Studies on Sintering and Melting Process of Powders by Laser Irradiation and Induced Heating Method

本课题的研究目标是建立一套适合于材料合成过程、功能性绿色体生产过程和烧结过程的工艺设计和控制方法。一系列的研究结果如下：从粉体技术的角度综述了精细陶瓷作为一种功能材料的发展。指出了评价和标准化的意义，介绍了杂交在技术和产业上的动向。从设备工程的角度对激光辐照法制备超细颗粒进行了研究。结果表明，基于布朗混凝模型的模拟结果可以很好地解释颗粒的生长机理。采用非定常传热模型，对物料内部传热进行了分析。为了对陶瓷粉末进行表征，对不同厂家生产的几十种材料粉末进行了测试。一系列的数据得出了绿密度和它们形成条件之间的经验相关性。这种相关性使得绿密度可以通过水龙头密度和压实压力来预测。建立了坯度与烧结密度之间的定量关系，阐明了工艺条件对坯度和烧结密度的影响。结果表明，烧结密度与生坯密度可以用简单的表达式关系式表示，提出的图形分析方法有助于了解工艺条件对烧结密度和生坯密度的影响。作为功能梯度材料的基础研究，提出了三种能够平稳、连续地改变成形材料组成的技术。在每一种工艺中，都对工作条件进行了实验研究，以控制成分分布。这些技术的吸引人的特点是它们的简单性，从而使它们易于应用于其他材料合成工艺。少

The objectives of this research project are to establish a series of process design and control methodology which can be suitabiy applied to the material synthesis process, production process of functionally green body and sintering process. A series of researches yields results as follows.1. Development of fine ceramics as a functional material is reviewed in connection with powder technology. Significance of evaluation and standardization pointed out, and movement of hybridization in technologies and industries is introduced.2. Production of ultrafine particles by laser irradiation method has been studied from a view point of apparatus engineering. It is shown that simulation results based on Brownian coagulation model can explain particle growth mechanism. Heat transfer inside the substance is also analyzed by making use of unsteady heat transfer model.3. To characterize ceramics powders a few tens of material powders produced by different manufacturers have been subjected to the sa … More me ceramics production process. A series of data yields an empirical correlation between green density and their forming conditions. The correlation enables green densities to be predicted from tap density and compaction pressure.4. The quantitative correlation between green and sintered density has been found out to clarify the effects of process condition on them. It is shown that the sintered density can be correlated with the green density by simple expression, and that graphical analysis proposed can be help to under stand the effect of process conditions on sintered and green density.5. As a basis research of functionally gradient material, three kinds of technique are proposed which can smoothly and continuously vary the composition of formed material. In each technique the working conditions have been experimentally investigated to control the composition profile. The attractive feature of these technique is their simplicity, which thus facilitates their application to other material synthesis processes. Less