Brass coated steel cord with increased iron content at the surface
AssigneeNV Bekaert SA
InventorsDegui XIA, Baoxing WANG
Life of this patent
Estimating the term…
Abstract
A steel filament for twisting into a steel cord for the reinforcement of rubber articles, which contains a steel substrate that is coated with a coating comprising brass. The coating is different in that the amount of iron at the surface is distinctively higher than that prior steel filaments. The coating has an average iron content of 4 or more atomic percent compared to the total of iron, zinc and copper atoms in the layer extending from the surface to a depth of 3 nanometer below the surface. The steel filaments show an improved adhesion retention under hot and humid conditions and in organic cobalt compound containing rubbers as well as rubbers that are substantially free of cobalt. The lifetime of the rubber article is extended.
Claims16
A steel filament with diameter ‘d’ expressed in millimeter for reinforcing rubber articles comprising
- a steel substrate coated with a coating comprising brass,
- said brass consisting of copper and zinc;
- said coating having an average thickness of 450×d nanometer or more as determined by the total mass of copper and zinc of said brass;
- said brass having a mass of copper of between 61 to 75 mass percent compared to the total mass of copper and zinc in said brass,
- said thickness of said coating and said amount of copper in said brass being determined by wet chemical analytical methods,
- wherein
- said coating has an average iron content of 4 or more atomic percent in the first layer, said first layer extending from the surface of said filament to a depth of 3 nanometer below said surface, said iron content being expressed as an atomic percent related to the total of iron, zinc and copper in said first layer,
- said iron, zinc and copper content being determined by X-Ray photo electron spectroscopy, said average being taken over the depth of said first layer and over 4 different spots on the surface of said steel filament.
Dependencies are inferred from the claim text.