Al2O3和Cr过渡层对Ag膜光学性质及其附着力的影响

研究了在玻璃基底上镀制Al2O3和Cr过渡层对Ag膜反射率及附着力的影响.分光光度计测试了Ag膜的反射率,结果表明,与Cr过渡层相比,Al2O3过渡层对Ag膜反射率的降低相对较小;而且,随着Al2O3厚度的增加,Ag膜的反射率先增大后减小.XRD与AES测试表明,引入Al2O3或Cr可明显细化Ag晶粒,减弱Ag膜(111)织构;Al2O3作过渡层时,Al原子向Ag层中扩散显著;而Cr作过渡层时,只有少量Cr原子扩散进入Ag层.因此,Al2O3作过渡层能显著增强薄膜与玻璃基体之间的附着力.     

复相Al2O3基陶瓷/钢大气中直接钎焊连接界面的微观组织结构

在大气中对复相Al2O3基陶瓷与钢进行了直接钎焊连接。采用扫描电镜、能谱分析和X射线衍射等测试手段，对接头的微观组织形貌、特征点的成分和界面反应产物等进行了分析研究。结果表明，在一定的工艺条件下，可以实现复相Al2O3基陶瓷／钢在大气中的直接钎焊连接。复相Al2O3基陶瓷／钢的接合为元素的扩散和界面反应的综合结果，界面反应产生的新相主要为复合化合物FeWO4。     

焊接工艺参数对镁合金CO2激光焊焊缝表面成形的影响

探讨了焊接工艺参数包括激光功率、焊接速度、正面和背面的保护气体流量对焊接工艺效果和接头成形的影响.结果表明,对AZ61和AZ31两种镁合金,激光功率的增大,焊缝正面和背面的熔宽都明显增大;而焊接速度的增大,焊缝正面和背面的熔宽明显减小.在同样的工艺参数情况下,AZ61的熔化效率比AZ31更高,获得的焊缝正面和背面熔宽更大.正面的保护气体流量大小对焊缝熔宽的影响较小,而背面保护气体流量对焊缝熔宽基本没有影响,但正面和背面气体流量主要影响到焊缝正反面的保护效果,影响到焊缝的表观.试验结果表明,在适当的工艺参数下,采用CO2激光焊接方法可以较好地实现不同厚度的AZ61和AZ31镁合金的焊接,而且焊缝成形良好,接头的力学性能优良.     

Microstructure and Strength of Laser Welds of Sub-micron Particulate-reinforced Aluminum Matrix Composite Al_2O_(3p)/6061Al

The special microstrUctUre of sub--micronaluminum matrix composites makes it dimcultto obtain a sa1isfactory welded joint l l--3]. Up tonow, there is no report abollt the systCm1c studyon the we1dability of the composites.T'he microstructure of laser welds of sub-mi-cron particulate-reintbrced aluminum matrixcomposite Al=O,/606lAl was analyzed bymeans of X--ray diffrac1ion, SFM and TEM, thewelding mechanism of the composite was stu-died, and the approach to improve the propertiesof the we…     

Structure and micro-tribological properties of PTFE/Al_2O_3 micro-assembling film

1　INTRODUCTIONComparedwithBabbittpadsofthrustbearing ,theelasticmetallic plasticpadspossessthecombina tionofreliablerunning ,excellentperformance ,flexi bleoperation ,convenientinstallationandlongservicelife.Thereforetheelasticmetallic plasticpadsarewidelyemployedinverticalelectricmachinesofhy dropower plants .Polytetrafluoroethylene (PTFE )hasbeenusedasthesurfacematerialoftheelasticmetallic plasticpadsbecauseofitslowfrictioncoeffi cientandelectricalinsulation[1] ;butitsstrengthandwearr…     

Na2SiF6活性激光焊接TC4钛合金焊缝成形和组织

采用Na₂SiF₆作为表面活性剂激光焊接TC4钛合金,通过观察焊缝表面,确定了Na₂SiF₆对TC4钛合金激光焊焊缝表面成形的影响;采用高速摄像技术,观察分析了焊件上方高温光致等离子体形态特征变化;借助光学显微镜观察分析了焊缝熔深和熔宽的变化及微观组织. 结果表明,涂覆Na₂SiF₆活性剂后TC4钛合金激光焊焊缝表面成形良好,可使焊缝熔深增加约0.8% ~ 12%,焊缝表面熔宽降低约10% ~ 29%,能够有效提高焊缝的深宽比;Na₂SiF₆活性剂改善了焊缝微观组织的不均匀性,改变了焊缝上部β柱状晶的结晶方向,细化了焊缝的晶粒尺寸和微观组织.     

Al-Ti基体上纳米网状钙磷陶瓷/多孔Al2O3生物复合涂层的原位生长

先采用PVD法在医用钛金属表面沉积一层Al膜,得到Al-Ti基体材料;而后采用阳极氧化与水热合成复合制备技术在Al-Ti基体上成功构造了由纳米网状磷酸盐组成的钙磷生物陶瓷/Al2O3多孔复合生物涂层.利用扫描电镜(SEM)、透射电镜(TEM)、电子能谱(EDAX)、X射线衍射(XRD)表征了阳极氧化前后铝膜和钙磷生物陶瓷涂层的微观形貌、元素构成以及晶相成分.结果表明:在阳极氧化过程中,钙、磷元素嵌入阳极氧化铝(AAO)膜,并经水热处理反应原位生成钙磷陶瓷;钙磷陶瓷晶体从Al2O3孔洞长出并覆盖于多孔氧化膜的表面;最终获得的钙磷生物陶瓷/多孔Al2O3复合涂层具有纳米网状、多孔的结构特征.分析探讨了钙磷生物陶瓷/多孔Al2O3复合涂层的原位生长过程,浓度梯度与电位差分别是Ca、P元素进入AAO膜的主要推动力.     

Al2O3陶瓷表面化学镀镍工艺及其低温连接

进行了Al2O3陶瓷表面的化学镀镍处理,对Al2O3陶瓷表面前处理工艺各个工序进行研究,制定了前处理流程.研究了硫酸镍浓度、次亚磷酸钠浓度、施镀温度、施镀时间等对镀层沉积速率的影响,对镀层进行了金相分析,在此基础上得到化学镀镍的优化工艺.进行了镀镍后Al2O3陶瓷低温钎焊工艺试验,研究了不同化学镀工艺条件对接头组织及力学的影响.结果表明,在试验条件下,硫酸镍、次亚磷酸钠浓度等化学镀工艺,焊接温度、焊接时间及压力等焊接工艺对接头组织及力学性能均有重要的影响.     

MORPHOLOGY OF AMORPHOUS SILICA DURING ALUMINUM REACTIVE PENETRATION

1. IntroductionSiC./AI composite is one of the important systems in the particle--reinforced metalmatrix composites. The more attention was focused on the interface between SiC particleand aluminum alloy[1--81. A thin layer amorphous silica was found at the surface of SiCparticles[4t6,8], which is beneficial to the fabrication of SiC/AI. This has two reasons.Firstly, Sioz may protects SiC from liquid aluminum etching and has good wettabilityto aluminum, and then oxygen has a strong affin…     

Structural Evolution During Mechanical Milling of Bimodal-Sized Al_2O_3 Particles Reinforced Aluminum Matrix Composite

Hybrid aluminum matrix composite powders reinforced with bimodal-sized Al_2O_3 particles were synthesized by mechanical milling. Two different approaches were investigated for the addition of submicron-and nano-sized Al_2O_3 particles to the aluminum powders. It was observed that the simultaneous addition of bimodal-sized Al_2O_3 particles to the aluminum powders resulted in an equiaxed morphology of the composite powders and the average particle size stabilized after 5 h of milling, indicating that the presence of bimodal-sized particles has greater effect on accelerating milling process as compared to nano-sized particles; the grain size of the aluminum matrix in composite powders was reduced to under 40 nm, approximate to the value obtained in the separate addition case, while a lower rate of refining was observed due to hindrance of submicron-sized particles on the interactions between nano-sized particles and the aluminum matrix.     

硼酸铝晶须增强铝基复合材料研究现状

介绍了硼酸铝(Al18B4O33)品须的特点和制备方法,并阐述了分别用溶胶-凝胶法、原位氮化法涂覆硼酸铝晶须,来实现品须与基体更好润湿的方法,然后介绍了基体中Fe3O4、晶须含量及制备工艺对硼酸铝增强铝基复合材料性能的影响.     

Molecular mechanics and dynamics simulation of hydrogen diffusion in aluminum melt

The main impurities in aluminum melt are hydrogen and Al_2O_3,which can deteriorate melt quality and materials performance.However,the diffusion process of H atoms in aluminum melt and the interactions among Al atoms,Al_2O_3 and hydrogen have been studied rarely.Molecular mechanics and dynamics simulations are employed to study the diffusion behaviors of different types of hydrogen,such as free H atoms,H atoms in H_2 and H~+ions in H_2O using COMPASS force field.Correspondingly,force field types h,h1h and h1o are used to describe different types of hydrogen which are labeled as H_h,H_(h1h) and H_(h1o).The results show that the adsorption areas are maximum for H_(h1o),followed by H_(h1h) and H_h.The diffusion ability of H_(h1o) is the strongest whereas H_h is hard to diffuse in aluminum melt because of the differences in radius and potential well depth of various types of hydrogen.Al_2O_3 cluster makes the Al atoms array disordered,creating the energy conditions for hydrogen diffusion in aluminum melt.Al_2O_3 improves the diffusion of H_h and H_(h1o),and constrains H_(h1h) which accumulates around it and forms gas porosities in aluminum.H_(h1o) is the most dispersive in aluminum melt,moreover,the distance of Al-H_(h1o) is shorter than that of Al-H_(h1h),both of which are detrimental to the removal of H_(h1o).The simulation results indicate that the gas porosities can be eliminated by the removal of Al_2O_3 inclusions,and the dispersive hydrogen can be removed by adsorption function of gas bubbles or molten fluxes.     

7A52铝合金电子束焊接参数及性能

对20mnrl厚7A52铝合金板材采用试件法进行电子束焊接,确定了焊接参数并对力学性能进行分析．结果表明,采用加速电压60kV,电子束流120mA,聚焦电流763mA,焊接速度800mm／min,可得到良好的焊缝表面．电子束流增大焊缝深宽比显著增加,聚焦电流微小的数值变化可引起焊缝形状突变．接头焊缝区晶粒细小均匀,抗拉强度为母材的87％,焊缝维氏硬度最低值为母材的61％,焊缝冲击韧度为母材的95．4％,表明了电子束接头的性能很高．     

高强铝合金激光粉末焊接过程

采用CO2激光(slab)系统进行了高强铝合金的激光填粉焊接,分析了激光与粉末相互作用的5个阶段过程;研究了填充合金粉对CO2激光焊接功率阈值、焊缝成形和焊接过程稳定性的影响.试验表明,合金粉末可以提高焊接过程中激光能量的有效利用率;激光深熔焊接时的临界功率密度明显降低,粉末束流只有作用在光致等离子体的恰当区域才能有效地进入熔池;在一定送粉量下,匹配适当的功率密度和热输入,才能保证得到理想的焊缝.高速摄像图片显示了激光支持的燃烧波及焊接中的过程孔洞,并且合金粉末还可以减弱等离子体的膨胀跳动,有利于获得较为稳定的焊接过程和理想的焊缝成形.     

Al-TiO_2-B_2O_3系XD合成铝基复合材料研究

主要讨论Al-TiO_2-B_2O_3系XD法制备铝基复合材料的合成工艺及其反应机理。结果表明:在B2 O3 与TiO2 摩尔比小于1时,真空炉温预热至10 0 0K左右时压坯爆燃,反应产物由TiB2 、Al3 Ti和Al2 O3 组成,其中Al3 Ti为棒状物,TiB2 、Al2 O3 为细小颗粒,粒径为数μm左右。同时分析了球磨时间、预紧实度对反应产物的影响规律。     

Al2O3对电沉积Ni-Co/Al2O3复合镀层性能的影响

应用直流复合电沉积技术制备Ni-Co/Al2O3复合镀层,并研究了Al2O3对电沉积Ni-Co/Al2O3复合镀层性能的影响。结果表明:在本试验范围内,镀层的硬度和耐磨性随着Al2O3含量的增加而提高。     

采用填充焊丝的外加电流铝合金CO2激光焊接

在铝合金CO2激光焊接时,通过填充焊丝向焊接熔池注入外加电流,直流电源的一极与填充焊丝相连,另一极在熔池后方与工件相连,由此构成电流回路.研究结果表明,随着外加电流的增加,焊缝熔深和面积增大,且焊缝表面成形更加均匀,鱼磷纹更加细密,即外加电流提高了焊接效率,改善了焊接过程的稳定性.进一步研究表明,外加电流的电阻热对焊接结果的影响极小.外加电流对铝合金CO2激光焊接的影响归因于电流的磁流体效应.     

La对Al2O3f/Al-Mg复合材料凝固溶质偏析的影响

利用挤压铸造法制备了Al2O3／Al-Mg-La复合材料。研究了La在铝合金基体中的分布，并探讨了La对基体凝固时溶质元素偏析的影响。结果表明，La富集在界面附近，有利于改善铝合金液对Al2O3f的润湿性，但是在界面上未发现任何富稀土相的形成。La的加入对基体合金中的Mg的偏聚没有很明显的影响，Mg和La作为表面活性元素都在界面处富集，且它们的分布位置大致一样。     

原位合成(Al_2O_3+Al_3Ti)_P/Al复合材料的制备研究

通过对Al-TiO_2-SiO_2体系混合粉末固-液原位合成制备出了(Al_2O_3+Al_3Ti)_P/Al复合材料.利用X射线衍射仪、扫描电镜等方法观察分析了其物相和显微组织形貌.结果表明:原位反应制备的(Al_2O_3+Al_3Ti)_P/Al复合材料,金属间化合物增强相Al_3Ti均匀分布于基体,陶瓷相Al_2O_3颗粒非常细小,弥散分布于基体中,使材料的硬度等性能得到提高.     

纳米-Al2O3颗粒对镍电结晶初期阶段的影响

利用循环伏安(CV)、计时安培(CA)和电化学阻抗(EIS)研究了纳米Al2O3颗粒在不同电位(vs.SCE)下对Ni自硫酸盐镀液在铜基体上电沉积的影响。结果表明,Ni-Al2O3体系共沉积的起始电位为:–740mV左右;在不同的电位下,纳米-Al2O3颗粒对镍沉积过程的影响有所差别;在电位–740～–830mV范围,与纯Ni沉积相比较,Ni-Al2O3体系沉积的峰电流所对应的孕育期tm明显缩短,反映Al2O3颗粒在阴极表面有利于镍沉积成核,且促进了电结晶成核。Al2O3颗粒吸附在阴极表面可能会阻碍部分离子电荷放电和物质传输过程,尤其在电位–250～–650mV范围,致使Ni-Al2O3体系沉积阻抗增加。在较高的过电位下,Al2O3颗粒的促进作用有所减弱,许多颗粒堆积在电极表面上还可能减小Ni-Al2O3沉积的还原反应电流。在电位–890mV,Ni-Al2O3体系电沉积初期阶段的成核过程基本遵循三维的Scharifker-Hill瞬时成核模式。