Origins of microstructure and stress gradients in nanocrystalline thin films: The role of growth parameters and self-organization

The development of depth gradients of texture, morphology and stresses in thin nanocrystalline films was experimentally demonstrated for a nanocrystalline CrN film by means of position-resolved synchrotron X-ray nanodiffraction and explained by atomistic processes at the growing film surface and the effect of interfaces, both controlled by the deposition conditions. Controllable changes in the energy of incident particles adjusted by bias voltages ranging from ?40 to ?120 V affect the competitive growth of grains with different orientations, induce disruption of grain growth and thus give rise to structural variations across the film thickness. Subsequent changes in the volume fraction of grain boundaries and film texture were found to be responsible for changes in the residual stress state as defect generation proceeds to different extents in the interior of differently oriented grains and in the interfacial area. While the defect density predominantly affects the development of intrinsic stress, the variation in the number of weakly bonded atoms of grain boundaries determines the thermal stress component. The structural dependence of both stress components thus contributes to the characteristic development of stress gradients in thin nanocrystalline films.     

Effect of deposition processes on residual stress profiles along the thickness in (Ti,Al)N films

The effect of deposition processes on the distribution of residual stresses in the thickness of the (Ti,Al)N films prepared by arc ion plating (AIP) was investigated in the present work, which indicates that the stress distribution exhibits a “bell” shape and the maximum compressive stress appears in the layer near the surface. The residual stress increases with the thickness of a film and the substrate bias voltage, respectively. The stress distribution can be altered, and the adhesion of the film/substrate can be improved by optimizing the deposition parameters. Finally, a film with a thickness of 7.57 μm was successfully directly deposited on the substrate through optimizing the bias voltage.     

基片负偏压对Cu膜纳米压入硬度及微观结构的影响

测试了不同溅射偏压下Cu膜的纳米压入硬度，探讨了溅射偏压、残余应力及压痕尺寸效应对Cu膜硬度的影响。结果表明，随着溅射偏压的增大，薄膜晶粒尺寸及残余压应力均减小，导致薄膜的硬度增大，并在-80V达到最大值，随后有所降低。同时薄膜中的压痕尺寸效应对薄膜硬度随压入深度的分布有很大的影响。     

Residual stress gradient analysis with GIXRD on ZrO2 thin films deposited by MOCVD

Zirconia (ZrO₂) films were deposited by metal-organic chemical vapour deposition (MOCVD) on (1 0 0) Si single crystals using Zr(thd)₄ precursor. The crystalline structure determined by X-ray diffraction (XRD) spectrum showed that the films exhibit the metastable tetragonal phase at room temperature. A method based on the pseudo-grazing incident X-ray diffraction (GIXRD) geometry was applied to study the residual stress gradient on the zirconia (ZrO₂) films. By varying the X-ray beam penetration depth and the associated geometry angles, the residual stress profile can be described in detail. The residual stress profile revealed that tensile residual stress was present in the near-surface region and then it decreased rapidly as a function of depth; whereas, in the deeper regions, the films were under compressive stress. The origin of the residual stresses, which are assumed to consist of the film growth stress during the MOCVD process and film thermal stress during film cooling after deposition, is discussed.     

The effect of applied substrate negative bias voltage on the structure and properties of Al-containing a-C:H thin films

Al-containing hydrogenated amorphous carbon (Al-C:H) films were prepared using a magnetron sputtering Al target in the CH₄ and Ar mixture atmosphere with various applied substrate pulse negative bias voltages. The hydrogen content and internal stress of the film decrease dramatically with the substrate pulse bias voltage increase. However, the hardness values of the films keep at high level (∼ 20 GPa) without any obvious changes with the increase of the applied substrate pulse bias voltages. The Al-C:H film prepared at applied substrate high bias voltage shows a long wear life and low friction coefficient.     

Micro-abrasive wear of DC and pulsed DC titanium nitride thin films with different levels of film residual stresses

In this work, six specimens with titanium nitride (TiN) thin films and cemented carbide (WC-Co) substrates were analyzed in terms of their micro-abrasive wear behavior. These specimens were obtained from a previous work, in which film depositions were conducted varying parameters such as bias (0, − 50 or − 100 V), type of target power (DC or pulsed DC) and, in the cases where substrate bias was zero, substrate condition (ground or floating). As a result, the level of film residual stresses varied from specimen to specimen, in the range from 4 to 11 GPa (compressive). In this work, micro-abrasive tests were run on these six specimens, using balls of AISI 1010 steel and an abrasive slurry with distilled water and silicon carbide particles with average particle size of 5 μm. Results were analyzed in terms of the wear mechanisms observed at the worn surface and also in terms of the wear resistance, characterized by the wear coefficient (k). Trends indicate a decrease in film wear rate with an increase in the value of film residual compressive stresses, as long as the adhesion was not impaired. Different values of film wear coefficient (k_c) were calculated for specimens obtained with ground and floating voltage substrates, although similar values of film residual stresses were measured in both cases.     

高功率脉冲和脉冲直流磁控共溅射CrAlN薄膜的研究

目的通过掺杂适量Al元素来固溶强化Cr N薄膜,从而提高薄膜的抗氧化性能和热稳定性。方法采用高功率脉冲磁控溅射和脉冲直流磁控溅射复合镀膜技术制备了Cr Al N薄膜,利用XRD、纳米压痕仪、应力仪、摩擦磨损试验机系统地研究了不同基体偏压对CrAlN涂层结构和力学性能的影响。结果所有CrAlN涂层均以fcc-(Cr,Al)N相为主,且随着基体偏压的增加,沿(111)晶面生长的衍射峰逐渐减弱,并向小角度偏移;薄膜压应力显著增加,最大值为-2.68GPa;薄膜硬度先上升后下降,在基体偏压为-30V时,硬度达到最大值22.3 GPa;H/E值和H~3/E~(*2)值随着基体偏压的增加,近似线性增大,当偏压为-120 V时,均达最大值0.11、0.21 GPa,同时摩擦系数和磨损率逐渐减小。结论当基体偏压为-120 V时,CrAlN薄膜具有最佳的耐磨性能,H/E和H~3/E~(*2)在一定程度上可评价涂层的耐磨性。     

Si和316L基片上TiN薄膜微观结构和应力的对比分析

目的 比较Si和316L基片上TiN薄膜的微观结构和应力,分析基片材料和基片初始曲率对薄膜应力的影响.方法 采用电弧离子镀技术在Si基片和316L基片上制备了TiN薄膜,实测了薄膜应力,通过XRD、SEM、TEM等方法对薄膜的微观结构进行了分析.运用有限元分析技术,以结构力学为原理,分别对不同初始曲率的Si基片和316...     

Characterisation and performance of partially filtered arc TiAlN coatings

It is now being recognised that the level of residual stress in physical vapour deposited (PVD) coatings is yet another important physical property of thin film PVD coating parameters that can critically affect their performance. In this study, titanium aluminium nitride (TiAlN) coatings were deposited using a dual source filtered arc evaporation system with a view to determine the effect of bias voltage increased from −50 to −250 V, the residual stress in the coating as well as the adhesion and cutting tool performance. The X-ray diffraction methods of Bragg–Brentano and glancing angle parallel beam (sin²ψ) were used to study the texture and residual stress in the as-deposited coatings. The results showed that as the bias voltage increased from –50 to –250 V and the residual stress increased from 7.67 to 11.81 GPa (compressive). However, little change in residual stress was observed with an increase in arc current from 75 to 175 A. All coatings exhibited a preferred orientation in the {111} direction, however, a reduction in the {111} intensity was observed for the coating deposited at –50 V. Coating hardness was observed to increase from 26.3 to 31.7 GPa when the bias voltage was increased from –50 to –150 V. However, no further increase was observed at –250 V. No effect on hardness was noted for any change in arc current. Scratch adhesion results showed little effect on the bias voltage with critical load values of 46, 48 and 43 N for the −50, −150 and −250 V biased coatings, respectively. However, increasing the arc currents above 75 A resulted in a reduction of critical load from 48 N for 75 A to 36 and 37 N for 125 and 175 A arc currents, respectively. Damiler Benz Rockwell ‘C’ adhesion tests carried out also revealed a similar trend. The Al content of the coating was found to decrease with increasing bias voltage but increase with an increase in arc current. Accelerated drill life tests suggested that an increase in residual stress associated with the higher bias voltages does affect tool life. For arc current variation, the balance between intrinsic and extrinsic stresses that contribute to the total residual stress may affect cutting tool life.     

偏压和氮分压对TiN膜层结构和膜/基体系性能的影响

采用多弧离子镀工艺在钛合金或低碳钢基材上制备TiN薄膜,研究了不同偏压及不同氮分压下制备的薄膜相结构、残余应力、膜/基体系硬度、膜/基结合及其摩擦磨损行为.结果表明:偏压影响TiN晶粒的择优取向,偏压绝对值越大则薄膜内部的残余应力也越大;偏压过高或过低都会降低薄膜与基材之间的结合强度,从而影响其摩擦学性能.氮分压上升,TiN熔滴粒度变大,Ti2N相减少,导致薄膜硬度提高;由过高或过低氮分压制备的膜/基体系在划痕试验中测得的临界载荷均较小;随着氮分压的增加,在试验范围内样品的摩擦因数下降但耐磨性并未获得预期的提高.     

纳米金刚石薄膜的微结构和残余应力

采用双偏压热丝化学气相沉积法在不同栅极和衬底偏流下制备出纳米金刚石薄膜.采用Raman谱、SEM、AFM、纳米压痕法和XRD分析纳米金刚石膜的微结构、弹性模量和残余应力.分析结果表明,金刚石晶粒尺寸随着栅极和衬底偏流的增加而减小,而衬底偏流的加入会引起非金刚石成分的显著增加.金刚石晶界的畸变使得弹性模量随着栅极和衬底偏流的增加而减小,薄膜热应力也随之减小.晶界非金刚石成分引起金刚石本征应力呈压应力性质,晶界密度的增加使得本征应力随着栅极偏流的增加而增加,但衬底偏流引起薄膜抵抗变形能力剧烈下降,导致金刚石本征压应力的减小.     

高功率脉冲磁控溅射制备的TiN薄膜 应力释放及其结合稳定性研究

目的 探究高功率脉冲磁控溅射（HPPMS）制备的氮化钛（TiN）薄膜在自然时效过程中,应力、薄膜/基体结合性能随时间的变化规律。方法 采用高功率脉冲磁控溅射（HPPMS）技术,通过调控基体偏压（-50、-150 V）,制备出具有不同残余压应力（3.18、7.46 GPa）的TiN薄膜,并采用基片曲率法、X射线衍射法、划痕法和超显微硬度计评价了薄膜的应力、薄膜/基体结合性能、硬度随时间的变化规律。结果 在沉积完成后1 h内,-50 V和-150 V基体偏压下制备的TiN薄膜压应力分别在3.12~3.39 GPa和7.40~7.55 GPa范围内波动,薄膜压应力没有发生明显变化;沉积完成后1~7天,平均每天分别下降28.57 MPa和35.71 MPa;7~30天,平均每天分别下降2.08 MPa和2.50 MPa;30~60天内,平均每天分别下降1.67 MPa和7.00 MPa。其压应力连续下降,且均表现出前期下降速率快,后期下降逐渐放缓的趋势。自然放置60天后,应力基本释放完毕,薄膜性质基本保持稳定。同时,薄膜/基体结合性能随时间逐渐变差,薄膜硬度下降。结论 HPPMS制备的TiN薄膜在自然时效过程中,其残余应力会随时间增加,连续下降,进而影响薄膜的力学性能。     

偏压对GLC镀层的结构及应力的影响研究

采用磁控溅射离子镀技术制备了类石墨镀层（GLC）,利用扫描电子显微镜（SEM）测量了镀层的厚度、X射线衍射仪（XRD）研究了材料的物相和应力,并结合透射电子显微镜（TEM）观察和分析了材料的组织结构。研究结果表明：不同偏压下得到的镀层结构相同,均为非晶为主的类石墨镀层,并且随着偏压增大,膜厚逐渐减小;在所研究的偏压下,应力变化规律是随着偏压的增加,样品与基体的复合应力先增大,后减小,其中～65V时达到最大值。     

Deposition of nanolayered CrN/AlBN thin films by cathodic arc deposition: Influence of cathode arc current and bias voltage on the mechanical properties

Thin films of CrAlBN were deposited on SKD 11 tool steel substrate using Cr and AlB cathodes in a cathodic arc plasma deposition system. The influence of AlB cathode arc current and substrate bias voltage on the mechanical and the structural properties of the films was investigated. The CrAlBN thin films had a multilayered structure in which the nano-crystalline CrN layer alternated with the amorphous AlBN layer. The hardness of the films increased as the AlB cathode arc current was raised from 35 to 45 A, and then decreased with further increase of the current. The hardness of the films increased rapidly with the increase of the bias voltage from − 50 to − 150 V. Further increase in the bias voltage decreased the hardness. The maximum hardness of 48 GPa was obtained at the bias voltage of − 150 V. With the increase of bias voltage, a good correlation between the residual stress and the hardness of the films was observed.     

Cathodic arc plasma deposition of nano-multilayered ZrN/AlSiN thin films

Thin films of ZrN/AlSiN were deposited on SKD 11 tool steel substrate using Zr and AlSi cathodes in an Ar/N₂ gas mixture in a cathodic arc plasma deposition system. The influence of the AlSi cathode arc current and the substrate bias voltage on the mechanical and structural properties of the films was investigated. X-ray diffraction, electron probe micro-analysis, high resolution transmission electron microscopy, nanoindentation and profilometry were used to characterize the films. The ZrN/AlSiN thin films had a multilayered structure by rotating the substrate in which nano-crystalline ZrN layers alternated with amorphous AlSiN layers. The hardness of the films increased as the AlSi cathode arc current was raised from 35 to 40 A, and then decreased with a further increase of the current. The hardness of the films increased with the increase of the bias voltage from − 50 to − 100 V. Further increase in the bias voltage decreased the hardness. The films exhibited a maximum hardness of 38 GPa. With the increase of bias voltage, the residual stress of the films correlated well with the hardness.     

Microstructure and residual stress of TiN films deposited at low temperature by arc ion plating

The TiN films were deposited on 316L stainless steel substrates at low temperature by arc ion plating. The influences of substrate bias voltage and temperature on microstructure, residual stress and mechanical properties of the films were investigated by EDS, SEM, XRD and nanoindenter tester, respectively. The results showed that the TiN films were highly oriented in (111) orientation with a face-centered cubic structure. With the increase of substrate bias voltage and temperature, the diffraction peak intensity increased sharply with simultaneous peak narrowing, and the small grain sizes increased from 6.2 to 13.8 nm. As the substrate temperature increased from 10 to 300 °C, the residual compressive stress decreased sharply from 10.2 to 7.7 GPa, which caused the hardness to decrease from 33.1 to 30.6 GPa, while the adhesion strength increased sharply from 9.6 to 21 N.     

基片偏压改变对镁合金 Ti / TiN 膜质量的影响

目的探讨基片偏压对镁合金Ti/TiN膜层质量的影响。方法利用多弧离子镀技术,在不同偏压条件下,对镁合金先镀Ti再镀TiN,通过SEM观察膜层形貌,通过划痕测定膜基结合性能,通过电化学工作站对比AZ31镁合金与不同偏压镀膜试样的耐蚀性。结果偏压为200V时,TiN膜层致密均匀且成膜速度快,膜层耐蚀性最好;偏压为200V时,基体结合最好且膜层较厚,有较好的耐蚀性。结论镀Ti膜时的偏压对随后镀TiN的质量有着显著的影响,以200V偏压的工艺镀TiN膜层质量最好,膜层致密,成膜速度快,耐蚀性优良。     

Effect of substrate bias voltage on the texture and microstructure of Cu thin films deposited by ion beam deposition

Cu thin films deposited by non-mass separated ion beam deposition under various substrate bias voltages were investigated. The film textures and microstructure were analyzed by X-ray diffraction and field emission scanning electron microscopy, and the resistivity of the film was measured with the Van der Pauw method. It was found that the optimum negative substrate bias voltage for Cu films was −50 V. The Cu films deposited without substrate bias voltage showed a columnar grain structure with small grains and random orientation. However, when a substrate bias voltage of −50 V was applied, the Cu films had a non-columnar structure with a strong (111) texture and large grains. The electrical resistivity of the Cu films decreased remarkably with increasing negative substrate bias voltage, and reaching a minimum value of 1.8±0.13 μΩ cm at the substrate bias voltage of −50V.     

DEPOSITION OF c-BN FILMS AND ADHESION IMPROVEMENT

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