SIMULATION OF THE MAGNETIZATION REVERSAL PROCESS OF RECTANGLE-SHAPED NiFe FILM ELEMENTS UNDER AN ORTHOGONAL MAGNETIC FIELD

The magnetization reversal process of nano-size rectangle-shaped NiFe film elements with different aspect ratios have been investigated under the orthogonally applied magnetic fields by micromagnetic simulation. Different magnetization reversal modes can appear depending on whether the bias field is applied or not. When there is no bias field, double “C” state is the initial reversal state. However, when there is a bias field, “S” state is the starting mode. The larger the aspect ratio is, the larger the switching field is. But, when the aspect ratio is larger than 3, the increase of the switching field ceases. These results can provide useful information to the application of the patterned NiFe film with rectangular elements.

Simulation of the Resin Film Infusion Process Based on the Finite Element Method

A physically accurate and computationally effective pure finite element method （FEM） was developed to simulate the isothermal resin infusing process. The FEM was based on conservation of resin muss at and instant of time and was objective of resin film infusion （RFI） fiber impregnation and mold filling . The developed computer code was able to simulate the resin infusing visually. A numerical example presented here demonstrated that compared with traditional finite element/ control-volume （FE/CV）, and FEM was physically accurate and computationally efficient.

Oxygen Evolution at Nickel Hydroxide Films Co deposited Light Rare Earth Elements

Composite nickel hydroxide films were prepared by cathodic co electrodeposition from metal nitrate solution and characterized by cyclic voltammetry in 1.0 mol/L KOH solution. The codeposited light rare earth elements were lanthanum, cerium, praseodymium and neodymium. The films were analyzed by spectrophotometry and optical transmission. The results of the cyclic voltammetry in 1.0 mol/L KOH solution showed that the current density for oxygen evolution at the film electrode was affected by the co deposited rare earth metal ions in the film. About 20 mA/cm 2 increase of current density for oxygen evolution was found when the film was obtained from the solution with cerium (7% v/v) and nickel (93% v/v) nitrate. The effects of galvanostatic cathodic current density for the film formation on the oxygen evolution at the film electrodes from the alkaline were discussed.

FINITE ELEMENT ANALYSIS OF SUBSTRATE LOCAL PLASTIC DEFORMATION INDUCED BY CRACKED THIN HARD FILM

It has been postulated that, with tensile loading conditions, micro-cracks onthin hard film act as stress concentrators enhancing plastic deformation of the substrate materialin their vicinity. Under favorable conditions the localized plastic flow near the cracks may turninto macroscopic plastic strain thus affects the plasticity behaviors of the substrate. Thisphenomenon is analyzed quantitatively with finite element method with special attention focused onthe analysis and discussion of the effects of plastic work hardening rate, film thickness and crackdepth on maximum plastic strain, critical loading stress and the size of the local plasticdeformation zone. Results show that micro-cracks on thin hard film have unnegligible effects on theplasticity behaviors of the substrate material under tensile loading.

Study on Properties of Ti(C,N)/TiN Multi-Element-layer Films Plus Nanometer Lubrication Dry Films

Ti(C,N)/TiN multi-element-layer films was deposited on aluminium alloy substrates by using multi-arc ion plating. The microhardness of the films was 2000HV0.i which was nearly 21 times of that of the substrates. XRD analysis show that the main composition of the composite films system were Ti(C,N), TiN, Al3Ti, Al and a little Ti2N. The presence of MjTi new phase in the interface of the films/substrates indicated some metallurgical bonding between them, which implies higher adhesive strength of the films/substrates system. Pin-on-disc tests showed that the wear resistance of the substrates was improved substantially. However, the coefficient of friction of the films/substrate system was high (u=0.66), which resulted in the wear of the counterparts. To reduce the coefficient of friction, nanometer lubrication dry films was applied on top of the multi-element-layer films to form composite films system and subsequent wear tests showed that the resulting composite films led to reduction of the coefficient of friction from 0.66 to 0.16. Meanwhile, wear mass loss of the counterpart was reduced from 1.29 mg to 0.02 mg, so that increased wear resistance and reduced friction effects were achieved.

Influence of additive element on surface oxide film of A356 alloy

The influences of RE-modification and Sr-modification on the hydrogen content and surface oxide film of A356 aluminum alloy melt were investigated. The hydrogen content of the melt was measured by reduce pressure test. The phases in the surface oxide film were analyzed by X-ray diffractometry (XRD), and the morphology of the surface oxide film was observed by scanning electronic microscopy (SEM). The results show that RE-modification reduces the hydrogen content of A356 aluminum alloy greatly. Contrarily, Sr-modification increases the hydrogen content remarkably. After being treated with RE, a large number of LaAl11O18 consisting of Al2O3 and La2O3, are generated in the surface oxide film of A356 alloy. The surface oxide film of Sr-modification is almost composed of Al2SrO4. According to the results of SEM, the surface oxide film of Sr-modification is very easy to crack, destroy the continuity and compactness of surface oxide film, accelerate the vapor diffusing into the melt, consequently, increase the hydrogen content of A356 alloy melt significantly. But RE-modification makes the surface oxide film compact, and restrains the aluminum exposed to water, so reduces the hydrogen content of A356 alloy melt.

Propagations of Rayleigh and Love waves in ZnO films/glass substrates analyzed by three-dimensional finite element method

Propagation characteristics of surface acoustic waves（SAWs） in ZnO films/glass substrates are theoretically investigated by the three-dimensional（3D） finite element method. At first, for（11ˉ20） ZnO films/glass substrates, the simulation results confirm that the Rayleigh waves along the [0001] direction and Love waves along the [1ˉ100] direction are successfully excited in the multilayered structures. Next, the crystal orientations of the ZnO films are rotated, and the influences of ZnO films with different crystal orientations on SAW characterizations, including the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency, are investigated. The results show that at appropriate h/λ, Rayleigh wave has a maximum k^2 of 2.4% in（90°, 56.5°, 0°） ZnO film/glass substrate structure; Love wave has a maximum k^2 of 3.81% in（56°, 90°, 0°） ZnO film/glass substrate structure. Meantime, for Rayleigh wave and Love wave devices, zero temperature coefficient of frequency（TCF） can be achieved at appropriate ratio of film thickness to SAW wavelength. These results show that SAW devices with higher k^2 or lower TCF can be fabricated by flexibly selecting the crystal orientations of ZnO films on glass substrates.

5Cr油套管钢在含Cl^(-)的CO_(2)环境中的腐蚀特性研究

目的掌握油气井生产中CO_(2)腐蚀对油套管的影响规律,研究兼顾耐蚀性和经济性的5Cr油套管材料在含Cl^(-)的CO_(2)环境中不同时间下的腐蚀演变规律。方法采用XRD、XPS、SEM和EDS等技术分析5Cr油套管钢在不同时间下腐蚀产物膜的演变情况,利用丝束电极(WBE)和阻抗测试(EIS)技术对其腐蚀电化学行为进行研究。结果5Cr油套管钢腐蚀后期的平均腐蚀速率约为初期的1/2,在腐蚀14 d后,腐蚀产物膜中的Cr富集大于30%,Cr、Fe质量比达到较高水平,约为基体的15倍。随着腐蚀的进行,电荷传递电阻和产物膜覆盖引起的电阻增大,电化学反应阻力增大。在腐蚀前期具有局部不均匀性,随着腐蚀的进行,电极腐蚀电位有负移现象,最终分布区间为−0.59~−0.61 V,电极表面阳极电流区域大幅减少。结论在腐蚀时间延长的条件下,5Cr油套管钢腐蚀产物膜的致密性增加,电荷传递电阻呈变大趋势。在产物膜下的5Cr油套管钢区域,电流发生由阴极向阳极极性转变的现象,产物膜存在的孔隙使5Cr油套管钢基体金属被腐蚀,从而导致阳极电流的出现。表面局部腐蚀电位阳极区的形成和扩展使其有产生点蚀的倾向,但腐蚀产物逐渐沉积在点蚀坑内壁,形成了Cr富集的保护性表面层,原发生点蚀区域由原阳极活性点位转变为阴极区,对其发展起到了抑制作用。

基于多频涡流技术的燃料棒包壳管氧化膜厚度测量方法

核燃料棒包壳管表面的氧化膜会影响其导热性能,使燃料棒的温度上升,加快燃料包壳的腐蚀速度,给反应堆带来潜在安全风险。故有必要对氧化膜厚度进行精确测量。为此,构建了燃料棒包壳管的三维有限元仿真模型,对燃料包壳多频检测进行了分析,总结了激励频率、包壳管电导率和金属涂层厚度对氧化膜测量结果的影响规律;提出了融合多频测量数据,抑制干扰因素影响,精确计算氧化膜厚度的方法,并进行了试验验证。结果表明,该方法的氧化膜厚度计算误差小于1μm,可用于燃料包壳管氧化膜厚度的量化表征。

掺硅类金刚石薄膜的HiPIMS-MFMS共沉积制备及其高温摩擦学行为研究

元素掺杂是提高类金刚石(DLC)薄膜高温耐摩擦性能的重要途径.本文中采用高功率脉冲磁控溅射(HiPIMS)和中频磁控溅射(MFMS)复合技术在304不锈钢表面沉积具有不同Si含量的掺硅类金刚石(Si-DLC)薄膜,利用原子力显微镜、扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)、纳米压痕和UMT-TriboLab摩擦试验机等系统分析了Si含量对Si-DLC薄膜的结构、力学性能及不同温度下的摩擦学性能的影响,重点探讨了Si-DLC薄膜在高温下摩擦磨损机制.结果表明:Si-DLC薄膜中Si以四面体碳化硅的形式随机分布于无定型DLC基体中,增强薄膜的韧性.同时,Si掺杂使DLC薄膜向金刚石结构发生转变并显著提高了薄膜的硬度.摩擦结果表明,当Si原子分数为15.38%时,Si-DLC薄膜在常温下的摩擦系数和磨损率最低,同时该薄膜在300℃下能维持在较低的摩擦系数(约0.1),主要是由于Si-DLC薄膜中的四面体碳化硅结构能够提升sp^(3)键的稳定性.此外,Si-DLC薄膜中的Si在高温摩擦时会在对偶球表面形成1层SiO_(2)保护层,减缓Si-DLC薄膜和过渡层的氧化,使得薄膜能够在高温下持续润滑.当Si含量进一步增加时,Si-DLC薄膜的力学性能显著提升,然而其摩擦学性能发生明显降低,主要是当DLC薄膜中的硅含量过高时,大气环境下的高温摩擦使得薄膜内的氧化加剧,过量氧化硅的生成破坏了薄膜结构从而导致摩擦性能下降.

20Cr2Ni3钢顶头表面氧化膜断裂行为的数值研究

基于试验数据,利用扩展有限元方法(extended finite element method,XFEM)和内聚力模型(cohesive zone model,CZM),对20Cr2Ni3钢顶头表面氧化膜的断裂行为进行了数值分析,研究了氧化膜受力方向和孔洞对裂纹生长行为的影响。结果表明:氧化膜受力方向影响裂纹扩展路径,外层氧化膜裂纹尖端的J积分和应力强度因子K_I随着θ角(受力方向与氧化膜的夹角)的增大而减小,当θ角增大到90°时裂纹停止生长;外层氧化膜上孔洞使得裂纹尖端的J积分和应力强度因子K_I减小。同时,孔洞的存在使得外力传递到内层氧化膜时产生应力集中和偏移,导致内层裂纹受力不均,减小了受力方向对内层裂纹生长的影响。

转光棚膜对‘翠碧1号’烟苗生长及养分积累的影响

为探究转光膜在南平烟区烟草育苗中的应用效果,以‘翠碧1号’为试验材料,设普通聚乙烯棚膜和转光棚膜2个试验处理,研究转光膜对育苗棚内光照、温度和烟苗生长、养分积累的影响。结果表明,转光膜可调节育苗棚内光照和温度,转光膜处理育苗棚内13:00和14:00的光合有效辐射强度和透光率低于普通膜,而15:00和16:00的光合有效辐射强度和透光率高于普通膜。通过分析育苗棚内温度日变化发现,转光膜处理育苗棚内白天(8:00—16:00)的温度低于普通膜处理,其他时间高于普通膜处理。转光膜促进烟株的生长,与普通膜相比,转光膜处理的根系总根长、根表面积、根系体积、分支数等指标和根系干重、总干重显著高于普通膜处理。转光膜显著影响了养分的吸收和积累,转光膜处理烟苗地上部氮含量、地下部钙含量、整株磷含量和铜含量显著高于普通膜处理,而地上部钙含量和镁含量低于普通膜处理;转光膜处理促进了烟苗氮磷钾的累积。转光膜通过调节育苗棚内的光强和温度,促进烟苗生长和养分吸收,提高烟苗干物质和养分积累量。

非平衡磁控溅射W掺杂类金刚石薄膜的制备与性能研究

为了研究W掺杂对类金刚石薄膜性能的影响,采用非平衡磁控溅射方法,通过改变WC靶功率,在YG6硬质合金基体上制备了5组不同W原子百分数(0%~14%)的含氢类金刚石薄膜(a-C:H:W)。用扫描电镜分析了薄膜的形貌,用拉曼光谱分析了薄膜的微观结构,分别用纳米压痕仪、划痕仪、摩擦磨损试验仪测试了薄膜的纳米硬度、膜基结合力和摩擦学性能。结果表明,a-C:H:W薄膜表面为丘状颗粒,随着WC靶功率的增加,颗粒尺寸先减小后增加;W掺杂可促进薄膜的石墨化;W原子百分数为4%的薄膜的临界划痕力Lc2值达到78.28 N,磨损率为5.8×10^(-8)mm^(3)/(N·m),摩擦因数为0.09。

虚拟现实视角下数字三维(3D)场景中镜头语言的应用探究

随着虚拟现实技术的发展,应用VR技术制作的各种影视作品也越来越多和越来越逼真,也更能够最大真实程度表达出作者意图和适应用户的需求。为了努力达到上述目标,该文通过对比虚拟现实影视作品场景中镜头语言与传统电影镜头语言,探究虚拟现实影视作品场景镜头语言的应用新优势,阐述景域、镜头运动、色彩及听觉等镜头语言元素在用户的心理、视觉以及情感等方面应用优劣势,并运用这些理论知识指导实际的工程项目。

电容器薄膜用聚丙烯原料微量元素分析方法

为了精确分析电容器薄膜用聚丙烯原料中微量元素,介绍了电容器薄膜用聚丙烯原料进行元素测定时的干法灰化法以及微波消解法两种预处理方法,比较了不同方法对分析结果的影响。对比了几种分析手段的特点,选择电感耦合等离子体质谱法作为分析手段。相比于干法灰化法,微波消解法的准确度和精密度都较高,微波消解法结合ICP-MS法适用于测定电容器薄膜用聚丙烯原料中的微量金属元素,建立了基于ICP-MS法测定电容器薄膜用聚丙烯原料中微量金属元素含量的方法。

中国青春电影中“萌”元素对大学生的美育影响

“萌”元素在中国青春电影中的发展呈现出本土化的流变过程,在这一发展过程中它的表现形式主要可以概括为“萌”元素的硬植入“、萌”元素的内化和“萌”元素的本土化三个基本特征。青年大学生群体作为以“萌”元素为代表的二次元文化和青春电影的重要欣赏群体,二者的结合演绎既给大学生带来了积极的美育价值,同时也存在负面的消极影响。应该辩证性地看待青春电影中“萌”元素对大学生美育的积极影响和消极影响,在严肃对待这一文化现象的美育影响的同时也无需过度焦虑其带来的消极影响,在全方位多途径的美育教育下,“萌”文化难以撼动当代大学生的审美认知。

基于碳纳米管和聚二甲基硅氧烷的光声换能器研究

为探究激光参数、光声转换层厚度对光声换能器输出声压的影响,本研究通过COMSOL仿真软件建立了光声换能器的物理模型。首先,基于聚二甲基硅氧烷(polydimethylsiloxane, PDMS)和碳纳米管(carbon nanotube, CNT)分别建立CNT、CNT-PDMS转换层模型;其次,改变激光脉冲持续时间和转换层厚度,对转换层输出声压进行测量;最后,对激光脉冲持续时间和转换层厚度所引起换能器输出声压强度的改变进行分析。结果表明,当CNT和CNT-PDMS转换层的厚度均为200μm、激光脉冲持续时间分别在10~30 ns和50 ns左右时,换能器能输出较高声压强度的超声波。仿真结果对光声换能器的研究有一定的指导意义。

聚酰亚胺薄膜疲劳寿命分析和可靠性增长措施

针对某涡扇发动机加力燃油分布器内有机材料聚酰亚胺薄膜过早失效的问题,基于聚酰亚胺薄膜的材料参数以及薄膜使用时的温度和波动幅值,通过在ANSYS软件中建立了聚酰亚胺薄膜有限元仿真模型,研究薄膜发生以断裂为主要形式的失效时,薄膜的Mises应力分布情况以及薄膜的薄弱区分布情况。基于概率断裂力学的疲劳寿命计算理论得到了不同可靠度下薄膜的疲劳寿命循环次数及其变化规律。结果表明:薄膜存在应力集中,且薄膜的应力集中部位与薄弱区均发生在薄膜夹持外沿;计算得到了不同可靠度下薄膜的疲劳寿命循环次数,且疲劳寿命循环次数随可靠度的提升而不断降低。

滚动接触状态下固体润滑薄膜界面损伤失效行为分析

以内聚力模型(CZM)为基础建立薄膜-基体承载系统的有限元分析模型,采用双线性本构关系描述薄膜-基体结合界面的承载及损伤失效行为,通过分析法向和切向载荷作用下界面的承载状态,研究了摩擦因数、薄膜弹性模量、膜厚对薄膜-基体承载系统的界面应力、分离位移、能量释放率的影响,结果表明:摩擦因数增大会导致接触前沿界面承载状态恶化,从而增加界面损伤和脱附失效的风险;薄膜弹性模量增大可以减小接触前沿界面损伤区域和损伤程度,当薄膜弹性模量小于基体弹性模量时界面承载性能急剧恶化;随膜厚增大,界面切向损伤区域和损伤程度先减小后增大,膜厚为0.2倍接触半宽时有利于提升薄膜-基体结合界面的承载性能。