保温时间对GaAs功率芯片钎缝组织及性能的影响

GaAs芯片的使用性能受其散热效果决定,而散热主要依靠散热垫块与芯片连接的钎缝来决定。为增加钎缝的散热效果和基体结合强度,文中分别在芯片层利用物理气相沉积方法沉积Pd和Au膜,而在Cu/Mo/Cu散热垫块上沉积Ni和Au膜,采用AuSn20共晶钎料,研究保温时间对钎焊缝组织和界面结合性能影响。研究结果表明:共晶结构主要由15～20μm厚的合金层和0.5～3μm厚的IMC层构成。随着保温时间延长,合金中Sn元素会逐渐被IMC层消耗,合金成分往富Au的(L+ζ′)相区迁移,相比例增加,保温时间超过60 s后, IMC层厚度超过3.9μm,剪切力快速减小至89.67 N。     

电阻散热壳体阳极氧化着金色的工艺研究

为了提高铝合金零件的耐蚀性、装饰性,在阳极氧化后通常进行染色处理,使零件膜层呈现各种各样的颜色。电阻散热壳体要求膜层颜色呈金黄色。在对5组染色配方试验、筛选的基础上,确定出一种有效的工艺配方。采用单因素试验方法探讨了膜层厚度、茜素红S、茜素黄GG、染色液温度、p H值对膜层染色质量的影响,得出了最佳的成分含量和工艺条件。     

等离子增强磁控溅射Ti-Si—C-N基纳米复合膜层耐冲蚀性能研究

介绍了等离子增强磁控溅射(PEMS)技术,系统研究了其制备的Ti-si-C-N纳米复合膜层.首先讨论该技术工作原理,并描述了膜层的制备工艺过程.通过SEM、XRD、EDS、纳米压痕、微米压痕及冲蚀试验等研究了膜层性能,发现膜层为纳米复合结构,以非晶SiCxNy为基质,内含4.7～30nm的TiCo.3N0.7纳米晶.膜层硬度高达40GPa,同时研究了Si含量的影响.膜层表现出的耐冲蚀性比基体材料高100倍以上,其韧性对耐冲蚀性影响很大.讨论了溅射工艺参数对膜层微观组织结构、纳米硬度、附着力及耐冲蚀性方面的影响,同时研究了多层膜层.此类膜层有望应用于气轮压缩机及固定式涡轮的严重固体颗粒冲蚀(SPE)和液滴浸蚀(LDE)的防护.     

NiFeSiMnMo/Cu/NiFeSiMnMo多层膜中Cu层对巨磁阻抗效应的影响

在康宁玻璃上用真空蒸镀法沉积NiFeSiMnMo单层膜、NiFeSiMnMo/Cu双层膜和NiFeSiMnMo/Cu/Ni-FeSiMnMo多层膜.对单层膜和双层膜的软磁性能进行了分析,对多层膜的巨磁阻抗效应随Cu层宽度的变化进行了研究.实验研究表明,NiFeSiMoMn/Cu双层膜比NiFeSiMnMo单层膜矫顽力小、饱和磁化强度高;多层膜Ni-FeSiMnMo/Cu/NiFeSiMnMo随着Cu层宽度的增加巨磁阻抗比上升到一个最大值后下降,在磁性层宽度3mm的情况下,Cu层宽度在0.7mm时,巨磁阻抗比最大.     

空调器铝箔的表面处理⑵

４亲（憎）水箔的性能对亲（憎）水箔的性能要求主要有：亲（憎）水性高,按涂层面与水的接触角大小判断;附着力强,膜层与膜层之间、膜层与铝基体之间结合牢固;抗蚀性高,根据盐雾试验与湿度试验指标判断;抗热性好,因为用铝箔制的翅片与铜管钎焊成散热板,要求在一定...     

正向氧化电压对ZAlSi12Cu2Mg1微弧氧化膜形成的影响

通过改变正向氧化电压,对ZAlSi12Cu2Mg1微弧氧化膜的形成进行研究,研究其对微弧氧化膜层特性的影响,并测定了膜层的相组成.结果表明:电压为430 V时,膜层厚度仅65 μm,膜层硬度434 HV,在30 min的干摩擦后膜层的磨损量为基体合金的29.86％;电压提高到440 V时,膜厚增到154 μm,膜层中含有3Al2O3·2SiO2、SiO2、α-Al2O3、γ-Al2O3和WO3,膜层硬度提高到898 HV,膜层的磨损量仅为基体的12.45％.超过440 V后,膜层厚、硬度及耐磨性均有所下降.     

温度对TiN/Ti多层膜微观结构和氧化行为的影响

研究了TiN/Ti多层膜不同温度下的微观结构和氧化行为.采用阴极弧离子镀沉积的方法制备了19层调制周期为200 nm的TiN/Ti多层膜及相应的TiN单层膜.采用高分辨场发射电子显微镜(HR-FESEM)、光学显微镜和X射线衍射仪(XRD)分别对膜层断面结构、表面形貌和物相进行分析.结果表明,随着加热温度的升高,TiN单层膜在350℃时开始出现局部剥落,550℃出现大范围的剥落,而多层膜未发生剥落;相对TiN单层膜,TiN/Ti多层膜具有层状结构,其抗氧化能力有一定的提高.结合试验结果,讨论了TiN/Ti多层膜和TiN单层膜的工作温度.     

AZ91D压铸镁合金微弧氧化的工艺研究

为了探索AZ91D压铸镁合金微弧氧化的工艺,研究了两种电解液体系中,恒电流时膜层生长动力学规律.分析了恒定电流密度值的大小、电源脉冲频率以及在溶液中添加NaF对膜层生长速率、表面粗糙度的影响.结果表明:电流密度越大,AZ91D压铸铁合金饭弧氧化膜层的生长速率越快,同时膜层表面粗糙度也会相应增大;频率越高膜层表面粗糙度越小,但频率的变化几乎对膜层的生长速率不产生影响;在溶液中添加NaF,可以明显地提高膜层的生长速率并降低膜层的表面粗糙度.     

镁合金微弧氧化膜有机封孔耐腐蚀性能的研究

镁合金AZ91D经微弧氧化处理后得到与基体结合牢固、表面多孔的氧化膜,研究了在该氧化膜上涂覆有机涂层进行封孔的方法,利用扫描电镜从复合膜层的横截面分析了有机涂层对微弧氧化膜层的封孔情况,并对封孔后的镁合金表面膜层的结合性能和耐腐蚀性能进行了初步试验分析.研究表明,有机涂层能渗入微弧氧化膜孔洞内5～30μm,与氧化膜层结合紧密.经1% HCl溶液浸泡试验,结果表明经过有机封孔后的微弧氧化膜层的耐腐蚀性能大大提高.     

添加剂对电镀锌层烷氧基硅烷钝化膜电化学行为的影响

为提高镀锌层钝化膜的耐蚀性,利用极化曲线和交流阻抗谱,研究了不同添加剂对镀锌层烷氧基硅烷钝化膜腐蚀性能的影响.并与加速腐蚀试验结果进行了对比.试验结果表明,添加剂的加入明显改变了钝化膜层的腐蚀电位,提高钝化膜的交流阻抗值,烷氧基硅烷钝化膜的耐蚀性明显提高.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。