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United States Patent 5,668,070
Hong , et al. September 16, 1997
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Ceramic composition for absorbing electromagnetic wave and a method for manufacturing the same


Abstract
A ceramic composition for absorbing electromagnetic waves and a method for manufacturing the same are disclosed. The composition comprises a raw powder comprising by weight between about 35% to 65% Fe.sub.2 O.sub.3, between about 1% to 5% Al.sub.2 O.sub.3, between about 0.5% to 1.5% Zn, between about 0.5% to 1.0% Cr, between about 3% to 10% Cu, between about 3% to 8% Mn, and between about 1% to 4% Co, and a mixture around the raw powder comprising by weight between 30% to 40% water, between 1.5% to 2.0% a dispersing, and between 1.5% to 2% a plasticizer. The method comprises the steps of grinding the powder, spray drying the grounded powder, forming the sprayed powder into a predetermined shape, calcinating and sintering the shape in a furnace, and cooling the sintered shape gradually. The ceramic composition absorbs the electromagnetic waves generated from electric devices such as cellular phones, beepers, computers, cordless telephones, etc. by attaching the ceramic composition at a predetermined position on the electric devices.