激光感应复合熔覆镍基涂层的裂纹研究

采用送粉激光感应复合熔覆技术制备了镍基合金熔覆涂层,研究了涂层的组织和裂纹行为.研究结果表明,镍基合金熔覆层具有很大的裂纹倾向,激光感应复合熔覆中工艺参数对裂纹形态有较大的影响,感应加热可以有效抑制熔覆层的开裂行为,感应能量的加入使熔覆层、热影响区和基体显微硬度有所降低.熔覆过程中主要产生残余热应力,随着感应能量的增加,熔覆层残余拉应力明显减小,当感应能量密度达到36J/mm2时,基体表面温度约为600℃,裂纹完全消除.     

CeO2对镍基碳化钨激光熔覆层性能的影响

研究了不同激光功率条件下不同含量的氧化铈对镍基碳化钨金属陶瓷熔覆层宏观质量、显微组织及熔覆层横截面硬度的影响。CeO2的掺入均能使镍基碳化钨金属陶瓷熔覆层中的相组织得到细化,裂纹大大减少,宏观质量得到显著改善。随稀土氧化物加入量的增加,稀土的细晶变质作用效果更加明显。当CeO2的含量为0.16wt%时,熔覆层的硬度达到最大约为900HV0.3～1300HV0.3,裂纹基本消失。激光功率对熔覆层的宏观质量、显微硬度及微观组织均有影响,当激光功率低于1.5kW时,难以得到连续光滑的熔覆层;当激光功率高于2.0kW时,熔覆层的晶粒长大,硬度明显降低。     

纳米CeO2对激光熔覆Ni基合金层组织与性能的影响

为了研究纳米CeO2颗粒对激光熔覆层的组织和性能的影响,在Q235钢基体上制备了加入不同量纳米CeO2的Ni基合金熔覆层,利用OLMPUS PME-3型光学显微镜,XD-3A型X射线衍射仪,HV-1000型显微硬度计,MM-200型环-块磨损试验机和扫描电镜等对激光熔覆层显微组织、相结构、显微硬度、磨损性能和磨损机理进行了研究。结果表明,在激光熔覆层中添加纳米CeO2能够细化组织,改变凝固组织的形态。当加入质量分数为1.5%的纳米CeO2时,熔覆层凝固组织形态为等轴树枝晶;生成了含Ce的新相Ce2Ni21B6,明显提高了熔覆层的显微硬度和耐磨性;熔覆层磨损由严重磨损转化为轻微磨损。但是加入过量的纳米CeO2,硬度反而降低。     

纳米SiC含量对激光熔覆镍基合金组织性能影响

采用预置式,在45^#钢基体表面,铺设0.8 mm厚度的纳米SiC增强NiFeBSi复合合金粉末。利用3 kW横流CO₂激光,熔覆不同增强比例的复合涂层。利用X射线衍射（XRD）仪,扫描电镜（SEM）、显微硬度仪、摩擦磨损试验机分别对不同增强比例涂层进行微观组织、力学性能的分析及讨论。探究了纳米SiC含量对熔覆层组织性能的影响。研究结果表明,NiFeBSi+纳米SiC复合涂层具有与NiFeBSi合金涂层相似的组织形貌特征,在激光熔覆过程中纳米SiC颗粒的分解,致使γ（Fe,Ni）枝晶间上形成了多种碳化物。因此,显著提高了NiFeBSi合金涂层的硬度,并随着纳米SiC的掺入量增多,硬度提高显著。纳米SiC的加入显著地增强了熔覆层的耐磨性能,但随含量增加磨痕表面产生脆性变形和裂纹,其中NiFeBSi+w（SiC）=7%复合涂层的耐磨性能最好。     

CeO2对激光熔覆Ni60合金涂层组织及性能的影响

为了研究稀土元素CeO₂对激光熔覆涂层性能的影响,以45#钢为基体、Ni60和Ni60+CeO₂粉末为熔覆材料,采用激光熔覆多道搭接工艺制备了含不同含量稀土氧化物的熔覆层。通过对熔覆层着色探伤、显微组织观察、显微硬度测定的试验,分析不同含量的稀土氧化物对熔覆层表面裂纹数量、显微组织、硬度的影响规律。结果表明,CeO₂的最佳掺杂质量分数为0.004;适量稀土元素CeO₂的掺杂,可使熔覆涂层裂纹数量减少,熔覆层的显微组织更加均匀而细小;熔覆涂层表面显微硬度远高于基体,维氏硬度是基体的3.6倍,搭接区域硬度值是基体的3倍左右。这表明稀土元素的添加可以抑制裂纹、细化晶粒,并在一定程度上提高熔覆层硬度。     

稀土氧化物对Al2O3-ZrO2激光熔覆层组织与性能影响研究

为了解决在钛合金表面通过激光熔覆技术制备得到的Al₂O₃-ZrO₂陶瓷涂层脆性大、易开裂的问题,有效提升钛合金性能,扩大其使用范围,采取在熔覆层材料中添加稀土氧化物CeO2的方法,对Al₂O₃-ZrO₂陶瓷熔覆层的裂纹敏感性进行了改善。通过分析熔覆层宏观、微观组织,测试熔覆层性能,研究CeO2含量对熔覆层裂纹敏感性的影响规律,探究CeO₂调控辅助激光熔覆制备Al₂O₃-ZrO₂陶瓷涂层最佳含量,揭示稀土氧化物对熔覆层裂纹敏感性影响的作用机理。结果表明：通过添加稀土氧化物调控,熔覆层裂纹数量明显减少,熔覆层裂纹控制主要归功于稀土元素对熔覆层组织的细晶强化效应;当CeO₂质量分数为0.8%时,熔覆层微观组织最为致密,对裂纹抑制作用最为明显;熔覆层断裂韧性相较未添加稀土调控辅助时有明显提高,从4.1 MPa·m^1/2提高至7.3 M...     

激光重熔功率对镍基自润滑涂层组织与性能的影响

为研究重熔功率对Inconel 718镍基自润滑涂层组织与性能的影响规律，采用激光熔覆技术在27SiMn钢板材上制备Inconel 718熔覆涂层，选用三种不同的激光功率二次重熔熔覆试样。使用超景深显微镜观察熔覆层表面形貌及金相组织，使用显微硬度计检测熔覆层的显微硬度，使用销-盘式摩擦磨损试验机检验及评价熔覆层的摩擦磨损性能。结果表明，激光重熔后熔覆层的晶粒得到明显的细化，随着重熔功率的增加，熔覆层晶粒尺寸先减小后增大，重熔功率为1 260 W时，熔覆层顶部晶粒尺寸最均匀细小；重熔后熔覆层的硬度均有较大提高，相较未重熔试件硬度最高可提升22%;从磨损形貌来看，试样的磨损机理主要为磨粒磨损，经重熔后试样的摩擦系数及磨损失重均得到了明显的降低。分析摩擦磨损试验数据可知，重熔功率在1 260 W时，试件的耐磨性能最好。     

CeO2、Y2O3和MgO对镍基碳化钨金属陶瓷熔覆层裂纹及组织的影响

研究MgO、CeO2、Y 2O3对镍基碳化钨金属陶瓷熔覆层宏观质量、显微组织及熔覆层横截面硬度的影响.这些氧化物的掺入均能使镍基碳化钨金属陶瓷熔覆层中的裂纹大大减少,使熔覆层的宏观质量得到改善,使熔覆层的相组织得到细化.对于相同的激光熔覆工艺参数,不同氧化物对熔覆层晶粒的细化变质作用的强弱依次为MgO＞CeO2＞Y2O3,对横截面的显微硬度值的影响大小依次为MgO＞Y2O3＜CeO2.     

碳纳米管含量对激光熔覆镍基复合涂层组织与性能的影响

针对Ni60A/WC复合涂层硬质相分布不均、减摩性能不足等问题,利用碳纳米管（CNTs）的高熔点和优良的自润滑性能,采用激光熔覆技术在45钢基体表面制备了添加不同含量CNTs的镍基耐磨涂层。通过扫描电子显微镜、能谱仪和X射线衍射仪（XRD）分析了涂层的显微组织、元素组成和相组成。通过显微硬度计和摩擦磨损试验机测试了涂层的硬度和耐磨性能。XRD图谱表明:熔覆层主要由Ni-Cr-Fe固溶体和WC、W₂C、Cr₃C₂、Cr₇C₃、Cr₂₃C₆、B₄C等硬质相组成。显微组织结果表明:CNTs的添加促进了异质形核,有利于硬质相均匀分布,明显细化了熔覆层的显微组织。由于CNTs具有细化晶粒以及提升自润滑性能的作用,适量添加CNTs可提升熔覆层的显微硬度和耐磨性能。当CNTs的质量分数为0.5%时,熔覆层的显微硬度为1100 HV,摩擦系数为0.3,磨损体积为1.24×10^-4 mm³     

稀土对Ti基激光熔覆层组织与摩擦磨损性能的影响

采用同轴送粉激光熔覆技术在Ti811表面制备了CeO_2质量分数分别为0,1%,3%的TC4+Ni45+CeO_2多道搭接激光熔覆层。采用X射线衍射仪、扫描电镜和能谱仪分析了熔覆层的微观组织和物相,利用显微硬度计、摩擦磨损试验机和白光轮廓仪测试分析了熔覆层的显微硬度和摩擦磨损性能。结果表明:熔覆层中的物相包括TiC、TiB_2、TiB、Ti_2Ni和α-Ti;随着CeO_2加入量增加,熔覆层中的物相未发生改变;当CeO_2添加量为0时,熔覆层内部组织粗大,显微硬度为590～640 HV,磨损机制主要为磨粒磨损和黏着磨损;当添加CeO_2的质量分数为1%时,熔覆层组织逐步细化,枝晶的方向性减弱,显微硬度为625～655 HV,磨损机制主要为磨粒磨损和黏着磨损;当添加CeO_2的质量分数为3%时,熔覆层中的增强相由树枝晶状、长条状、须晶状向颗粒状、层状、短棒状转变,且均匀弥散地分布于熔覆层中,显微硬度为560～575 HV,磨损机制主要为磨粒磨损。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks