Double-layer brake disc in nickel-free steel and manufacturing method
AssigneeBrembo S.p.A.
InventorsFabiano Carminati, Simone Biondo, Stefano Medici, Salvatore Giammarinaro
Life of this patent
Estimating the term…
Abstract
A brake disc for disc brake comprises 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 brake disc is provided with a base layer totally nickel-free and one or more carbides included in the nickel-free steel, which covers at least one of the two braking surfaces of the braking band. An intermediate layer composed of nickel-free steel is interposed between the base layer and at least one of the two braking surfaces of the braking band.
Claims14
A brake disc for a disc brake, comprising a braking band provided with two opposite braking surfaces, each of which defines at least partially one of 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 composed of steel totally free from nickel and of one or more carbides included in the nickel-free steel,
- and wherein an intermediate layer composed of nickel-free steel is interposed between the base layer and at least one of the two braking surfaces of the braking band,
- wherein the steel of the base layer has a content of molybdenum comprised between 0.5% and 10%, and a content of manganese between 0.5% and 7%.
A method for making a brake disc comprising the following operating steps:
- a) preparing a brake disc, comprising a braking band provided with two opposite braking surfaces, each of which defines at least partially one of two main faces of the disc, the braking band being made of gray cast iron or steel;
- a1) after step a), depositing on at least one of the two opposite braking surfaces, an intermediate layer composed of nickel-free steel;
- b) after step a1), depositing a base layer composed of steel totally free from nickel,
- wherein the step b) of depositing the base layer comprises depositing a composition in particle form composed of nickel-free steel, by means of a laser deposition technique, or by means of a Thermal Spray deposition technique, or by means of a Cold Spray deposition technique,
- depositing an auxiliary layer of ferritic-nitrocarburization 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 the intermediate layer, and/or between the base layer and a protective surface coating, and/or between the intermediate layer and the base layer.
A brake disc for a disc brake, comprising a braking band provided with two opposite braking surfaces, each of which defines at least partially one of 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 composed of steel totally free from nickel and of one or more carbides included in the nickel-free steel,
- and wherein an intermediate layer composed of nickel-free steel is interposed between the base layer and at least one of the two braking surfaces of the braking band,
- wherein the steel of the base layer is composed of 10% to 20% of chromium (Cr), at most of 1.5% of silicon (Si), at most of 2% of manganese (Mn), at most of 0.03% carbon (C) and, for the balance, iron (Fe).
A method for making a brake disc comprising the following operating steps:
- a) preparing a brake disc, comprising a braking band provided with two opposite braking surfaces, each of which defines at least partially one of two main faces of the disc, the braking band being made of gray cast iron or steel;
- a1) after step a), depositing on at least one of the two opposite braking surfaces, an intermediate layer composed of nickel-free steel;
- b) after step a1), depositing a base layer composed of steel totally free from nickel wherein the step b) of depositing the base layer comprises depositing a composition in particle form composed of nickel-free steel, by means of a laser deposition technique, or by means of a Thermal Spray deposition technique, or by means of a Cold Spray deposition technique,
- 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 the 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 diffusion of aluminum atoms into a surface microstructure of said cast iron or steel with consequent formation of ferroaluminum intermetallic compounds in a surface layer of said braking band, thus generating a layer comprising of ferroaluminum intermetallic compounds in said predetermined surface region of said braking band;
- removing said braking band from the molten aluminum;
- removing any aluminum remaining on said braking band after extraction, so as to expose said ferroaluminum intermetallic compounds on the surface,
- said ferroaluminum intermetallic compounds exposed on the surface imparting 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.