SiC晶须／Y—TZP（含Al2O3）复合材料力学性能的研究

通过SiC晶须对Y-TZP陶瓷材料的补强,发现:在SiC晶须分散均匀的情况下,尽管SiC晶须的体积含量高达30％,复合材料中单斜相氧化锆的含量并不高,氧化锆的应力诱导相变仍是复合材料的主要增韧机理,复合材料的力学性能并不随着SiC晶须含量的增加而降低。在复合材料中加入氧化铝后,发现少量的氧化铝加入有利于复合材料力学性能的提高。在氧化铝重量含量为6%,SiC晶须体积含量为20%时,复合材料的强度和断裂韧性分别为:1329±13MPa和14.8±0.7MPa·m~(1/2)。但是,过多的氧化铝加入又会使复合材料的力学性能出现下降趋势。SiC晶须加入后,复合材料的高温强度和抗热震性都有明显改善。     

直接浸渗法制备MoSi2/SiC复合材料

本文通过直接浸渗法制备了致密的MoSi2/SiC复合材料,在室温下该材料的强度为248±25MPa,1600℃下的强度为205±20MPa,室温下显微硬度为12.6GPa,断裂韧性为3.6MPa·m1/2.同时分析了复合材料的相组成;观察了材料的显微结构;讨论了热处理工艺和成型工艺对烧结体性能的影响.     

玻璃渗透氧化锆全陶瓷牙科材料的制备和表征

开发了一种适合渗透多孔四方相氧化锆的玻璃,并通过玻璃渗透工艺制备了氧化锆-玻璃全陶瓷牙科材料. 研究表明,该渗透玻璃在渗透温度下(1100~1200℃)具有合适的粘度、良好的渗透性和化学相容性,且热膨胀系数与氧化锆匹配;熔融态玻璃通过毛细管作用力填充预烧后的多孔四方相氧化锆坯体的孔隙,形成氧化锆和玻璃相互交融的致密的三维网络结构,渗透过程中没有发生氧化锆从四方相到单斜相的转变. 该氧化锆-玻璃复合材料的弯曲强度和断裂韧性分别为400 MPa和5.5 MPa×m1/2,较氧化玻璃复合材料分别提高了32%和41%.     

碳化硼增强氧化铝复合材料

添加两种不同形状的碳化硼颗粒,成功地提高了氧化铝的机械性能。氧化铝-碳化硼晶须复合材料,其K_(IC)为7.26±0.20MPa·m~(1/2);氧化铝-碳化硼粒子复合材料,其K_(IC)为5.27±0.12MPa·m~(1/2)。这些复合材料的断裂韧性取决于碳化硼颗粒的体积分数及其尺寸和形状。碳化硼添加量在5-20v％范围内,抗弯强度明显提高,碳化硼晶须复合材料其抗弯强度提高25％,而碳化硼粒子复合材料其抗弯强度提高47％。     

莫来石-氧化锆复合材料中氧化锆的强韧化机理

研究了莫来石-氧化锆复合陶瓷。用湿化学法制备的纯荚来石其常温抗弯强度和断裂韧性较低,σ_f=236MPa,K_(Ic)=2.5MPa·m~(1/2),而莫来石-氧化锆复合陶瓷的常温强度和韧性大大提高,σ_f=612 MPa,K_(Ic)=5.1MPa·m~(1/2)。研究结果表明:氧化锆的强韧化机理是微应力场作用、应力诱导相变增韧及第二相粒子强化。     

掺碳SiC颗粒对MoSi_2复合材料性能的影响

研究分析了掺碳SiCp/MoSi2 复合材料的相组成、室温和高温力学性能、高温抗氧化性能、耐磨性能以及电阻率 .结果表明 :(SiCp+C) /MoSi2 复合材料主要由MoSi2 ,α -SiCp,Mo5Si3和 β -SiC组成 .材料的密度和相对密度分别为 5.1 2 g/cm3和 91 % ;Vickers硬度 ,抗弯强度和断裂韧性分别为 1 2 .2GPa ,530MPa和 7.2MPa·m1 / 2 ;80 0℃的Vickers硬度为 8.0GPa ,1 2 0 0℃和 1 40 0℃的抗压强度分别为 560MPa和1 60MPa .材料的抗氧化性能优良 .在Al2 O3和SiC磨盘上表现出优异的耐磨性能 .电阻率为 40 .2 μΩ·cm .与非增强MoSi2 相比 ,材料的各种力学性能有大幅度的提高     

牙科用氧化锆/氧化铝/玻璃复合材料的研制

采用熔融渗入法制备了牙科用氧化铝基玻璃复合材料，为了提高材料的强度和韧性，在氧化铝预制体中加入一定量的氧化锆。借助sEM和XRD对材料的微观结构和晶相组成进行了研究。研究结果表明：4Y—TZP的引入量为15wt％，掣合材料的抗折强度可达到182MPa，氧化铝基体经玻璃渗透以后，抗折强度等性能明显改善，而且材料化学性能稳定，色泽逼真，是一种较理想的牙科用材料。     

Cf/SiC复合材料的制备及性能的研究

采用料浆渗积-有机前躯体裂解工艺制备碳纤维增强碳化硅陶瓷基复合材料.制备材料的抗弯强度达283 MPa,断裂韧性达12.1 MPa·m1/2.     

多晶YAG陶瓷的制备及力学性能

本实验采用共沉淀方法制备YAG微粉 ,Al和Y元素分布均匀 ,在 90 0℃煅烧 2h即可全部转变为YAG粉体 ,无过渡相 .15 0 0℃热压 1h可获得致密烧结体 ,其抗弯强度为 2 45MPa ,断裂韧性为 2 .0MPa·m1 /2 ,晶粒大小为 3～ 6μm ;14 0 0℃放电等离子烧结 5min可获得相对密度为 93 %的烧结体 ,其抗弯强度为 3 4 8MPa,断裂韧性为 2 .1MPa·m1 /2 ,晶粒大小为 1～ 2 μm .     

热压烧结法制备碳化钛/氧化铝复合材料

把TiC颗粒和金属Al以AlTiC中间合金的形式引入Al2O3陶瓷中,用过渡液相热压烧结法制备了TiC/Al2O3复合材料,并对其微观结构与力学性能进行了研究。结果表明:在1450℃,30MPa条件下,热压烧结制备的TiC/Al2O3复合材料中TiC与Al2O3能稳定共存,材料的断裂韧性和Vickers硬度均有明显提高。材料的Vickers硬度平均超过23.5GPa,断裂韧性超过8.7MPa·m1/2,密度低于纯Al2O3的。由于添加相AlTiC和Al2O3的成本均较低,因而找到了一种低成本制造高性能TiC/Al2O3复合材料的方法。     

乙烯酮(双乙烯酮)下游产品废水的治理技术

乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。     

Semi-empirical equation of state of metals. Equation of state of aluminum

A semi-empirical equation of state for metals is described. Its capabilities are demonstrated by the example of the equation of state for aluminum. New experimental data are presented on the location of the isentrope of aluminum for unloading from the state at p = 229.71 GPa on the shock adiabat to an aerogel (SiO₂) of density 0.08 g/cm³. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 61–75, March–April, 2008.     

水泥水化热测定方法综述

水泥水化热是中、低热水泥和核电工程用水泥的一项关键的技术指标。全球范围内测定水泥水化热的方法有溶解法、直接法/半绝热法、等温传导量热法三种。本文总结了中、美、欧相关方法标准,对其测试原理、仪器设备、试验过程等方面进行了比对,并对其在领域的应用做了简单的概括。     

我国聚碳酸酯工业发展概况

介绍我国聚碳酸酯生产能力和消费需求,对聚碳酸酯在信息工业中的应用作了简短介绍     

Calorimetric and Computational Study of Enthalpy of Formation of Diperoxide of Cyclohexanone

A thermochemical rather simple experimental technique is applied to determine the enthalpy of formation of Diperoxide of ciclohexanone. The study is complemented with suitable theoretical calculations at the semiempirical and ab initio levels. A particular satisfactory agreement between both ways is found for the ab initio calculation at the 6–311G basis This set level. Some possible extensions of the present procedure are pointed out.     

Effect of degree of deacetylation of chitosan on the kinetics of ultrasonic degradation of chitosan

The objective of the study was to explore the effect of the degree of deacetylation (DD) of the chitosan used on the degradation rate and rate constant during ultrasonic degradation. Chitin was extracted from red shrimp process waste. Four different DD chitosans were prepared from chitin by alkali deacetylation. Those chitosans were degraded by ultrasonic radiation to different molecular weights. Changes of the molecular weight were determined by light scattering, and data of molecular weight changes were used to calculate the degradation rate and rate constant. The results were as follows: The molecular weight of chitosans decreased with an increasing ultrasonication time. The curves of the molecular weight versus the ultrasonication time were broken at 1‐h treatment. The degradation rate and rate constant of sonolysis decreased with an increasing ultrasonication time. This may be because the chances of being attacked by the cavitation energy increased with an increasing molecular weight species and may be because smaller molecular weight species have shorter relaxation times and, thus, can alleviate the sonication stress easier. However, the degradation rate and rate constant of sonolysis increased with an increasing DD of the chitosan used. This may be because the flexibilitier molecules of higher DD chitosans are more susceptible to the shear force of elongation flow generated by the cavitation field or due to the bond energy difference of acetamido and β‐1,4‐glucoside linkage or hydrogen bonds. Breakage of the β‐1,4‐glucoside linkage will result in lower molecular weight and an increasing reaction rate and rate constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3526–3531, 2003     

气化给煤系统故障分析

气化给煤装置自投运以来,出现了气化煤仓堵煤、称重给煤机输送皮带因跑偏而损伤以及清扫装置故障频繁等问题,多次造成气化系统减负荷运行。通过对出现的各种问题进行分析,找到了产生这些问题的原因,并有针对性地采用配煤和改进清扫链等措施,使出现的问题得到了极大的改善。     

醋酸纤维素取代基分布与性质的关系

分析了以吡啶为溶剂的醋酸纤维素的13C-NMR核磁共振谱,得出了三种不同位置羟基的取代度。结合X—射线和DSC分析,初步说明具有相同取代度但未经水解和经过水解的醋酸纤维素(CA) 性质上的差异是由于三个羟基上的取代度分布不同及消晶程度差异所致。     

Generalization of vdW type of equations of state

1 INTRODUCTIONBecause of importance of equations of state (EOS)in science and industry,hundreds forms of EOS havebeen presented since latter 19th century.It seems impossible to develop a general equation covering vari-ous kinds of EOS.But for cubic EOS,several generalequations have been reported already. Martin presented the first general equation whichis following p=RT/V-α(T)/(υ β)(υ γ) δ(T)/υ(υ β)(υ γ) (1) Kumar et a1.presented an equation called the most general form of a density-cubic or, alterna tively,volume-cubic mathematical equation,the form of which is as follows     

船舶柴油机涡轮增压器的清洗

采用喷射清洗剂的方法，清洗涡轮叶片积炭。