Chemical Durability and Structural Properties of Al₂O₃-CaO-Na₂O-P₂O₅Glasses Studied by IR Spectroscopy, XRD and SEM

Various characterization techniques were used to study the composition of the glass series xAl2O3-(40 - x)CaO-10Na2O-50P2O5 (with 0 ≤ x ≤ 10) in terms of chemical durability, X-ray diffraction, IR spectroscopy and scanning electron microscopy (SEM). The improved chemical durability was attributed to the replacement of easily hydrated P-O-P bonds by covalent and resistant Ca-O-P and Al-O-P bonds. However, the change in the dissolution rate (DR) versus time showed a marked decrease in chemical durability with increasing the Al2O3 content to the detriment of the CaO content. The X-ray diffraction analysis of glasses annealed at 550°C and 660°C for 48 hours indicated the presence of pyrophosphate phases and predominant metaphosphates or cyclic metaphosphate phases when the Al2O3 content was ≤7.5 mol%. Nevertheless, both, X-ray diffraction and IR spectroscopy confirmed the structural tendency change from metaphosphate (Q2) and pyrophosphate structural units (Q1). Toward short isolated orthophosphate units (Q0) when the Al2O3 content above 7.5 mol%. SEM micrographs illustrated that the number of crystallites increased in the glass network when the Al2O3 content increased at the expense of the CaO content. An increase in the Al2O3 content to 10 mol% led to the formation of a larger number of crystallites of different sizes, dominated by small crystallite sizes assigned to short isolated orthophosphate groups. This phenomenon led to a decrease in chemical durability and seems to be a favorable factor for the formation of the apatite layers which enclose the glass, in a SBF solution test, able of regenerating bone tissue in biomedical application.

Study of Chromium-Lead-Phosphate Glasses by XRD, IR, Density and Chemical Durability

Glasses in the ternary system Cr2O3-PbO-P2O5 were prepared by direct melting of the mixture with stoichiometric proportions of the reagents Cr2O3, PbO and (NH4)2HPO4 at 1080℃. The glasses obtained are transparent in colour and have a non-hygroscopic appearance. The study of the dissolution rate was carried out on ternary glasses xCr2O3-(45-x)PbO-55P2O5 with (1 ≤ x ≤ 4;mol%), immersed in distilled water at 90℃ for 24 days, indicating a maximum of chemical durability when the level of chromium oxide passed through 2 mol%. Both, IR spectra and X-ray diffraction have indicated the predominance of metaphosphate or cyclic metaphosphate groups with some traces of isolated orthophosphate groups when the Cr2O3 content is equal to x = 2. Analysis of the density values also, has showed a maximum density for x = 2 mol%. The covalent radius values of oxygen have indicated that the minimum value rcal (O2–) is observed for x = 2 mol% and therefore a relatively high reinforcement of the metal-oxygen-phosphorus (Cr-O-P) bonds. SEM Micrographs have exhibited two phases, a vitreous phase and a crystalline phase. The radical change in the structure from ultraphosphate Q3 groups to ring metaphosphate Q2 and orthophosphate groups Q0 seems to be the cause of the formation of crystallites. Beyond 2 mol% of Cr2O3, the structure of the glass changed relatively and the orthophosphate phases increased to the detriment of the metaphosphate phases. We observed a decrease in chemical durability. However, it was confirmed that the dissolution rate (DR) of the S2 analysed compound is comparable to the values of borosilicate glasses which are used as alternative materials for the immobilisation of nuclear waste substances.

Elaboration and Structural Investigation of Iron (III) Phosphate Glasses

The regular melting-quenching method allowed isolating very large vitreous domains within the ternary system Li2O-P2O5-Fe2O3 at 1100. The vitrification and crystallization effects are discussed in terms of phosphorus pentaoxide concentration (mol%). In the course of the present study, we analyzed chemical durability along the glass domain and many sample glasses were isolated. We noticed that our compounds demonstrated very high chemical resistance to attack, even with very highly concentrated mineral acid solutions. This behavior can be assigned to the presence of poorly crystalline phases in these glasses, which tended to increase as the Fe2O3 content increased. This property is a prerequisite for many interesting industrial applications. XRD, IR spectroscopy and SEM micrographs allowed an efficient investigation of the structural changes versus composition within ternary diagrams. The results were found to be consistent with the regular structural changes of phosphate glasses.

Some Effect of Chemical Treatment by Ferric Nitrate Salts on the Structure and Morphology of Coir Fibre Composites

The present study shows some important effects of chemical treatment on the structure and morphology of coir fibre. The objective of the present study is to optimise overall properties of coir fibre so as to use coir fibre as a reinforcing agent in thermoplastic and thermosetting polymers. In the present study, coir fibre is treated with ferric nitrate salt. A thermal treatment has been done at temperature of 1000&degC by using annealing method. X-ray diffraction of the treated coir fibre reveals the crystalline nature of the fibre. Change in morphology has been found in coir fibre when subjected to scanning electron microscopy. Finally, the Fourier transform and infrared spectrographs show the presence of traces of iron oxide:fibre in the prepared composite.

Post-annealing effect on the structural and mechanical properties of multiphase zirconia films deposited by a plasma focus device

Nanostructured multiphase zirconia films （MZFs） are deposited on Zr substrate by the irradiation of energetic oxygen ions emanated from a plasma focus device. The oxygen operating gas pressure of 1 mbar （1 bar=105 Pa） provides the most appropriate ion energy flux to deposit crystalline ZrO2 films. X-ray diffraction （XRD） patterns reveal the formation of polycrystalline ZrO2 films. The crystallite size （CS）, crystal growth, and dislocation densities are attributed to increasing focus shots, sample axial distances, and working gas pressures. Phase and orientation transformations from t-ZrO2 to m-ZrO2 and c-ZrO2 are associated with increasing focus shots and continuous annealing. For lower （200 ℃） annealing temperature （AT）, full width at half maximum （FWHM） of diffraction peak, CS, and dislocation density （δ） for （020） plane are found to be 0.494, 16.6 nm, and 3.63×10-3 nm-2 while for higher （400 ℃） AT, these parameters for （111） plane are found to be 0.388, 20.87 nm, and 2.29×10-3 nm-2, respectively. Scanning electron microscope （SEM） results demonstrate the formation of rounded grains with uniform distribution. The estimated values of atomic ratio （O/Zr） in ZrO2 films deposited for different axial distances （6 cm, 9 cm, and 12 cm） are found to be 2.1, 2.2, and 2.3, respectively. Fourier transform infrared （FTIR） analysis reveals that the bands appearing at 441 cm-1 and 480 cm-1 belong to m-ZrO2 and t-ZrO2 phases, respectively. Maximum microhardness （8.65±0.45 GPa） of ZrO2 film is ～ 6.7 times higher than the microhardness of virgin Zr.

基于XRD和SEM的含碳微细粒金矿氧化焙烧机理研究

含碳微细粒金矿是世界难处理金矿主要类型,且储量巨大,矿石中的有机碳、石墨碳能吸附溶液中的金氰络合物,因而含碳金矿在浸出之前需进行预处理。氧化焙烧是应用时间最长、可靠性和适应性最好的预处理工艺,已经成功的用于生产实践。针对传统氧化焙烧法存在生产成本高,收尘系统复杂等不足,近年来国内外学者在焙烧工艺和设备方面进行了大量的研究工作,取得了丰硕的研究成果,为氧化焙烧技术的发展注入了新的活力。但关于焙烧理论方面的研究较少,研究方法也比较单一,尤其是对于焙烧过程的相关理论研究比较薄弱,这在一定程度上影响了氧化焙烧技术的发展。焙烧时间是影响焙烧效果的关键因素,决定化学反应进度及物相变化程度。在不同时间条件下(焙烧温度650℃),对含碳微细粒金矿石进行焙烧-浸出试验,首次采用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)和孔结构分析等手段对含碳金矿及焙砂进行分析表征,进而揭示氧化焙烧过程中碳质物的氧化、矿石晶体结构变化、物相变化等对金浸出效果的影响机理。工艺矿物学研究表明:矿石中主要矿物有石英、白云石、方解石、绢云母、高岭石、黄铁矿和石墨等;矿石中自然金粒度微细,以5~10μm粒级为主,部分微粒自然金被石英、碳质组成的碎屑包裹;碳质(有机碳和石墨碳)含量高、粒度细,且与脉石矿物紧密共生。焙烧-浸出试验结果表明:原矿直接浸出时,金浸出率仅为12.50%,碳质的"劫金"作用显著;随着焙烧时间的增加,金的浸出率先逐渐增大后变化平稳,焙烧时间为2h时,金浸出率最高;当焙烧时间为1h时,绢云母发生了脱羟基变化,高岭石分解生成蒙脱石,黄铁矿氧化为赤铁矿,碳质(有机碳和石墨碳)氧化且产生CO_2,但未完全氧化,此时焙砂中石英的d_(100)和d_(101)值以及平均孔径较小,不利于浸出剂的扩散,导致金浸出率仅为58.09%;当焙烧时间为1.5h时,白云石开始分解,碳质已完全燃烧,产生的CO_2使微孔数量增多,有利于浸出剂的扩散,此时金浸出率增加到73.34%;当焙烧时间为2h时,白云石分解较完全,焙砂中有MgO生成,此时焙砂中石英的d_(101)值达到最大值(4.255 03nm),焙砂松散密度变大且孔容和平均孔径达到最大值,分别为0.009 954cm^3·g^(-1)和6.64080nm,焙砂中产生的微孔最多,增加了浸出剂的扩散通道,有利于金的浸出,金浸出率也达到了最大值(91.28%);当焙烧时间为3h时,焙砂表面生成Ca_2SiO_4和CaSO_4等在高温时易形成低熔点物质,发生微弱的烧结现象,导致颗粒内部的微孔被填充、闭合,微孔减少,孔容和平均孔径降低,内部结构变得致密,不利于浸出剂的扩散,同时造成金的浸出率下降。

利用SEM图和XRD指纹图谱鉴别矿物类中药生石膏与玄精石

目的:采用性状鉴别、理化鉴别等传统方法结合扫描电子显微镜(SEM)及粉晶X-射线衍射(XRD)等现代分析技术,对矿物类中药生石膏和玄精石进行系统鉴别。方法:采集生石膏和玄精石样品,记录原药材及其粉末性状特点,进行理化鉴别,确定样品真伪及品种。在上述基础上,采集各药材样品SEM显微图,对比生石膏与玄精石各显微图之间的差异,总结两者SEM鉴别特征;同时采集各样品粉末的XRD图谱,分别计算并绘制生石膏与玄精石的XRD平均图谱,确定共有指纹峰,并对共有指纹峰相对强度数据分别进行相似度评价、聚类分析和主成分分析(PCA),验证生石膏与玄精石的XRD共有指纹峰用于两者鉴别的可行性。结果:生石膏和玄精石碎屑的SEM特征具有差异,玄精石均呈疏松层片状堆叠,细小碎屑均成沙粒状;而生石膏呈紧密聚合的长纤维状,且细小碎屑或粉末具碎裂状纤维特征。生石膏和玄精石粉末的XRD图谱峰位相似,但玄精石各峰相对生石膏各峰略左移,相同峰位衍射峰的相对强度存在差异。相似度评价显示生石膏与玄精石明显分离,聚类分析及主成分分析均可将两者准确区分。结论:SEM和XRD技术均可准确鉴别生石膏和玄精石及其粉末,传统鉴别方法结合SEM和XRD分析技术能够为生石膏和玄精石及其粉末的快速鉴别和质量控制提供快速准确的新方法。

Mesolamellar composite of TiN and CTAB using fluoride ion bridge: synthesis, mechanism &characterization

In an attempt to synthesize hexagonal mesopo- rous titanium nitride, a mesolamellar composite based on titanium nitride and cetyltrimethylam- monium bromide (CTAB) is obtained by the sol-gel route involving templating at 80oC. The mechanism underlying the above synthesis is discussed for the first time in the literature and till date there are no reports on the synthesis of mesoporous nitrides. The above mesolamellar composite is found to form an oxide of titania (anatase) upon heat treatment at 335oC for 1h.

Comparison of wear behaviour of LM13 Al−Si alloy based composites reinforced with synthetic(B_(4)C)and natural(ilmenite)ceramic particles

Dry sliding wear behaviour of stir-cast aluminium matrix composites(AMCs)containing LM13 alloy as matrix and ceramic particles as reinforcement was investigated.Two different ceramic particle reinforcements were used separately:synthetic ceramic particles(B_(4)C),and natural ceramic particles(ilmenite).Optical micrographs showed uniform dispersion of reinforced particles in the matrix material.Reinforced particles refined the grain size of eutectic silicon and changed its morphology to globular type.B_(4)C reinforced composites(BRCs)showed maximum improvement in hardness of AMCs.Ilmenite reinforced composites(IRCs)showed maximum reduction in coefficient of friction values due to strong matrix−reinforcement interfacial bonding caused by the formation of interfacial compounds.Dry sliding wear behaviour of composites was significantly improved as compared to base alloy.The low density and high hardness of B_(4)C particles resulted in high dislocation density around filler particles in BRCs.On the other hand,the low thermal conductivity of ilmenite particles resulted in early oxidation and formation of a tribo-layer on surface of IRCs.So,both types of reinforcements led to the improvement in wear properties of AMCs,though the mechanisms involved were very different.Thus,the low-cost ilmenite particles can be used as alternative fillers to the high-cost B_(4)C particles for processing of wear resistant composites.

Effect of Low Temperature on Hydration Performance of the Complex Binder of Silica Fume-Portland Cement

By analyzing the mechanical properties, composition of hydrates, content of Ca（OH）： and microstructure of the complex binder of silica fume-Portland cement, which cured at constant low temperatures（＋5--10 ℃）, the effect of different low temperatures on hydration performance of the complex binder at the age of 3, 7 days and 14 days was researched. Experimental results show that hydration processes of the complex binder can be restricted by low temperature. Reducing the curing temperature could cause compressive strength and flexural strength of the complex binder to decrease significantly. The gradient difference between strength diminishes, content of Ca（OH）2 in hydrates reduces, and compactness of the microstructure weakens. Therefore mixing with silica fume can modify various performance indicators of the complex blinder, but reducing the curing temperature restricts the pozzolanic activity of silicon fume.

硼砂煅制工艺优化及质量评价

目的 优化硼砂煅制工艺,并对其进行质量评价。方法 以铺设厚度、煅制温度、煅制时间为影响因素,失水率、蓬松度、粉碎率、四硼酸钠含量为评价指标,星点设计-效应面法优化硼砂煅制工艺。采用扫描电镜(SEM)、热重分析(TG)、拉曼光谱、X射线衍射(XRD),比较硼砂煅制前后质量差异。结果 最佳条件为铺设厚度2 cm,煅制温度365℃,煅制时间100 min。煅制后,硼砂微观形态、成分组成、晶型结构发生变化,失去全部结晶水而转变为非晶体状态。结论 该方法稳定可行,可用于工业大批量生产煅硼砂。

明代民窑青花瓷分析

青花瓷作为我国古陶瓷的典型代表之一,受到人们广泛的关注。本文采用SEM、SEM-EDS、XRD等科技手段分析了出自淮安古运河的明代晚期民窑青花瓷碎片坯釉的形貌特征与物相组成。结果表明:釉层中气孔直径较大但较为稀疏,坯体中气孔虽小但较为密集。烧成制度较好的情况下,釉层中残余石英会比坯体中少。釉层相对于坯体Ca含量高、Al含量低,坯体呈现“高硅低铝”特征,属于我国典型的南方陶瓷。明代民窑青花瓷釉层厚度小于0.5mm,且中间层发育完好。明代民窑青花瓷坯体中主要的物相为石英和莫来石,釉层中物相主要以玻璃相的形式存在,其中也含有少量方石英与莫来石分散于玻璃相中。

两种修复用竹纸的耐久性比较研究

为了研究两种手工竹纸抵抗环境因素作用、保持原有结构与理化性能的能力,研究其耐久性,采取干热加速老化处理,根据ATR-FTIR谱图、抗张性能、湿抗张强度、pH值检测、ISO亮度、超景深三维图像、扫描电镜图像等分析结果,观察老化竹纸显微形貌、微观结构的变化,结合两种手工竹纸的制作技艺,讨论老化竹纸的理化性能变化和造纸技艺之间的关联性,探讨连四纸修复纸的应用场景。结果显示,干热加速老化过程中,老化竹纸内部O—H、C—H、C—C等基团的红外吸收峰强度逐渐下降,糖苷键的C—O—C键的红外吸收峰强度出现先升后降的现象;抗张性能的差异主要受造纸技艺的影响,连四纸修复纸的优势在于纤维间的结合强度,古法连史纸的优势在于综合性能;干热老化时,两种手工竹纸出现了干角质化的现象,发生塑性变形,限制了纤维润胀;连四纸修复纸为弱酸性纸,古法连史纸为碱性纸,古法连史纸的pH值稳定性更好,主要受CaCO_(3)等组分的影响;羰基增多是竹纸黄化的主要诱因,ISO亮度的差异是由蒸煮剂和漂白处理的不同所致;超景深三维图像显示,连四纸修复纸的纤维间结合强度和纤维纯净度均高于古法连史纸;SEM图像显示,竹纸的纤维孔隙率降低,扁平化、干角质化、板结化等特征凸显,老化后期,长纤维表面毛糙起皮,出现细碎物。

昌化“硬地”鸡血石及其相似玉石的矿物学和谱学特征对比研究

随着鸡血石矿产资源的枯竭,市场上出现了种类繁多的鸡血石相似玉石品种,它们的主体矿物组成大多为石英,易与传统的昌化“硬地”鸡血石相混淆。为鉴别和定名此类鸡血石相似玉石,本文利用X射线粉末衍射、红外光谱、拉曼光谱和扫描电子显微镜等测试方法对产自四川、贵州、西安、云南的鸡血石相似玉石样品与昌化“硬地”鸡血石样品的矿物学和光谱学特征进行对比分析。结果表明:(1)X射线粉末衍射显示昌化“硬地”鸡血石样品的主要矿物组成为石英和地开石;不同产地鸡血石相似玉石样品的主要矿物组成为石英和碳酸盐矿物;(2)根据红外光谱的峰形特征可以较快地区分昌化“硬地”鸡血石和鸡血石相似玉石样品,后者在红外光谱常出现1450、881、729 cm^(-1)处的碳酸盐吸收峰,而“硬地”鸡血石样品显示为石英的特征峰位;(3)拉曼光谱结果表明,所有样品均含有石英特征峰,四川、贵州、云南鸡血石相似玉石样品含有方解石的特征拉曼位移,西安样品出现白云石的拉曼位移。“硬地”鸡血石的基质部分含有锐钛矿,而在其他产地的鸡血石相似玉石样品中未见锐钛矿。对于辰砂周围的黄色矿物,“硬地”鸡血石样品是黄铁矿,而贵州样品的黄色部分为雄黄;(4)扫描电子显微镜结果显示“硬地”鸡血石和相似玉石的微形貌特征差异主要集中在碳酸盐矿物,相似玉石样品中的碳酸盐矿物为片状,片与片之间呈叠瓦状堆叠,常见碳酸盐矿物的解理面和阶梯状断口,而“硬地”鸡血石未见此类现象。根据测试结果和国标规定,建议将此类鸡血石相似玉石定名为含辰砂的碳酸盐-石英质玉石。

桉木三组分在高温热水预处理及酶解糖化中的规律研究

为优化桉木高温热水预处理的工艺条件,用傅立叶红外光谱(FT-IR)、扫描电镜(SEM)、X射线衍射(XRD)等手段分析预处理渣的理化特性。结果表明,最佳的预处理条件为:预处理温度180℃,时间20 min,绝干木粉与水1∶20(g∶mL)。此条件下,预处理液中木糖、葡萄糖的转化率分别为81.93%和2.21%。桉木木粉经最优条件预处理后,大部分半纤维素被水解;纤维素的相对结晶度基本不变;碳水化合物的结构变的松散,纹孔膜破裂,纤维碎片增多,极大的提高了后续纤维素酶的可及度。对最优条件下预处理渣的进一步酶解:发现葡萄糖的转化率高达80.52%,比未经预处理直接酶解提高3.63倍。对酶解残渣的进一步分析可知,桉木原料87.12%的酸不溶木质素可在酶解残渣中得到回收,这有利于木质素的综合利用。

球形纳米复合方解石型碳酸钙的合成及表征

采用两亲嵌段共聚物聚丙烯酸-苯乙烯（PS-b-PAA）水溶液为介质合成了球形碳酸钙复合物，球形直径约3～4μm，由纳米级方解石微粒通过PS-b—PAA的有机键合紧密团聚而成．通过电镜、XRD、IR和差热热重分析复合物的微晶结构性质表明，复合物中有机质质量分数约为14％；其中的方解石微晶约几十纳米，较之普通碳酸钙晶体有更大的晶格畸变；热分解行为提前约15℃，红外V3吸收蓝移约10cm^-1．

偏高岭石的微观结构与键合反应能力

对450～1050℃下热变高岭石结构,尤其是偏高岭石结构进行了研究。针对晶体高岭石和非晶体偏高岭石的结构特征,采用了XRD、SEM和IR等测试技术手段进行矿物组成和结构分析。采用热重GT测试方法对高岭石的热分解过程进行了研究,通过对矿物化学键合材料强度试验来表征偏高岭石的反应活性。结果发现:偏高岭石中的铝氧层是化学键合反应能力的敏感结构单元,IR谱中表征Al—O键共振的817cm-1吸收峰与其化学键合反应能力相关联,存在该吸收峰的热变高岭石具有化学键合反应能力,相对吸收率越大,化学键合反应能力越高。

微波场中A型分子筛及分子筛膜合成的研究

Effects of aging time and alkalinity as well as cation concentration(Na+) on the synthesis of A type zeolite and zeolite membrane were investigated in this paper. The results showed that aging time for synthesis of A type zeolite and zeolite membrane had remarkable influence and alkalinity could accelerate the formation of zeolite but was disadvantage to zeolite membrane synthesis. Cation concentration(Na+) also couldn′t accelerate the synthesis of zeolite and zeolite membrane but it was probable an important factor to accelerate crystal growth .Moreover, more compact zeolite membranes could be synthesized by this method while the thickness of membrane was thinner than that of convention. Zeolites and zeolite membranes were characterized by XRD, TEM as well as IR characterization techniques.

尖晶石LiMn_2O_4的改性研究

Using water soluble organic compound as matrix, Carbon-coated LiMn2O4 was synthesized successfully. Co-doped LiMn2O4 was also synthesized. Physical and electrochemical performances were investigated by XRD, IR, SEM and electrochemical testing. The results showed that due to a better conductivity and stabilization of Co-doped LiMn2O4, the electrochemical performances of LiMn2O4 were improved. And Carbon-coated LiMn2O4 also showed a good property because of the reduction of Mn dissolution. Comparatively speaking, Carbon-coated LiMn2O4 showed a more stable electrochemical performance.