切削刀具PVD涂层技术的发展及应用

PVD涂层是利用蒸发、辉光放电等物理过程 ,在基材表面沉积出所需要的涂层的技术 ,通常采用的 PVD技术有蒸发镀膜、离子镀膜和溅射镀膜三大类 ,其中离子镀和溅射镀适合于对切削刀具进行超硬材料涂层。本文着重介绍了溅射镀技术及采用该技术生产的几种重要的涂层 ,结合实例介绍了它们的使用性能 ,并对 PVD涂层切削刀具技术的研究进展 ,工业化生产及应用现状进行了综述。     

刀具涂层材料的最新研究进展

随着难加工材料和绿色干切削等先进加工技术的开发与广泛应用,刀具切削环境日益严苛,刀具涂层材料不断更新换代。涂层材料已由最初的二元涂层逐渐发展成三元及多元涂层,结构由单层逐渐向多层、梯度、复合结构转变。首先总结了几种常用二元涂层的性能和特点。再以Ti基和Cr基三元及多元涂层为例,阐述了掺杂元素对涂层微观结构和性能的影响及强化机制,分析了多元涂层的研究现状和面临的难题,以及多种掺杂元素的协同作用机制。还讨论了纳米晶/非晶复合结构涂层、纳米多层涂层以及梯度涂层的结构优势及研究现状,介绍了金刚石、类金刚石和立方氮化硼三种超硬涂层以及具有低摩擦因数软涂层的特点和研究进展。最后介绍了近几年研究的热点涂层(如高熵合金涂层、含氧涂层和多元多层复合涂层)的研究现状,并对刀具涂层的未来发展方向进行了展望。     

纳米Al2O3/TiO2多层涂层的低温制备及其性能*

采用原子层沉积技术(ALD)在 200 ℃低温条件下将纳米 Al₂O₃ / TiO₂ 多层涂层沉积在硬质合金刀具表面。利用扫描电镜 SEM、划痕测试仪和三向测力仪以及数控机床等设备,对不同形式的纳米 Al₂O₃ / TiO₂ 多层涂层刀具的涂层-基体结合力和切削性能等进行研究。结果表明,基于原子层沉积技术低温制备的纳米多层涂层刀具的涂层-基体结合强度高;涂层层数、 涂层沉积顺序及涂层层厚比对纳米多层涂层刀具的切削力有不同程度的影响;纳米多层涂层刀具更适合高速切削,当切削速度大于 2.33 m / s 时,纳米多层涂层刀具的切削力和摩擦因数呈下降趋势,表现出良好的切削性能,其中双层纳米涂层刀具的切削性能更好;在高速切削时,纳米多层涂层刀具表面摩擦因数比普通未涂层硬质合金刀具低,纳米 Al₂O₃ / TiO₂ 多层涂层能够有效改善刀具的黏结磨损,减少刀-屑粘黏现象和烫伤现象,能够改善刀具表面的耐磨损性能。     

刀具氮化物涂层的研究进展

综述了刀具氮化物涂层的研究进展及发展趋势,分析了制备多元多层氮化物涂层的物理沉积技术及其优劣势.指出刀具氮化物涂层的种类从单一的金属涂层发展到二元合金涂层,目前又朝着多元合金复合涂层发展;涂层的层数从单层发展到多层,而且各单层涂层的厚度将趋于纳米化.多元多层氮化物涂层是今后刀具涂层的研究热点.     

超硬刀具涂层

在刀具表面沉积由CVD金刚石和PVD立方氮化硼（CBN）组成的超硬薄涂层极具应用潜力。因为这两种在所有材料中硬度最高的功能性耐磨涂层与刀具几何参数设计的灵活性相结合。能够满足给定加工任务的特殊要求。使高效加工策略（如高速切削）得到更有效的执行。其结果是通过减少生产时间和制造成本而增强竞争优势。因此。开发将涂层与超硬切削材料的优势相结合的创新型刀具涂层至关重要。同时。这两种超硬刀具涂层在连续和断续切削条件下都有良好表现。本文给出了有关CBN和金刚石涂层的一些试验结果和不同发展阶段的比较。[编者按]     

微细钻铣刀具表面涂层制备及应用研究进展(Ⅰ)

在微细钻铣刀具上进行涂层制备是有效提高微切削质量与加工效率的方法。金刚石涂层、类金刚石涂层和过渡族金属碳/氮化物涂层在微细钻铣刀具上得到了广泛应用,而应用于传统大直径刀具上的硼化物涂层、氧化物涂层等,在微细钻铣刀具上的应用仍处于开发阶段。刀具表面涂层制备技术主要有物理气相沉积技术、化学气相沉积技术和原子层沉积技术。本文从微细钻铣刀具出发,综述了各种制备方法的特点,介绍了近年来在刀具前处理、涂层晶粒直径、沉积参数控制及刀具夹具设计等关键技术点上的研究进展,对微细钻铣刀具表面涂层的制备具有指导意义。伴随着微细钻铣刀具涂层制备技术的优化更新,涂层材料和涂层结构的不断发展,使得刀具涂层的最高硬度和使用温度不断提高。     

涂层技术与现代切削刀具的互动发展

近几年来,在经济全球化背景下,我国的制造业获得了空前发展的机遇,而现代切削刀具成了提升制造业技术水平的关键因素之一,不断提高的切削加工要求和被加工材料的能级以及减少切削加工对环境污染等有力地推动了用于现代切削刀具涂层技术的发展.膜系材料多元合金化,涂层工艺组合的多样化中出现的TiAlN、TiAlCN、CrSiN等多元复合涂层和多层涂使刀具获得了高耐磨、低摩擦、热稳定性好和抗氧化能力强等良好的综合性能,大大提升了现代切削刀具的性能;纳米组分和纳米薄膜涂层的显微结构使得难加工材料的切削得到了新的解决办法;金刚石涂层和类金刚石涂层(DLC)在加工石墨零件和纤维增强等非金属材料和有色合金材料方面取得了良好的效果.为适应涂层工艺的发展,涂层的工艺装备亦实现了集成化、模块化和智能化.使涂层技术日趋个性化.涂层技术的发展也使现代切削刀具发展为一项高技术含量的产品,充分体现了两者发展的互动性.     

基于ALD低温制备的纳米涂层刀具性能研究

目的 探索基于原子层沉积法(Atomic Layer Deposition,ALD)的纳米涂层低温制备技术,并重点研究涂层沉积过程及纳米氧化铝涂层对刀具力学性能的影响.方法 利用原子层沉积法,在200℃的环境下制备不同涂层厚度的纳米Al2O3涂层刀具,对涂层的微观组织、厚度、硬度、断裂韧性、断口形貌、弯曲强度、结合力及摩擦系数进行检测.结果 ALD沉积技术能将纳米涂层均匀沉积在YT5刀具表面,且涂层光滑,无滴状气泡,涂层厚度可以精确控制在纳米级.ALD涂层与基体结合力的大小与涂层厚度相关,随着涂层厚度增大,结合力呈先增后降的趋势,测得50、100、200 nm等3种纳米涂层结合力大小分别为11.07、12.74、7.86 N.纳米涂层能够提高刀具的硬度,显著降低刀具表面的摩擦系数,测得刀具摩擦系数分别为0.56、0.43、0.67,最高降低摩擦系数达40％以上.此外在200℃的沉积温度下,没有产生金属相变,因而对刀具基体没有影响,刀具的断裂韧性和弯曲强度没有降低.结论 基于ALD的纳米涂层低温沉积技术所制备的纳米涂层刀具,具有良好的力学性能及涂层-基体界面结合力,能显著提高刀具性能,改善切削加工条件.     

日本住友电工开发的几种规削刀具新产品

为了保护环境、降低能耗,满足高速、高效、高硬度、高精度及干式切削加工的迫切需求,日本住友电工硬质合金工具公司应用先进的纳米技术、独立研发的PVD涂层技术以及超硬材料技术,开发了适用于高速干式切削加工的超级ZX涂层硬质合金刀具、     

PVD涂层刀具高速铣削CoCrMo合金的性能研究

目的为了提高涂层硬质合金刀具的切削性能,研究了物理气相沉积PVD法制备的涂层硬质合金铣刀在高速干式环境下的铣削性能。方法采用阴极电弧技术制备了TiN、TiAlN以及TiAlSiN涂层硬质合金铣刀刀头,通过一同沉积涂层的硬质合金圆片,间接测量得出涂层的显微硬度、厚度和平均摩擦系数,并以CoCrMo合金为切削对象,进行了PVD涂层与无涂层刀具高速铣削下的对比试验。结果TiAlSiN显微硬度最高达3800HV,摩擦系数达0.3,TiAlN涂层平均膜厚为2μm,间接测得TiN、TiAlN以及TiAlSiN涂层的结合力依次为60、58、42N。在三者的切削性能中,TiAlSiN涂层的切削性能比TiAlN和TiN涂层的好,同等切削参数时,TiN刀具的高速铣削时间最短,TiAlSiN涂层的平均磨损值为0.1895,TiN的平均磨损值为0.3047。结论涂层中添加Al、Si,极大地提高了刀具的使用性能,改善了刀具切削过程中的耐磨性、红硬性,极大地延长了刀具的使用寿命。TiAlSiN涂层的硬度高,耐磨损性好,切削性能好,适合高速铣削加工。     

Tribological Behaviour and Cutting Performance of PVD-TiN Coating/Substrate System with Discontinuous Surface Architecture

TiN coating was deposited by arc evaporation PVD (physical vapor deposition) onto tool steel. A netted screen made of the stainless steel was placed between substrate and vaporizer in order to get discontinuous TiN coatings. Three kinds of surface condition (uncoated, continuous and discontinuous TiN coatings) were prepared and examined for their performance. Tribological behavior was investigated by means of dry and lubricated sliding tests at room temperature and 200 °C, on a disk-on-block and sphere-on-flat tribometer. The results show that the discontinuous TiN coating significantly decreases both the wear and the wearing speed of tool steel under sliding tests, and reduces friction under conditions of bidirectional sliding. In the three kinds of surface condition, the discontinuously coating has superiority for high speed cutting owing to its lifetime increasing compared with uncoated and continuously coated.     

化学气相沉积制备硬质合金刀具涂层研究进展

化学气相沉积技术(CVD)广泛应用于硬质耐磨涂层的生产中,该类涂层可大大提高硬质合金工具的耐磨性和寿命。综述了CVD涂层技术在硬质合金切削刀具中的应用研究进展,首先介绍了CVD涂层技术的原理及其发展历程;其次阐述了模拟计算方法(相图计算、流体力学计算、第一性原理计算、相场模拟、机器学习等)在CVD涂层中的应用;再次介绍了CVD涂层的沉积实验及结构和性能表征方法;最后列举了几种典型的硬质合金刀具用CVD涂层,以期为高性能涂层的智能设计、智能集成和智能研发提供新的思路:即把多尺度计算模拟、科学数据库和关键实验集成到硬质涂层开发的全过程中,通过对成分-工艺-结构-性能进行关联分析,将耐磨涂层的研发由传统经验或者半经验方式提升到科学的微结构智能设计上,以实现基体与涂层微结构调控和性能的协同优化,获得最佳的综合性能。     

Nanocrystalline diamond coating tools for machining high-strength Al alloys

Diamond coating tools have been increasingly used for machining advanced materials. Recently, a microwave plasma-assisted chemical vapor deposition (CVD) technology was developed to produce diamond coatings which consist of nano-diamond crystals embedded into a hard amorphous diamond-like carbon matrix. In this study, the nanocrystalline diamond (NCD) coating tools were evaluated in machining high-strength aluminum (Al) alloy. The conventional CVD microcrystalline diamond coating (MCD) tools and PCD tools were also tested for performance comparisons. In addition, stress distributions in diamond coating tools, after deposition and during machining, were analyzed using a 2D finite element (FE) thermomechanical model.

The results show that catastrophic failures, reached in all except one machining conditions, limit the NCD tool life, which is primarily affected by the cutting speed. In addition, coating delamination in the worn NCD tools is clearly evident from scanning electron microscopy (SEM) and force monitoring in machining can capture the delamination incident. At a high feed, coating delamination may extend to the rake face. Furthermore, SEM observations of coating failure boundaries show intimate coating-substrate contact. Though the NCD tools are inferior to the PCD tools, they substantially outperform the MCD tools, which failed by premature delamination. The diamond coating tools can have high residual stresses from the deposition and stresses at the cutting edge are highly augmented. Further machining loading causes the stress reversal pattern which seems to correlate with the tool wear severity.     

Microstructure and physical properties of PVD TiN/（Ti, Al）N multilayer coatings

Magnetron sputtered （Ti, Al） N monolayer and TiN/（Ti, Al） N multilayer coatings grown on cemented carbide substrates were studied by using energy dispersive X-ray spectroscopy （EDX）, scanning electron microscopy （SEM）, nanoindentation, Rockwell A indentation test, strength measurements and cutting tests. The results show that the （Ti, Al）N monolayer and TiN/（Ti, Al）N multilayer coatings perform good affinity to substrate, and the TiN/（Ti, Al）N multilayer coating exhibits higher hardness, higher toughness and better cutting performance compared with the （Ti, Al）N monolayer coating. Moreover, the strength measurement indicates that the physical vapour deposition （PVD） coating has no effect on the substrate strength.     

Effect of number of layers on erosion,corrosion, and wear resistance of multilayer Cr–N/Cr–Al–N coatings on AISI 630 stainless steel

In the present study, multilayered Cr–N/Cr–Al–N coatings were prepared by cathodic arc physical vapor deposition (PVD) with different numbers of layers and the same total thickness on AISI 630 steel in an attempt to improve the wear and erosion–corrosion resistance. Structural analysis of the coatings was performed by field scanning electron microscopy, X-ray diffraction (XRD), and energy-dispersive spectroscopy. Depth profiles and roughness parameters of worn surfaces were calculated after erosion and wear tests. XRD indicated that nitride compounds were formed in multilayer coatings by PVD. The Cr–N/Cr–Al–N coating exhibited superior corrosion resistance compared with AISI 630 substrate. The erosion–corrosion results revealed that the smoothest wear track with the minimum erosion rate and wear depth was obtained for five- and seven-layered coatings. The failure mechanism of the bare substrate was influenced by plastic deformation via cutting and plowing, while the failure mechanism for coated samples was chipping and delamination. According to the wear results, the multilayer coatings showed a lower friction coefficient and better surface morphology that demonstrated their high ability for wear protection.     

Influence of the Discharge Voltage during Pulse-Plasma Process on the Durability of Edges coated with Superhard Coatings

FOR obtainment of different wear-resistant coatingsdeposited on cutting edges made of sintered carbides anumber of CVD and PVD methods are applied[1,2].Individual methods allow to obtain in differenttemperatures hard coatings with similar chemicalcomposition but with various morphology andexploitation properties.Differences among mentionedproperties of coatings mainly result from coatingstructure,adhesion to substrate,hardness and frictionalproperties of coating.Structure of coatings result…     

Microstructural and Tribological Characterization of Duplex Coatings with Additional Ion Bombardment

THE FILM DEPOSITION process exerts a number ofeffects such as crystallographic orientation,morphology,topography,densification of the films.The optimization procedure for coated parts could bemore effective,knowing more about the fundamentalphysical and mechanical properties of a coating,theirinterdependence and their influence on the wearbehavior.The effects on the structure as well asmechanical and tribological properties of the filmswere investigated in detail in the present research.…     

Multi-functional nano-multilayered AlTiN/Cu PVD coating for machining of Inconel 718 superalloy

Machining of Ni-based aerospace alloys is one of the major challenges of modern manufacturing. Application of cemented carbide tooling with nano-multilayered AlTiN/Cu PVD coating results in a significant tool life improvement under conditions of turning the hard-to-machine aerospace Ni-based Inconel 718 superalloy. Studies of the structure, properties, tribological and wear performance of the nano-multilayered AlTiN/Cu PVD coating have been performed. The structure of the coating has been investigated using High Resolution Transmission Electron Microscopy. Various properties of the coating including microhardness, thermal conductivity and coefficient of friction vs. temperature were measured.Investigations of the coated tool life, wear behavior and chip formation for cutting tools with nano-multilayered AlTiN/Cu PVD coating were performed. Morphology of the worn tools has been studied using SEM/EDX. AlTiN/Cu coatings present multi-functionality because they combine self-lubricating behavior with reduced thermal conductivity. This beneficial combination of properties results in significant improvement of the coated tool life.     

Hard AlTiN, AlCrN PVD coatings for machining of austenitic stainless steel

The austenitic stainless steels in general are considered to be difficult to machine materials. This is mainly due to the high plasticity and tendency to work-harden of the austenitic stainless steel, which usually results in severe cutting conditions. Additionally, austenitic stainless steels have much lower thermal conductivity as compared to structural carbon steels; this inflicts high thermal impact within the chip-tool contact zone, which significantly increase the cutting tool wear rate. The machineability of austenitic stainless steels can be improved due to application of coated cutting tools. Hard PVD coating with low thermal conductivity and improved surface finish should be used in this case. This can result in enhancement of frictional characteristics at the tool/workpiece interface as well as chip evacuation process. In this study the stainless steel plates were machined using cemented carbide finishing end mills with four high aluminum containing PVD coatings namely: AlCrN, AlCrNbN, fine grained (fg) AlTiN and nano-crystalline (nc) AlTiN. Both AlTiN and AlCrN-based coatings have high oxidation resistances due to formation of aluminum oxide surface layers. The influence of surface post-deposition treatment on tool wear intensity was investigated. The coating surface texture before and after post-deposition treatment was analyzed by means of the Abbot-Firestone ratio curves. Minimal wear intensity after length of cut 150 m was achieved for cutting tools with the nc-AlTiN coating.