PVD涂层陶瓷刀具切削灰铸铁的性能研究

发布时间：2018-01-17 14:47

本文关键词：PVD涂层陶瓷刀具切削灰铸铁的性能研究　出处：《广东工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：在现代高速、高效加工技术迅速发展下,陶瓷材料(主要分为氧化铝基和氮化硅基陶瓷材料)以其优异的耐磨性和稳定的高温性能成为当世纪最有应用前景的刀具材料之一,但目前仍有一些技术难点限制着陶瓷刀具材料在高速加工领域的广泛应用。氧化铝陶瓷材料的强度与抗热震性较弱,在切削冲击下容易崩刃甚至碎裂；而氮化硅陶瓷材料易与工件中的Fe发生亲和,在切削高温下会发生化学反应使刀具化学稳定性下降,导致刀具急剧磨损。随着硬质涂层技术的发展,在刀具表面沉积一层硬质、耐磨或者化学性能稳定的涂层,成为一种有效改善刀具切削性能的途径。其中,物理气相沉积(PVD)法制备涂层时,工艺温度要求低,且无污染物排放,是一种环境友好科学技术。而且该法所沉积的涂层还具有高硬度、低摩擦系数、优异的耐磨性和化学稳定性等特点,应用在陶瓷刀具上可与基体材料性能互补,大幅度提高陶瓷刀具的切削性能与使用寿命。为了研究PVD涂层陶瓷刀具的切削性能,本课题在采用物理气相沉积中阴极电弧蒸发镀(PVD-CAE)工艺在氧化铝刀具表面沉积TiN、TiSiN涂层,在氮化硅刀具表面沉积TiAlN、TiAlSiN涂层和CrAlN、TiAlN涂层。采用扫描电镜(SEM)测量观察涂层微观结构与厚度,分别采用显微硬度计和划痕仪表征涂层的结合强度与表面硬度。并结合涂层的微观结构与力学性能,通过切削灰铸铁实验研究多种PVD涂层陶瓷刀具的切削性能和磨损机理。本课题还以CrAlN、TiAlN涂层氮化硅刀具为研究对象,分析不同切削方式与切削速度对PVD涂层陶瓷刀具切削寿命、磨损机理和刀具加工质量的影响。结果表明：1)采用PVD法沉积在陶瓷刀具表面的涂层结构致密,与基体结合良好,均能有效提高刀具的表面硬度,从而提高刀具的切削寿命。2)TiN、TiSiN涂层和无涂层氧化铝刀具切削灰铸铁的磨损机制主要是磨粒磨损,无涂层刀具还会出现微崩刃。TiAlSiN涂层和无涂层氮化硅刀具切削灰铸铁过程中主要的磨损机制为磨粒磨损和少量的粘结磨损。而TiAlN涂层氮化硅刀具切削灰铸铁时,磨损初期主要发生磨粒磨损和少量粘结磨损,继而出现严重的粘结磨损。3)在连续车削过程中,PVD涂层氮化硅陶瓷刀具的切削寿命均随着切削速度的增大而迅速减少,不同切削速度下PVD涂层陶瓷刀具切削灰铸铁的磨损机理无明显区别。4)在高速面铣过程中,PVD涂层氮化硅刀具的使用寿命先是随着切削速度的增大而减少,当切削速度上升到某一值后,则随切削速度的上升而增加。不同切削速度下涂层刀具出现的磨损机理本质相同,只是刀具的粘结磨损轻重不同。面铣过程中刀具加工质量随切削速度的变化与刀具使用寿命变化相似。
[Abstract]:With the rapid development of modern high speed and high efficiency processing technology. Ceramic materials (mainly alumina and silicon nitride based ceramic materials) have become one of the most promising tool materials in the century for their excellent wear resistance and stable high temperature properties. However, there are still some technical difficulties which limit the wide application of ceramic tool materials in the field of high-speed machining. The strength and thermal shock resistance of alumina ceramic materials are weak, and it is easy to break down or even break under the impact of cutting. The silicon nitride ceramic material is easy to be compatible with Fe in the workpiece, and chemical reaction will occur at high temperature, which will lead to the tool chemical stability decline, leading to the sharp wear of the tool, with the development of hard coating technology. Deposition of a hard, wear-resistant or chemically stable coating on the surface of the cutting tool is an effective way to improve the cutting performance of the tool, especially when the coating is prepared by physical vapor deposition (PVD) method. The coating deposited by this method has the advantages of high hardness, low friction coefficient, excellent wear resistance and chemical stability. In order to study the cutting performance of PVD coated ceramic tools, the cutting performance and service life of ceramic tools can be greatly improved by complementing the properties of ceramic tools with substrate. In this paper, TiN- TiSiN coating was deposited on the surface of alumina tool and TiAlN was deposited on the surface of silicon nitride tool by cathodic arc evaporation deposition (PVD-CAE) process in physical vapor deposition. The microstructure and thickness of TiAlSiN and CrAlN TiAlN coatings were measured by scanning electron microscopy (SEM). The bonding strength and surface hardness of the coating were characterized by microhardness meter and scratch instrument respectively. The microstructure and mechanical properties of the coating were also combined. The cutting performance and wear mechanism of various PVD coated ceramic cutters were studied by cutting gray cast iron. The CrAlN TiAlN coated silicon nitride tool was also used as the research object. The cutting life of PVD coated ceramic tool with different cutting methods and cutting speed was analyzed. The results show that the coating deposited on the ceramic tool surface by PVD method is compact in structure and well bonded with the substrate, which can effectively improve the surface hardness of the tool. Thus, the wear mechanism of cutting gray cast iron with Al _ 2O _ 3 and without coating is mainly abrasive wear. The main wear mechanisms in cutting gray cast iron with uncoated silicon nitride tool are abrasive wear and a little bonding wear, while TiAlN coating nitridation is the main wear mechanism in the process of cutting gray cast iron with micro-disintegrating edge. TiAlSiN coating and uncoated silicon nitride tool. When cutting gray cast iron with silicon tool. Abrasive wear and a small amount of bond wear occur in the initial wear stage, and then serious adhesive wear. 3) in the continuous turning process. The cutting life of PVD coated silicon nitride ceramic tool decreases rapidly with the increase of cutting speed. The wear mechanism of cutting gray cast iron with PVD coated ceramic tool at different cutting speed has no obvious difference. 4) in the process of high speed surface milling. The service life of PVD coated silicon nitride tool decreases with the increase of cutting speed, when the cutting speed increases to a certain value. The wear mechanism of coated cutting tools at different cutting speeds is the same in essence. The change of cutting tool quality with cutting speed is similar to the change of tool service life.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG711

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