摘要
机械加工工艺的进步对切削刀具的性能提出了愈发严苛的要求,一方面刀具应具有更高强度及韧性以便应对高速切削带来的冲击载荷;另一方面刀具还应兼具优异的耐高温、抗氧化性能以满足极端工况下的服役需求。然而,传统刀具硬度的提升往往以牺牲韧性为代价,且传统刀具耐高温、抗氧化性能较差。通过在刀具表面沉积一层硬质、耐高温、抗氧化薄膜可有效解决这些问题。TiB_(2)具有高硬度、耐高温、抗氧化以及同金属间化学亲和力低等特性,因此,通过在零部件表面沉积TiB_(2)薄膜可显著改善切削刀具因摩擦磨损而导致的失效问题。采用直流磁控溅射技术在Inconel 718表面沉积一系列TiB_(2)薄膜,研究在溅射沉积阶段通过调控靶电流(3.0、4.0、5.0和6.0 A)对制备TiB_(2)薄膜在微观形貌、力学性能及摩擦学性能等方面的影响。结果表明:不同电流条件下沉积薄膜的截面形貌均为柱状结构,随着靶电流增加,薄膜沉积厚度、结晶度及晶粒尺寸增加;弱电流条件下沉积制备薄膜的硬度较低,使得其抗磨损性能较差;强电流条件下沉积制备的薄膜残余应力较大、膜基结合强度较差,从而导致其抗磨损性能较差;靶电流为4.0 A时,沉积薄膜拥有最佳综合性能,体现在最低的磨损率W=6.347×10^(−6)mm^(3)/(N·m)、较高的膜基结合强度L=36.78 N以及较低的残余应力σ=0.145 GPa。探究TiB_(2)最佳直流磁控溅射制备工艺,揭示TiB_(2)薄膜在溅射沉积阶段中不同电流强度对其结晶度、硬度及抗磨损性能的影响因素,将其沉积于切削刀具表面可改善切削刀具在高速切削过程中面临的摩擦磨损而导致的凹坑磨损问题。薄膜作为刀具表面涂层可有效防止刀具的高温氧化及元素扩散而导致的切削刀具过快失效问题,延长刀具使用寿命,改善加工精度,同时为高速切削刀具防护薄膜的后续研究提供一定的借鉴。
With the continual advancement of machining processes,cutting tools are facing increasingly demanding requirements.However,traditional tools often exchange hardness for toughness and have poor resistance to high temperatures and oxidation,which presents challenges in meeting high-speed cutting conditions.The deposition of a hard oxidation-resistant film on the tool surface can effectively address these issues.However,conventional protective films such as TiN and TiC fail to meet the demands of high-speed cutting and high-precision machining in terms of tool hardness,high-temperature resistance,and anti-adhesion.TiB_(2)is an ideal protective film for high-speed cutting tools due to its high hardness,high-temperature resistance,antioxidation properties,and low chemical affinity for intermetallic materials.In this study,a closed-field unbalanced DC magnetron sputtering technique was employed to deposit thin-film materials on P(100)-type silicon wafers and Inconel 718,which is a high-temperature nickel-based alloy.The results revealed a close correlation between the properties of the deposited TiB_(2)films and the magnitude of the target current during sputtering deposition.Specifically,increasing the TiB_(2)target current led to a higher target power,resulting in the deposition of thicker films within the given time frame,where the average thickness increased from 1.468 to 2.168μm.In addition,increasing the frequency of target sputtering particle bombardment and the temperature in the deposition chamber enhanced the crystallinity of the films and increased the grain size,where the half-peak width of the preferred crystal plane decreased from 2.795°to 1.993°.The difference in the thermal expansion coefficients of the film bases resulted in residual stresses in the films after cooling to room temperature.As the target current strength increased,the chamber temperature increased,leading to a greater temperature difference between the chamber and room.Consequently,the residual stress of the film increased with the target current.Specifically,the minimum residual stress of the deposited film under a target current of 3.0 A was 0.1099 GPa,whereas the maximum residual stress under a target current of 6.0 A was 0.3829 GPa.Moreover,the hardness of the film initially increased and then decreased with an increase in the target current,reaching a peak of 3.0 A under a hardness of 0.3829 GPa.The lowest hardness of the film occurred under the condition of 3.0 A,measuring 14.40 GPa,whereas the highest hardness was under the condition of 5.0 A,measuring 18.66 GPa.This hardness was closely associated with the crystallinity of the film and the ratio of boron-rich tissue phases.Enhancing the crystallinity of the film reduced the number of defects and concentrated the boron-rich phases at the grain boundaries,thereby preventing slippage when an external force was applied.This improvement was beneficial in enhancing the mechanical properties of the films.Depositing the film at 4.0 A yielded the highest hardness of 0.3829 GPa.In addition,films deposited at 4.0 A exhibited the lowest wear rate(W=6.347×10^(−6)mm^(3)/(N·m))within the system.This study explored the optimal DC magnetron sputtering preparation of TiB_(2)and elucidated the effects of different current strengths on the crystallinity,hardness,and antiwear properties of TiB_(2)thin films during sputtering deposition.The deposition of TiB_(2)thin films on cutting tool surfaces effectively mitigates wear problems caused by frictional wear during high-speed cutting,serving as a protective film that efficiently prevents excessive tool failure resulting from high temperature and oxidation.Additionally,it safeguards against wear caused by high temperature and oxidation,prolonging the tool’s service life and improving machining accuracy.These findings provide valuable insights for the research and development of protective films for high-speed cutting tools.
作者
冷啸
李红轩
吉利
张定军
LENG Xiao;LI Hongxuan;JI Li;ZHANG Dingjun(School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Lanzhou 730000,China)
出处
《中国表面工程》
EI
CAS
CSCD
北大核心
2024年第5期147-157,共11页
China Surface Engineering
基金
国家自然科学基金-叶企孙联合基金(U2141210)
中国科学院青促会优秀会员(Y202084)
“一三五”重大突破项目(KJZLZD-3,ZYFZFX-4)
甘肃省科技重大专项(22ZD6GA002)。
关键词
磁控溅射
TIB2
靶电流
晶面结构
摩擦磨损
magnetron sputtering
TiB2
target current
crystal phase structure
frictional wea
