摘要
目的 CrAlN涂层以其优异的抗氧化性能被广泛应用于切削刀具涂层领域,针对CrAlN涂层热稳定性较低,在超过900℃后会发生热分解,导致其力学性能显著下降的问题,通过B、Si共掺杂方法改善CrAlN涂层的性能。方法 采用阴极弧蒸发方法制备Cr_(0.42)A1_(0.58)N、Cr_(0.35)Al_(0.59)B_(0.06)N、Cr_(0.37)Al_(0.54) Si_(0.09)N涂层,借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)、纳米压痕仪,通过划痕和切削实验研究B和Si掺杂对CrAlN涂层晶体结构、硬度、结合力、热性能和切削寿命的影响。结果 Cr_(0.42)A1_(0.58)N和Cr_(0.35)A1_(0.59)B_(0.06)N涂层为单相立方结构,Cr_(0.37)Al_(0.54)Si_(0.09)N涂层为立方和六方的两相结构;Cr_(0.42)A1_(0.58)N、Cr_(0.35)Al_(0.59)B_(0.06)N、Cr_(0.37)A1_(0.54)Si_(0.09)N涂层的硬度分别为(29.8±1.5)、(36.9±1.4)、(33.8±1.6)GPa,与基体的结合力分别为116.2、58.3、58.0 N;通过B和Si掺杂抑制了CrAlN涂层的热分解过程,Cr-N键的断裂起始温度由Cr_(0.42)A1_(0.58)N的1 000℃提高到Cr_(0.35)Al_(0.59)B_(0.06)N的1 200℃和Cr_(0.37)Al_(0.54)Si_(0.09)N的1 100℃;在1 100℃下氧化15 h后,Cr_(0.42)A1_(0.58)N、Cr_(0.35)Al_(0.59)B_(0.06)N、Cr_(0.37)Al_(0.54)Si_(0.09)N涂层的氧化层厚度分别为2.38、1.80、0.53μm。结论 通过B和Si掺杂提高了CrAlN涂层的力学性能、热稳定性和抗氧化性,其中CrAlBN涂层呈现出最优异的热稳定性和切削性能,CrAlSiN涂层的抗氧化性最佳。
Because CrAlN coating has excellent oxidation resistance components,it is widely used in the field of cutting tool coating.However,the thermal decomposition of CrAlN coating above 900℃ leads to a drop in mechanical properties.Therefore,B and Si doping method was adopted in this study to further improve the performance of CrAlN coating.The structure,hardness,cohesion,thermal and machining properties of Cr_(0.)4_(2)A1_(0.58)N,Cr_(0.35)Al_(0.59)B_(0.06)N and Cr_(0.37)Al_(0.54)Si_(0.09)N deposited by cathodic arc evaporation were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),nano-indentation,scratch test and cutting experiment.The Cr_(0.42)Al_(0.58)N and Cr_(0.37)Al_(0.54)Si_(0.09)N coatings presented a single phase cubic structure,whereas the Cr_(0.35)Al_(0.59)B_(0.06)N coating was mixed cubic-wurtzite structure.Cr_(0.42)Al_(0.58)N coating presented typical columnar crystal morphology along the growth direction.The addition of B and Si inhibited the growth of columnar crystals.The fracture morphology of Cr_(0.35)Al_(0.59)B_(0.06)N coating and Cr_(0.37)Al_(0.54)Si_(0.09)N coating was composed of fine columnar crystals and nanocrystals respectively.The solid solution strengthening and grain refinement caused by B and Si doping increased the hardness of the coating from(29.8±1.5)GPa of Cr_(0.42)A1_(0.58)N coating to(36.9±1.4)GPa of Cr_(0.35)Ak_(0.59B0.06)N coating and(33.8±1.6)GPa of Cr_(0.37)A1_(0.54)Si_(0.09)N coating.However,B and Si doping reduced the cohesion with substrate from 116.2 N of Cr_(0.42)Al_(0.58)N coating to 58.3 N and 58.0 N of Cr_(0.35)Al_(0.59)B_(0.06)N and Cr_(0.37)Al_(0.54)Si_(0.09)N.The grain refinement caused by the addition of B and Si reduced the elastic modulus of the coating.The elastic modulus of Cr_(0.42)Al_(0.58)N,Cr_(0.35)Al_(0.59)B_(0.06)N and Cr_(0.37)Al_(0.54)Si_(0.09)N coatings was 523.6,484.8 and 431.7 GPa respectively.The addition of B and Si improved the plastic deformation resistance of the coating.The ratios of H~3/E~2 of Cr_(0.42)Al_(0.58)N,Cr_(0.35)A1_(0.59)B_(0.06)N and Cr_(0.37)Al_(0.54)Si_(0.09)N coatings were0.097,0.213 and 0.206 respectively.The addition of B and Si inhibited the fracture of Cr-N bond,thus retarding the thermal decomposition process.The initial fracture temperature of Cr-N bond increased from 1 000 ℃ of Cr_(0.42)Al_(0.58)N to 1 200 ℃ of Cr_(0.35)Al_(0.59)B_(0.06)N and 1 100 ℃ of Cr_(0.37)Al_(0.54)Si_(0.09)N.In addition the formation temperature of w-AIN increased from 1 000 ℃of Cr_(0.42)Al_(0.58)N to 1 100 ℃ of Cr_(0.35)Al_(0.59)B_(0.06)N.The doping of B and Si promoted the formation of dense oxides on the surface of the coating during oxidation,thus significantly improving the high-temperature oxidation resistance of the coating.After oxidation at 1 100 ℃ for 15 h,the oxide layer thickness of Cr_(0.42)Al_(0.58)N and Cr_(0.35)Al_(0.59)B_(0.06)N coatings was 2.38μm and1.80 μm,Cr_(0.37)Al_(0.54)Si_(0.09)N coating showed the best oxidation resistance,and the thickness of the oxide layer of the coating was only 0.53μm.A mixed oxide layer consisting of Al_(2)O_3,Cr_(2)O_(3) and SiO_(2) was grown on the surface of the coating containing Si.The oxide layer could avoid the formation of porous structure,thus maintaining a good combination with the residual nitride layer and providing effective protection for the coating.B and Si doping can improve the cutting performance of CrAlN coating on titanium alloy materials.After 45 min of cutting,the wear amount of Cr_(0.42)Al_(0.58)N,Cr_(0.35)Al_(0.59)B_(0.06)N and Cr_(0.37)Al_(0.54)Si_(0.09)N coated inserts is 0.5 mm,0.071 mm and 0.173 mm respectively.
作者
王羽中
史耀耀
张国飞
贺云鹏
WANG Yu-zhong;SHI Yao-yao;ZHANG Guo-fei;HE Yun-peng(School of Mechanical and Electrical Engineering,Northwestern Polytechnical University,Xi'an 710072,China;Zhuzhou Cemented Carbide Cutting Tools Co.,Ltd.,Hunan Zhuzhou 412007,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第10期360-366,393,共8页
Surface Technology
基金
国家科技重大专项(2017-Ⅶ-0002-0095)。
