低热膨胀系数堇青石材料的合成研究

以高岭土、烧滑石和氧化镁为原料合成堇青石,研究了烧成温度、镁铝硅含量及高岭土种类对合成堇青石热膨胀系数的影响。实验结果表明:合成堇青石的最佳配方1#高岭土82.4 wt%、滑石9.3 wt%、氧化镁8.4 wt%,试样热膨胀系数为1.24×10-6℃-1。适当的提高烧成温度可得到热膨胀系数低的堇青石材料,但合成温度过高则会因为形成过多的玻璃相而使其热膨胀系数增大。过多或过少的引入Si O2、Al2O3、Mg O均会由于形成高热膨胀系数的晶相而导致所合成堇青石的热膨胀系数增大。     

氧化镁含量及原料煅烧对堇青石陶瓷热膨胀性能的影响

以高岭土、滑石与氧化镁为原料合成堇青石陶瓷,研究了Mg O含量及原料煅烧对试样晶相种类、显微结构与热膨胀性能的影响。结果表明,Mg O不足时形成的α型堇青石较少,过量时易生成顽火辉石,致使膨胀系数升高。高岭土与滑石原料经高温煅烧后,所合成的堇青石陶瓷中杂相含量增多,膨胀系数增大。当原料组成中高岭土含量为81.2%、滑石为9.5%、氧化镁为9.3%且原料未经煅烧时,所合成的堇青石陶瓷材料的膨胀系数最低可达1.43×10~(-6)℃~(-1)(Rt—800℃)。     

煤系高岭土合成堇青石的研究

研究了利用煤系高岭土作为主要原料合成堇青石。实验结果表明:采用煤系高岭土,滑石和镁砂为原料合成堇青石的效果要优于用煤系高岭土,滑石和工业氧化铝为原料的合成效果。并测得以煤系高岭土配合滑石和镁砂(配方化学组成中富含SiO2)在1 340℃×3 h的烧成制度下,制得试样的体积密度为2.02 g/c,气孔率为16.1%,热膨胀系数(20~800℃)α为1.88×10-6/℃,堇青石含量≥95%。     

堇青石合成过程的研究

采用高岭土、滑石和氧化铝作原料合成堇青石,通过对高岭土和滑石的ＤＴＡ分析,并结合前人所做的工作对高岭土和滑石在１０００℃以前的加热变化过程进行了阐述,同时通过对不同烧成温度下的试样做ＸＲＤ分析及ＳＥＭ观察,重点研究了堇青石的合成过程。     

堇青石合成过程的研究

采用高岭土滑石和氧化铝作原料合成堇青石，通过对高岭土和滑石的ＤＴＡ分析，并结合前人所做的工作对高岭土和滑石在１０００℃以前的加热变化过程进行了阐述，同时通过对不同烧成温度下的试样做ＸＲＤ分析及ＳＥＭ观察，重点研究了堇青石的合成过程。     

绿泥石—高岭土合成堇青石的反应过程

一、前言本文是前文,即滑石(或蛇纹石)—高岭土—氧化铝合成堇青石反应过程研究的继续。目的是探讨不同含镁原料合成堇青石反应的特点,以达到合理选择合成堇青石的最佳含镁原料及确定正确的合成工艺的目的。通过研究及对比用滑石、蛇纹石、绿泥石为含镁原料合成堇青石反应过程特点及其它方面的优点,认为绿泥石是最理想的合成堇青石用的含镁原料。其特点是,开始生成     

“高岭土-滑石-氧化铝”系统合成堇青石研究

实验采用"高岭土-滑石-氧化铝"系统,以苏州土、滑石、工业氧化铝为原料,用固相烧结法在不同温度下进行合成堇青石试验,通过对产物的红外光谱及形貌分析,确定了此类配方的最佳烧成温度。     

影响合成堇青石材料热膨胀系数的因素

以苏州土52.3%(质量分数,下同),滑石35.5%,工业氧化铝12.2%为基本配比,合成堇青石材料。分别考察了晶核剂、气孔率、原料预煅烧和急冷处理等因素对合成堇青石材料热膨胀系数的影响。晶核剂采用堇青石熟料,外加量(w)分别为5%、10%、15%、20%、25%和30%;成孔剂采用磨细的面包渣,加入量(体积分数)分别为5%、8%、10%、15%和20%;滑石的预煅烧温度选定1000℃,研究滑石是否煅烧对合成堇青石材料性能的影响。结果表明:适量堇青石熟料在烧成反应中可作为晶种促进堇青石晶核的形成;一定数量均匀分布的小气孔对降低材料的热膨胀系数有利,但气孔率太高反而影响材料性能;通过对滑石的预煅烧试验,证明对滑石进行1000℃的预煅烧有利于降低热膨胀系数;对于急冷的处理方法,提出了与前人相反的观点,认为由于配料组成的差异,急冷未必能降低材料的热膨胀系数,当玻璃相组成为普通硅酸盐玻璃时,急冷的方法反而会增大合成堇青石材料的热膨胀系数。     

海城绿泥石合成堇青石的研究

利用海城绿泥石作为合成堇青石的主要原料.试验表明:用绿泥石合成堇青石其合成温度低,合成温度范围宽,合成堇青石的热膨胀系数达1.8×lO~-6/℃(22～800℃),膨胀曲线直线性好.与海城滑石作为合成堇青石原料相比,具有明显的优越性,为开发和应用海城绿泥石创造了条件.     

堇青石的低温合成与表征

堇青石具有很多优异的性能,被广泛应用于耐火材料,红外辐射陶瓷及计算机集成电路基片等。天然矿物中的堇青石含量很少,且收集需要的难度高,很难在工业上广泛应用,人工合成堇青石成了堇青石原料的主要来源。本实验采用高温固相法、用"滑石-高岭土-氧化铝"系统进行堇青石制备,以钾长石代替氧化铝,在1200℃的温度下合成出了堇青石。当钾长石掺量为15%的时候,所得到的堇青石样品具有最好的性能,除了有较高的红外发射率,抗压强度达到了110MPa外,所生成的堇青石的量最多,孔隙率较小。     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

几种针状焦性能对比

针状焦分石油系和煤系两大类,这主要取决于针状焦的原料来源。在同一系列中由于原料不同和工艺条件不同 ,针状焦的各自性能也不相同。针状焦是生产超高功率石墨电极和高功率石墨电极的主要原料 ,针状焦的性能对石墨电极的质量有至关重要的影响。所以对针状焦性能以及其对石墨电极质量影响的研究十分必要的。以下是常用的几种进口针状焦和国产针状焦的性能对比。１原料性能分析对比原料试样包括４种针状焦 ,其中两种为进口针状焦：三菱针状焦和新日化针状焦;另两种为国产针状焦：鞍山针状焦和锦州针状焦。其中除锦州针状焦是石油系针状焦外…     

聚酰亚胺的合成法

本文评述了缩聚型聚酰亚胺的主要合成方法和近年来国际上在合成中所做的探索。