碳化硅颗粒增强复合材料超疏水表面的制备

采用电化学蚀刻方法在碳化硅颗粒增强复合材料(SiC/Al)表面构筑了微纳结构, 重点分析了蚀刻电流密度和蚀刻时间等关键操作参数对所得表面微观形貌及润湿特性的影响。研究发现, 较高电流密度(6 A/dm²)下刻蚀的SiC/Al复合材料表面可形成由微米级“粒状”结构和纳米级结构(颗粒状和波鳞状)复合而成的微-纳双层结构, 且这种特殊结构不因后续刻蚀时间延长而改变; 优化条件形成的SiC/Al复合材料刻蚀表面呈现出静态接触角高达160.7°、滚动角低至4°的超疏水特性。本研究结果说明SiC/Al复合材料可用于制备自清洁表面。     

疏水/超疏水船用铝合金表面制备及其耐久性

采用溶胶-凝胶法将SiO2纳米粒子涂覆在抛光和经激光刻蚀的船用铝合金表面,制备疏水/超疏水铝合金表面。利用使试样负载并在砂纸上摩擦滑行的方法测试疏水/超疏水表面的耐久性,结果表明:抛光表面的接触角随SiO2浓度的增高而增大,最大可达150.8°,但表面对水滴具有强黏附力。当摩擦滑行距离达到10m时,接触角小于铝合金表面原始接触角72.3°;激光刻蚀的网格和点阵微结构表面既具有超疏水特性又呈现出低黏附力;且网格表面的接触角更大,最大达155.4°,滚动角更小,最小仅为0.34°。当摩擦滑行距离达到10m时,表面依然疏水,且网格微结构的耐久性更强。     

超疏水Ti6Al4V表面的制备及其润湿性

为了使Ti6Al4V合金具有超疏水特性,采用激光技术加工规则点阵状纹理,然后采用自组装技术在试样表面制备自组装分子膜,得到了超疏水Ti6Al4V表面.激光加工构造的微米级点阵结构规整,形成了具有一定高度的类似锥台或柱状的凸起.通过激光加工和沉积自组装分子膜,Ti6Al4V试样表面的水接触角显著增大,最大可达到151°.将测得的接触角与分别用Wenzel模型和Cassie模型计算的理论值进行比较,实测结果更接近Cassie模型的结果.通过改变激光加工表面微结构的参数,可以控制表面接触角的大小.随着表面粗糙度值的增大,接触角呈增大趋势.当表面粗糙度大于4μm时,接触角均大于150°,形成超疏水表面.     

氧化锌/硅橡胶复合超疏水表面的制备及其自清洁性能

使用正十二硫醇对氧化锌粉末进行疏水改性。采用简单的表面撒粉法将疏水改性的氧化锌粉末与硅橡胶复合制备了氧化锌/硅橡胶超疏水复合材料;采用红外吸收光谱、接触角测试仪和扫描电子显微镜对材料的表面特性进行了表征。结果表明:氧化锌/硅橡胶复合材料表面的接触角为165.6±3.2°,滚动角为8.7±2.1°,并且具有良好的机械稳定性。另外氧化锌/硅橡胶复合材料表面具有自清洁性能,在水滴冲洗下能够保持表面完全清洁。     

铝合金超疏水转化膜的制备与性能

通过超声辅助FeCl3/HCl混合溶液化学刻蚀、高锰酸钾钝化和超声沉积1H,1H,2H,2H-全氟癸基三氯硅烷(PFCPS),在AA6061铝合金表面构建一层超疏水转化膜。采用场发射扫描电镜、接触角测试及红外光谱分别表征该超疏水转化膜的微观形貌、疏水性能和化学成分。结果表明:铝合金经超疏水处理后,不仅其水接触角可达到153°,且具有较好的自清洁性、抗酸碱侵蚀能力、耐摩擦能力和抗腐蚀能力。相较于传统的静置法,超声制备的超疏水铝合金表面不仅可改善PFCPS在Al基体表面自组装的均匀程度,而且提高其与铝合金基体的结合力,形成具有良好防护性能的超疏水保护层。     

玻璃纤维增强环氧复合材料上超疏水表面层的制备

先采用真空袋压法制备含CaCO3/环氧树脂表面功能层的玻璃纤维增强环氧树脂复合材料,再通过化学刻蚀与表面修饰,在玻璃纤维增强环氧树脂复合材料上制备出超疏水表面。采用扫描电镜和动/静态接触角分析仪,表征表面的形貌和疏水性,结果表明,在复合材料表面构建了具有微-纳米尺度二元粗糙结构;采用1%(质量分数)的硬脂酸修饰后,其表面与水的接触角最高达160.03°;制备的超疏水表面结构在室温环境下具有长期的稳定性。     

锡青铜表面超疏水薄膜的制备及其水润滑减摩性能

为了改善锡青铜在水润滑条件下的摩擦性能,在其表面以1％氟硅烷乙醇溶液制备了超疏水薄膜.通过扫描电镜(SEM)观察了超疏水薄膜的表面形貌,测量了其接触角;在CETRUMT-2球-盘摩擦磨损试验机上考察了超疏水薄膜水润滑下的减摩性能.结果表明:锡青铜表面刻蚀并成膜后形成了粗糙的微纳复合结构,刻蚀40 min表面接触角可达151.1°,具备超疏水性能;超疏水薄膜在水润滑下具有较低的摩擦系数,可有效降低摩擦副的磨损.     

镁合金表面超疏水化及耐腐蚀性能

采用硫酸刻蚀和接枝疏水长链的方法,成功制备出了具有超疏水特性的镁合金表面。采用红外光谱、扫描电镜和电化学测试等技术对超疏水镁合金表面进行了表征和分析。研究结果表明:硫酸处理使得镁合金表面产生微米/纳米二元复合的花状粗糙结构;硬脂酸的疏水长链通过化学键键接在镁合金表面,从而显著降低了镁合金表面的自由能。最终得到接触角可达152°、滚动角小于10°的超疏水表面,从而极大地提高了镁合金的耐腐蚀性能。     

铝基表面超疏水材料的制备工艺、效果及耐蚀性

超疏水表面在自清洁材料、腐蚀防护及微流体运输等领域有着广阔的应用前景,目前对金属超疏水表面的研究较少,且制备方法较复杂,不能大面积制备。分别采用喷砂、阳极氧化、喷砂-阳极氧化等方法在铝基体表面构造粗糙结构并对其进行修饰,制备了超疏水表面,通过SEM、接触角及滚动角测定、腐蚀速率测定等分析了超疏水表面的微观形貌、疏水性能和耐海水腐蚀性能。结果表明:喷砂-阳极氧化法制备的铝金属表面具有微米-纳米二级结构,经氟化处理后,与水的接触角达158°,滚动角为1.5°,疏水性能良好;超疏水表面材料的腐蚀速率比铝材低1个数量级。     

CaCO3/SiO2复合粒子涂层的表面结构及其疏水性能研究

以机械高速搅拌法制备了具有草莓结构的CaCO₃/SiO₂复合粒子,并对其进行了表面修饰改性.利用聚硅氧烷的自组装功能,将制备的复合粒子与硅氧烷一起制备了具有“荷叶效应”的超疏水涂层,静态水接触角达169°,滚动角约为2°.通过扫描电镜观察涂层的表面微观形貌,发现该涂层具有微米-纳米相结合的双层粗糙结构.微米凸起的粒径在2～3μm左右,纳米凸起的粒径约为200nm左右,与荷叶具有类似的结构排布方式.通过原子力显微镜和接触角的测试,探讨了表面微观结构、涂层粗糙度和涂层疏水性能之间的关系.结果表明：复合粒子构成的非均相界面的水接触角符合Cassie模型.复合粒子赋予涂层的双微观粗糙结构与自组装成膜硅氧烷的低表面能的协同效应,使涂层具有了优良的超疏水性能.     

Lapping assisted dissolved wafer process of silicon for MEMS structures

Dissolved wafer process (DWP) is being extensively used to fabricate complex micro-electro-mechanical system (MEMS) structures. Etching non-uniformity, increased surface roughness and duration of DWP is often influence MEMS devices yields. This paper presents a modified DWP involving lapping and polishing followed by chemical etching of silicon to release MEMS based structure. The lapping experiments are performed using silicon-carbide (SiC) and alumina (Al₂O₃) abrasive. The polishing of the silicon samples is also done. The lapped and polished surfaces are compared with etched silicon surfaces in KOH and EDP solutions. The lapping-polishing process is found to be 2.5 (Al₂O₃)–3 (SiC) times faster than a standard etching processes based on KOH and EDP solutions. The average roughness (R_a) of the lapped–polished silicon surfaces are found to be 19.2 and 32.9 nm corresponding to SiC and Al₂O₃ abrasive respectively. The R_a value of EDP and KOH etched silicon surfaces are found to be 16.2 and 238.3 nm respectively. Based on the lapping—polishing results, SiC based lapping followed by polishing of silicon surface can be used as an alternate of etching of silicon during DWP. In this paper, a two-step DWP, involving lapping-polishing followed by EDP chemical etching of silicon, is used to fabricate suspended comb-type microaccelerometer structure.     

2A12铝合金基体超疏水表面制备及性能研究

铝合金在使用过程中极易引发基体腐蚀现象,如点蚀、晶间腐蚀等,为保障铝合金在腐蚀环境中的应用,可通过建立超疏水表面改变铝合金表面的润湿性,从而在一定程度上减少腐蚀液与铝合金表面的接触,进而改善耐蚀性。本文通过酸刻蚀和沸水刻蚀两种方法在铝合金表面构筑微纳米结构,并使用低表面能物质硬脂酸进行表面处理得到超疏水表面。采用扫描电子显微镜、接触角测试仪、原子力显微镜分别对铝合金表面形貌、疏水性和粗糙度进行测试,得到两种方法的最佳制备时间,而后通过极化曲线对两种方法制备的铝合金表面耐蚀性能进行对比,进而研究两种刻蚀方法对铝合金耐蚀性的影响。实验结果表明：酸刻蚀时间为15 s时,铝合金表面接触角达到峰值163.9°,呈现超疏水状态,相对于空白样品,表面粗糙度增加了24倍,电化学自腐蚀电位正向移动0.362 8 V;沸水刻蚀时间为1 min时,其表面接触角达到峰值109.6°,比空白样品疏水性强但未呈现超疏水状态,相对于空白样品,经沸水刻蚀的铝合金表面粗糙度增加了4.4倍,电化学自腐蚀电位正向移动0.074 8 V。两种方法处理得到的铝合金表面的耐蚀性与空白铝合金试样相比均有显著提高,而酸刻蚀法的缓蚀效...     

SiC材料的低速率浅刻蚀工艺研究

对比研究了SiC材料在CF4+O2混合气体中的ICP刻蚀和RIE刻蚀,获得了刻蚀速率、刻蚀表面粗糙度随刻蚀功率、偏置功率、工作真空、氧含量等工艺条件的变化规律,研究结果表明,通过牺牲一定的刻蚀速率可以获得原子量级的刻蚀表面粗糙度,能够满足SiC微波功率器件研制的要求.     

In situ joining of titanium to SiC/Al composites by low pressure infiltration

A method of in situ joining of titanium to SiC/Al composites by low pressure infiltration was proposed. The effect of infiltration temperature on microstructure and bending strength of in situ joining composites was investigated and the best infiltration temperature was confirmed to be 710 °C. The interfacial region of SiC/Al/Ti composites was consisted of Ti substrate, Al–Ti interfacial layer, Al layer and SiC/Al composite. The bending strength of SiC/Al composites kept nearly constant as the infiltration temperature changed while that of SiC/Al/Ti composites was influenced significantly by the infiltration temperature. The fracture occurred at the Al–Ti and Al–SiC/Al interfaces alternately as infiltrated at 670 °C. But as the infiltration temperature was increased to 710 °C, the fracture occurred only at the Al–SiC/Al interface which shows a great interfacial bonding at the Al–Ti interface. The formation of Al–Ti brittle intermetallics and the effect of crystallization and grain coarsening are two possible reasons which lead to the decrease of bending strength when the infiltration temperatures were increased from 710 °C to 730 °C.     

Wettability and spreading kinetics of molten aluminum on copper-coated ceramics

The purpose of this study was to investigate the influence of Cu-coating on the spreading kinetics and equilibrium contact angles of aluminum on ceramics using a sessile drop technique. Al₂O₃ and SiC plates were coated by electroless plating. The copper film overcomes the low wetting of the uncoated samples by dissolution in the drop at 800 °C in argon, showing an intrinsically favorable effect on the adhesion energy. Just after 2 min, the contact angle decreased to 12.6° and 26°for Al/Cu–Al₂O₃ and Al/Cu–SiC, respectively. However, a de-wetting behavior was observed, reaching equilibrium contact angles of 58.3° and 45.5° for the couples. The dissolution reaction rate at the triple junction was so high that the spreading process was controlled by local diffusion rather than chemical reaction kinetics.     

Anisotropy in wetting of oriented sapphire surfaces by liquid Al–Cu alloys

The coexistence of a liquid with a solid and a gas phase causes a contact angle at the triple line and results in a certain work of adhesion. These properties were studied for liquid Al, Cu, and their alloys on single-crystalline sapphire surfaces with C(0001)-, A(11-20)-, and R(1-102)- orientation. Measurements were performed at 1100 °C and under $3 \cdot 10^4\, \hbox{Pa}$ Ar atmosphere in a sessile drop apparatus. There, the sample was heated and melted separately from the substrate within a drop dispenser. Only after the desired measurement conditions were reached, the liquid metal was released. Depending on the alloy composition, the wetting angle approached a constant value within few minutes after the contact of droplet and substrate was established: For pure Cu the contact angle increased to an equilibrium value of 116° ± 5°, which is identical for all the studied sapphire surfaces. For pure Al an anisotropy of the contact angle with regard to these surfaces is found: time evolution of the Al contact angle is only observed for wetting of C-surfaces. Wetting of A- and R-surfaces shows no pronounced time dependence. In these cases, a smaller contact angle of about 90° is observed. Wetting of the different sapphire surfaces by Al–Cu alloys corresponds qualitatively to their wetting by pure Al: again, only for C-surfaces a time-dependent increase of the contact angle is observed. On A- and R-surfaces wetting is not time-dependent and the contact angle increases with Cu content of the alloy.     

Study on contact angles of Au,Ag, Cu,Sn, Al and Al alloys to SiC

Contact angles of Au, Ag, Cu, Sn, Al and Al alloys to SiC were measured by use of sessile drops heated by a high frequency induction coil designed to be convex against the SiC plate. Three crystal configurations of -SiC, polycrystalline plane of sintered SiC, SiC (1 1 1) plane, and SiC (1 0 0 0) plane were used as base plates. Au, Sn, Al and Al alloys showed a large contact angle of about 150 ° at each melting temperature, however those of Ag and Cu were in the range of 105–121°. Every contact angle of Al and its alloys decreased to under 90° when held at 1350 °C. SiC (1 0 0 0) plane gave a lower contact angle than the other two SiC planes for Cu, Al and Al-Si alloys.     

Thermal shock behavior of nano-sized SiC particulate reinforced AlON composites

Aluminum oxynitride (AlON) has been considered as a potential ceramic material for high-performance structural and advanced refractory applications. Thermal shock resistance is a major concern and an important performance index of high-temperature ceramics. While silicon carbide (SiC) particles have been proven to improve mechanical properties of AlON ceramic, the high-temperature thermal shock behavior was unknown. The aim of this investigation was to identify the thermal shock resistance and underlying mechanisms of AlON ceramic and 8 wt% SiC–AlON composites over a temperature range between 175 °C and 275 °C. The residual strength and Young's modulus after thermal shock decreased with increasing quenching temperature and thermal shock times due to large temperature gradients and thermal stresses caused by abrupt water-quenching. A linear relationship between the residual strength and thermal shock times was observed in both pure AlON and SiC–AlON composites. The addition of nano-sized SiC particles increased both residual strength and critical temperature from 200 °C in the monolithic AlON to 225 °C in the SiC–AlON composites due to the toughening effect, the lower coefficient of thermal expansion and higher thermal conductivity of SiC. The enhancement of the thermal shock resistance in the SiC–AlON composites was directly related to the change of fracture mode from intergranular cracking along with cleavage-type fracture in the AlON to a rougher fracture surface with ridge-like characteristics, crack deflection, and crack branching in the SiC–AlON composites.     

Preparation and characterization of super-hydrophobic and oleophobic surface

A novel method for preparing and characterizing super-hydrophobic and oleophobic surface is presented. Aluminum (Al) substrate was roughened by sandblasting and electrolytic etching to obtain micro- and nano-sized complex morphologies. Then, its substrate was covered by a chemically adsorbed monolayer (CAM) containing a fluorocarbon group. The surface of Al substrate roughened and covered with CAM was observed by scanning electron microscope and atomic force microscope. The roughnesses of the surface were ca. 100 μm and ca. 30–60 nm, respectively. The surface of the wettability was characterized by contact angle measurements and its surface indicated super-hydrophobicity and oleophobicity: the water contact angle (WCA) and oil contact angle (OCA) of hexadecane was 158.9° and 139.6°, respectively. The wettability was also characterized by solid surface energy. The solid surface energy of each solvent was obtained from the equation by Neumann et al. These values were extremely low, ranging from 0.31 to 1.29 mN/m. The total solid surface energy was obtained from the equation by Kaelble et al. The value was 0.3 mN/m. Their values indicated that the hydrophobicity and oleophobicity of our sample reached the highest level possible. In addition, our research demonstrates that it is easy to compare many different surfaces with super-hydrophobicity and oleophobicity using the solid surface energy.