Al_2O_3/Cu_(70)Ti_(25)Zr_5/Nb界面结构及强度

本研究选用Cu70 Ti2 5 Zr5 活性钎料钎焊Al2 O3/Nb .通过对Al2 O3/Cu70 Ti2 5 Zr5 /Nb界面结构及接头性能研究 ,旨在进一步揭示Al2 O3/含Ti活性钎料间界面反应机制 ,并为指导工程应用提供最佳工艺参数 .借助扫描电镜、能谱、X射线衍射探讨了Al2 O3/Cu70 Ti2 5 Zr5 /Nb钎焊接头界面结构 ,并采用拉剪试验评价了接头强度 .研究结果表明 ,时间 0 .6ks ,温度小于 12 2 3K ,界面产生了 3种新相 :Cu2 Ti4O ,Ti0 .5 Zr0 .5 O0 .1 9,CuTi,界面结构为Al2 O3/Cu2 Ti4O +Ti0 .5 Zr0 .5 O0 .1 9/CuTi/Cu固溶体 +CuTi;温度大于 12 93K ,界面产生了Cu2 Ti4O ,Ti,CuTi 3种新相 ,界面结构为Al2 O3/Cu2 Ti4O/Ti固溶体 /CuTi/Cu固溶体 +CuTi.在 12 93K ,0 .6ks条件下 ,接头剪切强度最高达到 162MPa ,温度大于或小于12 93K ,强度下降     

原位合成Al6．1 Cu1．2 Ti2．7／Al2O3／TiAl复合材料及热力学分析

采用真空热压烧结方法在Ti—Al—CuO体系下原位合成了Al6.1 Cu1.2 Ti2、Al2O3物相共同增强的TiAl基复合材料。通过DSC,XRD以及相关热力学计算研究了热压反应过程。结果表明：Al在高温熔化后对Ti、CuO颗粒润湿并发生反应,Ti颗粒表层形成中间产物TiaAly,在富Ti区生成稳定TiAl相;CuO颗粒表层由于Al-CuO置换反应的发生,生成稳定的Al2O3相和活度较高的Cu单质,一定条件下TiaAly与Cu反应形成Al6.1Cu1.2Ti2.7三元相。     

Al2O3/Cu70Ti25Zr5/Nb界面结构及强度

本研究选用Cu70Ti25Zr5活性钎料钎焊Al2O3/Nb,通过对Al2O3/Cu70Ti25Zr5/Nb界面结构及接头性能研究,旨在进一步揭示Al2O3/含Ti活性钎料间界面反应机制,并为指导工程应用提供最佳工艺参数。借助扫描电镜,能谱,X射线衍射探讨了Al2O3/Cu70Ti25Zr5/Nb钎焊接头界面结构,并采用拉剪试验评价了接头强度,研究结果表明,时间0.6ks,温度小于1223K,界面产生了3种新相：Cu2Ti4O,Ti0.5Zr0.5O0.19,CuTi,界面结构为Al2O3/Cu2Ti4O Ti0.5Zr0.5O0.19/CuTi/Cu固溶体＋CuTi,温度大于1293K,界面产生了Cu2Ti4O,Ti,CuTi3种新相,界面结构为Al2O3/Cu2Ti4O/Ti固溶体／CuTi/Cu固溶体＋CuTi,在1293K,0.6ks条件下,接头剪切强度最高达到162MPa,温度大于或小于1293K,强度下降。     

放电等离子烧结制备Ti/Al2O3复合材料

Ti基金属复合材料是一种新型高温结构材料.本文利用放电等离子烧结技术,在温度1250℃、压力30MPa、真空度6Pa,保温时间10min条件下,制备了相对致密度较高的Ti/Al2O3复合材料.借助XRD,SEM,EDS等测试手段对该复合材料的物相组成、界面反应、微观结构以及致密度进行了观察与分析.结果表明:利用SPS技术制备Ti/Al2O3的复合材料,晶粒细小且分布均匀,结构致密、2相之间结合状态良好,相对致密度随材料中陶瓷相含量的增多而有所降低.Ti,Al2O32相之间无明显界面化学反应发生.     

ZrSiO4-Al2O3系材料高温反应的研究

借助X衍射仪(XRD)和具有能谱仪(EDAX)的扫描电镜,研究了粉状ZrSiO4和a-Al2O3间生成化学计量成分3Al2O3·2Si02的固态反应.在1 400～1600℃温度区间和0.5～60h的时间内获取了试验数据.结果表明,ZrSiO4和-Al2O3反应形成晶体ZrO2和莫来石(基本为3Al2O3·2SiO2成分)及SiO2-Al2O3非晶相(前驱莫来石).在1 600℃时,反应最快的阶段是ZrSiO4的分解.试验结果表明错英石的分解是一级反应.Al2O3颗粒的溶解和Al扩散到非晶相可能是反应最慢阶段.     

浸入式水口复合内衬与钢水中Al_2O_3的反应

采用以AG（Al2O3-C）材料为主体,用ZCGS（ZrO2-CaO-C-SiO2）材质为内衬制成复合式连铸浸入式水口。ZCGS质内衬与钢液接触时,材料中的SiO2可促进CaZrO3分解生成CaO,形成CaO的扩散通道,加速CaO与钢液中的脱氧产物Al2O3反应生成低熔物相,从而起到防止Al2O3附着堵塞水口的作用。     

Si3N4/Al反应烧结制备AlN/Al复合材料

研究了采用Si3N4与Al的混合粉,经压制、烧结制备AlN/Al-Si复合材料的技术方法.试验结果表明:AlN的反应生成机制属于一种连续渐进式反应形成过程,即于高温下液相Al中的Al原子渗入Si3N4的晶体点阵取代Si原子而逐渐使之向AlN晶体点阵转化的过程.被取代的Si原子从固相Si3N4中析出,扩散溶入液相Al中,冷却后形成Al-Si合金固溶体,一般呈网状分布于AlN晶体相的周围.新生成的AlN与Al-Si合金相之间表现出很好的界面亲和性.     

Mo/Al2O3材料的微观结构和抗腐蚀性

无压烧结制备了不同体积比的Mo/Al2O3复相材料,对Mo/Al2O3复相材料进行了微观分析和抗酸腐蚀研究.经1 440 ℃烧结,含60%(体积分数,下同)Mo的Mo/Al2O3材料中,Al2O3分布不均匀,而含40%Mo的Mo/Al2O3材料中Mo的分布不均匀.电子探针成分分析发现:Mo和Al2O3之间无明显的相扩散.酸液腐蚀试验表明:Mo/Al2O3复相材料具有抗盐酸、硫酸和氢氟酸腐蚀的能力,其中抗盐酸腐蚀的效果最好;Mo/Al2O3复相材料不抗硝酸的腐蚀,腐蚀首先发生在Mo和Al2O3的界面上.     

Si_3N_4/Fe,Si_3N_4/Fe_3Al界面的固相反应(英文)

用扫描电子显微镜、电子能谱仪、X射线衍射等研究了在Ar气氛中,经1150℃,10h等温热处理后,Si3N4/Fe,Si3N4/Fe3Al平而偶界面固相反应区的形貌、成分分布、显微结构及相组成.结果表明:Si3N4/Fe界面固相反应形成约120μn厚的反应区,Fe含量从Si3N4侧到Fe侧逐渐增加,反应区中的Si成分约为5%(原子分数),反应区主要由Fe(Si)固溶体构成,其中均匀地分御着细小的孔洞:Si3NdFe3Al界面固相反应形成约3μm厚的反应区,反应区具有比Fe3Al高得多的Al含量,反应区由FeAl,Fc(Al,Si)固溶体及三元化合物AlgFeSi3构成.Si3NdFe3Al具有比Si3N4/Fe高得多的 界面化学相容性.     

工艺调控对原位合成Ti3AlC2陶瓷的影响

以TiC、Ti和Al粉为原材料,采用冷压预成型-热压辅助工艺原位制备Ti3 AlC2陶瓷.借助反应吉布斯自由能分析TiC-Ti-Al体系的合成机制,采用XRD和SEM分析工艺因素如升温速率、Al含量、烧结温度和压坯尺寸对原位合成Ti3 AlC2陶瓷的影响.结果表明,通过调控工艺,成功合成了高纯度Ti3 AlC2陶瓷,Ti3 AlC2具有典型的层状结构.该反应体系的最佳升温速率为:1000℃之前,20℃/min; 1000℃之后,10℃/min.用纳米TiC粉替代微米TiC粉,烧结温度由1450℃降至1350℃,且Ti3 AlC2的合成纯度更高.当采用大尺寸压坯时,发生了“热爆”现象,非平衡相较多,Ti3 AlC2的生成含量较低,且样品开裂严重.Ti3 AlC2的合成过程为:Ti与Al反应生成TiAl金属间化合物,接着TiAl与TiC反应生成Ti3AlC2.     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008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、不饱和聚酯树脂、环氧树脂)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.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006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生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。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（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。