MgO–Al_2O_3–ZrO_2复合粉对氧化锆质定径水口改性的作用

用溶胶–凝胶法制备的化学组成不同的MgO–Al_2O_3–ZrO2复合粉作为添加剂,制备改性氧化锆质定径水口,对其体积密度、显气孔率、热震稳定性、耐压强度、物相组成和显微结构进行表征。结果表明:加入MgO–Al_2O_3–ZrO_2复合粉后,随着MgO引入量的增加,改性定径水口的体积密度降低,气孔率上升,耐压强度呈先上升后略微下降趋势,热震之后的残余强度保持率显著升高;复合粉中MgO成分的引入,降低了镁铝尖晶石对原料中MgO稳定剂的消耗,减少了固溶于ZrO_2中MgO稳定剂的脱溶,保证了改性定径水口的稳定度;改性定径水口在烧结过程中生成了大小和分布都较均匀的镁铝尖晶石和收缩微孔,同时,形成的氧化锆晶粒尺寸均匀,结合强度较好,在保证抗侵蚀性和抗冲刷性的同时,可进一步提高样品的抗热震稳定性。MgO引入量为0.65%时,相变量较为合适,定径水口的综合性能最优;当没有引入MgO时,相变量过大,水口性能下降。     

氧化锆质定径水口在使用温度下矿物组成分析

为研究连铸用氧化锆质定径水口在使用温度下矿物组成和微观结构,对以氧化镁部分稳定氧化锆(Mg-PSZ)为原料制备的定径水口产品进行模拟实验研究.实验条件为:模拟浇钢使用条件试样在1540℃×5h后水淬冷却,模拟翻包后自然冷却条件试样在1540℃×5h后随炉冷却.借助X-ray荧光分析仪、X-ray衍射仪、扫描电子显微镜对试样的矿物组成及显微结构进行表征.研究结果表明:以Mg-PSZ制备的氧化锆质定径水口产品在1540℃浇钢温度下矿物相以立方相为主,在翻包自然冷却过程中,缓慢的冷却速率导致部分立方相转变为单斜相,矿物相以单斜相氧化锆为主.氧化锆质定径水口产品在高温使用环境中结构均匀,平均颗粒尺寸10 μm,而翻包自然冷却后,由于缓慢的冷却速率,定径水口产品中稳定剂脱溶,导致立方相转变为单斜相氧化锆,平均颗粒尺寸7 μm.即通过翻包自然冷却后所取试样的研究结果不能代表氧化锆质定径水口在中间包浇注过程中实际使用状态.     

添加Al2O3-ZrO2复合粉对氧化锆质定径水口性能的影响

以MgO、Y2O3复合稳定的部分稳定氧化锆(Mg,Y-PSZ)为主要原料,添加一定量采用溶胶-凝胶法制备的Al2O3-ZrO2复合粉,成型烘干后经1750℃×2h烧成制备定径水口.矿物组成、微观结构及微区成分分析显示,随复合粉加入量的增加,烧成制品中立方相ZrO2含量下降,单斜相含量相对增加;定径水口烧成后,复合粉中的氧化锆形成柱状增强结构,氧化铝与稳定剂MgO反应生成镁铝尖晶石.结果表明:选择合适的Al2O3-ZrO2复合粉添加量能提高制品的力学强度和断裂韧性,改善气孔结构并降低气孔率,从而使水口具有良好的抗侵蚀性和抗热震稳定性,在连铸现场试验取得了理想的使用效果.     

钇稳氧化锆的高温电性能

模拟氧化锆质定径水口基质组成和烧结稳定过程,以Y_2O_3为稳定剂,分别按照1.8%(质量分数)、3.6%和5.4%的掺杂量,与单斜氧化锆细粉混合后经1 710℃保温2 h烧成制备钇稳氧化锆试样。借助X射线衍射和扫描电子显微镜,研究了不同试样相组成和显微结构的差异。根据定径水口使用中杂质呈固相扩散的区域和温度范围,测定了不同试样室温到1 350℃的电导率。采用坩埚法测定了氧化锆材料的抗渣蚀性能。结果表明:随着稳定剂添加总量的增加,试样中立方相含量增加,单斜相含量明显减少。试样的电导率随稳定剂掺杂总量的增加呈上升趋势,且随着测试温度的升高而增大。由于相组成的变化,钇稳定氧化锆质材料在高低温区电导率存在显著差异。气孔的存在不仅降低了试样的电导率,也使其抗渣蚀性能减弱。     

金属铝对氧化锆制品的去稳定化行为

采用物质吉布斯自南能函数法对金属铝造成氧化锆制品的去稳定化行为进行了热力学分析,并结合扫描电子显微镜(SEM)进行了试验验证.结果表明:(1)含锆质制品中,金属铝易与氧化锆的稳定剂氧化钙发生反应,生成层片状六铝酸钙,造成氧化锆中稳定剂脱溶,体积失稳;(2)金属铝易与氧化锆的稳定剂氧化镁进行反应,生成正八面体的镁铝尖晶石,造成氧化锆中稳定剂脱溶,体积失稳;(3)金属铝对氧化锆制品的去稳定化行为,可界定为原始层、脱溶过渡层和反应层三层.     

长寿命定径水口的使用试验

定径水口是小方坯连铸用关键耐火材料之一,其品质的好坏直接影响连浇时间的长短.氧化锆定径水口抗冲刷、耐侵蚀、热震稳定性好,在我厂使用时其侵蚀速率为0.03～0.08 mm@H-1,年平均连浇时间达到了460min.1999年下半年,我厂方坯中间包开始采用镁质喷涂料取代硅质绝热板,中间包包衬的使用寿命明显提高,原有的普通氧化锆定径水口已不能满足使用要求.为此,研制开发了长寿命定径水口.     

氧化锆活性对烧结性能的影响

分别以化学法和电熔法制备的氧化锆及二者混合共磨粉为原料,通过造粒、成型、干燥、烧成制得样品,对烧成样品物理性能和微观结构进行分析,研究原料活性对烧结性能的影响.研究结果表明:在加入同样稳定剂的条件下,电熔氧化锆活性较差,烧结后气孔率较高,化学氧化锆烧结后收缩大,开裂严重,两者都无法满足作为制备氧化锆质定径水口基质原料要求,当二者的混合比例为1:1时,试样的烧结温度合适,气孔率、烧成收缩、耐压强度等各项理化指标较好,满足用作制备氧化锆质定径水口基质要求.     

国内外简讯

稳定化氧化锆的用途氧化锆是优秀的耐火材料、主要用于光学玻璃、陶瓷颜料等方面。近5—6年来,人们往氧化锆里添加百分之几乃至百分之十几的CaO,MgO,Y_2O_3等稳定剂,从而提高氧化锆耐高温性能、使之可以在高温状态下使用,象这样含有稳定剂的氧化锆称之为稳定化氧化锆。氧化锆的稳定化,就是将CaO等稳定剂与ZrO_2固熔,主要有电熔法,烧成法和共沉法。与前两种方法比较,固熔法得到的氧化锆在很低的温度下也稳定、稳定剂分布均匀、活性好,适于作结构材料。稳定化氧化锆的用途与其性质紧密相关。首先,它是很好的固体电解质,离子迁     

温度梯度对氧化锆质定径水口损毁的诱导作用

通过XRD和SEM对1300、1410和1540℃保温5 h热处理后氧化锆质定径水口的相组成和显微结构进行表征,研究温度梯度对水口损毁的影响.结果表明:定径水口原样分别在1300、1410和1540℃保温5 h后水淬冷却,试样中的c-ZrO2、m-ZrO2相含量和晶粒尺寸均发生了显著变化.随着热处理温度的提高,c-Zr...     

铝锆质定径水口性能研究

以溶胶凝胶法制备的氧化铝-氧化锆复合粉体为原料,制备定径水口试样,并对其各项性能进行检测,借助XRD、SEM对其矿物相组成和显微结构进行表征.结果表明:铝锆质定径水口烧成后,致密度高,氧化铝和氧化锆在晶界处结合良好,形成刚玉-斜锆石弥散状镶嵌结构,具备均匀的显微结构和优良的抗热震性能.     

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。