全方位离子注入与沉积TiN薄膜的纳米压痕和纳米划擦行为

用等离子体浸没离子注入与沉积(PIIID)复合改性技术在AISI52100轴承钢基体表面合成了高硬耐磨的TiN薄膜。膜层的相组成及其表面形貌分别用X射线衍射(XRD)和原子力显微镜(AFM)表征。合成薄膜前后试样的力学性能经纳米压痕和划痕实验评价。XRD结果表明,膜层中主要存在TiN相,择优取向(200),同时含有少量TiO2和钛氮氧的化合物。AFM形貌显示出试样表面TiN呈定向排列,膜层均匀完整,结构致密。纳米压痕测试结果表明,膜层具有较高的纳米硬度和弹性模量,最大值分别达到22.5和330 GPa,较基体分别增长104.5%和50%。根据纳米划痕形貌和划痕深度随划痕位置的变化关系分析出,薄膜在纳米划擦过程中先后经历了弹性变形,弹塑性变形,加载开裂或卸载剥落三个阶段。划擦剥落抗力达到80mN,表明TiN薄膜具有很好的弹性恢复能力和较强的疲劳剥落抗力。     

磁控溅射制备(Ti,Al,Cr)N硬质薄膜及其力学性能的研究

用反应磁控溅射的方法通过改变Cr靶溅射功率在不锈钢基体卜沉积不同Cr含量TiAlCrN薄膜.采用台阶仪测量薄膜厚度;采用纳米压痕仪测量薄膜的硬度、弹性模量和薄膜与基体的结合力.沉积的TiAlCrN薄膜随着Cr含量增加,薄膜硬度先增大,而后减小;TiAlCrN薄膜的第一临界载荷和第二临界载荷均随Cr含量增加而增大.     

单晶氮化镓纳米压痕与划痕实验

为分析单晶氮化镓的微观变形机理,使用纳米压痕仪对单晶氮化镓进行压痕与划痕实验.结果表明单晶氮化镓压痕过程存在弹塑转变过程即"pop-in"现象,分析得出此现象是由材料的位错萌生和扩展导致,压痕周围产生凸起现象导致计算硬度和弹性模量偏大,通过模型修正得到更真实的硬度和弹性模量数据.单晶氮化镓的变载划痕过程发生弹塑转变和脆塑转变,弹塑变形阶段深度-位移曲线波动平稳,表面光滑;而脆性阶段曲线波动幅度较大,表面产生侧向裂纹且朝着划痕方向45°对称分布.得到弹塑转变的临界载荷为389 mN,脆塑转变临界载荷为1227 mN,因此单晶氮化镓塑性加工区域应在389～1227 mN之间,该区域内易加工出光滑表面.通过不同载荷划痕实验,发现划痕压头所受的切削力和摩擦系数随划痕载荷的增大而增大,因此氮化镓加工时应选择合理的加工载荷.     

ZnO纳米晶薄膜的制备及特性分析

在低温下制备了粒径小于10nm的ZnO纳米晶,用旋涂法制备ZnO纳米晶薄膜,XRD分析ZnO晶相是纤锌矿结构;SEM与AFM表明,纳米晶薄膜在300％退火后薄膜的厚度明显减小到130nm,表面粗糙度降低到3．27nm,粒径明显增大;紫外-可见吸收和透射比光谱表明,随着退火温度的增加,吸收边发生了红移,吸收肩更明显,薄膜具有高的透射率（75—85％）;薄膜方阻随温度增加而增大,300℃以下退火方阻增加很小（小于8．5Ω／sq）,400℃以上退火方阻大幅增加（大于21．1Ω／sq）,因此,ZnO纳米晶薄膜最优退火温度点为300℃。     

基于划刻实验的单晶锗材料去除机理研究

采用Cube压头对单晶锗进行变载与恒载纳米划刻实验, 利用扫描电子显微镜和原子力显微镜对已加工表面进行观测, 根据表面形貌将划刻过程分为延性域、脆塑转变域及脆性域三种, 对各个阶段的表面成型及材料去除方式进行了研究。使用最小二乘法对不同阶段划刻力进行非线性拟合, 并利用相关系数检验拟合函数可靠性, 结果表明划刻力与划刻深度存在强相关性。同时分析了单晶锗的弹性回复率随划刻距离的变化趋势, 结果表明工件的弹性回复率将从纯弹性阶段的1逐步回落至0.76左右。基于脆塑转变临界载荷, 以裂纹萌生位置作为脆塑转变标志, 首次结合工件已加工表面弹性回复, 提出一种适用于计算单晶锗的脆塑转变临界深度模型, 其脆塑转变临界深度为489 nm。     

TC4钛合金表面电弧离子镀TiN/CrN纳米多层薄膜研究

用电弧离子镀技术在TC4钛合金基体上通过改变偏压制备了4组TiN/CrN薄膜,对薄膜的表面形貌、厚度、相结构、硬度、膜基结合力和摩擦系数等组织、性能进行了测试表征。结果表明,薄膜是由TiN相和CrN交替叠加构成的纳米多层薄膜,薄膜的调制周期为60 nm,总的厚度约为480 nm。与基体钛合金相比,镀膜后样品的表面性能与偏压幅值密切相关并有显著提高:显微硬度从基体的3 GPa提高到16.5~24.7 GPa;摩擦系数从基体的0.35大幅度降低到0.14~0.17;薄膜与基体结合牢固,膜基临界载荷在60~80N之间。经电弧离子镀TiN/CrN纳米多层薄膜处理后,TC4钛合金可以满足沙粒和尘埃磨损条件下的耐磨性能要求。     

镍磷化学镀温度对活塞杆用45钢表面Ni-P/TiN/DLC三层膜结合及划痕性能的影响

为了提高Ni-P/TiN/类金刚石(DLC)三层膜的结合及划痕性能,选择45钢作为基体材料在不同温度下化学镀Ni-P层,然后利用过滤阴极真空电弧(FCVA)技术在其上依次沉积TiN过渡层及DLC层制备得到了 Ni-P/TiN/DLC三层膜,对三层膜试样采用纳米压痕仪、拉曼光谱仪以及光学显微镜进行了相关性能测试。结果表明:随铢磷化学镀温度的上升,试样的G峰与M峰往更高波段处发生偏移,两者积分强度比AG/AM也随之增加;当辣磷化学镀温度到达500℃时,AG/AM比值迅速增大为3.64,石墨相数量增加,降低了三层膜的脆性;在初期压头刚压入三层膜时,试样的硬度都表现为随压入深度增加而减小的变化规律;在临界载荷F,处形成了半圆形的裂痕,并且沿着和划动方向相反的方向发生弯曲。     

基于原位纳米力学测试系统的单晶硅微观机械性能实验

在纳米硬度计上对单晶硅进行了微压痕测试实验,以对单晶硅的微观力学性能有所认识。微压痕测试表明:单晶硅的弹性模量在压入载荷小于2400μN的范围内随载荷变化而波动变化;而在压入载荷大于2400μN后保持相对的稳定值(约为214GPa);单晶硅的表面硬度在压入载荷小于1000μN的范围内随载荷变化而线性增大,而后突然降低并保持相对的稳定值(13.5GPa~15GPa);单晶硅在纳米压入过程中,材料的破坏形式为脆性破裂,并且随压入载荷的增大而在压痕边沿产生堆积,堆积程度亦逐渐增大。     

磁控溅射沉积Cu-W薄膜的特征及热处理的影响

采用磁控共溅射法制备含钨1.51%~14.20%(原子分数,下同)的Cu-W合金薄膜,并用EDX、XRD、SEM、显微硬度仪和电阻仪研究了其成分、结构及性能。结果表明,添加W可显著细化Cu-W薄膜基体相晶粒,晶粒尺寸随W含量的增加而减小,Cu-W薄膜呈纳米晶结构。Cu-W薄膜中存在W在Cu中形成的fcc Cu(W)非平衡亚稳过饱和固溶体,固溶度随W含量的增加而提高,最大值为10.65%。与纯Cu膜对比发现,薄膜的显微硬度和电阻率总体上随W含量的增加而显著增大。经200℃、400℃及650℃热处理1h后,Cu-W薄膜基体相晶粒长大,EDX分析显示晶界处出现富W第二相;薄膜显微硬度降低,电阻率下降,降幅与退火温度呈正相关。添加W引起的晶粒细化效应以及退火中基体相晶粒度增大分别是Cu-W薄膜微观结构和性能形成及演变的主要原因。     

氩气压强对PET基磁控溅射银膜结构及导电性能的影响

在室温条件下,采用磁控溅射法在PET纺粘非织造布上制备了纳米Ag薄膜,用原子力显微镜(AFM)表征磁控溅射真空室压强对纳米Ag薄膜结晶状态、粒径的影响;研究了溅射工艺参数与薄膜导电性能之间的关系.实验结果表明:在该实验范围内溅射速率随压强的增大先增大后减小;薄膜方块电阻的变化规律与溅射速率的变化规律一致;薄膜颗粒直径随压强的增大先增大后减小,但在压强大于1.5Pa时,薄膜颗粒直径随压强变化未呈现明显的变化规律.     

Influence of substrate temperature on the physical properties of thermally evaporated nanocrystalline bismuth sulfide thin films

Nanocrystalline bismuth sulfide thin films were deposited on glass substrate by thermal evaporation technique using the solvothermally synthesized nanometer-sized bismuth sulfide powder as the source material. X-ray diffraction (XRD) analysis revealed that the films are polycrystalline in nature with orthorhombic structure. The crystallinity of the thin films improved with substrate temperature, and the estimated crystallite size are in the nanometer regime. Scanning electron microscope (SEM) analysis showed homogenous distribution of grains with well defined grain boundaries. The optical transmittance of the nanocrystalline bismuth sulfide thin films increases with the increase in substrate temperature, and the optical transition was found to be direct and allowed. The estimated optical band gap energy was found to decrease with the increase in substrate temperature. The electrical resistivity of the bismuth sulfide thin films is of the order of 10⁻⁴ Ω-cm and exhibits semiconductor nature. Experimental results demonstrate that the structural, optical and electrical properties of bismuth sulfide thin films have strong dependence on the substrate temperature.     

氧分压对RF磁控溅射ZrO2薄膜生长特性的影响

采用反应射频(RF)磁控溅射法在n型(100)单晶S基片上沉积了ZrO2膜,研究了氧分压与ZrO：薄膜的表面粗糙度和沉积速率、SiO2中间界层的厚度以及ZrO2薄膜的折射率之间关系。结果表明：随着氧分压增高,薄膜的沉积速率降低,表面粗糙度线性地增加;在低的氧分压情况下,Si基片表面的本征SiO2层的厚度增加幅度较小,在高的氧分压情况下,Si基片表面的本征SiO2层的厚度有较大幅度地增加;在O2／Ar混和气氛下,溅射沉积的ZrO2薄膜的折射率受氧分压的影响不显著,而在纯氧气气氛环境下,ZrO2薄膜的折射率明显偏低,薄膜的致密性变差。     

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。     

Preparation and characterization of amorphous manganese sulfide thin films by SILAR method

Manganese sulfide thin films were deposited by a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method using manganese acetate as a manganese and sodium sulfide as sulfide ion sources, respectively. Manganese sulfide films were characterized for their structural, surface morphological and optical properties by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and optical absorption measurement techniques. The as-deposited film on glass substrate was amorphous. The optical band gap of the film was found to be thickness dependent. As thickness increases optical band gap was found to be increase. The water angle contact was found to be 34°, suggesting hydrophilic nature of manganese sulfide thin films. The presence of Mn and S in thin film was confirmed by energy dispersive X-ray analysis.     

Effect of microstructural evolution on magnetic properties of Ni thin films

The magnetic properties of Ni thin films, in the range 20–500 nm, at the crystalline-nanocrystalline interface are reported. The effect of thickness, substrate and substrate temperature has been studied. For the films deposited at ambient temperatures on borosilicate glass substrates, the crystallite size, coercive field and magnetization energy density first increase and achieve a maximum at a critical value of thickness and decrease thereafter. At a thickness of 50 nm, the films deposited at ambient temperature onto borosilicate glass, MgO and silicon do not exhibit long-range order but are magnetic as is evident from the non-zero coercive field and magnetization energy. Phase contrast microscopy revealed that the grain sizes increase from a value of 30–50 nm at ambient temperature to 120–150 nm at 503 K and remain approximately constant in this range up to 593 K. The existence of grain boundary walls of width 30–50 nm is demonstrated using phase contrast images. The grain boundary area also stagnates at higher substrate temperature. There is pronounced shape anisotropy as evidenced by the increased aspect ratio of the grains as a function of substrate temperature. Nickel thin films of 50 nm show the absence of long-range crystalline order at ambient temperature growth conditions and a preferred [111] orientation at higher substrate temperatures. Thin films are found to be thermally relaxed at elevated deposition temperature and having large compressive strain at ambient temperature. This transition from nanocrystalline to crystalline order causes a peak in the coercive field in the region of transition as a function of thickness and substrate temperature. The saturation magnetization on the other hand increases with increase in substrate temperature.     

Synergistic effects of metals co-sputtered with MoS2

Sputtered MoS₂ films providing satisfactory lubricating properties can be achieved by proper control of processing parameters. The sputtering process is ideally suited to applications which require very thin films of MoS₂ as it yields coatings with excellent substrate adhesion and which have endurances per unit thickness in excess of those of conventional dry film coatings. Sputtered interfacial coatings of other materials can be deposited onto certain substrates to enhance lubricating qualities and adherence.In the work presented here, the evaluation method was a sliding friction test run at a normal load of 63.4 kgf and a speed representing 800 load applications per minute. With this set of test parameters sputtered MoS₂ films produced under widely reported process parameters manifest irregular coefficients of friction and variability of endurance. The films also exhibit time-related changes in their coefficients of friction which stabilize from 6 to 12 h after sputtering. The observed irregularities are not peculiar to any particular method of sputtering and are most probably caused by residual stresses or inhomogeneous crystal growth as the film increases in thickness.The observed frictional instabilities and irregularities can be eliminated or greatly reduced by the codeposition of certain metals with MoS₂. These metal additives appear to increase the size of the acicular crystallites by approximately 35%, and in appropriate concentrations they provide synergistic effects such as a lowering of the coefficient of friction and an increase in the endurance per unit thickness.The ability to vary the ratio of metals to MoS₂ enables films to be produced which are controllably harder than those obtained with MoS₂ alone. Up to about 10% the metal additives do not adversely affect the lubricating qualities. The codeposited films have stable coefficients of friction with increased endurance per unit thickness and are clearly superior to standard sputtered MoS₂ films.     

Some optical properties of Se-Ge-As amorphous chalcogenide glasses

The effects of composition, film thickness, substrate temperature, and annealing of amorphous thin films of Se₇₅Ge_25−x As _x (5⩽x⩽20) on their optical properties have been investigated. X-ray diffraction revealed the formation of amorphous films. The absorbance and transmission of vacuum-evaporated thin films were used to determine the band gap and refractive index. Optical absorption measurements showed that the fundamental absorption edge is a function of glass composition and the optical absorption is due to indirect transition. The energy gap increases linearly with increasing arsenic content. The optical band gap,E _opt, was found to be almost thickness independent. The shapes of the absorption edge of annealed samples displayed roughly the same characteristic as those of the unannealed films, but were shifted towards shorter wavelengths; as a result,E _opt increased andE _e, the width of the band tails, decreases. The increase inE _opt is believed to be associated with void removal and microstructural re-arrangement during annealing. The influence of substrate temperature on the optical parameters is discussed.     

Effects of buffer layer thickness on properties of ZnO thin films grown on porous silicon by plasma-assisted molecular beam epitaxy

ZnO thin films with different buffer layer thicknesses were grown on Si and porous silicon (PS) by plasma-assisted molecular beam epitaxy (PA-MBE). The effects of PS and buffer layer thickness on the structural and optical properties of ZnO thin films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL). The ZnO buffer layers, the intensity of the (002) diffraction peak for the ZnO thin films and its full width at half maximum (FWHM) decreased with an increase in the thickness of the ZnO buffer layers, indicating an improvement in the crystal quality of the films. On introducing PS as a substrate, the grain sizes of the ZnO thin films became larger and their residual stress could be relaxed compared with the ZnO thin films grown on Si. The intensity ratio of the ultraviolet (UV) to visible emission peak in the PL spectra of the ZnO thin films increased with an increase in buffer layer thickness. Stronger and narrower UV emission peaks were observed for ZnO thin films grown on PS. Their structural and optical properties were enhanced by increasing the buffer layer thickness. In addition, introduction of PS as a substrate enhanced the structural and optical properties of the ZnO thin films and also suppressed Fabry-Perot interference.     

Microstructural characteristics and mechanical properties of magnetron sputtered nanocrystalline TiN films on glass substrate

Nanocrystalline TiN thin films were deposited on glass substrate by d.c. magnetron sputtering. The microstructural characteristics of the thin films were characterized by XRD, FE-SEM and AFM. XRD analysis of the thin films, with increasing thickness, showed the (200) preferred orientation up to 1·26 μm thickness and then it transformed into (220) and (200) peaks with further increase in thickness up to 2·83 μm. The variation in preferred orientation was due to the competition between surface energy and strain energy during film growth. The deposited films were found to be very dense nanocrystalline film with less porosity as evident from their FE-SEM and AFM images. The surface roughness of the TiN films has increased slightly with the film thickness as observed from its AFM images. The mechanical properties of TiN films such as hardness and modulus of elasticity (E) were investigated by nanoindentation technique. The hardness of TiN thin film was found to be thickness dependent. The highest hardness value (24 GPa) was observed for the TiN thin films with less positive micro strain.     

Investigation of the properties of diamond-like carbon thin films deposited by single and dual-mode plasma enhanced chemical vapor deposition

In this study diamond-like carbon (DLC) films were deposited by a dual-mode (radio frequency/microwave) reactor. A mixture of hydrogen and methane was used for deposition of DLC films. The film structure, thickness, roughness, refractive index of the films and plasma elements were investigated as a function of the radio frequency (RF) and microwave (MW) power, gas ratio and substrate substance. It was shown that by increasing the H₂ content, the refractive index grows to 2.63, the growth rate decreases to 10 (nm/min) and the surface roughness drops to 0.824 nm. Taking into consideration the RF power it was found that, as the power increases, the growth rate increases to 11.6 (nm/min), the variations of the refractive index and the roughness were continuously increasing, up to a certain limit of RF power. The Raman G-band peak position was less dependent on RF power for the glass substrate than that of the Si substrate and a converse tendency exists with increasing the hydrogen content. Adding MW plasma to the RF discharge (dual-mode) leads to an increase of the thickness and roughness of the films, which is attributed to the density enhancement of ions and radicals. Also, optical emission spectroscopy is used to study the plasma elements.