Pyrex玻璃金属化凹坑的湿法腐蚀

为在Pyrex玻璃基片上湿法腐蚀出易于金属化(如电镀等)的深凹坑(或凹槽),选用HF:HNO3:H3O为腐蚀液,分别以Cr/Au(30nm/300nm,溅射)加光刻胶(15μm)和Cr/Pt(30nm/300nm,溅射)加光刻胶(15μm)作为掩膜进行腐蚀实验.实验发现在Cr/Pt/光刻胶掩膜下,Pyrex玻璃的腐蚀凹坑横向钻蚀小(钻深比1.34:1),侧壁倾斜光滑,并在凹坑(深约28μm)内成功地电镀了焊盘.该实验结果对要求高深宽比沟槽的微流体器件的制造也有一定参考意义.     

The mechanical properties of carbon fibre reinforced Pyrex glass

The mechanical properties of carbon fibre reinforced Pyrex glass are discussed in terms of the volume fraction of fibre, the orientation of the fibres, fibre damage during fabrication, matrix porosity, matrix critical strain, interface properties and the mode of failure in bend tests. The stress at which matrix cracking occurs increases with fibre concentration indicating that the critical strain of the matrix increases as the fibre separation decreases. The ultimate strength of the composite is considerably greater than the stress at which the matrix begins to crack. Preliminary stress cycling experiments at stresses above that at which matrix cracks are formed suggest that propagation of these cracks is inhibited by the fibres.     

Hertzian fracture of Pyrex glass under quasi-static loading conditions

Hertzian fracture tests were conducted using an Instron on Pyrex glass specimens with various surface conditions, including lubricants, employing steel, Al₂O₃, WC and Pyrex glass indentors of 0.79 to 12.7 mm radius under ambient air and high vacuum environments at cross-head speeds of 8.5×10^–6 to 2.1×10^–4m sec^–1. The results were not in strict accord with Auerbach's law, nor any of the existing energy-balance Hertzian fracture theories. Rather, they indicated that surface roughness and friction modified the Hertz stress field so that the maximum tensile stress at the surface occurred outside the contact circle. Further, they indicated that Hertzian fracture occurred by the direct, unstable growth into a cone crack of a pre-existing flaw at the displaced site of the maximum tensile stress, the flaw size responsible for the fracture decreasing with decrease in ball size (contact radius). Once a cone crack occurred, its length and growth were described reasonably well by Roesler's theory; however, his constant appears to be too high by a factor of about 5. A surface energy of @ 4 J m^–2 was derived from bend tests on specimens similar to those used in the Hertzian fracture tests. Using this value, the crack sizes which lead to fracture were estimated to range between 0.6 and 3.5 m for the conditions investigated here. The increase in the critical load for Hertzian fracture with indentation velocity was concluded to be due to kinetic effects of water vapour acting at the tip of the crack.     

Development of a general surface contour by ion erosion. Theory and computer simulation

An analytical treatment of the development of a general contour under ion bombardment is proposed. The derived equations relate the properties of the eroded material through its yield variation upon the angle of incidence,S (θ). New specific angles (θs ₁ andθs ₂) are introduced which limit regions where the evolution process of the surface may be different. The theory allows prediction of the number of angular points which will appear in each region. A computer simulation program is used to describe the evolution of sine-type surfaces. With infinite time, such profiles in relief above a horizontal plane, tend towards the steady state which exists in a horizontal plane. The model is compared to one previously described.     

Microstructure and micromechanics of the interface in carbon fibre reinforced Pyrex glass

Detailed microstructural studies have been carried out on composites consisting of Pyrex glass reinforced with carbon fibres. Analysis of the fibre-matrix interface showed that some reaction had taken place during fabrication of the composite and that a carbide or oxycarbide layer had formed between the glass and the carbon fibre. The measured interlaminar shear strength of the composite indicated that the layer was not a source of weakness and appeared to be well bonded to the matrix. Substantial fibre pull-out had occurred, however, to expose clean fibre surfaces and smooth sockets. These observations led to the conclusion that the interfacial shear process was confined substantially to the outer layers of the carbon fibre. Confirmatory evidence for the low interfacial friction stress was available from micro-indentation tests which showed fibre displacement relative to the matrix at loads of less than 10 kPa. Heat treatment of the composite at 500°C in air caused preferential oxidation of the carbon fibre. Where fibres met the specimen surface, oxidation had proceeded down the fibre to produce a smoothly tapering shape. The rate of oxidation was estimated to be 3 m h^–1 parallel to the fibre axis, but much less than this in a direction perpendicular to the fibre, 0.5 m h^–1, due to the relatively slow diffusion rate of oxygen through glass.     

Study of the refractive index of microscopic glass beads by light-refraction analysis

The refractive index of submillimeter glass beads has been measured by means of a novel, to our knowledge, procedure with reference liquids that does not require close index matching and therefore avoids the use of toxic compounds for high-index glasses (i.e., n >/= 1.8). The method is based on the analysis of the light refracted by a monolayer of beads in comparison with ray-tracing simulations. For the three different types of glass beads investigated a satisfactory fit is achieved by the assumption of a radial variation of the refractive index inside the beads. This is ascribed to the tensile and compressive stresses originating inside the beads during rapid solidification of the glass.     

Static fatigue of glass: functional dependence of failure time on stress

Static fatigue of as-received Pyrex borosilicate glass was examined over a wide range of stress and failure time under constant temperature, relative humidity, and surface treatment. It was necessary to calculate the load on the sample from strain guage measurements. The mean log failure time was related to the reciprocal of stress or the reciprocal of stress squared; power law and direct proportionality to stress gave poorer fits.     

A computer simulation of LiKSO4

Molecular-dynamics computer-simulation of an ionic molecular solid LiKSO₄ has been carried out at 300 and 1000 K using the atom-atom potentials obtained from lattice dynamical studies. We observe hopping of lithium ions to interstitial positions which is related to reorientations of sulphate tetrahedra.     

A computer simulation of the structure of ZSM-18

The zeolite ZSM-18, whose structure has recently been elucidated and found to contain three-rings, has been investigated using atomistic simulation techniques. Agreement between the calculated and distance least-squares refined structure is very close, including reproducing the geometry of the strained three-ring. Both the site preferences for aluminum substitution and protonation are predicted, the most stable Brönsted acid site being located at the three-ring, despite aluminum being most readily accommodated in the seven-ring. Although the T1-O1-T1 is predicted to be linear for the purely siliceous zeolite, the presence of defects results in a distribution of oxygen positions around the c-axis.     

A computer simulation of unbiased digital recording

This simulation is intended for use at low, intermediate, and high bit densities. While simpler algorithms can be found for use with either very low bit densities only, or with very high bit densities only, they lack the generality needed for this purpose. The simulation is composed of three distinct sequential computations. First, using a noninteracting particle idealizedM_{r}-Hmodel and the arctangent head field formula, the tape magnetization is computed at 40 points per bit length in each of 5 laminae. Second, this magnetization is averaged throughout the tape thickness and harmonically analyzed. Finally, each harmonic component is weighted according to a demagnetizing-remagnetizing factor given previously, and the final output voltage waveform is computed. Linearity and superposition are thus assumed for all processes following the obviously nonlinear record mechanism. Computed outputs are compared with experimental results for both single transition and multiple transition inputs. The widths of computed and measured isolated output pulses differ by no more than 10 percent, without the adoption of physically unreasonable parameters. Output signals were computed for multiple transition inputs up to 20 000 flux reversals per inch (fr/in), and these compare well with experimental results up to 15000 fr/in.     

A criterion for the time dependence of dynamic fracture

Dynamic fracture is a time-dependent phenomena-in which the spall stress depends on the stress pulse duration. It is shown that the empirical relation between the spall stress and the square root of the stress gradient is equivalent to a simple impulse criterion. A more general criterion based on the concept of cumulative damage is proposed, and good agreement is obtained between calculated and observed values of the spall layer thickness in aluminum.

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Zusammenfassung Ein dynamischer Bruch ist eine zeitabhängige Erscheinung, wo die Absplitterspannung von der Dauer des Stosses abhängt. Es wird gezeigt, dass die empirische Beziehung zwischen der Absplitterspannung und der Quadratwurzel des Spannungsgefälles einem einfachen Impulskriterium equivalent ist. Ein allgemeineres Kriterium wird aufgestellt und vorgeschlagen, das auf den Begriff eines Sammelschadens beruht, und eine gute Übereinstimmung wird erlangt zwischen den berechneten und experimentell beobachteten werten der Ahsplitterungsschichtdicke im Aluminium.

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Résumé Une rupture dynamique est un phénoméne qui dépend du temps et dans lequel la contrainte d'écaillage est une fonction de la durée du choc. II a été démontré que la relation empirique entre la contrainte d'écaillage est la racine carrée du gradient d'écaillage équivaut un simple critère d'impulsion. Nous proposons un critère plus général, basé sur le concept d'un dommage cumulatif, ayant obtenu un bon raccordement entre les valeurs calculées et expérimentalement observées de l'épaisseur d'une couche d'écaillage dans l'aluminium.

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This work was supported by the United States Atomic Energy Commission.     

A criterion for the time dependence of dynamic fracture

Dynamic fracture is a time-dependent phenomena in which the spall stress depends on the stress pulse duration. It is shown that the empirical relation between the spall stress and the square root of the stress gradient is equivalent to a simple impulse criterion. A more general criterion based on the concept of cumulative damage is proposed, and good agreement is obtained between calculated and observed values of the spall layer thickness in aluminum.

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Zusammenfassung Ein dynamischer Bruch ist eine zeitabhängige Erscheinung, wo die Absplitterspannung von der Dauer des Stosses ab:hangt. Es wind gezeigt, dass die empirische Beziehung zwischen der Absplitterspannung und der Quadratwurzel des Spannungsgefälies einem einfachen Impulskriterium equivalent ist. Ein allgemeineres Kriterium wird aufgestellt and vorgeschlagen, das auf den Begriff eines Sammelschadens beruht, und eine gute Ubereinstimmutag wird erlangt zwischen den berechneten und experimentell beobachteten Werten der Absplitterungsschichtdicke im Aluminium.

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Résumé Une rupture dynamique est un phénomène qui dépend du temps et dans lequel la contrainte d'déaillage est une fonction de la duree du choc. II a été démontre que la relation empirique entre la contrainte d'écaillage est la racine carrée du gradient d'décaillage équivaut un simple critère d'impulsion. Nous proposons un critère plus général, basè sur le concept d'un dommage cumulatif, ayant obtenu un bon raccordement entre les valeurs calculées et expérimentalement observées de l'épaisseur d'une couche d'écaillage dans l'aluminium.

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This work was supported by the United States Atomic Energy Commission.     

以玻璃珠为载体制备纳米TiO2光催化膜滤料

研究了陈化时间及涂膜层数对纳米TiO2膜光催化性能的影响,结果表明:陈化3d时,膜的光催化性能最高;涂膜层数为3时,甲基橙的处理效率最高。同时研究了纳米TiO2膜对水和甲基橙的吸附性能,结果表明:水和甲基橙存在竞争吸附,随着加入甲基橙浓度的增加,光电催化测得的积分电量减少,膜的光催化活性降低。用制备的纳米TiO2膜光催化降解甲基橙,效率最高可达92.9%;在一定条件下累积运行93.8h,降解率均在83%左右,表明制备的纳米TiO2膜有较高的光催化性能及较长的使用寿命。     

In-situ thermoset polyurethane coating of glass beads dispersed in polystyrene by reactive extrusion

The condensation reaction between hydroxyl terminated polybutadiene and an uritonimine modified 4, 4 diphenylmethane diisocyanate (liquid MDI) was carried out by reactive extrusion in the presence of propyl trietoxy amino silane treated glass-beads and polystyrene. Reactants were selected having a surface tension favoring the glass bead coating using the spreading coefficient concept. FTIR, SEC (size exclusion chromatography) and rheological analysis of the resultant material showed that condensation reaction had occurred leading to crosslinked Polyurethane located principally around the glass beads.