基于划痕试验的超硬铝7A04微弧氧化膜基结合力的测试与评定

目前基于划痕试验法的金属防护层与基体结合力的研究大多是针对微弧氧化膜外的其他硬质膜层,且鲜有验证性试验.采用微弧氧化技术在7A04超硬铝合金表面成功制备出陶瓷膜层并观察了其微观形貌,利用WS-2005膜层附着力自动划痕仪在膜层上进行了划痕试验,采集了声发射信号,利用数显材料显微镜观察声发射图谱特征声信号峰对应划痕处的微观形貌,检测了划痕附近膜层显微硬度,判定了干扰信号,对膜基结合力进行了综合分析和评定.结果表明:7A04铝合金微弧氧化陶瓷膜层表面呈“火山喷射口”层叠状,划痕试验中膜层破坏仅发生在划痕内部,划痕周围没有发生大面积崩落,膜层与基体间结合力良好.     

试样参数对划痕试验临界载荷的影响

本文有摩擦力监测的划痕法研究了试样参数（基体硬度、膜厚、基体表面粗糙度等）对硬质摩膜（或软膜）的临界载荷Ｌｃ的影响．样品基材是Ｗ６Ｍｏ５Ｃｒ４Ｖ２、５ＣｒＭｎＭｏ、４５钢、Ａ３钢和不锈钢．膜层为磁控溅射离子镀ＴｉＮ膜和Ｔｉ膜、化学镀ＮｉＰＣＵ膜，以及在Ｓｉ３Ｎ４上溅射镀Ａｌ膜．结果发现离子度ＴｉＮ膜和Ｔｉ膜与ＮｉＰＣｕ膜规律不同，ＴｉＮ膜和Ｔｉ膜的临界载荷Ｌｃ随基体硬度的提高而提高，但当基体硬度接近和超过膜层硬度时，Ｌｃ变化不大；基体粗糙度增加时Ｌｃ下降；随膜厚的增加Ｌｃ提高．而化学镀ＮｉＰＣｕ膜的临界载荷Ｌｃ随基体硬度的提高而下降，随基体表面粗糙度的提高而增加．以Ｗ６Ｍｏ５Ｃｒ４Ｖ２为基体的ＮｉＰＣｕ膜，随膜厚的增加Ｌｃ变化不大．本文对上述规律的实质进行了初步探讨，并对目前生产中正在推广的工具钢磁控溅射离子镀ＴｉＮ膜的划痕法标准提出建议．     

金刚石涂层基体间结合力的测定

结合力是制约金刚石涂层工具大规模应用的关键因素之一.针对热丝化学气相沉积制备的金刚石薄膜的膜基结合力进行划痕实验,运用划痕仪所测的声发射数据、摩擦力数据及光学、电子扫描划痕形貌来综合评定膜基结合力.评定结果表明:单一的声发射图谱或摩擦力曲线不能准确判定膜基结合力的表征值临界载荷,声发射图谱、摩擦力曲线与划痕形貌综合评定临界载荷结果才可信.     

划痕法综合评定膜基结合力

用划痕实验探索了综合表征膜基结合力的方法.在瑞士CSM仪器的微划痕测试仪(Micro-Scratch Tester,MST划痕仪)对真空多弧离子镀设备制备的WC-Co/TiN膜基结合力进行划痕实验,系统地介绍了如何利用MST划痕仪所测的声发射数据、摩擦力数据及光学、电子扫描划痕形貌来综合评定膜基结合力,并用WS-92划痕仪对评定结果进行验证.评定结果表明,单一的声发射图谱或摩擦力曲线不能准确判定膜基结合力的表征值临界载荷,声发射图谱、摩擦力曲线与划痕形貌综合评定临界载荷结果才可信.WS-92划痕仪测量的结果验证了MST划痕仪评定结果的准确性.     

坡莫合金/铜磁性多层膜微观力学性能的研究

本文用直流磁控溅射方法在玻璃基片上制备了具有不同坡莫合金层厚度的坡莫合金/铜磁性多层膜,并采用纳米力学系统分别以压痕法、划痕法测定了坡莫合金层厚度对多层膜显微硬度、弹性模量以及划痕的临界载荷、宽度和深度等的影响.研究结果表明:在既定的接触深度,多层膜的显微硬度及弹性模量随坡莫合金层厚度变化不大,它们分别约为4.5 GPa和80 GPa,比坡莫合金单层膜的值低而比铜单层膜的值高;坡莫合金层厚度对多层膜微观摩擦学性能有较大的影响:随坡莫合金层厚度减小,特别是当其小于等于1.6 nm时,划痕有较高的临界载荷、较小的宽度和较浅的残余深度;多层膜的划痕临界载荷高于坡莫合金单层膜的值.     

TiN/TiCrN/TiCrAlN复合薄膜膜基结合力测定与分析

使用划痕仪对多弧离子镀制备的TiN/TiCrN/TiCrAlN复合薄膜进行了划痕实验,结合金相显微镜观察分析划痕表面形貌,综合判定了该复合薄膜的膜基结合力。结果表明,该薄膜的失效形式为周边剥落;单一的声信号曲线不能准确判定薄膜失效的临界载荷,需要声信号曲线与划痕形貌的综合判定。     

用涂层压入仪测定薄膜与基体结合强度的探讨

用新颖的能连续加载、卸载并配有声发射监测的涂层压入仪 ,对薄膜与基体的结合强度进行了探讨。实验结果表明 ,膜或膜 /基破坏的声发射信号各有特点 ,可区分压入过程中 (含卸载 )开裂和剥落及其对应的载荷值。压入法的临界载荷 pc 为加载过程中使膜发生初始剥落的外载 ,用涂层压入仪可精确测定。 pc 值对基体硬度和表面粗糙度的变化敏感。故用涂层压入仪可以实现用压入法考察膜 /基结合强度     

铜表面划痕过程声发射特性

以半导体互连材料铜为对象,研究铜表面划痕过程声发射特征,探索划痕载荷及速度对划痕过程声发射特征影响及铜表面划痕损伤机制,为基于声发射技术表征铜表面微纳尺度材料去除过程提供理论依据。研究发现,铜划痕过程主要以塑性变形为主,呈现周期变化形貌,并产生连续型声发射信号;随划痕速度的增加,信号强度增加,而载荷变化对信号影响较小;信号强度与变形体积增加速率呈指数关系。声发射信号能较好表征划痕过程。     

用涂层压入仪测定薄膜与基体结合强度的探讨

用新颖的能连续加载、卸载并配有声发射监测的涂层压入仪,对薄膜与基体的结合强度进行了探讨。实验结果表明,膜或膜／基破坏的声发射信号各有特点,可区分压入过程中（含卸载）开裂和剥落及其对应的载荷值。压入法的临界载荷ｐｃ为加载过程中使膜发生初始剥落的外载,用涂层压入仪可精确测量。ｐｃ值对基体硬度和表面粗糙度的变化敏感。故用涂层压入仪可以实现用压入法考察膜／基结合强度。     

合理使用划痕法及显微法测定TiN薄膜与基体结合力

采用反应磁控溅射的方法在TC4钛合金基板上制备了TiN薄膜,利用划痕法测试了TiN薄膜与基体之间的结合力,并结合薄膜硬度与显微法判断的临界载荷进行了对比分析。结果表明:单纯依靠划痕法判断临界载荷较为局限,结合显微法同时考虑硬度等力学性能共同判断临界载荷,是更为科学合理的办法。     

Micro-scratch analysis and mechanical properties of plasma-deposited silicon-based coatings on polymer substrates

Advanced optical applications require multifunctional coatings with specific mechanical properties, such as resistance to damage and good adhesion to different types of substrates, including polymers. In the present study we deposited amorphous hydrogenated silicon nitride (SiN_1.3) and oxide (SiO₂) films on polycarbonate and on silicon substrates by plasma enhanced chemical vapor deposition (PECVD), using a dual-mode microwave/radio frequency plasma system. The film adhesion was determined by the micro-scratch test. Depth-sensing indentation and substrate curvature measurements were used to evaluate the microhardness. Young's modulus and residual stresses of the films. The adhesion strength, represented by the critical load, L_c, when the film starts to delaminate, was determined as a function of the substrate material and the energy of bombarding ions. A direct correlation between the L_c values and the mechanical properties of the films was found. The formation of different crack patterns in the coatings during the scratch procedure is explained in terms of stress release mechanism depending on the mechanical properties of the film, the substrate and the interface region. In addition, different models applicable to the evaluation of the work of adhesion in the case of hard coatings on soft substrates are critically reviewed.     

压头曲率半径对硬质薄膜结合力划痕测量影响的比较研究

硬质薄膜的膜/基结合力是表征材料可靠性的重要特性参数。采用划痕法测试硬质薄膜的结合力时,有很多因素会影响到临界载荷Lc的判定,例如薄膜和基底的硬度、模量,薄膜的表面粗糙度等;此外,仪器机架刚度、划痕速率、压头的曲率半径等仪器的测量参数也会影响临界载荷Lc的判定。采用划痕测量法,研究了曲率半径为20μm,50μm和100μm的压头对单晶硅和304基底的亚微米类金刚石薄膜与基底的结合力测量的影响。研究结果显示:随着压头曲率半径的增加,2种材料的临界载荷也随之增大。     

磁控溅射法制备铁氧体薄膜的界面结合强度研究

利用磁控溅射法在单硅晶基底和玻璃基底上沉积铁氧体薄膜,采用AFM观察薄膜的微观形貌,采用划痕法测试薄膜的界面结合强度,测试结果表明:由于两种不同材质上沉积的薄膜粗糙度缘故,硅晶/铁氧体薄膜的临界载荷为19.7N,其划痕形貌为裂纹状扩展,玻璃/铁氧体薄膜的临界载荷为5.3N,其划痕形貌为剥落状。     

Scratch adhesion testing of hard coatings

The scratch test for adhesion is reviewed as the only method currently available for testing thin, hard and well-adhering coatings such as TiC on steel or cemented carbide substrates. The critical load, mode of coating removal and acoustic signals are discussed. It is found that the combination of acoustic signal with microscopic observations can indicate whether failure occurs following a cohesive or an adhesive mode. The critical loads increase with increasing coating thickness in a manner which is a characteristic of the coating-substrate combination being studied. Critical loads are higher for harder tougher substrate materials; they also appear to depend on the elastic modulus and the coefficient of friction of the coating itself.     

Hard coatings on light-metal components under mechanical surface loading

In this work the behaviour of hard coated light-metal components was investigated when they are mechanically loaded. Three lightmetal alloys, Ti-6Al-4V, AlSi7Mg and AlMgSi0.5 and 100Cr6 steel (as a reference material) were coated by two different physical vapour deposition processes: radio frequency magnetron sputtering and electron beam evaporation. The coating materials utilised were CrN and TiN. Standard test methods with different loading conditions were used to evaluate the substrate/coating-combinations: the hardness test (applying a static normal load), the scratch test (applying a combination of a static normal and a static tangential force) and the impact test (applying a dynamic normal load). It was observed that the load support of coated materials depends on the loading conditions. The coated aluminium alloys showed poor load support under all loading test conditions but produced a higher surface hardness than uncoated steel. Coated Ti-6Al-4V showed very good load support properties, similar to coated steel. All coated light-metal substrates demonstrated significant improvement in load support behaviour with an increase in coating thickness. The results of the scratch test, which is commonly used to asses adhesion properties of thin coatings, showed an immediate indenter-breakthrough on the aluminium alloy substrates, but causing no coating delamination. Due to this behaviour, the scratch test is not suitable to evaluate adhesion properties on coated soft light-metals. Yet the impact test allowed assessment of coating delamination on the aluminium alloys, proving its usefulness for adhesion measurement even on soft substrates. The study indicates that substitution of steel with coated lightmetal alloys is a viable proposition for certain applications.     

Effect of substrate temperature on the adhesion properties of magnetron sputtered nano-composite Si-C-N hard thin films

The adhesion and film failure studies on nano-composite SiCN thin films on silicon, glass and steel have been carried out. It was observed that both coating as well as the substrate has an influence on the adhesion of film. The films on hard substrate Si failed adhesively whereas on softer substrate, steel, cohesive failure was observed. The measured critical load was around 18 N and 24 N for SiCN film on silicon and steel substrate respectively. A decrease in critical load and interface toughness with the increase of substrate temperature during deposition for glass and steel substrate was observed.     

Oxygen-ion-assisted deposition of thin gold films

Thin gold films have been deposited on glass and silicon substrates using ion-assisted deposition techniques. The adhesion of the films to the substrates is assessed by a scratch test. Deposition assisted by 100 eV-1 keV oxygen ions yields highly adhesive films that can only be removed by damaging the substrate. Argon and hydrogen ions produce films with relatively poor adhesion. The results show that the reflectance of oxygen-assisted films is reduced by trapping of the oxygen in the gold but no bulk chemical or structural changes are detected. It is proposed that a thin stable layer of gold oxide is formed during film growth and diffuses into the substrate, providing a strong bond for subsequent film deposition. Highly adhesive films with bulk optical properties are deposited on glass and silicon using oxygen-ion assistance only to the point of continuous film formation.     

An experimental methodology for characterizing fracture of hard thin films under cyclic contact loading

Hard thin films are often employed as protective coatings for metal substrates and their fatigue/fracture property (especially that under contact) needs to be sufficiently understood. In this study, we present a combined experimental/computational framework for exploring the fracture characteristics of hard thin films upon both monotonic and cyclic contacts. The techniques of acoustic emission and corrosion potential fluctuation are combined to monitor the mode and initiation of crack, and numerical simulations based on the finite element method provide further information on the criterion of film fracture. For a model system of a TiN film physical vapor deposited onto a stainless steel substrate, ring cracks are produced when the stress in the film exceeds critical — such a critical moment arrives when the substrate undergoes excessive deformation, which makes the curvature of film bending critical just outside the contact zone. Since cyclic contact loading encourages large plastic deformation of substrate due to ratcheting plasticity, it is found that the critical contact force degrades, compared with monotonic loading. The present experimental/computational methodology is useful for obtaining the information of film fracture property under both monotonic and cyclic contact loads.     

Quantitative acoustic microscopy for characterization of the interface strength of diamond-like carbon thin films

Diamond-like carbon (DLC) films are emerging to be ideal materials in a variety of semiconductor, display, and film media applications. As with any deposited film, adhesion of the film to the substrate is of critical importance. The main objective of this paper is to report on the development of a technique based on acoustic microscopy for the quantitative characterization of the interface strength of thin (submicrometer) films. Preliminary results from 0.5 μm DLC films are presented to establish the feasibility of the new technique. Theoretical models of wave propagation indicate the Rayleigh wave velocity (at 600 MHz) is sensitive to the interface condition and could potentially be used to characterize the same. Acoustic material signatures (AMS) of DLC films which had varying levels of adhesion to silicon coated titanium substrates were obtained at 600 MHz using an acoustic microscope. The Rayleigh velocity (extracted from the AMS) had a strong correlation with the adhesion strength measured destructively using a pull tester. A model-based methodology for prediction of the interface strength of thin films through acoustic microscopy is also addressed.