Composite friction articles and methods of making same (US Patent 3,885,006, 1975)

Donald M. Hatch, George M. Studdert, John B. Williamson and Roger W. Wycinowski received US Patent No. 3,885,006 on May 20, 1975, filed May 2, 1973. It was assigned to BP Chemicals Hitco Inc.

The patent's abstract:

Composite friction articles comprise asbestos fibers in a resin binder which has been carbonized to improve bonding with the asbestos fibers and which contains modifiers or fillers comprising metallic chips or other relatively hard substances to impart substantial hardness to the resin binder. The composite friction articles are made by first forming a mixture of the asbestos fibers, the resin binder and the fillers. Thereafter the resin binder is cured at elevated temperatures and pressures, and subsequently carbonized at elevated pressures and even higher temperatures. The curing step may comprise a two-step process in which the mixture is first cured at 250*-400* F. and 500-12,000 psi for a relatively short period of time to drive away most of the volatiles in the resin binder and impart some hardness to the binder, after which the mixture is postcured for a longer period of time at a temperature on the order of 350500 F. and a pressure on the order of 1,000-5,000 psi to impart substantial hardness to the resin binder. Carbonization of the resin binder may comprise a pyrolizing step in which the mixture is heated to at least 700* F. at a pressure on the order of 500-1,000 psi for a selected period of time.

Where it was listed

• Asbestos, September 1975, in its patents department (the year's issues)