AlN/TiSiN纳米多层膜的微观组织和力学性能研究

采用TiSi复合靶和Al靶,用射频磁控溅射工艺沉积不同TiSiN层厚度的AlN/TiSiN纳米多层膜。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)和纳米压痕仪研究了不同TiSiN层厚度对AlN/TiSiN纳米多层膜的微观组织和力学性能的影响。结果表明,随着TiSiN层厚度的增加,AlN相的结晶程度先增加后降低,涂层的硬度先提高后降低,当TiSiN层厚度为0.5nm时具有最高的硬度和弹性模量。HRTEM观测可知,在TiSiN层厚度为0.5nm时,TiSiN层在AlN层的模板作用下呈密排六方结构,并与AlN层呈共格外延生长,薄膜的强化主要与共格外延生长结构有关。     

SiO2层晶化对TiN/SiO2纳米多层膜结构和性能的影响

采用多靶磁控溅射法制备了一系列具有不同SiO2调制层厚的TiN/SiO2纳米多层膜.利用X射线衍射、X射线能量色散谱、扫描电子显微镜、高分辨电子显微镜和微力学探针表征和研究了多层膜的生长结构和力学性能.结果表明,具有适当厚度(0.45～0.9 nm)的SiO2调制层,在溅射条件下通常为非晶态,在TiN层的模板作用下晶化并与TiN层共格外延生长,形成具有强烈(111)织构的超晶格柱状晶多层膜;与此相应,纳米多层膜产生了硬度和弹性模量异常增高的超硬效应(最高硬度达45 GPa).随着SiO2层厚度的继续增加,SiO2层转变为非晶态,阻断了多层膜的共格外延生长,使纳米多层膜形成非晶SiO2层和纳米晶TiN层的多层结构,多层膜的硬度和弹性模量逐渐下降.     

CrAlN/WS_2纳米多层膜的微观结构和力学性能研究

采用反应磁控溅射工艺在Si基体上沉积了不同调制周期的CrAlN/WS_2纳米多层膜,采用X射线衍射仪(XRD)、高分辨透射电子显微镜(HRTEM)、纳米压痕仪和HSR-2M涂层摩擦磨损试验机、扫描电子显微镜(SEM),研究了调制周期对CrAlN/WS_2纳米多层膜微观结构和力学性能的影响。研究结果表明,WS_2层厚度低于0.8nm时,六方结构的WS_2在CrAlN的模板作用下转变为B1-NaCl型面心立方结构并与CrAlN层发生共格外延生长,使薄膜得到强化,在WS_2层厚度为0.8nm时,薄膜硬度和弹性模量达到最大,分别为37.3和341.2GPa。随着WS_2层厚度的进一步增加,WS_2又转变回六方结构,使薄膜共格外延生长结构破坏,结晶度降低,耐磨性增强,硬度和弹性模量减小。CrAlN/WS_2纳米多层膜的摩擦系数均在0.2~0.3之间,远低于单层CrAlN的摩擦系数的0.6,磨损率亦明显减小。获得了综合力学性能优异的CrAlN/WS_2纳米多层膜。     

ZrN/TiSiN纳米多层膜的微观结构和力学性能研究

采用反应磁控溅射的方法,利用Zr靶与TiSi复合靶成功制备了不同TiSiN层厚度的ZrN/TiSiN纳米多层膜。利用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、扫描电子显微镜(SEM)和纳米压痕仪研究了不同TiSiN层厚度对ZrN/TiSiN纳米多层膜的微观结构和力学性能的影响。结果表明,ZrN/TiSiN纳米多层膜主要由面心立方的ZrN相组成,随着TiSiN层厚度的增加,纳米多层膜的结晶程度先增加后降低,其硬度和弹性模量也先升高后降低。当TiSiN层厚度为0.7nm时,纳米多层膜具有最高的硬度和弹性模量,分别为28.7和301.1GPa,远超过ZrN单层膜。ZrN/TiSiN纳米多层膜的强化效果可由交变应力场和模量差理论进行解释。     

TiAlN/VN纳米多层膜的微结构与力学和摩擦学性能

采用反应磁控溅射制备了TiAlN/VN纳米多层膜, 并使用X射线衍射分析(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、纳米压痕仪和多功能摩擦磨损试验机对多层膜的微结构与力学和摩擦学性能进行了表征和分析。研究结果表明: 不同调制周期的TiAlN/VN多层膜均呈典型的柱状晶生长结构, 插入VN层并没有打断TiAlN涂层柱状晶的生长。在一定调制周期下, TiAlN/VN纳米多层膜中的TiAlN和VN层之间能够形成共格生长结构, 其硬度和弹性模量相比于TiAlN单层膜均有显著提升, 其中, TiAlN (10 nm)/VN (10 nm)的硬度和弹性模量最大增量分别达到39.3%和40.9%。TiAlN/VN纳米多层膜的强化主要与其共格界面生长结构有关。另外, TiAlN单层膜的摩擦系数较高(~0.9), 通过周期性地插入摩擦系数较低的VN层能够使得TiAlN的摩擦系数大大降低, TiAlN/VN纳米多层膜的摩擦系数最低为0.4。     

反应溅射HfC/Si3N4纳米多层膜的微结构与力学性能

通过反应磁控溅射制备了一系列不同Si3N4层厚的HfC/Si3N4纳米多层膜,采用X射线光电子能谱、X射线衍射、扫描电子显微镜和微力学探针表征了多层膜的微结构、硬度与弹性模量,研究了Si3N4层厚度变化对纳米多层膜微结构与力学性能的影响。结果表明,溅射的Si3N4粒子不与C2H2气体反应,因NaCl结构HfC晶体调制层的模板效应,溅射态为非晶的Si3N4层在厚度小于约1 nm时被强制晶化,并与HfC晶体层形成共格外延生长结构,多层膜呈现强烈的(111)择优取向柱状晶,其硬度和弹性模量显著上升,最高值分别达到38.2 GPa和343 GPa。进一步增加Si3N4层的厚度后,Si3N4层转变为以非晶态生长,多层膜的共格外延生长结构受到破坏,其硬度和模量也相应降低。     

Si含量对NbN/CrSiN纳米多层膜微观结构和力学性能的影响

采用磁控溅射工艺在Si底片依次沉积NbN、CrSiN纳米层,通过改变靶材的Si含量,制备出一系列NbN/CrSiN纳米多层膜。分别采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、高透射电子显微镜(HRTEM)和纳米压痕仪研究Si含量对NbN/CrSiN纳米多层膜显微结构和力学性能的影响。实验结果表明,随着Si含量的增加,NbN相的结晶程度先增加后降低,薄膜的硬度和弹性模量也是先增高后降低,在n(Si)∶n(Nb)=3∶22时获得最高硬度和弹性模量,分别为31.92和359.3GPa。显微结构表征表明,当n(Si)∶n(Nb)=3∶22时,NbN/CrSiN纳米多层膜柱状晶生长状况最好,CrSiN层在NbN层的模板作用下转变为面心立方结构,并与NbN层呈共格外延生长。薄膜力学性能的提高主要与CrSiN与NbN形成的共格外延生长结构有关。     

射频磁控溅射法制备TiSiCN纳米复合膜的微观结构和力学性能研究

采用射频磁控溅射工艺在Si基底上制备TiSiCN纳米复合膜,固定靶材中的Ti含量,通过改变Si和C的含量比沉积得到一系列薄膜,采用X射线衍射仪(XRD)、高分辨透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)和纳米压痕仪研究了不同Si/C含量比对TiSiCN纳米复合膜的微观结构和力学性能的影响。结果表明,Si/C含量比对TiSiCN纳米复合膜的微观结构和硬度具有显著影响,当Si/C含量比为Si2C2时制得薄膜的微观结构为晶化的界面相(SiNx+C)与其包裹的TiN纳米晶粒共格外延生长,薄膜硬度达到最高值46GPa。     

TiN/Si3N4纳米晶复合膜的微结构和强化机制

采用高分辨透射电子显微镜对高硬度的TiN/Si3N4纳米晶复合膜的观察发现,这类薄膜的微结构与Veprek提出的nc-TiN/a-Si3N4模型有很大不同：复合膜中的TiN晶粒为平均直径约10nm的柱状晶,存在于柱晶之间的Si3N4界面相厚度为0.5～0.7nm,呈现晶体态,并与TiN形成共格界面.进一步采用二维结构的TiN/Si3N4纳米多层膜的模拟研究表明,Si3N4层在厚度约＜0.7nm时因TiN层晶体结构的模板作用而晶化,并与TiN层形成共格外延生长结构,多层膜相应产生硬度升高的超硬效应.由于TiN晶体层模板效应的短程性,Si3N4层随厚度微小增加到1.0nm后即转变为非晶态,其与TiN的共格界面因而遭到破坏,多层膜的硬度也随之迅速降低.基于以上结果,本文对TiN/Si3N4纳米晶复合膜的强化机制提出了一种不同于nc-TiN/a-Si3N4模型的新解释.     

NbSiN纳米复合膜的显微结构、超硬效应和机理的研究

采用NbSi复合靶,通过调节Nb与Si的比例,利用磁控溅射射频工艺,在单晶硅片上沉积不同Si含量的NbSiN纳米复合膜。利用X射线衍射仪、纳米压痕仪和高分辨透射电镜等,研究了Si含量对NbSiN纳米复合膜的微观结构和力学性能的影响。结果表明:随着薄膜中Si含量的增加,其结晶程度先升高,然后降低,硬度和弹性模量先增加后降低,当n(Si):n(Nb)=5:20时,NbSiN薄膜硬度和弹性模量均达到最大值33.6和297.2 GPa。微观组织观察表明,此时NbSiN薄膜内部形成Si_3N_4界面相包裹NbN纳米晶粒的纳米复合结构,Si_3N_4界面相呈结晶态协调相临NbN纳米晶粒间的位向差,并与NbN纳米晶粒之间形成共格外延生长,其微结构可用nc-NbN/c-Si_3N_4模型来表示,表明其超硬效应源于NbN基体相和Si_3N_4界面相之间形成的共格外延生长界面。     

Influence of TiN-nanolayered insertions on microstructure and mechanical properties of TiSiN nanocomposite film

TiN nanolayers with different thicknesses were inserted in TiSiN nanocomposite film by magnetron-sputtering technique. The influences of TiN insertion nanolayers with different thicknesses on microstructure and mechanical properties of TiSiN film were investigated X-ray diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, and nanoindentation techniques. When the TiN insertion layer thickness is <0.5 nm, TiN nanolayers can coordinate the misorientations between TiN nanocrystallites in adjacent TiSiN layers, leading to the transformation from the nanocomposite structure with TiN nanocrystallites encapsulated by SiN _x interfacial phase into columnar crystal structure, and disappearance of the strengthening effect from the nanocomposite structure. When the TiN insertion layer thickness increases to 1.0 nm, the film is strengthened with the epitaxial growth structures between TiSiN and TiN layers. As the TiN insertion layers further thicken, the hardness and elastic modulus evidently decrease, which can be attributed to the breakage of epitaxial growth structures between TiSiN and TiN layers.     

Influence of bias voltages on the structure and wear properties of TiSiN coating synthesized by cathodic arc plasma evaporation

Nanocomposite TiSiN films have been deposited on M2 tool steel substrates using TiSi alloy as target by a dual cathodic arc plasma deposition (CAPD) system. The influences of bias voltages on the microstructure, mechanical and tribological properties of the films were investigated. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction techniques were employed to analyse the microstructure, grain size and residual stress. Nano-indentation and tribometer testers were used to measure the mechanical and tribological properties of nanocomposite TiSiN thin films. The results showed that the hardness of the films ranged from 25 to 37 GPa, which were higher than that of TiN (21 GPa). The coefficient of friction of the TiSiN thin films was more stable but was higher than that of TiN when wear against both Cr steel and WC-Co ball, respectively. When encountered with both Cr steel and WC-Co ball of the counter ball, the tribological mechanisms of TiSiN thin films are adhesive and abrasion wears, respectively. It has been found that the microstructure, mechanical and wear properties of the films were correlated to bias voltage, grain size, and amorphous Si₃N₄ nanocomposite formed in film structure, resulting in a superhard TiSiN coating.     

Influence of multi-interfacial structure on mechanical and tribological properties of TiSiN/Ag multilayer coatings

The TiSiN/Ag multilayer coatings with bilayer periods of ~50, 65, 80, 115, 150, and 410 nm have been deposited on Ti6Al4 V alloy by arc ion plating. In order to improve the adhesion of the TiSiN/Ag multilayer coatings, TiN buffer layer was first deposited on titanium alloy. The multi-interfacial TiSiN/Ag layers possess alternating TiSiN and Ag layers. The TiSiN layers display a typical nanocrystalline/amorphous microstructure, with nanocrystalline TiN and amorphous Si₃N₄. TiN nanocrystallites embed in amorphous Si₃N₄ matrix exhibiting a fine-grained crystalline structure. The Ag layers exhibit ductile nanocrystalline metallic silver. The coatings appear to be a strong TiN (200)-preferred orientation for fiber texture growth. Moreover, the grain size of TiN decreases with the decrease of the bilayer periods. Evidence concluded from transmission electron microscopy revealed that multi-interfacial structures effectively limit continuous growth of single (200)-preferred orientation coarse columnar TiN crystals. The hardness of the coatings increases with the decreasing bilayer periods. Multi-interface can act as a lubricant, effectively hinder the cracks propagation and prevent aggressive seawater from permeating to substrate through the micro-pores to some extent, reducing the friction coefficient and wear rates. It was found that the TiSiN/Ag multilayer coating with a bilayer period of 50 nm shows an excellent wear resistance due to the fine grain size, high hardness, and silver-lubricated transfer films formed during wear tests.     

Correlation between thermal fatigue and thermomechanical properties during the oxidation of multilayered TiSiN nanocomposite coatings synthesized by a hybrid physical/chemical vapour deposition process

TiSiN and TiSiAlN coatings were deposited on M2 steel by a hybrid physical/chemical vapour deposition process. SiH₄ was used as precursor for Si, while metals were brought by arc evaporation. This hybrid process allowed us to control the silicon enrichment along the coating thickness. Both films were synthesized applying a serrated silane partial pressure during deposition, leading to a multilayered structure with a 700 nm period. X-ray diffraction analyses showed only TiN peaks, whose width revealed a mean grain size below 10 nm. The multilayer structure and the nanometric size of the grains in layers containing a high Si content were observed by cross-section microscopy in transmission mode. Mechanical properties were improved compared to both TiN and SiN_x references, in relation to the nanocomposite microstructure of layers enriched in silicon. The oxidation behaviour was assessed by thermogravimetric analyses. The oxidation resistance was studied in isothermal, dynamic as well as cycling (10-cycle runs 25-800-25 °C) conditions. The multilayered nanocomposite TiSiN film exhibited a high durability in terms of mechanical and oxidation behaviours. Thermal cycling experiments revealed its high resistance which seems to result from a synergy between the shield effect of the SiN_x network — that would limit the oxidation process — and the intrinsic “deformability” of TiN layers — that would withstand the volume modifications of the substrate due to temperature variations. A further addition of aluminium, without significantly affecting the mechanical properties, contributes to the improvement of the oxidation resistance thanks to the formation of the expected outer refractory alumina layer.     

Investigation on microstructure and mechanical properties of reactively synthesized TiAlN/AlON nanomultilayers

The novel TiAlN/AlON nanomultilayers with different AlON layer thickness were synthesized by reactive magnetron sputtering. The microstructure and mechanical properties were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM) and nano-indentation techniques. The results indicated that, under the template effect of fcc (face-centered cubic) TiAlN layers, originally amorphous AlON layers were crystallized and grew epitaxially with TiAlN layers when AlON layer thickness was below 0.7 nm. Accordingly, the hardness and elastic modulus of the nanomultilayers increase and reach the maximum values of 36.2 and 385.6 GPa, respectively. With further increase of AlON layer thickness, AlON layers transformed back into amorphous state and broken the coherent growth of nanomultilayers, leading to the decrease of hardness and elastic modulus. The strengthening mechanism of TiAlN/AlON nanomultilayers was further discussed.     

Coherent growth and superhardness effect of heterostructure h-TiB2/c-VC nanomultilayers

TiB₂/VC nanomultilayers with different VC layer thicknesses have been prepared by a multi-target magnetron sputtering system. X-ray diffraction, high-resolution transmission electron microscopy and nanoindentation measurements were employed to investigate the microstructure and mechanical properties of these films. The results revealed that a metastable structure of VC has been formed in epitaxial TiB₂/VC multilayers with VC layer thickness ≤0.8 nm. Meanwhile, the multilayers exhibited coherent interface between layers resulting in a significantly enhanced hardness of the films, with a maximum value of 43.9 GPa. The stable cubic structure of VC was observed for VC layer thickness ≥1.3 nm, which causes a gradual disruption of the coherent interface of the multilayers, resulting in the quick decrease of hardness.     

Coherent growth and superhardness effect of heterostructure h-TiB2/c-VC nanomultilayers

TiB₂/VC nanomultilayers with different VC layer thicknesses have been prepared by a multi-target magnetron sputtering system. X-ray diffraction, high-resolution transmission electron microscopy and nanoindentation measurements were employed to investigate the microstructure and mechanical properties of these films. The results revealed that a metastable structure of VC has been formed in epitaxial TiB₂/VC multilayers with VC layer thickness ≤0.8 nm. Meanwhile, the multilayers exhibited coherent interface between layers resulting in a significantly enhanced hardness of the films, with a maximum value of 43.9 GPa. The stable cubic structure of VC was observed for VC layer thickness ≥1.3 nm, which causes a gradual disruption of the coherent interface of the multilayers, resulting in the quick decrease of hardness.