LAS系统微晶玻璃的制备及析晶研究

采用烧结法和溶胶-凝胶法制备了LAS系统微晶玻璃,并研究了其析晶性能。结果表明,烧结法制备的样品中晶粒尺寸为100～150nm,分布均匀,主晶相为β-锂辉石相,另外含有少量的Moganite石英相,溶胶-凝胶法制备的样品中晶粒尺寸为10～60nm,分布均匀,样品中存在Al2O3和LiAlO2相,而SiO2没有结晶,形成玻璃体。核化温度为600℃、晶化温度为680℃时,微晶玻璃的结晶效果比较好。     

多孔微晶玻璃的制备、性能及用途

多孔微晶玻璃是一种密度小、质量轻、比表面积大、阻尼性能好的新型功能材料。研究了粉末烧结法、整体析晶-酸浸法、溶胶-凝胶法制多孔微晶玻璃的成孔机理和制备过程。分析了多孔微晶玻璃的力学性能和渗透性能。从过滤、保温、载体、分离4个主要方面阐述了多孔微晶玻璃的用途，展望了多孔微晶玻璃的发展趋势及应用前景。     

磁性生物活性玻璃陶瓷的制备研究进展

磁性生物玻璃陶瓷主要指将具有磁性的元素,如铁等引入到生物玻璃陶瓷中,制备出结构和性质类似于人体组织的生物材料,其独特的功能使之成为近来新材料研究的热点.介绍了较为常见的几种磁性生物玻璃陶瓷的制备方法,如熔融煅烧法、溶胶-凝胶法、共沉淀法、双相复合法等,并对它们的特点进行了分析.     

钙磷硅系生物活性玻璃的溶胶-凝胶法制备与表征

采用溶胶-凝胶法制备了CaO—P2O5-SiO2生物活性玻璃，研究了原料的加入顺序的影响，确定了溶胶-凝胶生物玻璃的制备工艺；利用差热分析、X射线衍射（XRD）分析、原子吸收光谱（IR）和扫描电镜（SEM）等手段，研究了溶胶-凝胶玻璃的热演变过程及微观结构和形貌。将该生物玻璃粉与柠檬酸混合，调和固化后于模拟体液申浸泡。研究其生物活性。结果表明，所制备的生物玻璃具有良好的生物活性，能有效地诱导钙、磷离子沉积。     

LAS系统微晶玻璃的制备及析晶研究

采用烧结法和溶胶-凝胶法制备了LAS系统微晶玻璃，并研究了其析晶性能。结果表明，烧结法制备的样品中晶粒尺寸为100-150nm，分布均匀，主晶相为β-锂辉石相，另外含有少量的Moganite石英相，溶胶-凝胶法制备的样品中晶粒尺寸为10-60nm，分布均匀，样品中存在Al2O3和LiAlO2相，而SiO2没有结晶，形成...     

磷灰石-硅灰石多孔玻璃陶瓷的制备与晶相结构研究

采用溶胶-凝胶法制备磷灰石-硅灰石(AW)生物活性玻璃陶瓷纳米前驱体粉末,前驱体粉末经热处理后,采用有机泡沫漫渍成型,烧结制备了多孔AW生物活性玻璃陶瓷.通过差热和热重分析、X射线衍射分析、红外图谱分析、扫描电镜、透射电镜等分析测试方法,对AW前驱体粉末的微观结构,及其在煅烧过程中的晶相转变进行了研究,确定了制备纳米级AW前驱体粉的最佳工艺条件,推测出微晶玻璃体中各晶相的析出温度,确定了溶胶-凝胶法制备多孔AW玻璃陶瓷的煅烧工艺,体外模拟体液浸泡实验表明材料具有较高的矿化功能和生物活性.     

SiO2-TiO2-ZrO2涂层的制备及其特性

用溶胶-凝胶法(sol-gel method)在不锈钢表面制备了 SiO\-2-TiO\-2-ZrO\-2系无机氧化膜(STZ).用DTA/TG、IR、XRD和SEM等手段研究了涂层制备时由凝胶向玻璃态的转变以及涂层薄膜的显微结构特点,考察了涂层对基体的保护效果. 试验结果表明,在溶胶至凝胶最终转变为无机氧化物的过程中形成了无机网络,Si4+ 和Zr4+充当了网络骨架的形成离子.涂层为无定型玻璃态,其间混有石英、锐钛矿或金红石等微晶.     

SiO2-Na2O-CaO-P2O5-Fe2O3铁磁微晶玻璃的制备与性能研究

铁磁性微晶玻璃由于具有磁性和生物活性,可以用作磁感应热疗的热种子材料.采用SiO2-Na2O-CaO-P2O5-Fe2O3五元系统,通过共沉淀-熔融法和熔融法两种不同的方法制备铁磁性微晶玻璃,利用XRD确定其晶相并计算晶体的晶格常数和晶粒尺寸,并通过VSM表征样品的磁性能.结果表明,玻璃液在自然冷却的过程中就形成了大量的磁铁矿,不经过热处理过程即可制得具有磁铁矿唯一晶相的铁磁性微晶玻璃并具有生物活性.共沉淀-熔融法制备的样品磁性更强.     

溶胶-凝胶法制备锂铝硅微晶玻璃

Li2O-Al2O3-SiO2（LAS）系统微晶玻璃是微晶玻璃中的一个重要分支。这种微晶玻璃的主要性能是低膨胀，耐热冲击性，其应用非常广泛。从原料角度总结了制备锂铝硅微晶玻璃的溶胶-凝胶方法，并对各种方法的特点进行了简要的评述，提出了研究中存在的问题及其今后的发展方向。     

裂纹玻璃晶化法制备建筑装饰用微晶玻璃

制备建筑装饰用微晶玻璃的现役工艺主要有烧结法和压延法两种,前者容易出现气孔缺陷,后者不能生成纹理.为克服现役工艺的不足,本文提出裂纹玻璃晶化法工艺,即以裂纹玻璃作为母玻璃,通过烧结、晶化二步热处理而制备出微晶玻璃.XRD测得裂纹玻璃晶化法微晶玻璃样品的主晶相为β-硅灰石;ESEM观察到样品的微观结构由不均匀分布的粒径在0.2~0.5μm的晶体组成;利用比重仪测得样品的气孔率低于现役烧结法样品.实验表明,裂纹玻璃晶化法能克服现役工艺的不足,制备出气孔率低、具有类似古生物残骸纹理的微晶玻璃,装饰效果更佳.     

虚拟MEMS加工工艺的定义、关键技术与实现框架

首先提出了虚拟MEMS加工工艺的概念,它是利用图形动态生长,来模拟每步工艺过程,整个工艺过程中形状变化均包含在虚拟工艺中。其次,分析了实现虚拟工艺所涉及的关键技术：工艺描述、工艺模型和加工过程的可视化。第三,给出了基于专家系统技术的虚拟工艺实现框架。最后,实现了一种表面硅工艺的例子,初步验证了实现框架时间和精确度的可行性。     

企业流程再造的熵模型

行比较分析的基础上,提出了适应于企业流程要素关系研究的4点假设。给出了流程熵计算的基本步骤,讨论了降低流程熵值的可操作性办法。结合实例验证了该研究的有效性。     

Near-infrared spectroscopic monitoring of a series of industrial batch processes using a bilinear grey model

A good process understanding is the foundation for process optimization, process monitoring, end-point detection, and estimation of the end-product quality. Performing good process measurements and the construction of process models will contribute to a better process understanding. To improve the process knowledge it is common to build process models. These models are often based on first principles such as kinetic rates or mass balances. These types of models are also known as hard or white models. White models are characterized by being generally applicable but often having only a reasonable fit to real process data. Other commonly used types of models are empirical or black-box models such as regression and neural nets. Black-box models are characterized by having a good data fit but they lack a chemically meaningful model interpretation. Alternative models are grey models, which are combinations of white models and black models. The aim of a grey model is to combine the advantages of both black-box models and white models. In a qualitative case study of monitoring industrial batches using near-infrared (NIR) spectroscopy, it is shown that grey models are a good tool for detecting batch-to-batch variations and an excellent tool for process diagnosis compared to common spectroscopic monitoring tools.     

模具曲面机器人智能抛光系统的研究

介绍了一个初步实现的模具曲面机器人智能抛光系统的构成,分析了模具机器人抛光的特性,重点对实现机器人具智能抛光系统的若干问题诸如工艺过程建模、工艺知识的获取与表达、工艺知识库与数据库建立、智能工艺规划系统的构造以及抛光刀具轨迹自动生成等进行了研究。     

Finite element modelling of solidification phenomena

The process of solidification process is complex in nature and the simulation of such process is required in industry before it is actually undertaken. Finite element method is used to simulate the heat transfer process accompanying the solidification process. The metal and the mould along with the air gap formation is accounted in the heat transfer simulation. Distortion of the casting is caused due to non-uniform shrinkage associated with the process. Residual stresses are induced in the final castings. Simulation of the shrinkage and the thermal stresses are also carried out using finite element methods. The material behaviour is considered as visco-plastic. The simulations are compared with available experimental data and the comparison is found to be good. Special considerations regarding the simulation of solidification process are also brought out. An erratum to this article is available at .     

Single-Spark Analysis of Electro-Discharge Deposition Process

Electro-discharge deposition (EDD) process is one of the newly developing, nonlithographic additive manufacturing methods to fabricate 3D microproducts. The advantage of the EDD process is that 3D microcomponents can be manufactured from the materials which are electrically conductive in nature. In this paper, a comprehensive attempt to develop a thermophysical model for single discharge deposition process has been reported. Experiments are designed and conducted by central composite design (CCD) and the obtained results are compared with simulation results. Parametric analysis is carried out to study the effects of EDD process parameters like current, pulse-on time, and duty factor on height, width, and weight of deposition. The objective of this research work is to simulate and predict the material deposition mechanism of EDD process in a single pulse. Simulation results are compared with experimental results and it is found that the developed model can predict results which are closer to experimental results. It is concluded from the results that the thermophysical model can be further modified to establish EDD process with optimum process parameters.     

多工位高速锻造工艺优化技术研究现状

简要介绍了多工位高速锻造工艺及其特点,阐述了基于有限元模拟的锻造工艺优化技术的发展现状,并在此基础上根据多工位高速锻造工艺的特点,阐明了多工位高速锻造工艺优化技术研究中存在的主要问题,探索了多工位高速锻造工艺优化技术研究的方向.     

圆形凸台件的冷挤压工艺及模具设计

对圆形凸台件的冷挤压工艺与机械加工工艺进行了比较,对圆形凸台件进行了冷挤压工艺分析,叙述了工艺难点,详细叙述了圆形凸台件冷挤压工艺的工序设计、毛坯计算、毛坯软化处理、凸、凹模的设计及模具整体设计、介绍了圆形凸台件的冷挤压工艺的优越性.     

基于LSSVM的多元过程非参数监控方法研究

多元控制图常用于对多个相关变量进行监控,用以发现制造过程中存在的系统性变异。当多元过程的分布未知时,常用非参数方法进行过程监控。针对多元过程监控问题,提出了一种基于最小二乘支持向量机(least squares support vector machine,LSSVM)的多元过程非参数监控方法。在仅有受控数据(参考数据集)的条件下,采用移动窗口技术对过程数据序列进行预处理,并与参考数据集一起用于对LSSVM进行动态训练,进而以移动窗口中的数据与分类超平面之间的距离为控制变量进行多元过程监控。讨论了监控模型设计与参数选择方法并通过仿真和实例进行了性能评估。     

小型内压缩流程空分设备流程探讨

随着来自第三世界国家的小型内压缩流程空分设备订单的不断增多,选择配置较简单、总价和能耗较低的空分设备流程显得很重要。分析正流膨胀流程、返流膨胀流程以及返流膨胀流程中单塔流程和双塔流程的特点、优势以及适用场合;阐述不同的空压机排气压力对空分设备相关参数的影响;探讨了保持高压液氧泵前液氧的过冷度等流程问题。