高热导AlN──新型陶瓷基片及封装材料

ＡＩＮ陶瓷具有高的热导率和与Ｓｉ相接近的热膨胀系数以及电绝缘特性，是一种应用前景极好的基片材料。本文介绍了ＡＩＮ陶瓷的基本特征、用于陶瓷基片和封装材料的工艺难点及ＡｌＮ陶瓷的应用现状和前景。     

H_2SO_4-H_2O_2-H_2O对GaAs晶片的择优腐蚀

为研制具有沟道衬底的单模激光器,讨论了H_2SO_4-H_2O_2-H_2O对GaAs晶片的择优腐蚀。实验证明,使用H_2SO_4∶H_2O_2∶H_2O=1∶8∶8腐蚀液,在GaAs(100)面上沿[011]和[01(?)]方向开槽分别获得燕尾槽和V型槽衬底,满足了器件设计的要求。     

Bridging Process Threshold for Sediment Infiltrating into a Coarse Substrate

Sand infiltration into gravel frameworks poses significant engineering and ecological difficulties. Ten flume experiments were conducted to quantify a sand bridging threshold in a static gravel bed. The D15?substrate/d85?sand ratio was computed for each of 37 unique sand-substrate pairs and the data were plotted, with previously published flume data, to determine the threshold between bridging and unimpeded static percolation. The process threshold boundary between bridging and unimpeded static percolation fell in the range of 12相似文献   

Spherical Indentation on an Elastic Coating/Substrate System: Determining Substrate Modulus

A vast amount of indentation studies on coating/substrate systems focused on extracting the mechanical properties of the film, by either avoiding or subtracting off the substrate effect. However, in engineering and biomedical applications, very often the substrate properties, in particular the substrate modulus, need to be measured from an indentation test and the protective layer cannot be removed. For the model system of an elastic film deposited on an elastic substrate, we establish the general approach of spherical indentation focusing on the substrate property determination. Indentation data are taken from different indentation depths which reflect different degrees of film and substrate effects. An effective reverse analysis algorithm is established such that, from an indentation test if either the film modulus or film thickness is known, the other variable can be measured along with the substrate modulus. Error sensitivity of the proposed formulation is analyzed in a systematic way.     

Photocatalytic activities of Ion doped TiO2 thin films when prepared on different substrates

Pure and ion doped TiO₂ thin films were prepared by sol-gel dip coating process on metallic and non-metallic substrates. Test metal ion concentration ranged from 0.000002 to 0.4 at.%. The resulting films were annealed in air and characterized by optical spectroscopy and X-ray diffraction. The photodegradation of methyl orange under UV irradiation by pristine and ion-doped TiO₂ films was quantified in a photocatalytic reactor developed in this study. In general, both doped and undoped TiO₂ crystals appeared in anatase phase and the photocatalytic activities of the TiO₂ thin films varied with substrates, calcination temperature, doping ions and their concentrations. The best calcination temperature for different substrates ranged from 450 to 580 °C. Films prepared on the metallic substrates resulted in higher photocatalytic activities, while ion doping lowered their efficiencies. On the contrary, for non-metallic substrates except ceramic the photocatalytic efficiencies of undoped films were much lower (< 30%), while ion doping was shown to increase the photocatalytic efficiencies remarkably in some cases, e.g., Cr³⁺ with the tile substrate. Overall, ion doping affected the photocatalytic efficiency of TiO₂ films, and an optimal doping concentration of between 0.0002 and 0.002 at.%, close to an estimate by the Debye length equation, resulted in the highest efficiency for most substrates.     

Effect of substrate on gradient domain morphology formed in acrylate copolymer/fluoro-copolymer blends

The effect of the substrate on the gradient domain morphology was investigated for immiscible blends of poly(2-ethylhexyl acrylate-co-acrylicacid-co-vinylacetate) [P(2EHA-AA-VAc)] and poly(vinylidene fluoride-co-hexafluoro acetone) [P(VDF-HFA)]. The blends were prepared on substrates of poly(dimethyl siloxane) (PDMS) coated on a liner and of poly(tetrafluoro ethylene) (PTFE) from a THF solution by coating. The chemical compositions and the cross-sectional morphology of the surface (surface in contact with air) and bottom (surface in contact with substrate) sides were examined by attenuated total reflection Fourier transform infrared spectroscopy and scanning electron microscopy. The P(2EHA-AA-VAc)/P(VDF-HFA) (50/50), (30/70) blends prepared on PDMS revealed a gradient domain morphology, whereas the (50/50) and (30/70) blends prepared on PTFE formed a sea-island type of phase separation structure. On the other hand, when the P(2EHA-AA-VAc)/P(VDF-HFA) (70/30) blend was prepared on PTFE, P(2EHA-AA-VAc) and P(VDF-HFA) components segregated at the surface and the bottom, respectively. We concluded that the affinity between P(VDF-HFA) and the substrates strongly influenced the formation of the gradient domain morphology and the surface segregation of P(2EHA-AA-VAc).     

Composite TiN–Ni thin films deposited by reactive magnetron sputter ion-plating

Composite TiN–Ni thin films were deposited by direct-current (DC) magnetron sputter ion-plating from an alloy Ti–48 at% Ni target in a mixture of argon and nitrogen gases at a total pressure of 0.1 Pa onto glass and stainless steel substrates heated to temperatures higher than 250 °C. The films deposited at the nitrogen flow Q_N2≥6.4 sccm consisted of a mixture of δ-TiN and fcc nickel phases. The effects of negative substrate bias and substrate temperature on the crystal structure of the films were studied. The substrate bias of −200 V resulted in improved crystallization of films and a smaller difference in size between the TiN and nickel grains, as compared with films deposited onto substrates at floating potential. It was possible to vary the crystal grain size of both phases by varying the substrate temperature in the range 270–430 °C. The maximum hardness measured in the films was 10.5 GPa. It is expected that the hardness can be increased by decreasing the content of nickel.     

陶瓷基体热喷涂涂层的研究进展

由于表面改性的需要,陶瓷基体对热喷涂涂层方案的需求也在日益增加.根据基体结构和性能的不同,需要开发特殊的基体相关的制备概念.本文展示一些在烧结氮化硅和AlN陶瓷上沉积涂层的概念.使用传统的喷砂工艺处理的基体近表面区域粗糙度低并会带来损害.作为替代方法,激光刻蚀被用来改变陶瓷基体的热喷涂表面特性.通过选择适当的激光刻蚀参数和喷涂方法,成功地制备了与陶瓷基体具有良好结合性能的大气等离子喷涂（APS）和悬浮液超音速火焰喷涂（suspension-HVOF A12O3）涂层.     

Process and characterisation of chemical bath deposited manganese sulphide (MnS) thin films

Manganese sulphide (MnS) thin films have been deposited by a simple and inexpensive chemical bath deposition (CBD) method using thioacetamide as a sulphide ion source from an aqueous medium. The effect of preparative parameters on the film growth and quality has been studied. The MnS films have been characterised by XRD, TEM, SEM, EDAX, RBS, optical absorption and (time resolved microwave conductivity) TRMC techniques for their structural, compositional, and optical properties. The as-deposited MnS film on glass substrate consists of nanocrystalline grains. The film consists of mixed (cubic and hexagonal) phases. The optical band gap of the film is estimated to be 3.02 eV.     

基片与膜厚对硬质薄膜力学性能的影响

采用毫牛力学探针技术的两步压入试验法研究了高速钢和不锈钢基片上不同厚度TiN薄膜的硬度和弹性模量。结果表明 :采用同样工艺制备的TiN薄膜 ,其力学性能随基片类型和膜厚的不同有明显变化。薄膜的硬度和弹性模量随膜厚的增加而提高 ;基体硬度的提高也使薄膜呈现较高的硬度和模量。分析认为薄膜内应力状态的改变是产生这些现象的主要原因。