Abstract: A molten resin is injected into a cavity together with long fibers. Opposite surfaces of the resin are solidified as a fiber-resin mixture temperature drops. These surface layers become non-foam layers. A foam layer is created between the non-foam layers. A pressure reduction process is applied to cause a spring back effect when the foam layer is created. A diaphragm having these three layers can be manufactured in an inexpensive process, but physical characteristics and appearances of the diaphragm are not sacrificed.

Abstract: A coating composition containing a zirconium compound and a silicon compound is applied on a conductor 1 and baked to develop a ceramic insulating coating 2. A bonding agent made by dissolving a polyamide resin or a polyimide resin into an organic agent is then applied on the ceramic insulating coating 2 and baked to develop a fusible coating 3. This produces a self-fusible ceramic insulation coated wire which can retain the favorable properties of coil at high temperatures. Also, it can be used as windings such as high-power loudspeaker voice coils.