Patent DE-102011121292-A1 (DE)
Title: Producing brake discs made of aluminum-matrix composite alloy, comprises heating spray-formed base-aluminum-matrix composite alloy having specified amount of silicon carbide particle in matrix-forming aluminum alloy in fusion mold
Inventor: LAMPKE THOMAS
IPC: C22C21/02
Filed: 2011-12-15
Abstract: The process comprises: providing a spray-formed base-aluminum-matrix composite alloy having a proportion of silicon carbide particle (12-25 vol.%) in a matrix-forming aluminum alloy; heating the base-aluminum-matrix composite alloy up to a solidus temperature of the matrix-forming aluminum alloy under inert gas atmosphere in a fusion mold (5) with a cylindrical cavity, which has a diameter corresponding to the brake discs, in a pressure chamber (7), where a rotation axis of the cylindrical cavity is vertically aligned; and structuring a gas pressure of 1200-2000 bar in the pressure chamber. The process comprises: providing a spray-formed base-aluminum-matrix composite alloy having a proportion of silicon carbide particle (12-25 vol.%) in a matrix-forming aluminum alloy; heating the base-aluminum-matrix composite alloy up to a solidus temperature of the matrix-forming aluminum alloy under inert gas atmosphere in a fusion mold (5) with a cylindrical cavity, which has a diameter corresponding to the brake discs, in a pressure chamber (7), where a rotation axis of the cylindrical cavity is vertically aligned; structuring a gas pressure of 1200-2000 bar in the pressure chamber; again heating the base-aluminum-matrix composite alloy over a liquidus temperature of the matrix-forming aluminum alloy and melting the aluminum alloy for applying the aluminum-matrix composite alloy heated over the liquidus temperature with the gas pressure; creating vibrations by a vibration source (6) and introducing the vibrations into the fusion mold; allowing the vibrations on the melt of the matrix-forming aluminum alloy for a certain period of time to reduce a viscosity of the melt and to reduce a gravity of a laser of the silicon carbide particles; enriching the silicon carbide particles in a lower layer of the melt present in the fusion mold and enriching a second layer of the silicon carbide particle located above the first layer; deterring the melt in the fusion mold in the pressure chamber under the gas pressure and solidifying the laser to a cylindrical aluminum-matrix composite alloy semi finished product (1) having the first layer enriched with the silicon carbide particle (45 vol.%) and having the second layer enriched with the silicon carbide particle; demolding the aluminum-matrix composite alloy semi finished product; performing a metal-cutting machining process of the aluminum-matrix composite alloy semi finished product to remove the second layer enriched with the silicon carbide particle and to remove the first layer as a cylindrical brakediscs-semifinished product with the aluminum-matrix composite alloy (40 vol.%) provided for the brake disc enriched with the silicon carbide particle; and finally machining the brake disc semi finished product to the brake disc. The machining step comprises separating the brake discs semi-finished product into the brake discs and/or performing a heat-treatment of the brake disc semi-finished product or the brake disc by a T6-heat treatment with solution annealing and artificial aging. The vibration source is proximally arranged to the cavity of the fusion mold, and is a compressed air vibrator or an ultrasonic transmitter. The method further comprises compressing the base-aluminum-matrix composite alloy by hipping, hot forging, extruding, and/or hot rolling before heating the base-aluminum-matrix composite alloy, mechanically machining the base-aluminum-matrix composite alloy, and adjusting a desired composition of the first layer by adjusting a pressure and/or a temperature exposure period of 30-120 minutes and/or by adjusting the temperature (640[deg] C) as a function of the liquidus temperature of the matrix-forming aluminum alloy. An independent claim is included for a brake disc.