压合法二层挠性覆铜板制造技术

本文主要介绍二层挠性覆铜板的产品结构、压合法制造流程和产品特性。

二层挠性覆铜板制造技术-压合法

本文主要介绍二层探性覆铜板的产品结构、制造流程和产品特性.

拉压组合法消减铝合金环形件淬火残余应力研究

针对环形件淬火残余应力突出的问题,提出一种消减淬火残余应力的新方法即拉压组合法。该方法通过沿环形件内侧45°方向施加压力,同时产生拉伸和压缩的效果。利用ABAQUS有限元软件对7085铝合金环形件淬火残余应力及拉压组合法进行数值仿真。进行拉压组合法消减铝合金环形件淬火残余应力工艺实验,采用环形件切口法来表征环形件应力的变化。研究结果表明:环形件淬火残余应力主要表现为集中在截面芯部区域的周向拉应力,最大值为46 MPa;当高度方向变形量为0.6%时,芯部残余应力降至10 MPa左右;随着压下量增加,芯部残余应力由拉应力变为压应力;施加0.6%变形量的环件切口由淬火时内缩2.26 mm变为张开0.34 mm,实验结果与仿真结果一致。

一种基于点压技术的新型晶圆键合方法

金金热压键合法在半导体制造领域中应用广泛,为了进一步改进该键合方法,首次提出了一种基于点压技术的新型晶圆键合方法,并研究了工艺温度、压强以及时间对点压键合法单点键合面积的影响.通过超声扫描显微镜图像,着重比较了传统金金热压键合法与点压键合法的键合面积比.对点压键合法的可选择键合性进行了讨论.结果表明,点压键合法工艺步骤简单,工艺稳定性较好,且具有一定的可选择键合特性,在半导体制造领域中将具有广泛的应用前景.

苎麻栽压结合繁殖法技术小结

苎麻定植常用方法,一般都是种苗直立栽于窝内,每植一亩需种苗少则2000株左右,多则10000株左右,其繁殖速度慢,缺窝断垄严重,特别是投资大,在缺少种源的贫困地区,麻农难以解决繁殖投资过大的问题。1985年5月15日。

B/Al复合板材复合工艺的研究

介绍了热压扩散结合法制备 Ｂ／ Ａｌ 复合板材的工艺过程，研究了热压工艺参数对 Ｂ／ Ａｌ 复合板材性能的影响，获得了热压扩散结合法制备 Ｂ／ Ａｌ 复合板材比较理想的工艺参数，得到了拉伸强度σｂ ＝ １ ２８０ Ｍ Ｐａ 、弹性模量 Ｅ＝ ２３３ Ｇ Ｐａ 的 Ｂ／ Ａｌ 复合板材。

Establishment of continuous cooling transformation diagrams of aluminum alloys using in situ voltage measurement

An effective method was proposed to establish the continuous cooling transformation（CCT） diagrams of aluminum alloys using in situ voltage measurement.The voltage change of samples with predefined dimension was recorded under the constant current state during continuous cooling.Solutionizing time,together with starting and finishing temperatures of phase transformation of the alloy can be obtained from relationships of voltage vs time and temperature.A critical cooling rate without detectable phase transition during continuous cooling can be determined.Continuous cooling transformation diagrams of tested samples can be established conveniently based on these results.Microstructure observation and differential scanning calorimetry（DSC） testing were applied to verify the reliability of continuous cooling transformation diagram.

Finite element analysis of strain distribution in ZK60 Mg alloy during cyclic extrusion and compression

Finite element method was used to study the strain distribution in ZK60 Mg alloy during multi-pass cyclic extrusion and compression （CEC）. In order to optimize the CEC processing, the effects of friction condition and die geometry on the distribution of total equivalent plastic strain were investigated. The results show that the strain distributions in the workpieces are inhomogeneous after CEC deformation. The strains of the both ends of the workpieces are lower than that of the center region. The process parameters have significant effects on the strain distribution. The friction between die and workpiece is detrimental to strain homogeneity, thus the friction should be decreased. In order to improve the strain homogeneity, a large corner radius and a low extrusion angle should be used.

Solving Navier-Stokes equation by mixed interpolation method

The operator splitting method is used to deal with the Navier-Stokes equation, in which the physical process described by the equation is decomposed into two processes： a diffusion process and a convection process; and the finite element equation is established. The velocity field in the element is described by the shape function of the isoparametric element with nine nodes and the pressure field is described by the interpolation function of the four nodes at the vertex of the isoparametric element with nine nodes. The subroutine of the element and the integrated finite element code are generated by the Finite Element Program Generator （FEPG） successfully. The numerical simulation about the incompressible viscous liquid flowing over a cylinder is carded out. The solution agrees with the experimental results very well.

Finite element simulation of ball spinning of NiTi shape memory alloy tube based on variable temperature field

As a new attempt,ball spinning was used to manufacture the nickel-titanium shape memory alloy（NiTi SMA） tube at elevated temperature.The NiTi bar with a nominal composition of Ni50.9Ti49.1（mole fraction,%） was solution treated and was used as the original tube blank for ball spinning.Based on the variable temperature field and the constitutive equation,rigid-viscoplastic finite element method（FEM） was applied in order to simulate the ball spinning of NiTi SMA tube.The temperature field,the stress field,the strain field and the load prediction were obtained by means of FEM.FEM results reveal that there is a temperature increase of about 160 ℃ in the principal deformation zone of the spun part.It can be found from the stress fields and the strain fields that the outer wall of NiTi SMA tube is easier to meet the plastic yield criterion than the inner wall,and the plastic deformation zone is caused to be in a three-dimensional compressive stress state.The radial strain and the tangential strain are characterized by the compressive strain,while the axial strain belongs to the tensile strain.The variation of spinning loads with the progression of the ball is of great importance in predicting the stable flow of the spun part.

表面残留颗粒对晶圆键合影响机制的研究

着重分析了晶圆表面残留颗粒对晶圆键合的影响,并从表面残留颗粒统计意义的角度,得到了一个晶圆键合的判定标准。为了改善键合界面出现的气泡问题,一种基于点压技术的新型点压键合法被应用到整片键合中,并和传统的金金热压键合法进行了比较。实验表明,采用点压键合法能够有效抑制晶圆表面残留颗粒对晶圆键合的影响。

PIEZOSPECTROSCOPIC STUDY OF RESIDUAL STRESSES AROUND INDENTATIONS IN SiC/AlO3 NANOCOMPOSITE

A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R lines in the fluorescence spectra va ry with the distance from the centre of indentation. The magnitude of load appli ed on the surface of the materials through the indenter influences the shifts of R lines to great extent. The luminescence of R lines of the materials before indenting is used to determine the residual stresses around the indentation in the materials, assuming that the stress tensor is transversely isotropic. Final ly, the term of hydrostatic stress is adopted to explain and compare different residual stresses around indentations with the increase of the indenting load an d the distance from the centre of indentations. 【

Microstructures and mechanical properties of 2024Al/Gr/SiC hybrid composites fabricated by vacuum hot pressing

The 2024Al/Gr/SiC hybrid composite plates with 5%-10% SiC particles （volume fraction） and 3%-6% flaky graphite （Gr） （volume fraction） were fabricated by vacuum hot pressing and hot extrusion processing. The effects of SiC and Gr on the microstructures and mechanical properties of the composites aged at 160, 175 and 190℃ were studied by optical microscopy, scanning electron microscopy （SEM）, and hardness and tensile tests. The results indicate that the SiC particles have a more obvious effect on accelerating the aging response as compared with the Gr. Both the tensile strength and elongation are reduced by the Gr and SiC particles added into the matrix, while the Gr has a more negative influence on the elongation than the SiC particles. The tensile strength （ab）, yield stress （as） and elongation （δ） of the 2024Al/3Gr/10SiC composite aged at 165℃ for 8 h are 387 MPa, 280.3 MPa and 5.7%, respectively. The hybrid composites are characterized by ductile fracture, which is associated with the ductile fracture of the matrix and the tearing of the interface between the matrix and the particles.

Effects of heat treatment on phase contents and mechanical properties of infiltrated B_4C/2024Al composites

The B4C/2024Al composites were successfully produced by pressureless infiltration method, and the effects of heat treatment on phase content and mechanical properties were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and mechanical properties testing. The results show that phases of BnC/2024Al composites include B4C, Al, Al3BC, AlB2 and Al2Cu. The phase species remain unchanged; however, the phase content of the composites changes significantly after heat treatment at the temperature of 660, 700, 800 or 900 ℃ for 12, 24 or 36 h. It is found that the heat treatment results in not only considerable enhancement in hardness, but also reduction in bending strength of the composites. Heat treatment at 800 ℃ for 36 h does best to hardness of the composites, while at 700 ℃ for 36 h it is the most beneficial to their comprehensive mechanical properties.

Upper bound analysis for hybrid sheet metals extrusion process through curved dies

The extrusion process of hybrid sheet metals through arbitrarily curved dies was analyzed by the method of upper bound. The material under deformation was divided into two deformation regions, bimetal and mono-metal regions, and the flow of the material in each region was assumed as plane strain state. The internal, shearing and frictional power terms were derived and they were used in the upper bound model. The extrusion forces for two types of die shapes, an optimum wedge shaped die and an optimum streamlined die shape for a hybrid sheet composed of copper as sleeve and aluminum as core were determined. The corresponding results for those two die shapes were also determined by using the finite element code, ABAQUS, and compared with the upper bound results. These comparisons show a good agreement.

Establishment of a model for pregnancy-induced hypertension syndrome resulting from cold-stress in rats

Objective: To establish a model for pregnancy-induced hypertension syndrome in rats. Methods: Adult female Wistar rats were randomized into non-pregnant control (NN), non-pregnant cold-stress control (NC), pregnant control (PN) and pregnant cold-stress (PC) groups. The rats of NN and PN groups were put under 25 ℃ and those of NC and PC groups under (4±2)℃ for 4 h every morning respectively in the whole experimental period. The blood pressure, urine protein, body weight, haematocrit, weight of the placenta and weight and length of the fetus were recorded and the histological changes of the placenta and the kidneys were also studied. Results: The blood pressure and urine protein of the rats of the NC and PC groups after 2 weeks of cold-stress were more significantly increased than the rats of the NN and PN groups. In addition, the weight of the placenta and the weight and length of the fetus were more significantly lower in the former than the latter. Obvious changes of anoxia and ischemia were observed in the tissues of the kidneys and every layer of the placenta. Conclusion: Our findings of hypertension syndrome induced with repeated cold-stress in pregnant rats can be applied to illustrate the pathogenesis of pregnancy-induced hypertension syndrome in human beings.

Synthesis and structural characterization of macroporous bioactive glass

Porous sol-gel glass of CaO-SiO2-P2O5 system with macropores larger than 100 μm was prepared by adding stearic acid as pore former when the sintering was carried out at 700 ℃ for 3h.The sol-gel porous glass shows an amorphous structure. The diameter of the pore created by pore former varies from 100 to 300 μm, and macroporous glass has a narrow and small pore size distribution in mesoporous scale. The porosity and pore size of macroporous bioactive glass can be controlled.

Refracturing candidate selection for MFHWs in tight oil and gas reservoirs using hybrid method with data analysis techniques and fuzzy clustering

The selection of refracturing candidate is one of the most important jobs faced by oilfield engineers. However, due to the complicated multi-parameter relationships and their comprehensive influence, the selection of refracturing candidate is often very difficult. In this paper, a novel approach combining data analysis techniques and fuzzy clustering was proposed to select refracturing candidate. First, the analysis techniques were used to quantitatively calculate the weight coefficient and determine the key factors. Then, the idealized refracturing well was established by considering the main factors. Fuzzy clustering was applied to evaluate refracturing potential. Finally, reservoirs numerical simulation was used to further evaluate reservoirs energy and material basis of the optimum refracturing candidates. The hybrid method has been successfully applied to a tight oil reservoir in China. The average steady production was 15.8 t/d after refracturing treatment, increasing significantly compared with previous status. The research results can guide the development of tight oil and gas reservoirs effectively.

Die structure optimization of equal channel angular extrusion for AZ31 magnesium alloy based on finite element method

Three-dimensional（3D） geometric models with different comer angles （90° and 120°） and with or without inner round fillets in the bottom die were designed. Some important process parameters were regarded as the calculation conditions used in DEFORMTM-3D software, such as stress--strain data of compression test for AZ31 magnesium, temperatures of die and billet, and friction coefficient. Influence of friction coefficient on deformation process was discussed. The results show that reasonable lubrication condition is important to plastic deformation. The change characteristics for distributions of effective stress and strain during an equal channel angular extrusion （ECAE） process with inner angle of 90° and without fillets at outer comer were described. Inhomogeneity index （C） was defined and deformation heterogeneity of ECAE was analyzed from the simulation and experiment results. The deformation homogeneity caused by fillets at outer comer increased compared with the die without fillets. The cumulated maximum strains decrease with increasing the fillets of outer comer in ECAE die and the inner comer angle. The analysis results show that better structures of ECAE die including appropriate outer comer fillet and the inner comer angle of 90° for the die can improve the strain and ensure plastic deformation homogenization to a certain extent. The required extrusion force drops with increasing the fillet made at outer comer in ECAE die. It is demonstrated that the prediction results are in good agreement with experiments and the theoretical calculation and the research conclusions in literatures.

Adsorption Refrigeration Performance of Shaped MIL-101-Water Working Pair

A new metal-organic framework of MIL-101 was synthesized by hydrothermal method and the powder prepared was pressed into a desired shape. The effects of molding on specific surface area and pore structure were investigated using a nitrogen adsorption method. The water adsorption isotherms were obtained by high vacuum gravimetric method, the desorption temperature of water on shaped MIL-101 was measured by thermo gravimetric analyzer, and the adsorption refrigeration performance of shaped MIL-101-water working pair was studied on the simulation device of adsorption refrigeration cycle system. The results indicate that an apparent hysteresis loop ap-pears in the nitrogen adsorption/desorption isotherms when the forming pressure is 10 MPa. The equilibrium ad-sorption capacity of water is up to 0.95 kg·kg^-1 at the forming pressure of 3 MPa （MIL-101-3）. The desorption peak temperature of water on MIL-101-3 is 82℃, which is 7 ℃ lower than that of silica gel, and the desorption temperature is no more than 100 ℃. At the evaporation temperature of 10 ℃, the refrigeration capacity of MIL-101-3-water is 1059 kJ·kg^-1, which is 2.24 times higher than that of silica gel-water working pair. Thus MIL-101-water working pair presents an excellent adsorption refrigeration performance.