Ti（C，N）基金属陶瓷的制备与性能研究

采用真空热压烧结工艺制备了Ti（C,N）基金属陶瓷复合材料。借助于SEM和XRD分别分析了其显微结构和组分,并测试了其力学性能和相对密度。实验结果表明：其晶粒较细、均匀,具有明显的黑芯-灰壳结构,气孔较少,致密度较高。断裂机理主要是沿晶断裂,部分为混合型断裂（穿晶断裂和沿晶断裂）。金属相存在着明显的撕裂棱。其维氏硬度22．74GPa,断裂韧性10．1MPa·m^1／2,抗弯强度1192．83MPa,相对密度达到了99．12％。     

WC含量对Ti(C,N)基金属陶瓷组织和性能的影响研究

用传统的粉末冶金方法制备了不同WC含量的超细Ti(C,N)基金属陶瓷试样,运用SEM,EDX等手段对材料的显微组织进行了表征分析,并用这些显微组织的特征和差异解释了材料宏观力学性能的特点.结果表明,金属陶瓷的组织为典型的两相结构特征,其中陶瓷相的芯、壳结构(core/timstructure)与溶解析出机制有关.少量WC的加入能提高材料的力学性能.断口SEM分析表明:断裂机理为典型的混合型断裂(穿晶断裂和沿晶断裂),金属相存在着明显撕裂的痕迹.     

SiC/(W,Ti)C陶瓷喷嘴材料的制备及其性能

本文以SiC为基体,添加(W,Ti)C固溶体增韧相,采用热压烧结工艺制备出新型Sic/(w,Ti)C陶瓷复合材料.研究表明:SiC/(W,Ti)C陶瓷材料的性能与(W,Ti)C的含量、成烧温度、保温时间等密切相关.随(W,Ti)C含量的增加,材料的致密度、抗弯强度和断裂韧性增加,硬度减小;SiC/(W,Ti)C陶瓷复合材料的最佳性能参数为:抗弯强度631 MPa,维氏硬度25.944 GPa,断裂韧性4.38 MPa·m1/2.通过分析材料的显微结构和断口SEM照片,发现SiC/(W,Ti)C陶瓷材料的断裂机制为沿晶和穿晶断裂特征同时并存,即断裂方式为沿晶断裂和穿晶断裂相结合的混合断裂.     

Ti(C,N)基金属陶瓷的力学性能与显微结构的研究

烧压烧结制备了不同Mo2C和Cr3C2含量的Ti(C0.7N0.3)-(Ni—Co)-Mo2C—Cr3C2金属陶瓷，对其性能测试表明，低Mo2C，Cr3C2含量材料具有良好力学性能。利用透射电镜、能谱分析和扫描电镜对低Mo2C，Cr3C2含量金属陶瓷显微组织进行了分析。研究表明，材料显微组织中没有发现明显可见的环形相，Mo元素富集在硬质相颗粒边缘附近，Cr元素富集在粘结相中。未完全溶解的Cr3C2分布在粘结相内和相界上抑制了裂纹的扩展，断口上沿晶断裂面弯曲不规整以及穿晶解理条纹较多，这是材料具有较高的断裂韧性的原因。     

ZrB2-SiC复相陶瓷的制备及其力学性能研究

以ZrB2和SiC粉为原料,采用Si3N4球为球磨介质,通过热压烧结制备了ZrB2-SiC复相陶瓷.并对ZrB2-SiC复相陶瓷进行了相对密度、力学性能检测和微观结构分析.结果表明:随着ZrB2球磨时间和SiC含量的增加,该复相陶瓷相对密度先增加后略有降低,ZrB2最佳球磨时间为8小时,SiC最佳含量为20vol.%.ZrB2+20vol.%SiC复相陶瓷的相对密度达到98.3%,抗弯强度达到631±4MPa,断裂韧性达到5.4±0.2 MPa·m1/2.随着球磨时间的增加,ZrB2+20vol.%SiC复相陶瓷的断裂方式由穿晶断裂向沿晶断裂转变.     

高能球磨和热压烧结制备SiC/Ti_3SiC_2复相陶瓷及其性能

以Ti,Si和C粉为主要原料,利用高能球磨及热压烧结制备了SiC/Ti3SiC2复相陶瓷。研究了工艺条件尤其是烧结温度和压力对合成产物相组成、微观结构及性能的影响,并结合X射线衍射、扫描电镜等检测结果探讨了Ti-Si-C体系反应合成机理。结果表明:通过高能球磨18h,在25MP和1300oC热压,可得到均匀、致密的SiC/Ti3SiC2复相陶瓷材料。Si含量对SiC/Ti3SiC2材料的相组成及性能有较大影响。起始原料中的Ti,Si,C和Al的质量比为3:1.2:2:0.2时,材料性能提高明显,其弯曲强度、断裂韧性、密度和相对密度分别为526.65MPa,8.67MPa·m1/2,4.058g/cm3,89.78%。显微结构的观察表明,SiC/Ti3SiC2复合材料的断裂具有沿晶和穿晶混合断裂特征。SiC颗粒增韧抑制了微裂纹在Ti3SiC基体中的扩展。     

加入添加剂对MgO-MgAl_2O_4质耐火材料力学性能的改善

研究了ZrSiO4-3mol%Y2O3添加剂对MgO-MgAl2O4耐火材料的力学性能和抗热应力参数的影响。研究表明,加入添加剂后力学性能显著改善,R-Rst参数提高到原材料的2~3倍。改善耐火材料的力学性能和热性能的参数取决于：（1）ZrSiO4分解后生成的Mg2SiO4阻止了裂纹的产生和传播;（2）微裂纹在短距离内相互交叉传播;（3）微裂纹遇到气孔或由ZrSiO4分解产生的ZrO2晶粒（Y2O3与ZrO2晶粒在同一位置分布）会被吸收或扩展;（4）引入ZrSiO4-Y2O3后穿晶裂纹和沿晶裂纹同时存在;（5）致密度增加;（6）MgO晶粒粒径明显变小。     

钇铝石榴石恒速无压烧结行为及激活能研究

通过溶胶凝胶方法制备了平均粒径约为1 μm的钇铝石榴石(YAG)粉体,研究了其在室温至1600 ℃温度范围的恒速无压烧结行为,发现当升温速率为2 ℃/min时,样品在1236 ℃开始收缩,最终收缩率为17.04%;钇铝石榴石坯体样品在200～1100 ℃之间的平均线膨胀系数为9.34×10-6/℃;显微结构观察表明样品烧结过程中颗粒长大不明显,主要以沿晶断裂方式为主;以烧结曲线为基础,使用基于相对收缩率和相对密度的Arrhenius拟合法,计算了YAG烧结过程的烧结激活能,分别为116 kJ/mol和149 kJ/mol.     

烧结温度对Al_2O_3 WC陶瓷强韧性的影响

采用不同常压烧结（CP）温度制备了Al2O3＋WC复合陶瓷材料。利用扫描电镜（SEM）、X一射线衍射、能谱分析（EDAX）等手段和三点弯曲、单边切口梁等力学方法研究了该材料的组织结构、力学性能及增韧机制。结果表明,1600℃烧结Al2O3＋WC陶瓷各相结合致密、分布均匀且晶粒微细,其断裂形式为沿晶断裂;室温断裂强度为520MPa;断裂韧性为6.2MPa·m1／2;第二相WC弥散分布细化了基本晶粒,韧化机制主要为裂纹弯曲偏转韧化。     

FeCuCoY超细合金粉末胎体的烧结及其力学性能研究

采用共沉淀还原扩散法制备了不同Y含量的FeCuCoY超细合金粉,并采用真空热压机将之烧结为胎体试样块.重点研究了Y含量、烧结温度(700℃～900℃)对FeCuCoY胎体断口形貌、相对密度、硬度和抗弯强度的影响.实验结果表明:添加适量Y元素可明显改善FeCuCo超细合金粉胎体的硬度和抗弯强度,并能在一定程度上加快胎体烧结过程的进行.在不同的烧结温度下,FeCuCoY超细合金粉胎体的断口为沿晶断裂和穿晶断裂的混合型断口,且穿晶断裂所占比例随着温度的升高而增大;Y元素在合金中的最佳添加量为0.5wt.%,最佳烧结温度为800℃.此时,胎体的相对密度为98.0%,硬度为103.6HRB,抗弯强度为1531.41MPa.     

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.     

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.     

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…     

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。     

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.     

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。     

用两个形状指数表征粉煤灰颗粒形貌的研究

引用两个形状指数表征颗粒形状的概念,即先将颗粒形状近似为椭圆,再将椭圆图像分离:以圆为基准的颗粒宏观形状指数δ;以光滑椭圆为基准的颗粒轮廓凹凸度,即微观形状指数ζ。分析和发展了近似椭圆模型。并运用图像分析仪对粉煤灰、水泥样品进行实验。结果表明,粉煤灰颗粒的两个形状指数δ和ζ都大于水泥颗粒。证明粉煤灰颗粒的球形度、表面光滑度优于水泥,而且,随着粒径增大,δ和ζ呈下降趋势,表明磨制颗粒越粗。(?)粒形状越不规则。文中还运用近似椭圆模型再现了颗粒的模拟图像。     

典型煤碳燃烧特性研究和数值模拟

本文以三种典型煤的碳燃烧为研究对象，分别采用简单一维沉降燃烧方式和等温加热燃烧方式，实验研究了煤在快速加热条件下，其碳的初期和中，后期燃烧过程。以实验为基础，建立了煤的碳燃烧模型，变工况数值模拟了煤的碳燃烧过程，揭示了煤不同条件下的单颗粒碳燃烧特性。