Mirror-like surface

The morphology of alkaline-etched (100) and (110) silicon surfaces varies from rough surfaces that exhibit micron-sized pyramids or ridges [Sc5] to smooth orange peel-like surfaces, depending on the etchant composition and substrate doping density. Mirror-like surfaces can be obtained on (111) crystal planes. 

For molded-plastic patls, vacuum coating techniques are increasingly replacing conventional coating methods, such as electroplating. For example, using vacuum coaling methods, automobile reflectors obtain a mirror-like surface, plastic articles in the furniture, decoration, clock and vratch as ell as electronics industry are metal-coated and optical effects are created on articles in the decoration industry. 

The presence of particles can modify the fracture surface from a mirror-like surface (for a brittle material), to a rough stress-whitened surface. The roughness can act as a multiplication factor for the absorbed energy. 

Activation (of noble metal electrodes) — Noble metal electrodes never work well without appropriate pretreatment. Polycrystalline electrodes are polished with diamond or alumina particles of size from 10 pm to a fraction of 1 pm to obtain the mirror-like surface. The suspensions of polishing microparticles are available in aqueous and oil media. The medium employed determines the final hydrophobicity of the electrode. The mechanical treatment is often followed by electrochemical cleaning. There is no common electrochemical procedure and hundreds of papers on the electrochemical activation of -> gold and platinum (- electrode materials) aimed at a particular problem have been published in the literature. Most often, -> cyclic and - square-wave voltammetry and a sequence of potential - pulses are used. For platinum electrodes, it is important that during this prepolarization step the electrode is covered consecutively by a layer of platinum oxide and a layer of adsorbed hydrogen. In the work with single-crystal (- monocrystal) electrodes the preliminary polishing of the surface can not be done. 

Even more extremely, one can realize the influence of the smoothness of the pigment surface, if one looks at applications with vacuum metallized aluminum pigments manufactured from vacuum metallized films. These pigments have a foil- or mirror-like surface, achieving extra brilliant and high gloss effects. They are therefore... 

Due to the role of surface states, the dark limiting current of silicon electrode is extremely sensitive to surface defects and thus surface preparation. Any scratch even barely visible on the mirror like surface can result in a significant increase of the anodic limiting current. According to Chazalviel, defects associated with surface treatment are primarily responsible for the large limiting current values reported in the literature. The effect caused by surface states may, however, be reduced by the formation of a... 

For further processing, the surface is polished by CMP (chemomechanical polishing). Stepper lithography with very high resolution can be performed on the resulting mirror-like surface. 

Instrumentation. A cantilever with a sharp tip interacting with the surface under investigation is used. The actual bending of the cantilever is measured with a laser beam deflected from a mirror-like surface spot on the back of the cantilever towards a position-sensitive photodetector. The measured signal is used to control the piezo actuators. A constant force mode in which the cantilever-surface distance is kept at a preset interaction force and a constant height mode of scanning operation are possible. The principle of operation is schematically outlined in Fig. 7.9. 

The true colors of some minerals can only be seen when the sample is finely powdered. Rather than grinding up a specimen, a small area is rubbed against a hard porcelain surface until a streak of the mineral is obtained. The color obtained in this streak test can be quite different from the appearance of the sample itself. For example, samples of specular hematite (the word specular refers to the mirror-like surface) have a very shiny black appearance due to the reflective nature of the naturally polished surface. The streak test reveals the true color of hematite—a red-brown. 

ELID double-side grinding can be employed to produce mirror-like surface finish. 

Mirror-like surface finish was obtained after grinding with 4000 mesh size wheel (see Figure 9.16 and Figure 9.17). 

It is possible to achieve mirror-like surface with an appropriate coarse grinding wheel the roughness obtained after ELID HI grinding with 2000 grit size is almost the same with the roughness obtained after ELID with 4000 with cBN. 

Mirror-like surface finish is strongly dependent on the grinding direction the grinding at 90°C with respect to fiber direction permits the best results. 

Dew-Point Hygrometer A smooth, shiny mirror-like surface is cooled imtil water vapour in the air begins to condense on it. The humidity is determined by comparing... 

While the roughness of the polished surface is of very high importance for More Moore because of the further decreasing layer and stracture dimensions, optically flat, that is, mirror-like, surfaces are especially required for MOEMS devices. For mirror stmctures using poly-Si surface micromachining, processes based on those developed for atomically flat surfaces for Si wafer fabrication can be employed successfully. 

The GCE was polished with 0.3um alumina slurry to a mirror like surface. After polishing the GCE was immersed in concentrated H2SO4 for Ih and througly rinsed with H2O prior to use. In kinetic studies before each measurement the GCE was cycled in the potential range +0.3V around the standard potential of the reaction in a given solvent. The electrode modification was accomplished by cycling the potential between 0.0 and +0.6V in freshly prepared deareated solutions of the studied complexes in strongly alkaline solutions. 

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