Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1990-02-02
1990-12-04
Bell, James J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
181157, 428284, 428408, B32B 700
Patent
active
049753185
ABSTRACT:
An improved acoustic diaphragm may be produced by a process which includes the steps of impregnating non-woven fabric or woven fabric of carbon fiber having a high degree of elasticity with a thermosetting resin, thermally molding it into a diaphragm shape, calcining the shaped fabric in an inert gas atmosphere to obtain a porous carbon molding, heating the porous molding to a uniform temperature, and depositing vapor phase, thermally decomposed carbon upon a surface of the porous molding. The deposited carbon is generated by thermal decomposition of a hydrocarbon-containing material introduced together with a carrier gas. The acoustic diaphragm so prepared has a dense surface layer of carbonized fiber-carbonized thermosetting resin-thermally decomposed carbon, and a porous interior of carbonized fiber bonded together by carbonized resin and the thermally decomposed carbon. Thus, the process permits manufacture of a diaphragm made of a carbon material having a large E/P value with the carbon material mostly made of a carbon fiber having high elasticity and a carbonized residue of a thermosetting resin.
REFERENCES:
patent: 3233014 (1966-02-01), Bickerdeke et al.
patent: 3238054 (1966-03-01), Bickerdike et al.
patent: 3317338 (1967-05-01), Batchelor
patent: 3936535 (1976-02-01), Boder
patent: 4178413 (1979-12-01), De Munda
patent: 4855093 (1989-08-01), Yoshida
Bell James J.
Mitsubishi Pencil Co. Ltd.
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