PURPOSE: To prevent the lowering of gas permeability due to the blocking of gaps among fibers by mixing brass fibers with phosphor bronze fibers in a prescribed ratio, molding and sintering the mixture and inhibiting the evaporation of zinc at the time of the sintering.

CONSTITUTION: Brass fibers are mixed with phosphor bronze fibers preferably in 2:3 weight ratio. This mixture is densely molded into a prescribed shape and sintered. The evaporation of zinc is minimized at the time of the sintering and the deformation of the brass fibers and the losing of the characteristics of brass are prevented.