Propeller Anodic Oxide Coating Abrasion Resistance
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Solution Overview
Problem
Aluminum alloy propellers for watercraft face issues with corrosion and abrasion due to sand and water exposure, leading to a short propeller life, as conventional coatings lack sufficient hardness and uniformity, and thick anodic oxide layers compromise hardness and increase production time.
Innovation Solution
A propeller with a die-cast aluminum alloy body, subjected to blast treatment followed by anodic oxidation, achieving an anodic oxide coating with a thickness of 20-100 μm, surface roughness of 25-40 μm, and hardness of 350-450 Hv, providing uniformity and improved abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a painted film is applied to protect the aluminum alloy propeller from corrosion, then corrosion resistance is improved, but abrasion resistance deteriorates due to insufficient hardness of the paint coating
Solution Approach 1:
The invention changes the material parameter from conventional paint coating to anodic oxide coating through electrochemical oxidation. This parameter change transforms the coating properties to achieve both high hardness (400-450 Hv) for abrasion resistance and sufficient thickness (20-100 μm) for corrosion resistance, resolving the contradiction between corrosion protection and abrasion resistance.
Solution Approach 2:
The invention creates a composite structure consisting of the aluminum alloy base material and the anodic oxide coating layer. This composite material combines the corrosion resistance of the oxide layer with the mechanical strength of the aluminum alloy, while the oxide layer provides superior hardness and abrasion resistance compared to conventional paint coatings.
2Strength
If a thick anodic oxide coating is formed to improve abrasion resistance, then abrasion resistance is improved, but film hardness decreases and production time increases
Solution Approach 1:
The invention applies a blast treatment before anodic oxidation to pre-condition the aluminum alloy surface. This preliminary action creates a roughened surface with increased surface area and improved anchoring, allowing the subsequent anodic oxide coating to form more rapidly and uniformly, thereby reducing the overall production time while maintaining high abrasion resistance.
Solution Approach 2:
The invention optimizes the anodic oxidation parameters including electrolyte composition, temperature, current density, and oxidation time to achieve the desired coating thickness (20-100 μm) with high hardness (400-450 Hv) in a shortened production cycle. By carefully controlling these parameters, the process achieves both thick coating formation and high film hardness simultaneously.
3Strength
If a thick anodic oxide coating is formed to improve abrasion resistance, then abrasion resistance is improved, but coating uniformity deteriorates due to variations in coating thickness
Solution Approach 1:
The blast treatment applied before anodic oxidation serves as a preliminary action that uniformly roughens the entire propeller surface. This pre-treatment creates consistent surface conditions across all areas, ensuring that the subsequent anodic oxide coating forms uniformly with minimal thickness variation, thereby improving coating uniformity while achieving the required thickness for abrasion resistance.
Solution Approach 2:
The invention implements process control through monitoring and adjusting anodic oxidation parameters based on coating development. By using feedback control of current density, temperature, and oxidation time, the process maintains optimal conditions throughout the coating formation, ensuring uniform thickness distribution and consistent hardness across the entire propeller surface.
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 solution results in a propeller with enhanced abrasion resistance and durability, preventing corrosion and extending product life, while maintaining propulsion efficiency and aesthetic appeal.
Implementation Method 1
an anodic oxide coating arranged so as to cover a surface of the propeller body, the anodic oxide coating being obtained by performing a blast treatment for the surface of the propeller body and thereafter subjecting the surface to anodic oxidation
Implementation Method 2
performing a blast treatment for the surface of the propeller body and thereafter subjecting the surface to anodic oxidation
Data Source
AI summary
A propeller for watercraft having excellent abrasion resistance includes a propeller body having a blade and a hub portion, the propeller body being molded by casting an aluminum alloy, and an anodic oxide coating provided so as to cover a surface of the propeller body, the anodic oxide coating being obtained by performing a blast treatment for the surface of the propeller body and thereafter subjecting the surface to anodic oxidation.