Magnesium Alloy Stent Dual-Layer Coating Corrosion Resistance
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Solution Overview
Problem
Bioabsorbable magnesium alloy stents face challenges with rapid corrosion and mechanical strength issues due to decomposition in aqueous environments, limiting their practical application in maintaining blood vessel patency.
Innovation Solution
A bioabsorbable stent design featuring a magnesium fluoride layer as a first anticorrosive layer and a diamond-like carbon (DLC) or silicon-containing DLC layer as a second anticorrosive layer, applied to a magnesium alloy stent to enhance corrosion resistance and mechanical strength, with specific thickness ranges for each layer to ensure safety and effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a magnesium alloy stent is used to provide bioabsorbability, then the stent can be gradually degraded in the living body and allow blood vessel movement recovery, but the mechanical strength is spoiled immediately during expansion in aqueous solution due to acceleration of decomposition
Solution Approach 1:
The patent applies preliminary protective action by forming a magnesium fluoride coating layer on the magnesium alloy stent surface before implantation. This coating layer serves as a preliminary barrier that prevents direct contact between the magnesium alloy and aqueous environment, thereby preventing premature decomposition and maintaining mechanical strength during the critical expansion period.
Solution Approach 2:
The patent creates a composite structure combining magnesium alloy core material with a magnesium fluoride coating layer. This composite material approach allows the stent to benefit from both the bioabsorbability of magnesium alloy and the corrosion resistance of magnesium fluoride, resolving the contradiction between degradation capability and mechanical strength maintenance.
2Reliability
If a magnesium fluoride layer is formed on the magnesium alloy surface to delay corrosion, then corrosion resistance is improved, but the layer thickness must be controlled to maintain deformation followability
Solution Approach 1:
The patent applies parameter control by specifying a precise thickness range (0.1 to 3 μm) for the magnesium fluoride coating layer. This parameter optimization ensures that the coating is thick enough to provide effective corrosion protection while remaining thin enough to allow the stent to maintain its deformation followability and expansion characteristics.
3Strength
If aluminum and rare earth elements are used in the magnesium alloy to improve mechanical properties, then strength is enhanced, but safety to the human body is compromised
Solution Approach 1:
The patent applies the extraction principle by removing harmful elements (aluminum and rare earth elements) from the magnesium alloy composition. The alloy is reformulated to contain only magnesium and trace impurities, eliminating toxic components while maintaining biocompatibility and safety for human implantation.
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 dual-layer coating significantly improves corrosion resistance and mechanical strength, allowing the stent to maintain radial force for an extended period in simulated body conditions, while ensuring safety by avoiding aluminum and rare earth elements, thus addressing the limitations of existing magnesium alloy stents.
Implementation Method 1
a first anticorrosive layer containing magnesium fluoride as a main component formed on the core structure
Implementation Method 2
a second anticorrosive layer of a carbon-coated layer containing a diamond-like carbon on the first anticorrosive layer
Data Source
Figure 1~3
Figure 4
AI summary
Provided are a magnesium alloy stent with improved corrosion resistance, and a method for producing same. The bioabsorbable stent including a core structure of a magnesium alloy, the stent is composed of: a first anticorrosive layer containing magnesium fluoride as a main component formed on the core structure, and a second anticorrosive layer coated with a diamond-like carbon on the first anticorrosive layer.