Appliance Design - November 2007 - (Page 49)

METALS & METAL PARTS layer has much better adhesion to the surface than most deposited coatings such as plasma sprayed ceramics. In addition to this inward growth, the Keronite layer grows out from the original surface in a very consistent way. The extent of the outward growth depends upon the alloy in question, but it is typically between 10 percent and 40 percent of the overall thickness of the Keronite ceramic layer. In some Fig. 2. Scanning electron microscope image of a Keronite surface. applications, this may be desirable, but if not, it is possible to polish the surface back to the original dimensions of the part. The natural Keronite surface has surface roughness (Ra) of approximately 10 percent of the thickness of the applied layer, but can be polished back to a very smooth finish if required. Under a scanning electron microscope, three distinct layers can be detected. (See Fig. 2.) Beginning with the bottom, the different and produces very different results. It also has advantages over conventional ceramic coatings in that the Keronite layer is atomically bonded to the substrate alloy and, therefore, has outstanding adhesion and little tendency to crack or peel away. Because Keronite is an immersion process, it is capable of coating complex shapes and even the internal surfaces of cavities. This gives it an advantage over line-of-sight processes like conventional plasma spray. During the process itself, a layer of oxide grows following the creation of the plasma discharge as the oxide film is fused and subsequently re-crystallized. Any metal dissolution is at microscopic levels. Although the Keronite PEO process is quite aggressive in terms of the extensive plasma discharge activity, and the oxide eruptions at very high local pressures, these processes are occurring on a minute scale, and there is no distortion or other adverse effect on the component being treated. The process temperature and the component itself typically remain in a temperature range of 12 DegC to 30 DegC. The resulting oxidation of the alloy surface will include some elemental co-deposition from the electrolyte, producing a ceramic layer comprising both crystalline and amorphous phases. Unlike conventional surface treatments, the proprietary electrolyte solutions used in the Keronite PEO process contain no heavy metals, ammonia, or other toxic chemicals. The low concentration alkaline solutions (pH 10 to pH 12) are non-hazardous. They need no special treatments before disposal, nor do they present any health or safety risk to the operator. Keronite is a conversion coating that grows into the surface of the substrate in a uniform, controlled manner, forming a clean interface with the base metal. As a result, the Keronite For more Information Enter 119 www.applianceDESIGN.com AD11074Amern.indd 1 applianceDESIGN November 2007 49 10/3/07 11:10:04 AM http://www.americannickeloid.com http://www.americannickeloid.com http://www.appliancedesign.com

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Appliance Design - November 2007 Contents Editorial Shipments/Forecasts News Watch Today’s LEDs are Brighter and More Colorful than Previous Versions, Allowing Designers More Opportunities to Improve and Differentiate Their Products. When Converting from CCFL to LED Backlights in LCD Panels, New Driving Methods are Needed. Electrowetting Technology Allows Displays to be Designed in an Extensive Range of Colors. Noise Problems are Not Always Easy to Find or Fix, but Acoustic Labs Can Help Designers Ferret Out the “Good” Noise from the “Bad.” A New Sanitization Protocol for Clothes Washers Combines the Best of Three Well-Established Provisions to Ensure Efficiency, Quality and Safety. Stricter EMC Requirements Raise the Bar for Appliances with Electronic Controls and Require Testing to New Levels. Despite Added Cost and Complexity, Gas-Modulating Systems have Migrated from Large-Scale Boiler Applications to Smaller Residential and Commercial Furnaces and Appliances. A New Treatment Technology Hardens the Surface of Light Alloys such as Aluminum and Magnesium and Expands Their Potential Applications. DesignMart Advertiser’s Index Association Report: AHAM

Appliance Design - November 2007

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