Aluminum-CNT Extrusion Hard Anodizing for Corrosion Resistance
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Solution Overview
Problem
Carbon nanotube-reinforced aluminum matrix composites face challenges in achieving sufficient corrosion resistance and durability for use in harsh environments such as seawater and radiation-exposed areas, where existing methods struggle to enhance their physical properties effectively.
Innovation Solution
A manufacturing method involving the preparation of a multi-layered billet by ball-milling aluminum alloy and carbon nanotube powders, followed by spark plasma sintering and extrusion, and subsequent anodizing in a mixed solution of sulfuric acid and oxalic acid to form a hard oxide film, which improves corrosion resistance and insulation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon nanotube-reinforced aluminum matrix composite is used to improve mechanical properties, then strength and durability are enhanced, but corrosion resistance deteriorates in harsh environments
Solution Approach 1:
The patent divides the composite material into two functional segments: an inner core layer containing carbon nanotube-reinforced aluminum matrix composite for mechanical strength, and an outer cladding layer of pure aluminum or aluminum alloy for corrosion resistance. This segmentation allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
The patent creates a composite structure combining two different aluminum-based materials (carbon nanotube-reinforced composite and pure aluminum/aluminum alloy) into a single integrated extruded product. This composite material approach allows the final product to exhibit both high mechanical strength from the CNT-reinforced core and excellent corrosion resistance from the pure aluminum cladding.
2Reliability
If hard anodizing is applied to enhance surface hardness and corrosion resistance, then durability is improved, but the process is difficult to implement on composite materials due to corrosion characteristic differences
Solution Approach 1:
The patent segments the material into a corrosion-resistant outer cladding layer and an inner core layer, allowing the anodizing process to be applied uniformly to the entire surface without the complications of treating dissimilar materials with different corrosion characteristics. The cladding layer provides a consistent surface for anodizing.
Solution Approach 2:
The patent performs preliminary protection by applying the corrosion-resistant aluminum cladding layer to the composite material before the anodizing process. This pre-protection layer ensures that the subsequent anodizing process can proceed uniformly without encountering the corrosion characteristic differences that would complicate direct anodizing of the composite.
3Reliability
If multi-layered billet with different compositions is used to improve corrosion resistance, then manufacturing complexity increases
Solution Approach 1:
The patent implements a nested billet structure where the core layer containing carbon nanotube-reinforced aluminum matrix composite is placed inside the cladding layer of pure aluminum or aluminum alloy. This nested configuration allows the complex multi-material structure to be manufactured as a single integrated billet through sequential filling and sintering processes.
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 method effectively forms a hard oxide film with enhanced corrosion resistance, abrasion resistance, and insulation properties on the surface of the composite material, significantly improving its usability in extreme environments.
Implementation Method 1
forming a hard oxide film on the surface of the extruded material by anodizing the extruded material in a mixed solution of sulfuric acid and oxalic acid
Implementation Method 2
anodizing the extruded material in a mixed solution of sulfuric acid and oxalic acid
Implementation Method 3
subjecting the composite powder to spark plasma sintering performed at a pressure of 30 to 100 MPa and a temperature of 280° C. to 600° C. for a duration of 1 second to 30 minutes
Data Source
AI summary
A method of manufacturing an extruded material of carbon nanotube reinforced aluminum matrix composite having improved corrosion resistance, and the extruded material manufactured thereby are proposed. The method may include manufacturing an extruded material comprising an aluminum-carbon nanotube composite material and forming a hard oxide film on the surface of the extruded material by anodizing the extruded material in a mixed solution of sulfuric acid and oxalic acid. The method can form a hard oxide film with excellent corrosion resistance, abrasion resistance, and insulation properties on the surface of a composite material (an extruded material of carbon nanotube reinforced aluminum matrix composite material), which is known to be difficult to conduct hard anodizing due to the difference in corrosion characteristics between materials and, accordingly, the usability of the composite material can be significantly improved.