硬质合金表面预处理状态对TiAlCrSiN/TiAlN涂层结构与机械性能的影响

余晶; 敬正彪; 鲜广; 冉龙姣

doi:10.13922/j.cnki.cjvst.202311012

成都工业职业技术学院智能制造与汽车学院成都 610218

四川大学机械工程学院成都 610065

成都大学机械工程学院成都 610106

通讯作者: E-mail: 182417953@qq.com;

中图分类号: TG174.4

Effect of Surface Pretreatment States of Cemented Carbide on the Structure and Mechanical Properties of TiAlCrSiN/TiAlN Coating

Institute of Intelligent Manufacturing and Automobile, Chengdu Vocational & Technical College of Industry, Chengdu 610218, China

School of Mechanical Engineering, Sichuan University, Chengdu 610065, China

School of Mechanical Engineering, Chengdu University, Chengdu 610106, China

Corresponding author: Zhengbiao JING, 182417953@qq.com ;

MSC: TG174.4

摘要: 采用电弧离子镀工艺在不同预处理后的硬质合金表面制备TiAlCrSiN/TiAlN涂层，采用扫描电镜、X射线衍射仪、纳米压痕仪、压痕法等研究硬质合金表面形态和涂层结构、力学性能和结合强度。结果表明：抛光处理后的硬质合金表面十分平整，表面粗糙度低至7.7 nm。酸洗处理使硬质合金表层Co相溶解而暴露出更多的硬质相，表面粗糙度增大，TiAlCrSiN/TiAlN涂层在酸洗处理的硬质合金上生长速率增大，晶粒细小，硬度和弹性模量高，但硬模比较低。喷砂处理使Co相塑性变形而包络更多的硬质相，表面粗糙度大幅增加， TiAlCrSiN/TiAlN涂层在喷砂处理的硬质合金上生长速率稍降低，晶粒粗大，硬度和弹性模量小，但硬模比较高。酸洗+喷砂复合处理的硬质合金表面TiAlCrSiN/TiAlN涂层的硬度、弹性模量、硬模比介于两种单独处理方式的之间。

关键词:

Abstract: TiAlCrSiN/TiAlN coatings were prepared on different pretreated cemented carbides using arc ion plating technology. The surface state of cemented carbide substrates and coating structure, mechanical properties and bonding strength of the as-deposited coating were studied using scanning electron microscopy, X-ray diffraction, nano-indentation and indentation methods. The results show that the surface of the polished cemented carbide was very flat, with a surface roughness as low as 7.7 nm. Pickling treatment dissolved the Co phase in the surface of the cemented carbide and exposed more hard phases, resulting in an increase in surface roughness. The growth rate of TiAlCrSiN/TiAlN coating on the pickled cemented carbide increased, with small grains, high hardness and elastic modulus, but low hard modulus. Sandblasting treatment caused plastic deformation of the Co phase and enveloped more hard phases, resulting in a significant increase in surface roughness. The growth rate of TiAlCrSiN/TiAlN coating on the sandblasted cemented carbide was slightly reduced, with coarse grains, low hardness and elastic modulus, but high hard modulus. The hardness, elastic modulus, and the ratio of hardness to elastic modulus of TiAlCrSiN/TiAlN coating deposited on cemented carbide with duplex pretreatment of pickling and sandblasting were between those of coatings by the two separate treatment methods.

Key words:

substrate pretreatment method

grain size / nm

average lattice strain

residual stress / GPa

polishing

28.3

0.22%

−0.94

pickling

19.1

0.13%

−0.78

sandblasting

36.4

0.30%

−0.86

pickling + sandblasting

21.2

0.14%

−0.48

硬质合金表面预处理状态对TiAlCrSiN/TiAlN涂层结构与机械性能的影响

通讯作者: E-mail: 182417953@qq.com;

1. 成都工业职业技术学院智能制造与汽车学院成都 610218

2. 四川大学机械工程学院成都 610065

3. 成都大学机械工程学院成都 610106

收稿日期: 2023-11-16

关键词:

Effect of Surface Pretreatment States of Cemented Carbide on the Structure and Mechanical Properties of TiAlCrSiN/TiAlN Coating

Corresponding author: Zhengbiao JING, 182417953@qq.com ;

1. 成都工业职业技术学院智能制造与汽车学院成都 610218

2. 四川大学机械工程学院成都 610065

3. 成都大学机械工程学院成都 610106

Received Date: 2023-11-16

Keywords:

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硬质合金因具有高硬度、高耐磨性以及良好的耐蚀性等优良性能被大量用作切削刀具、石油和地矿钻采工具以及耐磨机械零件^[1-3]。但随着服役工况愈加苛刻和对服役寿命要求的提高，以硬质合金制作的切削刀具及耐磨零件的性能依然面临严峻挑战^[4]。为提升硬质合金制品的耐磨性能和使用寿命，通常在硬质合金表面制备一层或多层硬质耐磨涂层，涂层后硬质合金的表面硬度较未涂层硬质合金成数倍提高，耐磨性得到显著改善^[5]。

硬质合金表面耐磨涂层主要有氮化物涂层^[6-9]、氧化物涂层^[10]、硼化物涂层^[11]以及金刚石涂层^[12]。其中，氮化物涂层最为常见及应用最广。由于涂层与硬质合金在晶格类型及晶格常数方面往往存在差异，涂层在硬质合金上的沉积通常需要重新形核和生长。因此，涂层的结构和性能往往与硬质合金表面微结构有关。基体表面粗糙度、应力状态、纹理织构、化学成分等均是影响涂层结构与性能的重要因素^[13-15]。Huang等^[14]研究指出，TiAlN涂层的耐磨性随基体表面粗糙度的增加而降低。Tillmann等^[15]研究指出，基体表面存在的低压应力可提高涂层和基体之间的结合强度。Shum等^[16]研究表明，通过激光蚀刻形成的纹理表面有利于提高涂层与基体直接的结合强度和增强涂层的耐磨性。Xian等^[17]研究指出，TiN涂层的生长速率、晶粒尺寸和择优取向度与基体的预处理状态有关，沉积在酸洗处理Ti(C,N)基金属陶瓷基体上的TiN涂层生长快，择优取向度低，耐磨性好，但涂层与基体界面处存在大量孔洞。上述这些研究证实，在沉积涂层之前对基体表面进行适当的预处理，可以调控涂层的结构与性能。然而，何种预处理方式适合硬质合金基体以利于其表面氮化物硬质涂层获得优良的性能尚需进行系统探索。

本文采用电弧离子镀工艺在不同预处理后的硬质合金基体上制备TiAlCrSiN/TiAlN涂层，探究不同预处理方式下硬质合金的表面形态及其对TiAlCrSiN/TiAlN涂层结构与性能的影响。

1. 实验材料与方法

1.1. 基体预处理

基体试样为15 mm×15 mm×5 mm的硬质合金（成分：12.6%C、70.8%W、7.1%Ti、1.2%Ta、1.0% Nb、7.3%Co）。首先采用机械抛光方法在2.5 μm金刚石抛光液作为辅助介质的条件下对硬质合金表面进行抛光至镜面，再对部分抛光后的硬质合金试样分别进行酸洗和喷砂处理，酸洗用溶液为Murakami溶液（NaOH、K₃[Fe(CN)₆]、H₂O体积比为1:1:10)，酸洗时间为2 min，喷砂用砂粒为刚玉（Al₂O₃）粉末，粉末射流与试样表面成45°夹角，喷砂压力为0.6 MPa，时间为2 min。最后，对酸洗后的部分样品再进行喷砂处理，喷砂工艺条件与上一步相同。经过上述步骤处理，分别得到抛光态、酸洗态、喷砂态、酸洗+喷砂态四种预处理表面状态的硬质合金试样。所有试样在无水乙醇中超声波清洗10 min，然后冷风吹干。

1.2. 涂层制备

采用将洁净的四种预处理状态的硬质合金试样放入电弧离子镀设备中，所有样品在沉积室内的位置是等同的。首先，对沉积室抽真空和加热，当时沉积室内温度和背底真空分别达到400℃和3.0×10⁻² Pa时，向沉积室内通入氮气和打开Cr靶，沉积Cr过渡层以提高涂层结合强度。然后，依次利用Al₆₀Ti₄₀和Al₆₀Ti₂₅Cr₁₀Si₅靶分别沉积TiAlN内层和TiAlCrSiN外层，靶电源的工作功率为4 kW，基体偏压为−50 V，沉积时间分别为60 min和20 min。

1.3. 结构与性能表征

采用JSM-IT500型扫描电镜分析涂层硬质合金和涂层的组织形态，并利用电镜附带的Oxford型能谱仪分析其化学成分。采用Bruker D8 Advance型X射线衍射仪分析涂层的物相结构工作电压为40 kV，工作电流为40 mA，Cu Kα射线，波长0.15416 nm，略入射角为1°，2θ范围为30°~70°，扫描步长0.02°。采用NanoTest Vantage型纳米压痕仪测试涂层的硬度和弹性模量，每个样品测试6次求平均值。根据德国工程师手册（VDI3198）采用Rockwell压痕法对涂层与基体的结合强度进行评级。

3. 结论

（1）硬质合金经不同预处理后表面形态和粗糙度发生改变。经酸洗处理后的硬质合金表层Co粘结相被去除，表面暴露更多的硬质相，表面粗糙度增大；经喷砂处理后的硬质合金表层的Co粘结相发生塑性变形并包络硬质相的边缘，表面粗糙度大幅增加。酸洗+喷砂复合处理后的硬质合金表面形态和粗糙度与酸洗处理的接近。

（2）酸洗处理使硬质合金表面TiAlCrSiN/TiAlN涂层生长速率较快，喷砂处理略微降低涂层的生长速率。酸洗处理具有细化TiAlCrSiN/TiAlN涂层晶粒的作用，且可减少晶格的平均应变。喷砂处理使硬质合金表面TiAlCrSiN/TiAlN涂层的晶粒尺寸和平均晶格应变增大。

（3）酸洗处理后的硬质合金基体表面TiAlCrSiN/TiAlN涂层结合强度更高，硬度和弹性模量均增大，但硬模比降低；喷砂处理后的硬质合金基体表面涂层硬度和弹性模量均降低，但硬模比增大；酸洗与喷砂复合处理后的硬质合金表面涂层硬度、弹性模量和硬模比介于酸洗和喷砂处理的之间。

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