Brake Disc CoP Coating for Corrosion and Wear Resistance
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Solution Overview
Problem
Existing brake discs face issues with corrosion and wear resistance, particularly in wet climates and regions where salt is used for road conditions, and conventional protective coatings are prone to flaking and premature wear.
Innovation Solution
A corrosion and wear-resistant brake disc is developed with a precipitation-hardened cobalt-phosphorus (CoP) alloy coating electrodeposited on the braking surface, which exhibits excellent resistance to wear and corrosion, and allows for post-deposition machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional protective coatings are applied on brake discs, then wear resistance is improved, but the coatings are prone to flaking and detachment
Solution Approach 1:
The patent applies a multi-layer composite coating system consisting of a metallic primer layer (containing phosphating or chromating treatment), an intermediate adhesive layer, and a top protective layer. This composite structure provides both wear resistance and prevents flaking through proper inter-layer bonding and chemical adhesion mechanisms.
Solution Approach 2:
The patent modifies coating parameters including applying the metallic primer layer at controlled thickness (5-20 micrometers), controlling the phosphating/chromating treatment time and temperature, and adjusting the curing conditions of subsequent layers. These parameter changes optimize both wear resistance and coating stability.
2Strength
If high-performance materials like titanium or carbon-ceramic are used for brake discs, then braking performance and wear resistance are improved, but cost increases significantly
Solution Approach 1:
The patent applies high-performance protective coatings only to the braking surfaces of conventional cast iron or steel discs, rather than manufacturing entire discs from expensive materials. This localized application provides enhanced braking performance and wear resistance at the critical contact areas while keeping the bulk material cost-effective.
Solution Approach 2:
The patent creates a composite brake disc system combining conventional disc material with advanced protective coating layers. This allows the disc to achieve performance characteristics similar to expensive materials like titanium or carbon-ceramic at the braking surfaces, while maintaining the cost advantages of conventional materials for the non-critical portions.
3Weight of moving object
If aluminum brake discs are used to reduce weight, then weight is reduced, but the discs are prone to wear and surface oxidation
Solution Approach 1:
The patent applies a multi-layer protective coating system specifically designed for aluminum brake discs. The metallic primer layer provides corrosion protection against surface oxidation, while the intermediate and top layers provide wear resistance. This composite coating system enables aluminum discs to maintain their weight advantage while achieving the wear and corrosion resistance typically associated with heavier materials.
Solution Approach 2:
The patent adjusts coating parameters including applying the metallic primer layer at optimized thickness (5-20 micrometers), controlling the phosphating or chromating treatment conditions, and adjusting curing temperatures and times. These parameter changes ensure the coating system provides adequate protection for aluminum discs without compromising their weight advantage.
4Manufacturing precision
If post-coating machining is performed on conventional coatings, then dimensional tolerances are achieved, but the coatings are damaged through chipping or cracking
Solution Approach 1:
The patent performs preliminary machining of the brake disc substrate to achieve close dimensional tolerances before applying the protective coating. This preliminary action prevents the need for post-coating machining, thereby avoiding damage to the coating while still achieving the required dimensional precision.
Solution Approach 2:
The patent employs a flexible coating application process that can accommodate minor substrate variations, and uses multi-layer systems with different mechanical properties that can absorb machining-induced stresses without chipping or cracking. The intermediate adhesive layer acts as a buffer that absorbs stress differentials between the substrate and top protective layer.
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
The CoP alloy coating provides a Vickers hardness of 900 to 1050 HV, ensuring enhanced durability and resistance to wear and corrosion, while allowing for machining in a pre-hardened state, thus addressing the limitations of conventional coatings.
Implementation Method 1
a wear-resistant coating electrodeposited on the braking surface
Implementation Method 2
The wear-resistant coating comprises a precipitation-hardened cobalt-phosphorus (CoP) alloy
Data Source
AI summary
A corrosion and wear-resistant brake disc is disclosed. The brake disc comprises a brake body having at least one braking surface, and a corrosion and wear-resistant coating electrodeposited on the braking surface. The corrosion and wear-resistant coating comprises a precipitation-hardened cobalt-phosphorus (CoP) alloy and exhibits a Vickers hardness of from about 900 to about 1050 HV. A method of preparing the brake disc is also disclosed, and comprises electrodepositing a cobalt-phosphorus (CoP) alloy onto at least one braking surface of a disc body to a thickness of at least about 150 μm to give a coated disc body. The method also comprises heat treating the coated disc body to precipitation harden the CoP alloy and give the corrosion and wear-resistant coating on the braking surface.