Copper-Cobalt-Zinc Alloy Coating for Steel Wire Adhesion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cobalt, used to enhance adhesion in rubber products, accelerates rubber oxidation and crack growth, is expensive, and existing methods to concentrate it on steel wires or cords are inefficient, requiring additional process steps.
Innovation Solution
A ternary or quaternary alloy coating of copper-M-zinc on steel elements, where M includes cobalt, nickel, tin, indium, manganese, iron, or molybdenum, with copper ranging from 58 to 75 weight percent and metals from 0.5 to 10 weight percent, applied without extra treatment steps, and with controlled phosphorus amounts to prevent insoluble film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cobalt is added to the rubber compound to enhance adhesion, then adhesion formation is improved, but rubber oxidation is accelerated and adhesion degradation increases
Solution Approach 1:
The patent concentrates cobalt locally on the steel wire surface through a multi-layer coating system rather than distributing it throughout the rubber compound. The coating includes a copper layer with cobalt concentration at the interface, creating localized adhesion enhancement without widespread oxidation catalyst distribution.
Solution Approach 2:
The patent introduces copper and zinc as intermediary materials between the steel core and rubber compound. The copper-cobalt-zinc coating system acts as a mediator that provides adhesion benefits while the copper and zinc layers buffer the harmful oxidation effects of cobalt, preventing direct contact between cobalt and the rubber diene molecules.
2Strength
If cobalt is added to the whole rubber compound to enhance adhesion, then adhesion is improved, but cost increases due to excessive cobalt usage
Solution Approach 1:
The patent applies local quality by concentrating cobalt exclusively in the coating layer on the steel wire surface rather than distributing it throughout the entire rubber compound. This localized approach ensures cobalt is present only where adhesion is needed, dramatically reducing overall cobalt consumption while maintaining effective adhesion performance.
Solution Approach 2:
The patent uses partial action by applying only the necessary amount of cobalt at the steel-rubber interface through the coating system, rather than the excessive amounts required when dispersing cobalt throughout the entire rubber compound. This achieves the minimum effective concentration needed for adhesion without waste.
3Reliability
If a ternary alloy copper-cobalt-zinc coating is used to reduce adhesion degradation, then adhesion stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated coating process. The electroplating operation simultaneously deposits copper, zinc, and cobalt in controlled proportions to form the ternary alloy coating, combining what would otherwise require separate manufacturing steps into one unified process.
Solution Approach 2:
The patent controls the coating composition by adjusting electroplating parameters such as electrolyte composition, current density, and plating time. By changing these process parameters, the desired copper-cobalt-zinc ratio is achieved in a single coating operation, managing complexity through parameter optimization rather than process complexity.
4Strength
If a thin layer of cobalt on top of brass coating is applied followed by wire drawing, then adhesion is improved, but process complexity increases due to extra operation steps
Solution Approach 1:
The patent incorporates cobalt into the coating layer during the initial electroplating process, before wire drawing occurs. This preliminary incorporation of cobalt in the copper-cobalt-zinc alloy coating eliminates the need for subsequent cobalt application steps, maintaining adhesion benefits while preserving manufacturing efficiency.
Solution Approach 2:
The patent combines the cobalt application with the base coating process by creating a ternary alloy copper-cobalt-zinc coating in a single electroplating operation. This merging of cobalt deposition with the primary coating process eliminates separate operation steps, maintaining productivity while achieving improved adhesion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves adhesion performance without additional process steps, reduces rubber heat ageing, and enhances tire endurance with lower rolling resistance.
Implementation Method 1
covered with a ternary alloy or quaternary alloy of a copper-M-zinc coating
Implementation Method 2
reduces the rate of degradation of adhesion, particularly due to ageing in hot humid conditions
Implementation Method 3
drawing the thus coated elongated steel element in an aqueous lubricant containing a phosphorus compound, the amount of phosphorus compound being such that phosphorus is present on the coating in an amount of less than 1 milligram per square meter
Data Source
AI summary
A process for manufacturing an elongated steel element for reinforcing rubber products includes forming, on an elongated steel element, a coating of a ternary or quaternary alloy of copper-M-zinc, where M is one or two metals selected from cobalt, nickel, tin, indium, manganese, iron, bismuth and molybdenum; drawing the elongated steel element in an aqueous lubricant containing a phosphorus compound and nitrate; and twisting two or more of the elongated steel elements into a steel cord. A copper content inside the coating is 58 to 75 wt %. A content of the one or two metals inside the coating is 0.5 to 10 wt %. A final reduction in a diameter of the elongated steel element occurs during the drawing step. The phosphorus compound is present on and/or in the coating in an amount of 0.3 to 1 mg/m2 of the coating, as measured via an Inductively Coupled Plasma technique.