【作者】 邓朝晖；

【导师】 孙宗禹；

【作者基本信息】 湖南大学 ， 机械制造及其自动化， 2004， 博士

【摘要】 本文对近些年来新出现的纳米结构（nanostructured）和普通结构（conventional）陶瓷涂层（n／c-WC／Co和n／c-Al₂O₃／TriO₂）的精密磨削的磨削机理及磨削工艺仿真预报技术进行了研究。通过实验研究、理论建模和分析，揭示了纳米结构陶瓷涂层精密磨削机理，初步构建了纳米结构陶瓷涂层精密磨削的基础理论，结合磨削工艺仿真预报软件的开发应用，寻求以最优化的磨削工艺参数来实现纳米结构陶瓷涂层的高效经济、优质、低损伤精密加工。其研究成果对纳米结构陶瓷涂层工业化应用和陶瓷材料精密磨削理论的完善以及我国特种材料精密加工技术水平的提高具有重要的理论价值和实用价值。 论文首先在文献综述的基础上对纳米结构陶瓷涂层精密磨削的基础理论进行了初步的分析，提出了构建纳米结构陶瓷涂层精密磨削基础理论的研究思路。论文对纳米结构陶瓷涂层精密磨削实验研究方案进行了详细的介绍。 论文对磨削用量、砂轮特性、材料特性及涂层显微结构等磨削参数对磨削纳米结构陶瓷涂层时的磨削力、磨削力分力比、比磨削能、磨削表面粗糙度、磨削表面／亚表面损伤（裂纹）及材料去除机理等可磨削性指标的影响规律进行了实验研究。以砂轮单颗磨粒法向磨削力的实验结果及所建立的理论模型为重要依据和线索，进行相关磨削现象的分析；磨削力理论模型综合考虑了砂轮磨削深度、工件进给速度和砂轮速度等磨削用量参数，考虑了材料初始切入力和工件材料的特性。通过研究，基于磨削力随磨削用量参数变化的分阶段特征，分段建立了纳米结构陶瓷涂层精密磨削的单颗磨粒法向磨削力模型。研究表明：纳米结构陶瓷涂层精密磨削所产生的磨削力和比磨削能比普通结构陶瓷涂层的要大；砂轮磨粒尺寸参数、砂轮粘结剂／磨屑厂工件涂层表面间滑擦作用和热喷涂工艺固有缺陷等因素对陶瓷涂层精密磨削的可磨削性指标有较大影响；精密磨削工艺能大大提高陶瓷涂层的轮廓支承率（承载比）；磨削纳米结构陶瓷涂层时，存在一个获得较小磨削表面粗糙度R_α值的砂轮磨削深度范围。 论文分析总结了陶瓷磨削时材料去除机理的三种分类方式，基于纳米结构陶瓷涂层可磨削性规律的实验结果结合磨削后表面／亚表面的SEM等形貌观测，以非弹性变形去除方式和脆性去除方式充分揭示了纳米结构陶瓷涂层磨削时的材料去除机理。 论文对纳米结构陶瓷涂层磨削过程的材料变形行为和裂纹系统进行了理论分析。在实验研究的基础上，建立了磨削纳米结构陶瓷涂层时产生横向裂纹和中位裂纹的临界磨削条件模型，以及反映磨削参数与纳米结构陶瓷涂层磨削后亚表面平均损伤（裂纹）深度之间定量关系的磨削模型。研究表明，产生中位裂纹所需纳米结构陶瓷涂层精密磨削机理及仿真预报技术的研究的临界载荷比产生横向裂纹所需的临界载荷要小得多。磨削时亚表面裂纹的形成及扩展与单颗磨粒法向磨削力有直接关系，还与磨削过程中所消耗能量及热喷涂工艺的固有缺陷有关。论文就材料晶粒尺寸对陶瓷涂层精密磨削可磨削性的影响规律进行了研究。 最后，论文介绍了所研制的磨削工艺仿真预报软件的开发思路、关键技术和软件的体系结构，基于本文通过实验所建立的单颗磨粒磨削力模型和磨削裂纹预报模型，给出了该软件在纳米结构陶瓷涂层精密磨削工艺仿真预报中的应用实例。更多还原

【Abstract】 This dissertation deals with the precision grinding mechanisms, grinding process simulation and prediction techniques for nanostructured and conventional ceramic coatings (n/c-WC/Co and n/c-Al2O3/TiO2) which have emerged in recent years. Through experimential investigation and theoretical modeling and analysis, precision grinding mechanisms for nanoatructured ceramic coatings are discussed, a guideline of grinding of nanoatructured ceramic coatings has been established preliminarily. Combined with the development of grinding process simulation and prediction software, the grinding processes are optiumed to realize low damage, high precision and cost-effective machinning of nanostructured ceramic coatings. The theoretical and experimental results add a great value to the nanoatructured ceramic coatings in terms of industrial application.Firstly, based on the literature reviews, the dissertation puts forward the preliminary analysis for the guideline of grinding of nanoatructured ceramic coatings, as well as the train of thought for studying it. The dissertation comprehensively introduces the scheme for the experimental study in grinding of nanoatructured ceramic coatings.The dissertation discusses the influences of the grinding process parameters, grinding wheel characteristics, material responses to grinding and coating mirostructure on grindablity, including grinding forces, grinding force ratio, specific grinding energy, surface roughness, surface integrity and materail removal mechanisms. Grindability is analyzed based on the experimental results and the theoretical modeling. The theoretical model of grinding force involves grinding depth of grinding wheel, feedrate of worktable, speed of grinding wheel, and the break-in force of material as well as material response to grinding. Different grinding force models have been established for single abrasive grits at different stages of the grinding process. It turns out that grinding forces and specific grinding energy for the nanostructured ceramic coatings are greater than that for conventional ceramic coatings. The abrasive grits of the grinding wheel, the tribological interactions of bond/chip/workpiece surface in the grinding zone, and defects from the spraying process all have an effect on the grindability. The bearing ratio of ground surfaces can be improved by precision grinding. There is a proper grinding depth for getting lower ground surface roughness.The dissertation reviews material removal mechanisms in grinding of ceramic ofthree kinds. Material removal mechanism including inelastic deformation and brittle damage of nanostructured ceramic coatings are explored in the dissertation, based on the experimental result of grindability combined the SEM analysis of ground surface of nanostructured ceramic coatings.Theoretical analysis is conducted on material deformation and crack formation during grinding process of nanostructured ceramics coatings. The dissertation proposes critical grinding condition models for predicting grinding induced lateral crack and median carak in the nanostuctured ceramic coatings, and verifies the models with experiments. The models reflecting the quantitative relation between the grinding parameters and the average depth of grinding induced subsurface damage (cracks) in the nanostrucured ceramic coatings is also proposed in the paper. It turns out that the critical force for lateral crack is higher than that of median carak. The formation and propagation of grinding induced subsurface damage (cracks) depend directly on the normal grinding force of single abrasive grit. They are also related to the grinding energy consumed during the grinding process and the defects from the spraying process. The effect of material grain size on the grindability of grinding for the nanostructured ceramic coatings is also discussed in the dissertation.Finally, this dissertation describes the simulation and prediction software developed for grinding nanostructured ceramic coatings. Described are also the key techniques and system str更多还原