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1.
An aluminum nitride (AlN) thick film for ultrasonic transduction was deposited on a silicon wafer by magnetron sputtering. A columnar structure with uniform elemental depth profiles with 40 at.% to 60 at.% (Al-N) concentrations and with a c-axis preferential orientation was observed by X-ray diffraction. The ultrasonic response of the Al/AlN/Si overmoded resonator was characterized from 1.24 MHz to 2 GHz using a vector network analyzer. The time domain transform and the gate features of the vector network analyzer were used to characterize the AlN thick film capabilities in the time and frequency domains. The results show that the obtained resonator operates over a broad frequency range with a central frequency at approximately 930 MHz and a 738 MHz bandwidth at -6 dB. The results were compared with those obtained from a one-dimensional simulation to highlight and predict the AlN response features. A comparison was performed to validate the experimental measurements and to validate the circuit modeling. Overall agreement between the experiment values and the simulation was observed. 相似文献
2.
Effects of humidity on nanometer-scale oxidation of silicon nitride thin film using atomic force microscope in contact mode are studied at various values of relative humidity (RH) (30-70%). The shape of oxide protrusion is determined by the concentration of oxyanions under the tip apex and oxyanions diffusion laterally on the surface. At low RH (60%), the kinetics of silicon nitride oxidation has a logarithmic relationship to oxide height versus oxidation time. The threshold time decreased and initial oxidation rate increased simultaneously as humidity increased because a high concentration of oxyanions at the oxide/silicon nitride interface was generated. When a high sample voltage (9-10V) is applied at high RH (60%), the effective electric field is decreased because of the electron being trapped in the oxide and oxyanions accumulating on the oxide surface. 相似文献
3.
The purpose of this study is to synthesize diamond onto Si, Cu, and Fe (SUS632J2) substrates and to analyze the effect of carbon diffusion on their surfaces. Diamond was synthesized using the in-liquid microwave plasma chemical vapor deposition (IL-MPCVD) as a novel method for synthesizing diamond on various base materials. The IL-MPCVD method is superior one due to its efficiency in terms of cost, space and speed as compared to a conventional gas phase microwave plasma CVD (MPCVD). Microwaves of 2.45 GHz generated plasma in a solution which was comprised of methanol: ethanol (M:E = 97:3). Evaluation of deposited diamond films was done by a Scanning Electron Microscope (SEM) and Raman spectroscopy. Results shows that the IL-MPCVD method can form diamond films on Cu, Si and Fe substrates. The minimum time of film formation of Cu, Si and Fe are 2.5, 3.5 and 5 min, respectively. The material that forms carbide layers such as Si is a better substrate to form diamond film by the IL-MPCVD than other metal substrates such as Cu and Fe. Synthesizing diamond directly on the Fe substrate results in poor quality layers. The effect of carbon diffusion influences diamond film nucleation and diamond growth. In order to alleviate the carbon diffusion and improve the quality of the diamond film on the Fe substrate, Si has been sputtered on the Fe substrate as an interlayer. It is found that the diamond film can be formed on a Fe substrate using a Si interlayer and that heat treatment and thickening the interlayer improve its quality. 相似文献
4.
5.
针对Lamb波压电声波传感器高品质因数(Q值)、低检测极限(LOD)和易集成的性能要求,本文基于SOI(Siliconon-insulator)硅片,通过底层硅(Handling layer)干法刻蚀和中间层(Boxing layer)自截止的方法实现2μm超薄均一的硅衬底结构,然后沉积2μm厚具备高C轴择优取向的氮化铝(AlN)压电薄膜。传感器薄膜区域外设置双端增强反射栅结构用于提高Q值,从而有效降低器件的检测极限,并通过微量水分测试验证性能。该谐振器零阶反对称模式(A0)和零阶对称模式(S0)的谐振状态的实测结果和COMSOL二维模型仿真结果一致,所制作的Lamb波谐振器A0模式的主峰Q值为703,S0模式的主峰Q值为403。微量水分测试S0模式的检测极限优于A0模式,最低检测极限值为0.06%RH。结果表明,氮化铝超薄硅衬底Lamb波压电谐振器能够实现微量水分等高精度检测。 相似文献
6.
基于ZnO压电薄膜的柔性声表面波器件 总被引:4,自引:0,他引:4
提出并制备了基于聚酰亚胺柔性衬底的声表面波(SAW)器件。在柔性聚酰亚胺衬底上低温反应磁控溅射沉积了ZnO压电薄膜;采用X射线衍射仪,扫描电子显微镜,原子力显微镜等设备对ZnO薄膜进行了检测,结果表明:ZnO薄膜晶粒呈柱状生长并且(002)择优取向,膜粗糙度小于9nm,适合制作压电器件。在柔性衬底上制备了基于ZnO压电薄膜的SAW器件,该器件表现出良好的谐振性能。采用矢量网络分析仪检测器件的传输曲线,实验结果与仿真结果具有很好的一致性。随着波长减小,谐振频率和相速度增加,当ZnO厚度为4μm,波长为8μm时,器件的谐振频率为268MHz,相速度为2 144m/s,机电耦合系数为1.1%;当ZnO厚度增加时,此叠层结构的声表面器件的叠层声速也增加。 相似文献
7.
B.R. Sarkar B. Doloi B. Bhattacharyya 《The International Journal of Advanced Manufacturing Technology》2006,28(9):873-881
The electrochemical discharge machining (ECDM) process has a potential in the machining of silicon nitride ceramics. This
paper describes the development of a second order, non-linear mathematical model for establishing the relationship among machining
parameters, such as applied voltage, electrolyte concentration and inter-electrode gap, with the dominant machining process
criteria, namely material removal rate (MRR), radial overcut (ROC) and thickness of heat affected zone (HAZ), during an ECDM
operation on silicon nitride. The model is developed based on response surface methodology (RSM) using the relevant experimental
data, which are obtained during an ECDM micro-drilling operation on silicon nitride ceramics. We also offer an analysis of
variance (ANOVA) and a confirmation test to verify the fit and adequacy of the developed mathematical models. From the parametric
analyses based on mathematical modelling, it can be recommended that applied voltage has more significant effects on MRR,
ROC and HAZ thickness during ECDM micro-drilling operation as compared to other machining parameters such as electrolyte concentration
and inter-electrode gap. 相似文献
8.
Influence of environmental humidity on scanning-scratched wear tests of a carbon film deposited by electron cyclotron resonance plasma sputtering are evaluated in both air and nitrogen with an atomic force microscope and a diamond tip. Wear depth is larger in higher humidity and also larger in air than in nitrogen. Effect of humidity on scratch load dependence and repeated scanning-scratch tests are larger in nitrogen than in air. Effect of humidity on wear is clearer in the repeated scanning-scratch test than in the scratch load dependence test especially in air, and also clearer at larger scratch load. In scratch velocity dependence test, there is a tendency that wear depth decreases with increase in logarithm of scratch velocity both in air and nitrogen. Wear models to explain the experimental results are discussed. 相似文献
9.
TiN/NbN ultrathin superlattices deposited on silicon by physical vapor deposition technique were tested. The test were performed for superlattices with constant thickness (5.84 nm) of NbN layer and varied thickness (2.2–13 nm) of TiN layer. The nanowear tests on 5 × 5 m scan size were carried out. The effect of the construction of the film on its wear resistance was observed. The specific energy of wear was estimated. The nanoscratch tests were performed additionally to estimate the friction force during the wear and to calculate the energy of friction. The results of the nanowear studies were also compared with the results of nanoindentation tests. The wetting studies by contact angles measurements were also carried out. The smallest wear was found for the thinnest TiN layer. 相似文献
10.
The in-situ observations of wear particle generation of carbon nitride coating on silicon repeatedly sliding against a spherical diamond have been studied in terms of the critical friction cycles and normal loads. An environmental scanning electron microscope (E-SEM), in which a pin-on-disk tribotester was installed, has in-situ provided direct evidence of when and how the wear particle generation do occur during the repeated sliding of carbon nitride coating against a spherical diamond. The in-situ observations of non-conductive carbon nitride coating are therefore available free from surface charging with controllable relative humidity. The repeated sliding tests at a sliding speed of 50 μm/s have been carried out with the purpose of observing the ‘No wear particle generation’ region when varying normal load from 10 to 250 mN. It appears that until 20 friction cycles, the maximum Hertzian contact pressure Pmax for ‘No wear particle generation’ can be improved from 1.39 Y to 1.53 Y if silicon is coated by carbon nitride with a thickness of 10 nm, where Y is defined as the yield strength of silicon. The applicable enlargement of the ‘No wear particle generation’ region of carbon nitride coating has therefore been comparatively discussed with the silicon substrate from the view points of the friction coefficient and the specific wear rate. The mode transition maps have also been summarized for the repeated sliding of carbon nitride coating in terms of ‘No wear particle generation’, ‘Wear particle generation by microcutting’ and ‘Wear particle generation by microcutting and microfracturing’ three typical modes. 相似文献
11.
不同金属基材上类金刚石薄膜的摩擦特性 总被引:2,自引:1,他引:1
针对类金刚石(DLC)薄膜在精密机械零件中的应用,研究了在常温条件下沉积高界面强度的DLC薄膜的技术,以提高DLC薄膜与金属基材之间的结合强度.通过在基材与薄膜之间沉积加入a-Si:H中间过渡层,研究了在不同金属基材上DLC薄膜的结合强度.采用Ball-on-Disk方法评价了薄膜的摩擦特性并测定其摩擦系数、疲劳破坏寿命和磨耗.实验结果表明:在薄膜与金属基材之间加入a-Si:H过渡层后,界面的结合(键合)强度得到了明显的改善,在金属基材上沉积的DLC薄膜在磨耗过程中被完全磨穿而没有发生剥离.实验显示,在自制的化学气相沉积RF-DCCVD装置上沉积的DLC薄膜的最大沉积厚度是3.3μm;在1μm厚度的薄膜上施加2.94 N的负荷(点载荷),其疲劳破坏寿命达到了70万循环;DLC薄膜与SiC,Si3N4,SUS304和SUJ2材料之间的摩擦系数为0.1~0.15.得到的结果验证了薄膜与金属间的结合强度和摩擦特性能够满足精密机械零件的使用要求. 相似文献
12.
荧光纳米材料及血管荧光成像技术的研究应用已引起人们的广泛关注。然而,现有的荧光材料功能化修饰复杂、合成过程耗时长且产品收率低。因此,基于氮化碳具有优异的光致发光性能、低毒性、良好的生物相容性及卓越的发光性能。设计了一种石墨相氮化碳材料,利用X射线衍射、扫描电子显微镜对其结构进行了表征,通过紫外可见漫反射光谱和荧光光谱研究了其光学性质,表明其具有良好的光学性能。通过细胞毒性评估以及共聚焦细胞荧光成像,表明其具有较低的生物毒性和较好的细胞荧光效果,显示了其在生物成像应用领域有着较大的应用潜能。 相似文献
13.
The ‘critical load' for wear particle generation of carbon nitride coatings sliding against a spherical diamond under a linearly increasing load has been examined in situ in relation to different nitrogen incorporation conditions, i.e. assisted N ion acceleration energy and N ion beam current density, and different coating thickness. An environmental scanning electron microscope (E-SEM), in which a pin-on-disk tribotester was installed, has provided direct evidence in situ of when, how and where wear particle generation occurs during the sliding of carbon nitride coatings against a spherical diamond. The in-situ examination of non-conductive carbon nitride coatings are available in E-SEM free from surface charging with controllable relative humidity. The sliding tests under linearly increasing load up to 300 mN at a sliding speed of 10 μm/s have been carried out with the purpose of measuring the ‘critical load' for wear particle generation in a similar way to the traditional macro scratch testing. However, instead of the ‘critical load', the critical maximum Hertzian contact pressure Pmax will also be used in the following for better understanding. Based on the systematic study of seven combinations of nitrogen incorporation parameters and five kinds of thickness (0, 10, 50, 100 and 200 nm), the applicable range of Pmax for wear particle generation can be increased from 1.6Y to 1.831.92Y or to 1.801.89Y, where Y is defined as the yield strength of silicon of 7 GPa, by coating carbon nitride onto silicon with changing nitrogen incorporation conditions of ion acceleration energy and ion current density, or varing coating thickness from 10 to 200 nm. It also appears that the observed wear particle generation of carbon nitride coatings was associated with a failure initiated in the silicon substrate rather than within the carbon nitride coating or at the coating–substrate interface in the light of both the empirical identification and the theoretical discussion. 相似文献
14.
Tribochemical effects on the friction and wear behaviors of
diamond-like carbon film under high relative humidity condition 总被引:1,自引:0,他引:1
Friction and wear behaviors of diamond-like carbon (DLC) film in humid N2 (RH-100%) sliding against different counterpart ball (Si3N4 ball, Al2O3 ball and steel ball) were investigated. It was found that the friction and wear behaviors of DLC film were dependent on the friction-induced tribochemical interactions in the presence of the DLC film, water molecules and counterpart balls. When sliding against Si3N4 ball, a tribochemical film that mainly consisted of silica gel was formed on the worn surface due to the oxidation and hydrolysis of the Si3N4 ball, and resulted in the lowest friction coefficient and wear rate of the DLC film. The degradation of the DLC film catalyzed by Al2O3 ball caused the highest wear rate of DLC film when sliding against Al2O3 ball, while the tribochemical reactions between DLC film and steel ball led to the highest friction coefficient when sliding against steel ball. 相似文献
15.
Effects of laser surface texturing on friction behavior of silicon nitride under lubrication with water 总被引:1,自引:0,他引:1
Hiroki YamakiriShinya Sasaki Tsuneo KuritaNagayoshi Kasashima 《Tribology International》2011,44(5):579-584
Water lubrication is one of the candidates of the tribo-system with low negative environmental impact. It is well known that some kinds of ceramics show excellent tribological properties under lubrication with water. The characteristic improvement was attempted by giving texturing to Si3N4 so that the water lubrication might spread as a representative of the ecotribology system. The surface laser texturing showed the friction reducing effect under the sliding condition of the low bearing characteristic number. The mechanism of the triblogical property improvement by the laser surface texturing was discussed based on the experiment results and the surface analytical results. 相似文献
16.
M. Abdul SamadSujeet K. Sinha 《Tribology International》2011,44(12):1932-1941
Ultra-high molecular weight polyethylene (UHMWPE) coatings on steel substrate were reinforced with 0.05, 0.1 and 0.2 wt% of plasma treated single-walled carbon nanotubes (SWCNTs) to improve their mechanical, thermal and tribological properties. Nanoindentation results showed that the addition of SWCNTs up to 0.2 wt% to the UHMWPE film significantly improved the mechanical properties such as hardness (∼66%) and elastic modulus (∼58%). Wear durability of the reinforced coating increased significantly (more than two orders of magnitude) though with a slight increase in the coefficient of friction (from ∼0.08 for pristine UHMWPE film to ∼0.16 for the nanocomposite). 相似文献
17.
Self-reinforced silicon nitride ceramics with additions of either yttrium oxide or ytterbium oxide have been investigated at room temperature after various processing heat treatments. Devitrification of the intergranular phase in these materials is very sensitive to the heat treatment used during processing and does not necessarily improve their strength and toughness. Hot-pressed ceramics without a subsequent devitrification heat treatment were the strongest. The ytterbium oxide-doped silicon nitride ceramics were consistently tougher, but less strong, than the yttrium oxide-doped silicon nitride ceramics. In all the ceramics examined, the fracture toughness showed evidence for R -curve behaviour. This was most significant in pressureless sintered ytterbium oxide-doped silicon nitride ceramics. A number of toughening mechanisms, including crack deflection, bridging, and fibre-like grain pull-out, were observed during microstructural analysis of the ceramics. In common with other silicon nitride-based ceramics, thin amorphous films were found at the grain boundaries in each of the ceramics examined. Arrays of dislocations left in the elongated silicon nitride grains after processing were found to belong to the {101¯0}<0001> primary slip system. 相似文献
18.
Temperature-programmed desorption and scanning force microscopy have been used to probe the interaction of a perfluorinated lubricant (Fomblin ZDOL) with hydrogenated amorphous carbon (a:C-H
x
) and amorphous carbon nitride (a:C-N
x
) substrates, two materials used as hard coatings in disk drive products. Temperature-programmed desorption measurements indicate that the nitride surfaces are more reactive toward this perfluorinated lubricant and, as a result, the thin lubricant film is more tightly bound to this substrate. Frictional force microscopy has been used to measure the coefficient of friction of the lubricated surfaces, 0.18 ± 0.02 for both substrate materials, and finds that frictional properties of these interfaces in the low load regime are influenced more by the presence of the lubricant rather than the adsorbed state of the film. Likewise, similar disjoining pressures were measured for the lubricant adsorbed on the different coating materials and suggest that the ultrathin nature of the adsorbed lubricant film dominates this property rather than adsorption states. 相似文献
19.
Carbon nanotube (CNT) has excellent field emission characteristics and could play as a good cold cathode in the application of vacuum electronic devices. However, the practical application faces a big obstacle regarding current fluctuation and deterioration of the CNT cathode. In this research, the formation of amorphous carbon (ac) layer between the CNT film and the substrate, and the effect of the existence of this layer on field emission stability of the CNT film are studied. The formation of the ac layer could be controlled by adjustment of growth temperature and hydrocarbon flow rate. The field emission character and current stability of the CNT film without ac layer are better than those of the CNT film with ac layer. The results attribute to the ac layer a thermal disequilibrium state under high current level. Moreover, adhesion capacity of the CNT film without ac layer is also better than that with the ac layer. It is concluded that the ac layer between the CNT film and substrate is a key factor in the stability of field emission characteristics and should be eliminated before applications. 相似文献