温度和厚度对纳米金刚石涂层残余应力的影响
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摘要
目的通过改善液相等离子喷涂制备纳米金刚石涂层的工艺参数,提高纳米金刚石涂层的显微硬度与结合强度。方法利用Ansys有限元软件对纳米金刚石涂层中的残余应力进行数值模拟。建立纳米金刚石涂层的有限元分析模型与热传导方程,探讨了涂层的厚度与降温速度对纳米金刚石涂层残余应力的影响。通过扫描电子显微镜对制备的纳米金刚石涂层表面进行分析,并且利用显微硬度计和表面划痕仪测定纳米金刚石涂层的显微硬度和结合强度。结果纳米金刚石涂层的主应力为拉应力,涂层的最大主应力随着厚度的增大而具有先增大、后减小、再增加的特点。随着涂层厚度的增加,涂层的最大剪应力由涂层表面转移到涂层界面,其值先减少,后保持稳定。涂层整体、涂层界面和涂层表面的最大主应力与最大剪应力,随涂层温度的升高而呈线性递减的趋势。纳米金刚石涂层的主应力集中在涂层的四周,而涂层的剪应力分布在涂层表面。纳米金刚石涂层表面较光滑,由大量纳米级的细小扁平颗粒紧密排布而形成。结论采用适当的工艺参数制备出厚度为0.1 mm的纳米金刚石涂层,其显微硬度和结合强度分别约为150HV和9 N。
The work aims to improve microhardness and bonding strength of nano-diamond coating by changing process parameters of nano-diamond coating which was prepared in the method of suspension plasma spraying. Numerical simulation was applied to residual stress of nano-diamond coating using finite element software ANSYS. Finite element analysis model and heat conduction equation were established for nano-diamond coating. The effects of coating thickness and cooling rate on residual stress of the nano-diamond coating were discussed. Surface of the nano-diamond coating was analyzed by scanning electron microscope, and microhardness and bonding strength were measured by microhardness tester and surface scratch tester. Principal stress of the nano-diamond coating was tensile stress, and the maximum principal stress first increased, then decreased and finally increased as the coating thickness increased. The maximum shear stress of the coating was transferred from coating sur-face to coating interface as the coating thickness increased. Moreover, the maximum shear stress first decreased and then remained stable. For the bulk coating, coating interface or coating surface, the maximum principal stress and the maximum shear stress decreased linearly with the increase of coating temperature. The maximum principal stress was concentrated around the coating while the shear stress was distributed on the coating surface. The surface of the nano-diamond coating was smooth because its smooth surface consisted of compact flat particles through a large number of nanoscale particles. The microhardness and bonding strength of the 0.1 mm thick nano-diamond coating prepared provided with proper process parameters is about 150 HV and 9 N, respectively.
The work aims to improve microhardness and bonding strength of nano-diamond coating by changing process parameters of nano-diamond coating which was prepared in the method of suspension plasma spraying. Numerical simulation was applied to residual stress of nano-diamond coating using finite element software ANSYS. Finite element analysis model and heat conduction equation were established for nano-diamond coating. The effects of coating thickness and cooling rate on residual stress of the nano-diamond coating were discussed. Surface of the nano-diamond coating was analyzed by scanning electron microscope, and microhardness and bonding strength were measured by microhardness tester and surface scratch tester. Principal stress of the nano-diamond coating was tensile stress, and the maximum principal stress first increased, then decreased and finally increased as the coating thickness increased. The maximum shear stress of the coating was transferred from coating sur-face to coating interface as the coating thickness increased. Moreover, the maximum shear stress first decreased and then remained stable. For the bulk coating, coating interface or coating surface, the maximum principal stress and the maximum shear stress decreased linearly with the increase of coating temperature. The maximum principal stress was concentrated around the coating while the shear stress was distributed on the coating surface. The surface of the nano-diamond coating was smooth because its smooth surface consisted of compact flat particles through a large number of nanoscale particles. The microhardness and bonding strength of the 0.1 mm thick nano-diamond coating prepared provided with proper process parameters is about 150 HV and 9 N, respectively.
引文
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[11]黄贞益,曹奔,牛亚然,等.等离子喷涂高温涂层残余应力模拟比较研究[J].热喷涂技术,2015(1):15-17.HUANG Zhen-yi,CAO Ben,NIU Ya-ran,et al.Analysis of residual stress in plasma spray coating[J].Thermal spray technology,2015(1):15-17.
[12]LIU Jiang-wei,WANG Yan,COSTIL S,et al.Numerical and experimental analysis of molten pool dimensions and residual stresses of Ni Cr BSi coating treated by laser post-remelting[J].Surface and coatings technology,2017,318(25):341-348.
[13]YU Q M,CEN L.Residual stresses distribution along interfaces in thermal barrier coating system under thermal cycles[J].Ceramics international,2017,43(3):3089-3100.
[14]林欢庆,卢文壮,左敦稳,等.整体硬质合金铣刀上制备CVD金刚石涂层的系统三维流场研究[J].人工晶体学报,2010,39(2):345-349.LIN Huan-qing,LU Wen-zhuang,ZUO Dun-wen,et al.Study on three-dimensional flow field of CVD diamond coating cemented carbide milling cutter preparation system[J].Journal of synthetic crystals,2010,39(2):345-349.
[15]简小刚,张允华.温度对金刚石涂层膜基界面力学性能的影响[J].物理学报,2014,64(4):269-273.JIAN Xiao-gang,ZHANG Yun-hua.The effect of temperature on the mechanical properties of the diamond coating at the film-substrate interface[J].Acta physica sinica,2014,64(4):269-273.
[16]NIBENNAOUNE Z,GEORGE D,AHZI S,et al.Numerical simulation of residual stresses in diamond coating on Ti-6Al-4V substrate[J].Thin solid films,2009,518(12):3260-3266.
[2]戴达煌,周克崧.金刚石薄膜沉积制备工艺与应用[M].北京:冶金工业出版社,2001.DAI Da-huang,ZHOU Ke-song.Deposition preparation process and application of diamond film[M].Beijing:Metallurgical Industry Press,2001.
[3]WAN B Q,SUN X Y,MA H T,et al.Plasma enhanced chemical vapor deposition of diamond coatings on Cu-W and Cu-WC composites[J].Surface and coatings technology,2015,284(25):133-138.
[4]卢文壮,左敦稳,任卫涛,等.金刚石涂层的纳米压痕力学性能研究[J].人工晶体学报,2009,38(1):159-164.LU Wen-zhuang,ZUO Dun-wen,REN Wei-tao,et al.Mechanical properties of diamond coatings on YG6 cutting tools characterized by nano-indentation method[J].Journal of synthetic crystals,2009,38(1):159-164.
[5]王强,王四根,唐伟忠,等.沉积温度对硬质合金金刚石涂层附着力影响的研究[J].金属热处理学报,2000,21(4):6-12.WANG Qiang,WANG Si-gen,TANG Wei-zhong,et al.Influence of deposition temperature on adhesion of diamond coating on cemented carbide cutting tools[J].Heat treatment of metals,2000,21(4):6-12.
[6]王大志,徐康,贾云波,等.纳米金刚石及其稳定性[J].无机材料学报,1995,10(3):281-287.WANG Da-zhi,XU Kang,JIA Yun-bo,et al.Nanocrystalline diamond and its stability[J].Journal of inorganic materials,1995,10(3):281-287.
[7]REN X D,TANG S X,ZHENG L M,et al.Direct transfer-adsorption:The new molecular dynamics transition mechanism of nano-diamond preparation by laser shock processing[J].Journal of crystal growth,2015,421(1):1-7.
[8]刘巧平,杨延宁,张富春,等.纳米金刚石场发射阴极制备及性能研究[J].人工晶体学报,2016,45(7):1976-1980.LIU Qiao-ping,YANG Yan-ning,ZHANG Fu-chun,et al.Study on the preparation and property of nano-diamond field emission cathode[J].Journal of synthetic crystals,2016,45(7):1976-1980.
[9]王志平,董祖钰,李丽,等.热喷涂残余应力的测试与分析[J].焊接学报,1999,20(4):278-285.WANG Zhi-ping,DONG Zu-yu,LI Li,et al.Measuring and analysis of residual stress in thermal sprayed coating[J].Transactions of the China welding institution,1999,20(4):278-285.
[10]李德英,张坚,赵龙志,等.激光沉积制备Si Cp/Cu梯度涂层残余应力分析[J].中国激光,2015,42(12):169-175.LI De-ying,ZHANG Jian,ZHAO Long-zhi,et al.Study on the residual stress of Si Cp/Cu gradient coating by laser deposited[J].Chinese journal of lasers,2015,42(12):169-175.
[11]黄贞益,曹奔,牛亚然,等.等离子喷涂高温涂层残余应力模拟比较研究[J].热喷涂技术,2015(1):15-17.HUANG Zhen-yi,CAO Ben,NIU Ya-ran,et al.Analysis of residual stress in plasma spray coating[J].Thermal spray technology,2015(1):15-17.
[12]LIU Jiang-wei,WANG Yan,COSTIL S,et al.Numerical and experimental analysis of molten pool dimensions and residual stresses of Ni Cr BSi coating treated by laser post-remelting[J].Surface and coatings technology,2017,318(25):341-348.
[13]YU Q M,CEN L.Residual stresses distribution along interfaces in thermal barrier coating system under thermal cycles[J].Ceramics international,2017,43(3):3089-3100.
[14]林欢庆,卢文壮,左敦稳,等.整体硬质合金铣刀上制备CVD金刚石涂层的系统三维流场研究[J].人工晶体学报,2010,39(2):345-349.LIN Huan-qing,LU Wen-zhuang,ZUO Dun-wen,et al.Study on three-dimensional flow field of CVD diamond coating cemented carbide milling cutter preparation system[J].Journal of synthetic crystals,2010,39(2):345-349.
[15]简小刚,张允华.温度对金刚石涂层膜基界面力学性能的影响[J].物理学报,2014,64(4):269-273.JIAN Xiao-gang,ZHANG Yun-hua.The effect of temperature on the mechanical properties of the diamond coating at the film-substrate interface[J].Acta physica sinica,2014,64(4):269-273.
[16]NIBENNAOUNE Z,GEORGE D,AHZI S,et al.Numerical simulation of residual stresses in diamond coating on Ti-6Al-4V substrate[J].Thin solid films,2009,518(12):3260-3266.