几种高岭土的组成与可塑性研究

采用X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)、透射电子显微镜(TEM)、激光粒度仪及可塑性仪对龙岩高岭土、临沧高岭土和星子高岭土的组成、结构形貌和可塑性进行了表征.结果表明,龙岩高岭土主要是由片状高岭石和伊利石及管状多水高岭石组成,其结晶度较差,Fe2O3和TiO2含量低,颗粒尺寸最小,d50为5.12 μm,可塑性最好;临沧高岭土则大部分为呈卷曲短柱状的多水高岭石,并含有少量的片状高岭石,颗粒尺寸较小,d50为8.45μm,可塑性差;星子高岭土大部分为片状结构,粒度较粗,d50为14.77 μm,可塑性差.     

龙岩高岭土的组成与结构研究

本文采用X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)、激光粒度仪、综合热分析仪(DTA/TG)、场发射扫描电镜(FE-SEM)以及透射电镜(TEM)等测试手段对福建龙岩高岭土进行了组成及结构的研究.结果表明:龙岩高岭土的矿物组成主要由高岭石、多水高岭石和伊利石组成.一定量伊利石的存在是龙岩高岭土的化学组成中含有较高K2O组分的直接原因,这导致其耐火度不高.龙岩高岭土的显微结构为片状和管状混合结构,多水高岭石呈管状,结晶程度最差;高岭石呈不规则薄片状,结晶程度较差;伊利石呈板片状,晶化程度最好.     

吉水高岭土原矿理化性能分析及成瓷应用的研究

分析测试了吉水高岭土原矿和精矿的化学组成和矿物组成,并对吉水高岭土精矿的结构形貌、粒度分布和物理性能进行了研究。将吉水高岭土原矿替代龙岩高岭土应用于日用陶瓷泥料配方中,研究其加入量对泥料可塑性、干燥抗弯强度、干燥收缩和烧成收缩的影响。研究结果表明:吉水高岭土原矿的主要矿物组成为石英、白云母、高岭石和微斜长石,属高岭石类矿物,高岭石矿物呈片状不规则叠置排列;吉水高岭土精矿颗粒较粗,体积平均粒径为19.562μm,是一种中可塑性、粘结性一般的高岭土原料;在日用陶瓷配方泥料生产中,吉水高岭土原矿用量控制在30%~50%范围内,泥料工艺性能可满足生产要求。     

中国主要类型制瓷高岭土的特征

我国制瓷高岭土分布广泛,开采历史悠久。其主要产区是江苏苏州、湖南界牌、山西大同、广东潮州和江西景德镇。近年来对制瓷高岭土的研究表明,我国北方所产高岭土多属沉积型,矿床赋存于古生代及中生代煤系地层内。南方所产高岭土在成因上则与花岗岩等酸性火成岩有关,多属风化残积型与热液蚀变型。各地高岭土由于成矿地质条件的差别,导致矿石的矿物、化学成分和工艺性能的差别。苏州高岭土的化学成分接近于标准高岭石的理论成分,它的主要矿物成分是高岭石、7多水高岭石和10多水高岭石,特高可塑性和结合性能,焙烧后白度高,耐火度亦高,所以它是制瓷工业重要原料。界牌高岭土的化学成分具征是SiO_2含量高,Al_2O_3、Fe_2O_3含量低,并含少量Na_2和K_2O,它主要由结晶差高岭石、7多水高岭石、白云母、石英和钠长石等组成,其工艺性能特征是细颗粒含量高、焙烧后白度高、耐火度高,但收缩小,因此是制造高档日用细瓷的优质原料。大同高岭土是一种硬质高岭土,其化学成分类似于苏州高岭土,主要矿物成分是高岭石,由于有机质的存在,球磨后具可塑性和成形性能。潮州飞天燕高岭土的化学成分特征是SiO_2高、Al_2O_3低,K_2O比一般高岭土高,它的主要矿物成分是伊利石和高岭石,可塑性中等,焙烧后的白度能达到70—80度,因此可直接用于制瓷。景德镇高岭土的化学成分特征是SiO_2和Fe_2O_3含较高,淘洗后Al_2O_3含量能提高到34—36％,其主要矿物成分是高岭石和7多水高岭石。     

湖南界牌高岭土

湖南界牌高岭土是我国南方各大瓷厂常用的制瓷原料。它是一种软质富硅高岭土。其化学成分特征是SiO_2含量高,Al_2O_3、Fe_2O_3含量低,并含少量Na_2O和K_2O,主要矿物成分是结晶程度差的高岭石、7A多水高岭石、白云母、石英和钠长石。矿石类型有高火泥、桃红泥、猪肝泥、黄砂泥、低火泥、砂白泥、三级泥等。其中高火泥(白色块状高岭土)和桃红泥(桃红色片状高岭土)具有颗粒细、煅烧后白度高、耐火度高、收缩小等特点,是制造高档日用细瓷的优质原料。其它类型矿石,可供制造陶炻器、旅馆瓷等。本文对各种类型界牌高岭土的物质成分、工艺性能作了较详细的报导。     

凉山稀土矿伴生高岭土理化性能及应用研究

采用化学常规分析、XRD、SEM、TG-DTA等测试手段,对四川凉山冕宁县稀土开采中出现的具有大量黑色腐殖质的高岭土矿样LRAK的物质成分、晶体结构及煅烧性能等进行了系统的研究,并以该高岭土为原料进行了合成NaY分子筛研究.结果表明,凉山稀土矿伴生高岭土LRAK主要化学组成是Al2O3 45.40％、SiO2 54.08％,接近高岭石矿物的理论值;XRD分析显示,LRAK高岭土晶相是纯的0.7 nm埃洛石;晶体结构为管状结构,径向直径0.1μm;在一定温度下煅烧后可以产生含量较高的活性A12O3和活性SiO2;晶化实验所得的晶化产物结晶度可达到35％,硅铝比可达5以上,符合催化剂前驱体要求.以LRAK高岭土制备FCC催化剂,其综合性能与商用高岭土S2相当,满足FCC工业催化剂常规要求.因此LRAK高岭土可以作为制备FCC催化剂的原料,具有较好开发利用价值.     

贵州大方县骂陇村高岭土的理化及工艺性能研究

从矿山采集具有代表性的高岭土样品,球磨并过80目筛备用。利用X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)、综合热分析仪(DTA-TG)、场发射扫描电子显微镜(FE-SEM)和透射电子显微镜(TEM)对高岭土的化学成分、矿物组成、理化性质和微观形貌进行了表征,并详细考察了其多项工艺性能指标。研究结果表明:该高岭土样品的主要矿物组成为高岭石(61.59wt%)、多水高岭石(12.86wt%)和三水铝石(23.63wt%),其中高岭石与多水高岭石呈典型的六方管状结构,而三水铝石呈假六方片状结构。该矿物原料可塑性良好、阳离子交换容量值很小、流动性和触变性较小、干燥收缩很小、干燥强度较大。由于该矿物中碱金属和碱土金属氧化物含量均较低,因此烧结温度较高(>1350℃),并且其含有相对较高的Fe2O3(1.19wt%),导致样品的烧成白度不高,1250℃下烧成的白度仅为46.84%。     

北海高岭土矿物特征及铁赋存状态的研究

本文采用X射线衍射、电子探针、透射电子显微镜、扫描电子显微镜等手段研究了北海高岭土化学组成、形貌和物相组成等,依据这些检测探究北海高岭土的基本特征及其中杂质铁的赋存状态,为北海高岭土的精制处理提供科学依据.研究结果表明:北海高岭土的主要矿物成分为高岭石、白云母和石英,铁是北海高岭土中主要的染色元素,一部分以结构铁的形式存在,其余则以氧化物的形式吸附在高岭土颗粒表面,它是除铁增白的主要对象,可采用化学漂白法将其除去.     

我国硬质高岭土在玻璃纤维领域应用研究进展

硬质高岭土是指在煤系地层中,以高岭石为主要矿物成分的高岭土,俗称煤系高岭土或高岭岩,包括煤层的顶底板、煤矿夹层和煤矿夹石。我国煤系高岭土资源丰富、分布广泛。高岭土是一种含水铝硅酸盐,与煤矿伴生的高岭土常含钙、镁、钠、钾、铁、钛等杂质,这些杂质限制了其在玻璃纤维(下称玻纤)中的广泛应用。高岭土加热过程中会发生脱水和结构性变化,在不同温度下形成偏高岭石、硅尖晶石、莫来石等。高岭土是玻纤行业增加铝的重要原料,随着中国玻纤行业的发展,对高岭土矿的需求量迅速增长。硬质高岭土中SiO2和Al2O3含量符合玻纤原料要求,通过磁选、浮选等选矿技术降低原料中Fe2O3、TiO2的含量、煅烧工艺降低COD值,硬质高岭土可作为一种质量稳定的优质玻纤生产原料。梳理了在玻纤领域近年应用硬质高岭土的技术研究成果,对下一步硬质高岭土矿物材料在玻纤领域应用技术研究提出建议。     

丰顺九龙高岭土工艺性质及出口瓷泥的研究

测定了九龙高岭土的可塑性、化学组成、粒度及其分布、白度等 ,并且做了X—射线和透射电子显微镜分析。测定结果表明 :九龙高岭土的主要矿物组成为高岭石、石英和伊利石 ,其晶体形貌一部分呈假六角片状 ,一部分呈不规则片状 ,少部分为粒状。在出口瓷泥中 ,加入了 12 %的可塑粘土。     

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.     

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.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.