氧化铝基陶瓷/金属系统的润湿性研究

本文采用座滴试验技术研究了氩气保护条件下Ag-Cu-Ti系钎料对氧化铝基陶瓷的润湿性,探讨了钎料成分、保护气氛以及陶瓷材质对润湿性的影响规律。随着钎料中Ti含量的增加以及保护气氛中氧含量的减少,Ag-Cu-Ti钎料的润湿性提高;钎料中加入少量的Sn-Bi或稀土镁时,Ag-Cu-Ti钎料的润湿性明显改善;陶瓷材料中某些不稳定、易挥发的组分对钎料/陶瓷系统的润湿性有不利的影响。     

润湿性梯度表面上液滴运动的数值模拟

建立液滴在具有润湿梯度表面上运动的物理和数学模型,用Fluent软件模拟出液滴在润湿梯度表面上的运动过程,并从能量变化的方法得到液滴在润湿梯度表面上运动的机制.计算结果表明润湿性梯度表面上的液滴具有不同的能量状态,当液滴的接触角较大时,液滴的表面能较大,此时液滴可以自发地向低接触角的方向运动,润湿性梯度的分布状况将决定液滴运动过程的速度和加速度的大小.     

Ni—P—B4C化学复合镀工艺的研究

本文介绍了Ｎｉ－Ｐ－Ｂ４Ｃ化学复合镀的工艺性能。探讨了镀液中Ｂ４Ｃ粒子添加量，试件的装截量及镀覆时间对沉积速度的影响。并试验了镀液中Ｂ４Ｃ粒子添加量对镀层中Ｂ４Ｃ析出量及镀层表面状态的影响，镀液中Ｂ４Ｃ粒子添加量对镀液老化规律的影响。试验Ｂ４Ｃ中添加量越高，镀液老化越快，文中还分析了添加粒子加快镀液老化的原因。     

碳化硼增强铝基复合材料的摩擦磨损性能

为了比较两种含量不同的碳化硼颗粒增强铝基复合材料的摩擦学性能,将其加工成销试样,在多功能摩擦磨损试验机上分别与钢盘试样进行对比摩擦磨损试验,重点研究了接触载荷和相对滑动速度对两种复合材料摩擦磨损性能的影响.结果表明:碳化硼增强铝基复合材料的磨损量随载荷与相对滑动速度的增大而增大,而摩擦因数随载荷与相对滑动速度的增大而减小,较高碳化硼含量的复合材料的耐磨性能比较低含量的复合材料好.     

T/R壳体的表面状态对铟锡润湿性的影响

铝硅封装材料具有低膨胀、高导热、轻质等特点,可作为微波T/R组件的封装壳体材料。然而,在铟锡低温焊接时却出现了焊料不铺展、起球等现象,妨碍了正常的生产。为此,文中对T/R壳体(表面镀镍金的铝硅壳体)的状态与铟锡焊料润湿性的关系进行了探讨。试验统计发现,铟锡焊料的不润湿表观上是因为接触角滞后,实际上是因为受到了T/R壳体表面粗糙度和镍镀层厚度的共同制约。     

铝散热器在汽车上的应用

铝散热器己取代铜散热器广泛用于汽车发动机冷却系统中。文中介绍了铝散热器芯子结构变化过程及散热器结构对散热效率的影响，并以哈尔滨交通器材股份有限公司产品为例，介绍了国内铝散热器研制现状。     

植物油润湿性的实验研究

微量润滑加工一般采用可降解的植物油作为润滑剂,其渗透性是决定切削加工质量的重要因素之一,而切削液对固体表面的润湿性是影响渗透性的主要指标。为了研究植物油的润湿性,利用躺滴法对润湿角进行动态测量,得到切削液的固-液润湿平衡时间和平衡润湿角,并以其作为评价指标,分析植物油黏度和分子结构对它们的影响,同时还分析润湿角与时间之间的关系。结果表明:植物油中包含的极性基团有利于减少固-液润湿平衡时间,润湿角与接触时间存在着幂次方关系;低黏度的植物油不仅可以减小润湿平衡时间,还可以得到较小的平衡润湿角,从而提高润湿效率,改善加工质量,减少加工成本。     

CBN刀具车削高铝陶瓷

本文通过使用CBN刀具车削高铝陶瓷的实践,阐述了CBN刀具加工陶瓷的可行性,对诸如陶瓷这类难加工材料,拓宽机械加工领域。一、高铝陶瓷的性能及其切削加工性与金属材料比较,陶瓷材料具有更好的耐高温、抗氧化、抗腐蚀及良好的机械性能。我厂生产的NB140泥浆泵中的柱塞系高铝陶瓷材料,柱塞的工作介质是     

Abrasive wear behaviour of B4C particle reinforced Al2024 MMCs

In this study, the effects of volume fraction and particle size of boron carbide on the abrasive wear properties of B₄C particle reinforced aluminium alloy composites have been studied. For this purpose, a block-on-disc abrasion test apparatus was utilized where the samples slid against the abrasive suspension mixture at room conditions. The volume loss, specific wear rate and roughness of the samples have been evaluated. The effects of sliding time, particle content and particle size of B₄C particles on the abrasive wear properties of the composites have been investigated. The dominant wear mechanisms were identified using scanning electron microscopy. The results showed that the specific wear rate of composites decreased with increasing particle volume fraction. Furthermore, the specific wear rate decreased with increasing the size of particle for the composites containing the same amount of B₄C. Hence, it is deduced that aluminium alloy composites reinforced with larger B₄C particles are more effective against the abrasive suspension mixture than those reinforced with smaller B₄C particles.     

Laser cutting of 7050 Al alloy reinforced with Al2O3 and B4C composites

In the present study, laser cutting of 7050 aluminum alloy sheets reinforced with Al₂O₃ and B₄C particles are carried out. The cut geometry is examined using scanning electron microscope and the optical microscope. The lump parameter analysis technique is used to formulate and determine the kerf width size. The predictions for kerf width are compared with experimental data. The percentage kerf width size variation along the cut edges is determined and the influence of the laser power level and duty cycle of the laser pulses on the percentage kerf width size variation is examined. It is found that 7050 aluminum alloy reinforced with 20% Al₂O₃ composite results in relatively large kerf width size as compared to its counter parts that corresponding to 7050 aluminum alloy reinforced with 20% B₄C composite. The kerf width size predicted agreed with the experimental data for both composites.     

B4C/6061Al复合材料焊接接头组织与力学性能研究*

基于碳化硼中¹⁰B同位素优良的热中子吸收能力,铝基碳化硼复合材作为中子吸收材料越来越多的应用于核电站中。但碳化硼颗粒的加入使该材料的可焊性变差,因此研究其焊接行为变得十分必要。采用钨极氩弧焊(Tungsten inert gas,TIG)和搅拌摩擦焊(Friction stir welding,FSW)对体积分数为30%的B₄C/6061Al复合材料进行焊接,研究不同焊接方法、焊缝填充材料对复合材料对接接头微观组织及力学性能的影响。B₄C/6061Al复合材料焊接接头拉伸性能如下：FSW焊>TIG焊(Al-Si焊丝)>TIG焊(6061Al焊丝)>TIG焊(6061Al-Mg焊丝)>TIG焊(无填充)。TIG焊缝区容易产生气孔、B₄C颗粒分布不均匀及有害生成相是导致其力学性能不佳的主要原因。FSW可以有效避免基体金属与增强相的高温化学反应,使得焊缝区的晶粒细化,增强相颗粒的分布比TIG焊均匀,为30%B₄C/6061Al复合材料最佳焊接方法,其接头的室温拉伸强度达247 MPa,为母材强度的85%。     

B4C/Al复合材料的组织、力学性能和制备研究进展

B4C颗粒增强铝基复合材料不仅比强度高、耐磨性能优异,还兼具多种功能特性,是核工业、航空航天、汽车工业等领域中不可缺少的结构材料和功能材料.综述了B4C/Al复合材料的研究现状,总结了搅拌铸造法、粉末冶金法和冷喷涂增材制造法等各种方法的优缺点,对比了不同工艺下制备的B4C颗粒增强铝基复合材料的硬度、拉伸强度、屈服强度、...     

硼酸铝晶须增强铝基复合材料的探讨

硼酸铝晶须的优良特性,使人们逐渐开始认识到硼酸铝的价值,在金属基复合材料中的应用也越来越广泛.介绍了硼酸铝晶须增强铝基复合材料的研究现状,对其制取方式作了简要说明,并指出了进一步研究中需要解决的问题.     

Slotted-electrical discharge diamond cut-off grinding of Al/SiC/B4C hybrid metal matrix composite

Advanced manufacturing industries need materials with high strength and low weight in the fields of advanced engineering, such as automobiles and aeronautics. Metal matrix composites (MMCs) are one of the advanced engineering materials that meet the above requirements. To enhance the properties of MMCs, researchers added an additional phase of reinforcements into single reinforced MMCs; such developed MMCs are known as hybrid MMCs. The additional phase of reinforcements enhances the properties of MMCs, but simultaneously leads to rapid tool wear and poor machinability. This study developed an innovative hybrid machining process (HMP) consisting of electrical discharge grinding and diamond grinding in such a way that both the processes occur alternately with equal intervals due to the rotation of a slotted abrasive grinding wheel. The performance of the hybrid process was tested on an Al/SiC_p/B₄C_p work-piece in cut-off grinding mode. The experiments were conducted on an electrical discharge machining machine, which consists of a separate attachment on a vertical column to rotate the wheel. Pulse current, pulse on-time, pulse off-time, wheel RPM, and abrasive grit number were taken as input parameters while material removal rate (MRR) and average surface roughness were taken as output parameters. Result were shown that the HMP gives higher MRR with better surface finish as compared to the constituent processes. Pulse current ranging from 3 A to 21 A, pulse on-time ranging from 30 μs to 200 μs, and pulse off-time ranging from 15 μs to 90 μs were also found to be more suitable for higher MRR, and a wheel RPM at 1300 RPM was more suitable for higher MRR with better surface finish.     

TC4固态渗碳化硼的试验研究

为改善钛及钛合金的表面性能,对TC4在不同温度条件下固态渗碳化硼后的渗层显微组织及硬度等情况进行了试验研究。结果表明,渗层表面为致密分布的化合物层,而在基体内部则形成沿晶界分布的板条状或等轴状的颗粒扩散层;表面渗碳化硼处理可以显著提高TC4的表面硬度,而且由表及里具有良好的硬度梯度;断口形貌分析发现材料由韧性断裂转变成脆性断裂。该工艺设备简单、操作方便、效率高、成本低。     

封装用铝金属基板表面金属化图形的制作

利用化学镀铜方法，结合光刻技术，研究了在阳极氧化Al基板上的金属化布线，设计了完成化学镀铜金属化图形的工艺流程，并对影响图形制作的主要因素进行了分析，最终确定了工艺参数。     

合金基体上激光熔覆Ti+Al粉末的显微组织分析

在合金表面进行了Ti Al的激光熔覆试验研究,利用SEM分析手段对Ti Al熔覆层的显微组织进行了分析,阐述了熔覆层强化相的形成机制,显微组织分析表明,Ti-6Al-4V合金表面Ti Al激光熔覆层的显微组织沿层深方向可分为熔覆区、结合区和热影响区3个区域,在3个区域呈现出不同的组织形态,对基体和熔覆层进行的硬度测试表明,由基体向熔覆层的硬度变化呈上升趋势,在结合区和最外层区域有所下降.     

锡青铜超疏水表面纳秒激光制备及润湿性转变机理研究

以锡青铜为基底,研究采用纳秒紫外激光代替飞秒激光制备金属超疏水表面的方法。通过改变激光加工参数制备了不同表面微观结构,并采用扫描电子显微镜和接触角测量仪对所制备的微观结构和润湿性进行了表征,通过X射线光电子能谱(XPS)分析了所制备的样片表面化学元素含量及其随时间的演变,对润湿性转变的机理进行了解释。研究结果表明,采用纳秒紫外激光可以在锡青铜基底制备类似飞秒激光加工得到的金属超疏水表面;激光加工后的样片润湿性随时间变化,转变机理是激光加工过程中生成的CuO在磷元素的催化脱氧作用下生成了本征疏水的Cu2O;在紫外激光能量密度为5.61 J/cm2下,激光扫描速度100 mm/s时,所制备的表面具有微纳复合结构的表面接触角超过150°,滚动角小于10°。