连铸板坯凝固壳形貌测试及模拟

通过射钉法在铸坯横断面1/2,1/4,1/8三个位置测量170mm×1400 mm断面AH 36钢在1.25和1.35 m/min两个拉速下的连铸板坯凝固坯壳厚度,根据凝固定律,利用铸坯凝固坯壳厚度确定液相穴长度以及凝固终点.应用板坯连铸二次冷却仿真软件对其进行凝固过程模拟计算,得到凝固壳生长形貌,横向和纵向凝固壳厚度变化趋势,以及横向内弧表面温度.对比测量结果与模拟结果,验证在同一位置凝固壳厚度基本一致,铸坯最先凝固的位置为1/4处,凝固末端位于1/8处.对连铸板坯凝固壳形貌的研究为二冷制度的设计以及优化提供了有效依据.     

二次冷却和结晶器电磁搅拌对高碳钢中心缩孔的影响

通过对二次冷却配水和结晶器电磁搅拌(M-EMS)参数进行优化,解决方坯连铸浇注70#钢出现的较严重的中心缩孔问题.结果表明,二次冷却比水量为0.83 L/kg,结晶器电磁搅拌参数为电流强度200 A/频率4 Hz,并采用考虑过热度和冷却水温的二冷控制模型进行优化二次冷却配水,铸坯的缩孔等级可控制在1.0以下.     

连铸板坯二次冷却动态模型

将连铸二冷动态模型分成实时传热数学模型和动态喷水控制两部分进行描述.连铸二冷区每段传热系数与实际参数间的函数是在线模拟钢液凝固传热过程的关键,总结了几种常用的函数关系;对于动态喷水控制,也提出了几种可供选择的方法.最后对二次冷却动态模型的发展进行了阐述.     

电脉冲处理钢液改善铸坯凝固组织的工业化试验

在鞍钢工业生产中利用电脉冲孕育处理技术,开展了改善和细化连铸坯凝固组织的探索性工业化试验研究.对方坯和板坯的浇注过程进行电脉冲处理的结果表明,连铸坯的凝固组织明显细化,与未经电脉冲处理的连铸坯相比,连铸坯的柱状晶低倍形态由粗长的凝固组织变成细短的凝固组织,柱状晶的长度明显缩短,连铸坯的中心等轴晶区扩大,可减少连铸坯的内部质量缺陷.     

方坯结晶器角部弧形区热流密度测定

设计了方坯结晶器角部温度测定装置,测量了不同条件下结晶器壁的温度.结果表明,在连铸初始凝固区,随结晶器角部圆角半径的增大,热流密度减小;凝固后期,由于气隙的形成,圆角半径增大,热流密度增大;同一圆角半径处,结晶器对角线方向(45°方向)热流密度最大,22.5°方向稍小,偏离对角线较大的90°方向热流密度最小;随结晶器冷却水晕增大,同一位置处的热流密度也随之增大;适当增大圆角半径、结晶器实行弱冷,可以改善结晶器角部在高度方向和周向上的热流密度均匀性.     

连铸凝固过程热模拟实验方法及应用案例

凝固是制约冶金产品质量的重要环节,但因高温、不透明、大规模和连续化的生产特点,连铸生产条件下的凝固问题研究极为困难。目前的研究方法主要包括数值模拟、物理模拟和热模拟,其中热模拟方法因可以直接获取接近生产条件的实验数据而备受关注。本工作系统介绍了连铸凝固热模拟研究方法,简述了热模拟技术原理,并对结晶器热模拟方法及特征单元热模拟方法的原理和应用进行总结。其中,基于特征单元热相似性提出的连铸坯枝晶生长热模拟及凝固裂纹热模拟等方法成功地将十几吨铸坯的凝固过程“浓缩”到实验室用百克钢研究,不仅可以揭示钢液成分、浇注和冷却条件等因素对凝固过程、组织和元素分布的影响规律,而且还可以获得铸坯固液界面形貌、界面前沿溶质扩散和夹杂物演变、凝固裂纹形成的可能性及条件等其他手段无法得到而冶金界非常关注的问题。要点：(1)概述了连铸凝固过程研究方法。(2)重点介绍了连铸凝固过程热模拟方法的分类、原理和应用。(3)总结展望了连铸热模拟研究方法的研究方向。     

方坯连铸机定尺切割控制系统的设计与应用

介绍连铸方坯定尺切割控制系统的设计与应用。描述了系统硬件配置、工艺流程,分析辊道测长定尺控制的优势以及实现方法,采用火切机控制技术,满足了铸坯自动定尺的需要。     

基于交替方向隐式差分算法的连铸坯凝固传热模型

针对连铸板坯的凝固传热问题,考虑板坯形状规则的特点,基于交替方向隐式差分算法建立沿连铸板坯宽度和厚度方向的二维凝固传热模型.该模型可以模拟铸坯液相区和两相区的变化、铸坯坯壳厚度变化及铸坯凝固末端的位置等参量,可实现对铸坯温度场分布特征的计算跟踪.以某炼钢厂立弯式板坯连铸机为研究对象进行工业测试,铸坯断面尺寸为1082 mm×200 mm,铸机拉速为1.3 m/mm,钢种为Stb32z条件下的模拟计算和实测结果表明,凝固传热模型的计算效率可以满足生产要求,计算结果符合凝固规律,计算温度与便携式红外测温仪的实测温度误差为1.4%.     

薄板坯连铸结晶器内钢液流动与传热及凝固耦合的数值模拟

针对断面为135 mm×1200 mm的薄板坯连铸结晶器,建立了4孔浸入式水口下薄板坯连铸结晶器内钢液流动、传热和凝固耦合的三维数学模型,引入F数评价薄板坯连铸结晶器内液面波动情况,分析结晶器内钢液流动、温度分布及凝固坯壳厚度的变化情况. 结果表明,用F数评价薄板坯连铸结晶器内液面波动可行,拉速由1.44 m/min增加到1.80 m/min时,钢液液面波动的F数由1.05增加到2.55,凝固壳厚度(dshell)与凝固时间(t)满足关系式dshell=18.92t1/2?1.05,模拟结果与文献实验结果基本一致.     

方坯连铸高效化二冷技术

建立了方坯高效连铸二冷数学模型,提出了喷嘴有效喷淋系数和二冷有效比水量的概念.依据二冷均匀冷却的思想,重新设计并优化了二冷喷淋结构和喷嘴的布置,增加了一个二冷喷淋段.提出了新的二冷水模型,即Qi=a bv cv2=d(△T-30) F;二冷各段的喷水量与拉速、浇铸温度、钢水成分和二冷水温相关.实践证明,经优化后的二冷结构和二冷水模型合理,拉速大幅度提高,150×150 mm2断面的最高拉速达3.8～4.0 m/min;铸坯质量明显改善,产量显著提高,经济效益显著.     

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。