曲线及交流阻抗为测试手段,通过控制单一变量的方法,分别研究了主盐、pH值、温度、时间及钙剂等对钢铁高温锰系含钙磷化膜耐蚀性的影响。确定最佳的磷化液配方及工艺条件为:磷酸140mL/L,硝酸10mL/L,碳酸锰90g/L,氢氧化钙10g/L,柠檬酸2g/L,pH值1.2,90℃,16min。氢氧化钙为适宜的钙剂,其最佳的质量浓度为10g/L。     

黄铜化学镀锡及其形貌变化过程的研究

讨论了黄铜化学镀锡工艺过程中氯化亚锡和次磷酸钠的质量浓度、pH值、温度以及时间对镀层沉积速率的影响,获得较好的工艺参数如下:氯化亚锡10 g/L,硫脲30 g/L,次磷酸钠5 g/L,pH值2,60℃,4 min,在此条件下获得纯锡镀层.简要分析了不同时间下黄铜表面形貌的变化情况及其原因.     

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.