Brake disc with steel layer with reduced nickel content and manufacturing method
AssigneeBrembo S.p.A.
InventorsFabiano Carminati, Simone Biondo, Stefano Medici, Salvatore Giammarinaro
Life of this patent
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Abstract
A brake disc for a disc brake may have a braking band made of gray cast iron or steel, provided with two opposite braking surfaces, each of which defines at least partially one of the two main faces of the disc. The disc is provided with a base layer constituted by steel having a nickel content of at most 15% which covers at least one of the two braking surfaces of the braking band.
Claims13
A brake disc for disc brake, comprising a braking band provided with two opposite braking surfaces, each of which defines at least partially one of the two main faces of the disc, the braking band being made of gray cast iron or steel;
- said disc being provided with a base layer, which covers at least one of the two braking surfaces of the braking band, said base layer being constituted by steel having a nickel content at most equal to 15%,
- wherein an auxiliary ferritic-nitrocarburized layer or an auxiliary ferroalumination layer is interposed between one of the two braking surfaces of the braking band and the base layer, and/or between one of the two braking surfaces of the braking band and an intermediate layer, and/or between the base layer and a protective surface coating, and/or between the intermediate layer and the base layer.
A method for making a brake disc comprising the following operating steps:
- preparing a brake disc, comprising a braking band provided with two opposite braking surfaces, each of which defines at least partially one of the two main faces of the disc, the braking band being made of gray cast iron or steel;
- depositing a base layer constituted by steel with a nickel content of at most equal to 15%;
- depositing an auxiliary ferroalumination layer between one of the two braking surfaces of the braking band and the base layer, and/or between one of the two braking surfaces of the braking band and an intermediate layer, and/or between the base layer and a protective surface coating, and/or between the intermediate layer and the base layer, wherein the step of depositing the auxiliary ferroalumination layer comprises the step of:
- immersing at least partially said braking band into molten aluminum maintained at a predetermined temperature so that the molten aluminum covers at least a predetermined surface region of said braking band, said immersion being protracted for a predetermined period of time to allow the diffusion of aluminum atoms into a surface microstructure of said cast iron or steel with the consequent formation of ferroaluminum intermetallic compounds in a surface layer of said braking band, thus generating a layer constituted by ferroaluminum intermetallic compounds in said predetermined surface region of said braking band;
- removing said braking band from the molten aluminum;
- removing the aluminum remaining on said braking band after extraction, so as to expose said layer of ferroaluminum intermetallic compounds on the surface,
- said layer of ferroaluminum intermetallic compounds exposed on the surface conferring a superior resistance to corrosion and wear at said predetermined surface region to said braking band made of cast iron or steel.
Dependencies are inferred from the claim text.