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Laser Glazing (14 Nisan 2011 00:22)

Laser glazing involves some surface melting. As the beam from a multikilowatt CO2 laser is scanned over a surface, a thin melt layer is produced under proper conditions of irradiance and traverse speed. The interior of the workpiece remains cold. After the beam moves on, resolidification occurs very rapidly. The surface layer is quickly quenched. As a result of this process, one may produce surface microstructures with unusual and possibly useful characteristics. The grain size near the surface is very small, because of the high quench rate. The surface structure can appear glassy; hence, the name laser glazing. This technique is applicable both to metals and ceramics. It appears to be controllable and reproducible. Laser glazing can produce surfaces that are amorphous or that have a glassy, noncrystalline structure. Such surfaces can have increased resistance to corrosion. One example of laser glazing is surface melting of cast iron with rapid resolidification. This produces a thin surface layer of very hard material called white cast iron, which can provide excellent wear resistance. Another example that has been demonstrated is the glazing of aluminum bronze, which leads to surface structures with enhanced corrosion resistance.

(Industrial Applications of Lasers, John F. Ready; Page: 380)

Magnagold (15 Nisan 2011 11:41)

Since the introduction of titanium nitride to the industrial sector oating companies have been offering this service without sufficient knowledge of its engineering properties. The coating was known to be extremely hard, and it was being applied to cutting tools exclusively. One of the unique features of the titanium nitride process is the uniformity of the coating. This is critical for many applications involving missile, computer, and semiconductor applications. Other excellent applications are found in the plastic extrusion industry (which utilizes the superior release properties in molds and dies); the medical industry (for coating delicate surgical instruments, and preventing solder adherence when special heat treatments are employed in the complex multistep process). In this Magnagold process, a uniform coating. held to within a few millionths of an inch thickness, can be applied safely to even the most critical, closest tolerance parts via special cleaning fixturing mechanisms and techniques that enable the part to be rotated 360" while traveling throught he vapor stream. Because the parts to be coated are rotated both radially and axially within the unique ion bombardment chamber, there are no restrictions on shapes. In addition, all surfaces, except clamp and fixture areas, are uniform in coating thickness. Normally, the thickness ranges from 0.00003 and 0.0002 in., with final determination being edge sharpness and/or wear. (Load life is the ultimate criterion for the final decision.) Since the condition of the substrate surface is a key element in the effectiveness of any physical vapor deposition (PVD) process, General Magnaplate has engineered an exclusive, proprietary predeposition surface preparation. A combination of specialty designed equipment and chemical cleaning techniques prepares the component surface to assure permanently interlocked anchoring of the “coating.” Conventional vapor deposition applicators are not equipped with the extensive facilities that permit the meticulous care and attention required in the precleaning phase of the process. The parts are mounted on a specially designed cylindrical fixture, and then the entire work cylinder enters the vacuum chamber. A vacuum (1 X torr) is achieved, after which the system is purged with argon gas as an additional cleaning step. Titanium metal (99.9%) is then vaporized by a plasma energy source. This is followed by the precise introduction of nitrogen, the reactive gas, into the chamber. The parts to be coated are cathodically charged by high voltage (DC), thereby attracting accelerated ions of titanium. Simultaneously, they combine with nitrogen to produce the tightly adhering, highly wear-resistant titanium nitride PVD coating.

(Coating Technology Handbook 2. Edition,D. Satas, Arthur A. Tracton ; Page: 308-311)

Lectrofluor (15 Nisan 2011 11:47)

The properties that can be easily achieved using polymoer organic coatings are dielectric, chemical corrosion, and radiation resistance; in addition, special organic coatings can be used with food and pharmaceuticapl plications in compliance with regulations of the U.S. Food and Drug Administration. All coatings are proprietary, since they are new developments, and specific nomenclature (601, 604, 615, 611, etc.) is used for identification.Coatings can be applied by spraying, by dipping. or by an electrostatic powder process. In most cases, a curing temperature will be in the range of 300-750°F will achieve maximum surface hardness and minimize porosity. Polymer coatings normally range from 0.001 to 0.015 in. in thickness.

Salt spray resistance of these coatings is excellent: approximately 2000 hours (6 years in the atmosphere). The chemical resistance is the main property of the 60 1 coating. which can withstand strong acids and alkalies at temperatures up to 2000°F. The 604 material has similar resistance but can be utilized in food applications. The 615 is a tough. durable coating (D-80 durometer) that can withstand temperatures from -400 to 500°F and can also be used i n food applications. The 61 1 coating, which has good release characteristics, also is used in applications in the baking industry and comes in a variety of colors.

(Coating Technology Handbook 2. Edition,D. Satas, Arthur A. Tracton; Page: 307-308)

Magnadize (15 Nisan 2011 12:12)

A system for hardfacing magnesium has been developed which is basically an electrochemical process. The synergistic coating system is still far the best for a wear application, however, and special fluoropolymers or dry lubricants are infused into the hardfacing. For magnesium the thickness can vary from a minimum of 0.0002 in. to a maximum exceeding 0.00 15 in. Normal application thickness is approximately 0.0005-0.00 I in. A typical application for Magnadize would be a magnesium engine mount for aircraft. The entire mount would be hardcoated, and the gear spline would receive dry lubricant to improve the efficiency of the part.

(Coating Technology Handbook 2. Edition,D. Satas, Arthur A. Tracton; Page: 308)