复合材料导电铝涂层的表面喷丸

在火焰喷涂过程中,金属Al的熔滴表面被氧化,在涂层中凝固时形成一层电绝缘的氧化物(Al2O3).同时涂层中的空隙都会影响Al涂层的导电性能.本文通过对涂层表面进行喷丸处理,从而细化熔滴颗粒,降低涂层孔隙率.提高涂层的导电性能.经过喷丸处理后的涂层,电阻可以减小至0.043mΩ,与未经过喷丸处理的涂层比较,电导率提高至1...     

表面预处理对复合材料铝导电涂层性能的影响

以喷砂和砂纸打磨2种方式对玻璃纤维增强复合材料进行表面预处理,利用火焰喷涂在处理过的试样表面上制备铝导电涂层,分析了表面预处理对导电涂层的表面形貌、结合强度、导电性能的影响.结果表明:采用喷砂和打磨制备的导电涂层的导电性都满足使用要求,影响铝导电层导电性的主要因素是导电层厚度,表面预处理方式对铝导电层导电性能影响不大,但对铝导电层结合强度的影响较大,喷砂处理制备的涂层比砂纸打磨处理的涂层结合强度高,因此更适宜采用喷砂的方法进行预处理.     

喷涂温度对复合材料表面铝导电层性能的影响

采用火焰喷涂的方法在玻璃纤维增强复合材料表面制备导电铝涂层,研究喷涂温度对涂层性能的影响.采用扫描电镜、电子万能试验机、微欧计等手段对导电层的表观形貌、结合强度、电学性能进行分析.研究结果表明:采用火焰喷涂的方法在复合材料表面制备的铝导电层具有较好的性能,影响铝导电层导电性的主要因素是导电层厚度,喷涂温度对铝导电层导电性能的影响不大;影响铝导电层结合强度的主要因素是喷涂温度,随着喷涂温度的升高,铝导电层与复合材料基体的结合强度不断降低;复合材料火焰喷涂制备铝导电层最佳喷涂温度应该控制在49℃以下.     

火焰铝喷涂技术在碳纤维／复合材料飞机制件上的应用

火焰铝喷涂（热喷涂）技术在国内一般主要用于钢结构上作防腐蚀涂层,其工艺及技术都比较成熟。随着科学技术的进步,火焰铝喷涂技术的应用也就不仅仅局限于金属材料,现时它在飞机得材制件上的应用对我国来讲尚属一项新工艺。介绍了火焰铝喷涂（热喷涂）技术在飞机碳纤维／复合材料制件方面应用的研究工作。     

冷喷涂技术制备Al基复合材料涂层研究进展

首先对冷喷涂铝基复合材料涂层的装备开发现状进行了总结,通过对比低压、中高压、真空、激光辅助、原位喷丸辅助冷喷涂技术的优缺点,指出现有冷喷涂装备对制备铝基复合材料的适用性。其次,通过总结冷喷涂技术在制备铝基金属间化合物、铝基陶瓷、铝基石墨烯等复合材料涂层方面的研究现状,证明冷喷涂技术在各类型铝基复合材料制备方面的优势和可行性。最后,对热处理、搅拌摩擦、热等静压和激光重熔等冷喷涂制备涂层的常用后处理方法进行了分析,阐述合理的后处理策略对提升冷喷涂铝基复合材料性能方面的重要意义。总之,专用冷喷涂装备开发、复合材料结构设计和后处理策略的体系化研究,是推动冷喷涂技术应用于金属基复合材料开发的关键。     

利用有限元方法分析复合材料表面铝涂层的结合性能

采用有限元热分析方法对复合材料表面火焰喷涂铝过程的温度场进行了模拟,并对不同厚度(0.2,0.3,0.5 mm)铝涂层的热应力进行对比,分析了涂层厚度对热应力状态及分布的影响.结果表明:涂层厚度越大,涂层/基体界面的拉应力就越大,涂层越容易剥落和分离:而且在试样边界(x=4.3mm)附近热应力发生陡变,为应力集中区域....     

Ti-Al合金表面热喷涂铝涂层的抗高温氧化性

利用火焰热喷涂在Ti-Al合金表面喷涂铝涂层,通过金相显微镜、扫描电镜（SEM）观察及显微硬度测试等方法研究了铝涂层在850 ℃下的高温抗氧化性能。结果表明,涂层基体界面处平直,结合较好,主要为机械结合;在氧化过程中由于Al和Ti之间的相互扩散,形成了冶金结合的扩散层。高温氧化后,扩散层硬度明显提高,有涂层试样氧化速率明显低于无涂层的试样,其高温抗氧化性能好。     

6061铝合金表面电弧喷涂纯铝涂层的研究

采用电弧喷涂技术在6061铝合金基材表面制备纯铝涂层.利用金相显微镜、扫描电镜、X射线衍射仪对其显微组织结构、涂层形貌、腐蚀产物、孔隙率进行了分析.采用电化学试验、浸泡试验、中性盐雾试验检测了涂层在w(NaCl)=5%的溶液中的耐腐蚀性能.研究结果表明,在铝合金基材表面能够获得组织均匀致密,低孔隙率的纯铝涂层,涂层与基体为机械嵌合,涂层封孔处理后,试样的耐蚀性能有很大提高,涂层对基体无阴极保护作用.     

镁合金表面电子束熔覆铝涂层

为提高镁合金表面耐蚀性,采用火焰喷涂与高能电子束重熔技术在AZ91D镁合金表面制备了A1涂层.分析了涂层的微观组织结构和各区域的元素分布情况,测试了涂层硬度与耐蚀性.结果表明,在电子束重熔过程中,Al-Mg元素在涂层与基体间产生了明显的扩散,呈现交错的界面结合特征.涂层主要由熔覆区、合金化区和热影响区三部分组成,其中合金化层为典型的树枝晶结构.由于涂层中形成大量金属间化合物如Mg2Al3、Mg17Al12,使硬度由基体的70～80 HV0.05提高到220 HV0.05.这些相的存在也显著的提高了AZ91D镁合金表面的耐蚀性.     

Mg-8.5Li合金表面氧-乙炔火焰喷涂铝涂层的研究

为了提高Mg-Li合金的耐蚀性能,采用氧-乙炔火焰喷涂技术在Mg-8.5Li合金表面制备铝涂层,利用扫描电镜、金相显微镜研究了涂层的组织形貌、抗热振性能和抗中性盐水腐蚀性能。结果表明,采用氧-乙炔火焰喷涂技术可在Mg-8.5Li合金基体上获得致密、具有一定结合强度且具有良好抗腐蚀性能的铝涂层。     

氧化铝纤维的生产和应用

随着我国轻金属工业的迅猛发展，大家越来越清楚地认识到深入了解国外技术与发展的必要性。为了适应新的发展形势，满足读者需要，《轻金属》从2004年第4期起增设“国外技术与发展”这一新栏目。本栏目主要刊登评介国外技术与发展的技术性短文。本刊除希望广大作者继续撰写评介国外技术与发展的综述性较长篇的论文和简短的动态报道之外，更希望科研设计单位、高等院校和生产企业的科技工作者，在学习、引进和消化国外技术的同时，结合学习体会．采取摘编和编译等形式撰写一些介绍国外技术与发展的技术性短文，寄给本刊。投稿时请注明“国外技术与发展”栏目稿。     

On the machining of alumina and glass

Machining of electrically non-conducting materials like alumina and glass is still a major problem. Electrochemical spark machining (ECSM) process is a potential process for machining these materials. However, ECSM has its own inherent limitations. So far, only ordinary cutting tools have been used during ECSM by previous researchers, but the results obtained are not as good as anticipated. In the present work, electrochemical spark abrasive drilling (ECSAD) experiments have been conducted using abrasive cutting tools, with a view to enhance the capabilities of the process. Use of an abrasive cutting tool, when compared to a conventional cutting tool, has been found to improve the process performance, viz. enhanced material removal and increased machined depth. The workpiece materials used are alumina and borosilicate glass.     

预浸料工艺制备氧化铝纤维增强氧化铝陶瓷基复合材料

氧化物/氧化物陶瓷基复合材料的增强体和基体均由氧化物构成,不存在氧化问题,是长寿命高可靠性构件的理想选材,可在1000~1300℃的高温环镜中可长期使用。本文借鉴树脂基复合材料单向纤维湿法预浸料制备工艺,通过配置氧化铝粉体料浆在缠绕式湿法预浸机上制备了单向氧化铝纤维预浸料,然后预浸料经铺层模压和高温热处理获得了氧化铝纤维增强氧化铝陶瓷基复合材料,同时对复合材料性能进行了表征。结果表明,氧化铝粉体料浆的固含量在50vol%,料浆溶剂中水和丙三醇的比例为3:1,纤维的走丝速度为6m/min,滚筒平行进度为0.5mm时可获得无缝隙,无纤维重叠、表面平整光滑的预浸料。通过预浸料铺层热压成型制备的复合材料拉伸强度高达208.2MPa,弯曲强度为386.7MPa。和料浆涂刷二维纤维布工艺相比,力学性能大幅度提高,且预浸料工艺具有易存储、操作简单、适于工业化生产等优势。     

Electrodeposited nickel/alumina composite coating on NdFeB permanent magnets

NdFeB magnets are highly susceptible to corrosion in various environments. A nickel/alumina composite coating for NdFeB magnets was investigated in this paper. The microstructures of electrodeposited nickel coating and nickel/alumina composite coating were determined by scanning electron microscope (SEM). The corrosion behavior of nickel coating and nickel/alumina composite coating in 3.5 wt% sodium chloride solution was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the nickel coating and nickel/alumina composite coating can both provide adequate protection to the NdFeB substrate. Furthermore, the free corrosion potential of nickel/alumina composite coating is more positive and the passivation region is more obvious compared with nickel coating, and the capacitance loop diameter of nickel/alumina composite coating is significantly larger than that of nickel coating. With the increase in immersion time, a flat of passivation film is formed on the surface of nickel/alumina composite coating, resulting in excellent corrosion resistance after 288 h immersion in 3.5% sodium chloride solution according to EIS testing.     

Influence of interlayer thickness of a thin noble metal MSIP-PVD coating on compound and system properties for glass lens moulding

The replicative production of complex optical lenses made of glass has become very important over the last decades. The technology precision glass moulding has a great potential to fulfil the optical demands on high surface quality, small tolerances and high uniformity of glass lenses at high production volumes. A noble metal MSIP-PVD coating is used to increase lifetime of the precision moulds. Beside the chemical resistance and protection of the moulds against the hot glass, prevention of glass sticking and oxidation adhesion between coating and substrate is of great importance. As state-of-the-art a noble metal coating based on platinum and iridium is used with a nickel interlayer. As a result of previously presented research replacement of the nickel interlayer by a chromium interlayer has increased adhesion between coating and substrate significantly. The present research work shows an increase of this adhesion as a function of interlayer thickness. Application oriented heating tests show an influence of the interlayer on the glass behaviour during the heating cycle due to a diffusion process between interlayer and toplayer. A coating system of 20?nm Cr interlayer and 300?nm Pt₄₀Ir₆₀ function layer exhibits a good combination between good compound adhesion and little influence on the glass behaviour.     

氧化铝增强化学镀镍基合金涂层的性能

研究了氧化铝微粒增强化学镀镍 (铜 ,磷 )合金涂层的性能。在Al2 O3和Ni(Cu ,P)合金共沉积过程中 ,Al2 O3在溶液中的加入量增多 ,Al2 O3在镀层中的复合量逐渐提高 ;Al2 O3的复合 ,显著改变了Ni(Cu ,P)合金沉积层的组织与性能 ,使Ni(Cu ,P) Al2 O3复合材料具有更高的硬度、耐磨性和抗氧化性。     

The effect of grain refinement on the adhesion of an alumina scale on an aluminide coating

To understand the effect of grain refinement on the thermally grown alumina scale adhesion to the metal substrate, two δ-Ni₂Al₃ coatings, one coarse-grained (∼70 μm) and the other ultrafine-grained (generally below ∼500 nm), were prepared. The cyclic oxidation in air at 1100 °C shows that the ultrafine-grained (UFG) coating is better oxidation resistant than the coarse-grained (CG) coating due to the formation of a more adherent alumina scale. The latter is intrinsically correlated with the fact that the aluminide grain refinement helps to increase the oxide/metal strength through a route to prevent the formation of large-sized voids at the interface.     

Characterization of the alumina scale formed on a commercial MCrAlYHfSi coating

A commercial NiCoCrAlYHfSi coating deposited on a Ni-base superalloy substrate was characterized before and after high temperature oxidation. The combination of Y, Hf and Si additions is reported to improve coating performance. Advanced characterization techniques including scanning-transmission electron microscopy were used to study the segregation behavior of Y and Hf ions to the alumina grain boundaries after 200 h at 1050 °C and 100 and 200 h exposures at 1100 °C. After both exposure times, two distinct oxide layers were observed. The outer transient layer included many Y- and Hf-rich oxide particles. The inner layer consisted of columnar α-Al₂O₃ grains normal to the surface of the coating. Segregation of Y and Hf ions was found on the alumina grain boundaries as has been observed in model alloys with similar compositions. Isothermal exposures for up to 200 h at 1050° and 1100 °C caused a minimal increase in surface roughness. However, 200 1-h cycles at 1100 °C resulted in a more significant increase in surface roughness.     

空心玻璃微球表面仿生沉积羟基磷灰石涂层

用NaOH和生物活性玻璃依次对空心玻璃微球进行预处理.将处理过的空心玻璃微球浸泡在1.5 SBF溶液中,仿生沉积得到羟基磷灰石涂层.利用X射线衍射仪、扫描电镜以及热场发射扫描电镜对空心玻璃微球和涂层进行表征.结果表明,浸泡15天后在空心玻璃微球表面形成一层均匀致密的羟基磷灰石涂层,随时间延长涂层厚度增加.