Thin layer chrome

Starting up a tool that has a poor finish can damage the tool without proper presurfacing. If the tool surface is unsound (no prior treatment was used although required), a thin layer of metal plating, particularly chrome plating, will not make it correct. A poorly prepared surface... 

The free chromium produced in this reaction is laid down in a thin layer on the surface of another metal, such as steel. The chromium protects the steel from corrosion and gives it a bright, shiny surface. Many kitchen appliances are chrome-plated this way. 

Chromium What gives these rims their mirrorlike finish The metal alloy rim has been plated, or coated, with a thin layer of chromium. Chrome plating has been used in the automobile Industry for decades because of Its beauty and its corrosion resistance. 

The octahedral, cubic crystals are violet to black in colour, and appear ruby-red in thin layers and J. H. Kastle found that the intensity of the colour is very much reduced at liquid air temp. F. Klocke, C. F. Rammelsberg, C. von Hauer, and J. W. Retgers showed that the crystals are isomorphous with other alums, for they show similar corrosion figures. E. Dittler obtained overgrowth with potassium aluminium sulphate. T. V. Barker found a close connection between parallel overgrowths in chrome-alum, potash-alum, and ammonia-alum and the mol. vols which are respectively 542-2, 541-6, and 552-2. C. von Hauer found that with the introduction of a crystal of iron-alum in a sat. soln. of chrome-alum nearly all the latter separates out while L. de Boisbaudran found that a sat. soln. of basic ammonium aluminium alum does not affect the octahedral faces of the... 

In most cases a correction is necessary for radiation. In order to reduce the radiation correction, the plate surfaces must have low emissivities, and thin layers of fluid (from 0.15 mm to 0.3 mm) should be employed. For this purposes the plate surfaces are polished and protected against oxidation, sometimes by coating with nickel, chrome, silver or silicon dioxide. Furthermore, the heat losses due to radiation, Qs, are rendered very small, as the temperature differences between plates are very small and the plate surfaces are gilded. From the Stefan-Boltzmann law for an upper and lower plate system, we can write... 

Among the various plastic materials used for chrome-plated parts, ABS (copolymer of acrylonitrile-butadiene-styrene) and PC/ABS (blends of ABS with polycarbonate) are most common. Nearly 85% of the total plated plastic surface area is based on ABS or PC/ABS. The technology for etching out the rubber particles from the ABS phase using an oxidative mixture of sulfuric and chromic acid has been widely used in the industry for nearly 40 years. The etched surface is subsequently activated using precious metal species, which is then followed by an electroless deposition of a thin layer of nickel or copper. In this marmer, the smface of the otherwise non-conductive plastic is rendered electrically conductive. Subsequently, multiple layers of different... 

The device is completed by a Si02 layer 13, thin transparent read-out electrodes 13 of chrome and opaque accumulation electrodes 15. 

In spite of such complications, magnetic sorting is used constantly in the field. Magnets can also be useful identification tools in conjunction with sophisticated quantitative instruments. For example, x-ray fluorescence analysis of a component showed it to be 100% chromium. This is because the technique utilizes only a very thin surface layer. A test with a magnet indicated attraction. It was concluded that the part was chrome plated and not solid chromium (which would have been very unlikely). 

Chromium plated parts on automobiles consist of steel substrates with an intermediate layer of nickel, or in some cases, layered deposits of copper and nickel. The thin chromium deposit provides bright appearance and stain free surface while the nickel layer provides the corrosion protection to the steel substrate. With this system it is essential that the nickel cover the steel substrate completely because the iron will be the anode and nickel the cathode. Any breaks or pores in the coating will result in the condition shown in Figure 16.3. This figure illustrates the reason for the corrosion of chrome trim on automobiles after World War II. 

Because the adhesion layer in thin film is usually a resistive material such as Nichrome, chrome, or titanium-tungsten, precision-integrated substrate resistors are available. 

Barrier coatings are of two types. The first consists of a thin surface layer of a more resistant metal. This can be accomplished by roll bonding (e.g.. stainless steel to non-heat-treatable aluminum alloys), by chrome plating, or by vapor deposit or ion deposition of a variety of metals. The latter methods are expensive and have size limitations. Unlike Alclad coatings, metal barrier coatings do not provide any electrochemical protection at a break in the coating. 

The chrome especially is subject to oxidation when exposed to wet air. But the metallic oxides so formed adhere tightly to the surface of the metal. This rugged metallic oxide layer acts as a barrier to prevent further destructive oxidation of the base metal. The oxide layer is so thin that it is smaller than the wavelength of visible light. Thus, it is quite invisible to the human eye. Stainless steel piping appears shiny after years of service, even though its surface has been oxidized after just a few minutes of service. 

The final layer is a 0.5 pm thick gold metal layer on top of Poly2 for wires, bond pads, bimorphs, and potentially as an optically reflective surface. The gold is deposited on top of a thin (20 nm) chrome layer to promote adhesion. It is not possible to deposit gold on top of the Polyl layer. For a flat mirror to be formed, the stress-induced curvature from the metallization should be comprehended in the design [13]. 

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