【摘要】：金屬的表面處理技術作為一種融合了多個行業(yè)和多個學科的技術門類,其涉及到的內容較廣,工藝方法較多,知識涵蓋面較寬。常見的金屬表面處理技術包括:表面改性技術,表面鍍層技術,熱噴涂技術,氣相沉積技術以及高能束表面處理等。而激光毛化技術作為一種新型的表面處理微加工技術,通過對金屬材料表面的改形改性,從而對材料表面的摩擦磨損現(xiàn)象起到良好的改善作用�；诩す饷庸さ倪@種良好效果,展開與激光毛化技術相關的基礎理論與實驗研究,將其應用到不同種類、不同需求的工作表面上,具有十分重要的意義。圍繞激光毛化形貌的成形機理和工藝實驗研究,國內外研究學者做了大量的工作,從機理解釋、模擬仿真再到實驗研究,均獲得一系列研究成果,通過實驗所獲得的毛化形貌種類豐富多樣,但是,針對毛化技術領域的研究仍然存在諸多問題。本文主要針對毛化形貌類型的判定標準和表征方法、如何實現(xiàn)毛化形貌的工藝可控性等關鍵問題,通過理論分析和工藝實驗相結合的方法,對毛化形貌的成形機理進行闡述,建立一種表征和判定毛化點的方法,并通過特種工藝方法來盡可能地實現(xiàn)毛化點形貌與大小的可控性。綜上所述,本文主要的研究工作如下。一、根據(jù)激光和物質相互作用的機理,對毛化形貌的成形過程進行了詳細的分析、闡釋,包括毛化形貌形成的物理過程變化、熔池的形成過程分析、氣化現(xiàn)象對熔池的影響,以及熔池內部的熱傳導過程和溫度場的分析等。二、利用SPI型光纖激光加工設備,采用單因素分析法,通過控制不同工藝參量在C r12mov模具鋼試樣上進行了系統(tǒng)的激光毛化工藝實驗,對不同實驗參數(shù)下加工出的毛化形貌進行檢測,進行對比分析,總結了不同實驗參數(shù)下毛化形貌的演變規(guī)律;并根據(jù)實驗中所獲得的毛化點的外形特征,建立了一種毛化點幾何尺寸的表征方法和形貌種類的判定標準;研究了不同激光功率、脈沖寬度、離焦量對毛化形貌幾何大小的影響規(guī)律,并對形貌形成的過程進行了分析。三、為盡可能改善毛化形貌,獲得較好的毛化點質量,進而實現(xiàn)可控性要求,采用輔助氣體、表面涂層以及水環(huán)境等不同的特種工藝方法,來探究對毛化點的影響規(guī)律。結果發(fā)現(xiàn)采用輔助氣體為氮氣時,在合適的氣體壓力下,所得到的毛化形貌更加均勻、規(guī)整;當表面涂層采用黑漆涂料時,毛化形貌的規(guī)律性更強,更易實現(xiàn)可控性。四、利用金相顯微鏡對毛化形貌區(qū)域的金相組織和顯微硬度進行了檢測,并與基體材料進行對比分析。結果發(fā)現(xiàn),毛化區(qū)域材料的金相組織形態(tài)全部為馬氏體組織,更加致密,毛化點位置的顯微硬度整體上比基體要高出30%~45%。
[Abstract]:Metal surface treatment technology is a kind of technology that combines many industries and disciplines, which involves a wide range of contents, many process methods and wide knowledge coverage. The common metal surface treatment technologies include surface modification technology, surface coating technology, thermal spraying technology, vapor deposition technology and high energy beam surface treatment. As a new kind of surface treatment micro-processing technology, laser texturing technology can improve the friction and wear phenomenon of the metal surface by modifying the metal surface. Based on the good effect of laser texturing, it is of great significance to develop the basic theory and experimental research related to laser texturing, and to apply it to different kinds of working surfaces with different demands. A great deal of research work has been done by domestic and foreign scholars on the forming mechanism and process experiment of laser texturing. A series of research results have been obtained from mechanism interpretation, simulation and simulation to experimental research. There are many kinds of textures obtained by experiments, but there are still many problems in the field of wool technology. In this paper, aiming at the key problems, such as judging standard and characterization method of texturing morphology, how to realize the process controllability of woolening morphology, the forming mechanism of texturing morphology is expounded by combining theoretical analysis with process experiment. A method of characterizing and judging the wool point is established, and the shape and size of the wool point can be controlled as much as possible by the special process method. To sum up, the main research work of this paper is as follows. First, according to the mechanism of the interaction between laser and matter, the forming process of the Mao morphology is analyzed in detail, including the changes of the physical process of the formation of the morphology, the analysis of the forming process of the molten pool, and the influence of the gasification phenomenon on the molten pool. And the analysis of the heat conduction process and temperature field in the molten pool. Secondly, by using SPI type fiber laser processing equipment and single factor analysis method, a systematic laser wool processing experiment was carried out on C r12mov die steel sample by controlling different process parameters. The morphologies of the textures processed under different experimental parameters were examined and compared and analyzed. The evolution of the textures was summarized under different experimental parameters. According to the shape characteristics of the wool points obtained in the experiment, a method for characterizing the geometric size of the wool points and a standard for judging the morphology of the points are established. The effects of laser power, pulse width and defocus on the geometric size of the textured morphology were studied, and the formation process of the morphology was analyzed. Third, in order to improve the morphology of the wool as much as possible, obtain better quality of the wool point and realize the controllability requirement, different special process methods, such as auxiliary gas, surface coating and water environment, are adopted to explore the law of influence on the wool point. The results show that when the auxiliary gas is used as nitrogen, the morphology of the wool is more uniform and regular under the suitable gas pressure, and when the surface coating is used the black paint, the regularity of the morphology of the wool is stronger and the controllability is easier to be realized. 4. Metallographic microstructure and microhardness of the textured area were examined by metallographic microscope, and compared with the matrix material. The results show that the microstructure of the textured materials is all martensite and denser. The microhardness at the position of the wool point is 30% higher than that of the matrix as a whole.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG76;TG665

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