SiC结合刚玉材料的抗高炉渣侵蚀性

采用电熔刚玉、Si粉和SiC粉为原料,用酚醛树脂做结合剂,混练成型后于1 450℃埋炭烧成,采用静态坩埚抗渣试验研究了烧后试样对碱度为1.1的高炉渣在1 500℃的抗渣侵蚀性。结果表明:Si与C、CO在高温下原位反应生成纤维状SiC,形成原位SiC结合刚玉材料,该材料具有良好的抗侵蚀性能,渣蚀厚度都在2.6mm以下,其中,加入8%(w)Si粉和5%(w)SiC粉的试样抗渣侵蚀性最好。通过对抗侵蚀后试样的侵蚀层、渗透层和未变层的相组成和显微结构的分析认为:(1)这种复合材料抗渣侵蚀性能良好的主要原因是熔渣难润湿的SiC自身抗渣侵蚀性较好,且原位生成的纤维状SiC穿插在刚玉骨架结构的空隙中,阻挡了熔渣的侵蚀和渗透;(2)熔渣侵蚀材料的过程是SiC先被氧化,然后其氧化产物SiO2与熔渣中的CaO和SiO2以及材料基质中的A l2O3反应生成钙长石低熔相。     

SiC加入量对MgO-MgAl2O4-SiC材料性能的影响

以电熔镁砂颗粒(3~1 mm,≤1 mm)、电熔镁砂粉、镁铝尖晶石粉和SiC粉为原料,研究了SiC加入量(w)分别为5%、10%、15%、20%时对MgO-MgAl2O4材料经1 100℃和1 500℃保温3 h后的物理性能、抗氧化性能以及1 600℃保温3 h后的抗渣性能的影响。结果表明:加入SiC有利于提高材料的烧后强度。材料经1 100℃处理后,SiC几乎完全氧化;1 500℃烧后表明,当SiC加入量不超过10%时,抗氧化性能随着SiC加入量增加而增强;超过10%时,反而降低;1 600℃烧后表明,随着SiC加入量的增加,试样抗渣性能有所下降。对1 500℃烧后试样进行XRD和SEM分析发现,在试样氧化层中生成大量的镁橄榄石。     

尖晶石对Al2O3-SiC-C质铁沟浇注料性能的影响

以新型亚白刚玉(8~5 mm、5~3 mm、3~1 mm、≤1 mm、≤0.044 mm)、SiC(≤1 mm、≤0.088 mm)、尖晶石粉(≤0.044 mm)、SiO2微粉、α-Al2O3微粉、铝酸钙水泥、Si粉和球状沥青等为主要原料,在Al2O3-SiC-C质铁沟浇注料的配料组成中分别加入质量分数为0、4%、7%、10%、13%的镁铝尖晶石粉,混练均匀后振动成型为40 mm×40 mm×160 mm的条状试样和50/20 mm×50/20mm的坩埚试样,经110℃24 h和1 450℃3 h热处理后测定试样的体积密度、显气孔率、常温抗折强度、常温耐压强度、烧后线变化率和抗渣性能,并且进行了XRD、SEM和EDS分析。结果表明:加入适量镁铝尖晶石粉后,由于改善了试样的成型密度,促进了试样的烧结,因而提高了试样的密度、强度、体积稳定性和抗渣性;但是,由于尖晶石和刚玉的热膨胀系数不同,加入过多的镁铝尖晶石粉会导致试样中产生过多的微裂纹,从而对试样的密度、强度、体积稳定性和抗渣性不利;本试验中,尖晶石粉的最佳加入量(质量分数)为10%;尖晶石加入量为10%的试样中有长度为30~80μm的SiC晶须生成,并且其颗粒与基质之间结合紧密。     

结合相对氧化物结合SiC窑具结构和性能的影响

以45%(质量分数,下同)的SiC(0.5~1.43 mm)和20%的SiC(≤0.5 mm)为骨料,基质中固定SiC细粉的含量为20%,根据不同的结合相(粘土、SiO2和莫来石)和Si粉变化基质组成。物料混匀后,压制成型为125 mm×25 mm×25 mm(20 MPa)和36 mm×36 mm(12 MPa)的试样,干燥后于1 450℃保温3 h制备了SiC窑具,同时又分别在1 400℃、1 450℃和1 500℃保温3 h分别制备了SiO2结合、粘土结合和莫来石结合的SiC窑具。对试样的显气孔率、体积密度、常温抗折强度、高温抗折强度、热震后和氧化 热震后的抗折强度进行了检测,并借助XRD和SEM研究了材料的物相组成和显微结构。结果表明:(1)SiO2微粉因粒度细,表面积大,活性高,高温下能促进窑具的烧结,其结合的窑具的综合性能优于另外两种结合;(2)SiO2结合SiC窑具在1 400℃烧成时的综合性能较好;(3)添加剂Si粉由于防止了SiC氧化和促进了烧结,使粘土结合SiC窑具性能得以改善。     

MgO-SiC-C材料的抗渣性能研究

以电熔镁砂、碳化硅、鳞片石墨(w(C)>97%)、铝粉(≤0.088mm,w(Al)>98%)和硅粉(≤0.088mm,w(Si)>98%)为主要原料,按w(电熔镁砂)=81%,w(SiC)=10%,w(鳞片石墨)=4%,w(铝粉 硅粉)=5%的组成配料,以酚醛树脂为结合剂,压制成125mm×25mm×25mm的MgO-SiC-C试样,在220℃干燥24h后采用感应炉法进行了抗转炉终渣试验,并对抗渣试验后试样进行了XRD、SEM和EDAX分析。结果发现熔渣对MgO-SiC-C试样的侵蚀和渗透并不显著,试样的侵蚀速率为0.25~0.3mm·h-1;抗渣试验后试样原质层主要组成为MgO、SiC和MgO·Al2O3;在与熔渣接触后,SiC被氧化成SiO2,由此导致在试样和熔渣间形成一高粘度的液相反应层,有效地减轻了试样受熔渣渗透和侵蚀的程度,提高了试样的抗渣能力。     

埋炭气氛对高铬材料烧结及抗侵蚀性的影响

以电熔氧化铬颗粒和细粉、α-Al2O3微粉、ZrO2微粉为原料,以磷酸二氢铝为结合剂,压制成型的试样在1 400、1 450、1 500、1 550和1 600℃,保温5 h条件下埋199石墨烧成,并进行性能测试,采用扫描电镜观察分析试样的裂纹、渗透层的形貌,并进行了XRD分析,判断埋炭气氛下烧成温度对高铬材料性能的影响程度。结果表明:埋炭气氛可以促进高铬材料的烧结,试样在1 500~1 550℃温度范围内可以烧结致密,且试样表层会生成反应层,但抗侵蚀试验后表面没有挂渣层,使试样的抗熔渣渗透性显著降低。     

氧化铁粉对MgO-Al2O3质浇注料性能的影响

以电熔镁砂、二氧化硅微粉、MA尖晶石粉、α-Al2O3微粉、氧化铁粉为原料制备MgO-Al2O3质浇注料,研究氧化铁粉加入量(0、2%、4%、6%)对MgO-Al2O3质浇注料常温物理性能、抗热震性和抗渣性的影响.按照国家相关标准进行各项物理性能检测,并用X射线衍射仪对1550℃3 h烧后试样进行物相分析,采用风冷法进行抗热震性试验,静态坩埚法进行抗渣试验.结果表明加入氧化铁粉对MgO-Al2O3质浇注料的抗渣渗透性能和常温力学性能有利.随着基质中氧化铁粉加入量的增加,试样抗渣侵蚀能力有所减弱,抗渣渗透能力明显增强,试样经1100℃3 h和1550℃3 h热处理后的常温力学性能得以提高,但抗热震性降低.氧化铁粉加入量≤2%时,试样的抗热震性较好.     

MgO部分稳定氧化锆陶瓷的抗渣侵蚀性研究

分别以3.5%(质量分数,下同)MgO部分稳定或4?O部分稳定的ZrO2陶瓷材料为试样,以CaO-Fe2O3-SiO2系的3种不同碱度与Fe2O3含量的渣为侵蚀剂,对试样分别进行静态和动态旋转(试样与渣的相对速率分别为0.06和0.5 m.m in-1)侵蚀试验,研究渣的碱度、流速及Fe2O3含量对材料抗侵蚀性的影响。结果发现,MgO部分稳定ZrO2材料抗渣侵蚀性较好,试样在渣线部位较严重的侵蚀归因于Marangoni效应。试样侵蚀情况与渣的碱度、成分有密切关系,高碱度渣侵蚀的方式主要是形成新的化合物而降低试样强度,中碱度或低碱度高Fe2O3渣则先将稳定剂MgO溶出,使材料遭受侵蚀的同时还发生相变化。     

微晶β-SiAlON材料的制备

以原料配比(w):硅粉39.4%、金属铝粉12.7%、氧化铝粉47.9%为基础配方进行配料,分别经1 300、1 350、1 400、1 450、1 500℃保温3 h或5 h氮化反应制备β-SiAlON材料。研究了Fe2O3烧结助剂、煅烧温度和保温时间对制备β-SiAlON材料的体积密度、耐压强度、物相组成和显微结构的影响。结果表明:添加2%(w)的Fe2O3,提高煅烧温度和延长保温时间,都有助于烧结的进行。添加2%(w)的Fe2O3作烧结助剂,在N2气氛中于1 500℃下保温5 h烧成试样的耐压强度达到85.44 MPa,体积密度达到2.92 g·cm-3,以β-SiAlON为主晶相,晶粒发育良好,呈棱柱状,直径大约1μm,长度大约2μm,且分布比较均匀。     

原位催化氮化制备β-SiAlON结合SiC材料

以SiC颗粒、Si粉、Al粉和活性α-Al₂O₃粉为原料,以Fe为催化剂,采用原位催化氮化法制备了β-SiAlON（z=3）结合SiC材料。研究了氮化温度（分别为1 350、1 400和1 450℃）和Fe加入量（分别为Si粉质量的1%、2%和3%）对合成材料的物相组成、显微结构、显气孔率、体积密度和高温抗折强度的影响。结果表明：氮化温度以1 400℃为佳,Fe加入量以Si粉质量的1%为佳;加入Si粉质量的1%的Fe、在1 400℃保温3 h氮化制备的试样中生成的β-SiAlON晶须直径较为均匀,试样的氮化程度、致密度和高温抗折强度均较大。     

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。