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纳米TiO2的制备方法 总被引:25,自引:2,他引:23
系统地介绍了纳米二氧化钛的制备方法,在总结归纳的基础上,将制备方法分为两大类:气相法和液相法,对各种方法进行了比较,指出了它们的优缺点及适用范围。 相似文献
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超疏水表面在自清洁、油水分离、水下减阻等方面具有巨大的应用价值。传统制备超疏水表面的方法往往工艺复杂、操作难度大、效率低下。等离子喷涂是一种常见的表面改性技术,利用等离子喷涂制备超疏水表面具有制备工艺简单、制备效率高的特点。本文综述了近年来利用等离子喷涂法制备超疏水表面的研究进展。首先介绍了超疏水表面和等离子喷涂技术的基本原理;然后,总结了大气等离子喷涂和液相等离子喷涂两种方法制备超疏水表面的工艺演变过程,阐述了两种方法的制备特点;最后,指出等离子喷涂法制备超疏水表面具有操作简单、成本低、制备性能优异等优点,但也面临着工艺参数探索复杂、性能与制备效率之间难以平衡等挑战。本文期望能在航空航天、海洋科学、军事装备涉及的关键零部件表面改性方面提供一定的参考价值。 相似文献
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超疏水表面在自清洁、油水分离、水下减阻等方面具有巨大的应用价值。传统制备超疏水表面的方法往往工艺复杂、操作难度大、效率低下。等离子喷涂是一种常见的表面改性技术,利用等离子喷涂制备超疏水表面具有制备工艺简单、制备效率高的特点。本文综述了近年来利用等离子喷涂法制备超疏水表面的研究进展。首先介绍了超疏水表面和等离子喷涂技术的基本原理;然后,总结了大气等离子喷涂和液相等离子喷涂两种方法制备超疏水表面的工艺演变过程,阐述了两种方法的制备特点;最后,指出等离子喷涂法制备超疏水表面具有操作简单、成本低、制备性能优异等优点,但也面临着工艺参数探索复杂、性能与制备效率之间难以平衡等挑战。本文期望能在航空航天、海洋科学、军事装备涉及的关键零部件表面改性方面提供一定的参考价值。 相似文献
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van Sprang EN Ramaker HJ Westerhuis JA Smilde AK Gurden SP Wienke D 《Applied spectroscopy》2003,57(8):1007-1019
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. 相似文献
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METHODS FOR BRAZING CERAMIC AND METAL-CERAMIC JOINTS 总被引:5,自引:0,他引:5
Owing to improved manufacturing processes technical ceramics on the basis of oxide as well as nonoxide ceramics have gained an increasing technical potential. Among other joining techniques brazing has proved to be the most flexible joining process that can easily be adapted to various ceramic-metal-combinations. In order to induce a wetting reaction there are two different approaches. The more complicated process encircles a pre-metallization process and a subsequent brazing process. The less sophisticated process is the 'active brazing process' where special brazing alloys are employed that are able to wet ceramic base materials. Although both joining processes are very flexible there are restrictions regarding the filler metals to be used, the premetallization process and the actual (active-) brazing process. 相似文献
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Process capability indices are widely used in industry to achieve and maintain a high-quality level of manufactured items. The successful application of process capability indices requires the process to be stationary. This is not the case for trended processes with regular adjustment, which are very common in manufacturing processes. An interesting and important question is how to define and interpret the process capability for such a process. In this paper, the traditional process capability indices are modified for these trended processes. Two different sources of process variation, one from the process trend, the other from random variation, are identified and used to develop new process capability indices. Based on these new indices, we show that the capability of trended processes can be improved through periodic adjustment to its maximum achievable value. We also develop the procedures to determine the adjustment frequency to meet any prespecified requirements on the capability index or on the process yield. 相似文献
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《低温学》2014
Liquefaction of natural gas is usually a kind of high energy consumption process. Therefore, any performance improvement of the liquefaction process will definitely reduce the energy consumption. Nitrogen expansion liquefaction process is regarded as a suitable process for small-scale LNG plant due to its simplicity, quick startup and convenient maintenance. However, the disadvantage of the process is high-energy consumption. An efficient way to lower its energy consumption is to add a precooling cycle. In this paper, two different precooling cycles including propane precooling cycle and R410a precooling cycle are proposed to the nitrogen expansion liquefaction process to improve the liquefaction process performance. Unit energy consumption as an objective function is optimized in terms of several key operating parameters. Based on the optimization results, the effects of the liquefaction rate and methane recovery rate on the process performance are investigated. The thermodynamic analyses are adopted to the processes as well as the two precooling cycles. Furthermore, the exergy analyses of the main equipment are also presented and discussed. The results show that the unit energy consumption for the nitrogen expansion process with R410a precooling and with propane precooling reduce by 22.74% and 20.02% respectively, compared with nitrogen expansion process without precooling. 相似文献
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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。 相似文献
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B. Muralidharan H. Chelladurai Praveen Singh Mukesh Kumar Roy 《Materials and Manufacturing Processes》2016,31(14):1853-1864
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. 相似文献
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Collison welding is a promising material‐closed joining process that enables bonds with various advantages. It is already used as explosion welding to produce clad materials that cannot be joined otherwise. Other collision welding processes as electromagnetic pulse welding do not contain that amount of energy, but they can be used in mass production. In order to achieve a high process and product reliability, the process has to be designed accurately. But the process boundaries are not yet completely understood. In this paper, process windows for aluminium and copper joints, produced by a model test rig, are compared. Additionally, high speed observation and micro sections are used to enhance the knowledge about process boundaries and the influence of the jet. 相似文献
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Wai Chung Yeong Michael B. C. Khoo Ou Yanjing Philippe Castagliola 《Quality and Reliability Engineering International》2015,31(5):863-876
In this paper, the effects of process parameter estimation on the cost of the synthetic chart are studied. We study the increase in cost when the optimal chart's parameters corresponding to the known process parameters case are used to estimate the cost when the process parameters are actually just estimated. By studying the increase in cost, practitioners will be able to determine whether the optimal chart's parameters, computed based on known process parameters, can still be used to reliably estimate the cost when the target values of the process mean and variance are estimated. We also look at the minimum number of preliminary subgroups needed for the estimation of process parameters so that the cost for the estimated process parameters case is almost the same as the cost for the known process parameters case. Furthermore, we also look at the cost savings, in the case of process parameter estimation when the optimal chart's parameters are computed based on estimated process parameters, instead of adopting the chart's parameters corresponding to known process parameters. This enables practitioners to determine the cost advantages of selecting the chart's parameters that minimize the cost when process parameters are estimated, instead of adopting the optimal charting parameters corresponding to the case of known process parameters. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献