Strengthening Steel Passive Layers with Maleic Acid
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Solution Overview
Problem
Chromium-containing steel surfaces in medical instruments are prone to corrosion and surface damage from mechanical stress and corrosive conditions, such as exposure to blood and aqueous solutions, which can lead to increased contamination and malfunction, posing health risks.
Innovation Solution
A method involving an acid-containing aqueous solution, specifically with maleic acid, maleic anhydride, or itaconic acid, is used to increase the chromium/iron ratio and thickness of the passive layer on chromium-containing steel surfaces, enhancing corrosion resistance and surface durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard cleaning and sterilization procedures are used, then medical instruments are disinfected and sterilized, but the passive layer on steel surfaces is damaged and corrosion resistance is reduced
Solution Approach 1:
The patent applies preliminary action by treating the steel surface with an acid-containing aqueous solution (maleic acid, itaconic acid, or citric acid) before sterilization to strengthen the passive layer. This pre-treatment creates a more robust protective layer that can withstand subsequent sterilization processes and regular cleaning, preventing surface damage and corrosion while maintaining sterilization effectiveness
Solution Approach 2:
The patent changes the chemical parameters of the passive layer by using acid-containing aqueous solutions to modify its composition and structure. The acid treatment increases the chromium content and improves the protective properties of the passive layer, making it more resistant to damage from sterilization and cleaning processes while maintaining its barrier function
2Object-affected harmful factors
If the passive layer thickness is increased to improve corrosion resistance, then corrosion protection is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent uses parameter changes by selecting specific acids (maleic acid, itaconic acid, or citric acid) at optimized concentrations to modify the passive layer composition. This approach achieves enhanced corrosion resistance through chemical parameter optimization rather than complex physical processes, maintaining manufacturing simplicity while improving protective properties
Solution Approach 2:
The patent employs inexpensive acid-containing aqueous solutions that can be easily prepared and applied. These simple, low-cost chemical treatments provide effective passive layer strengthening without requiring complex equipment or multi-step processes, making the enhancement economically viable and easy to implement in existing manufacturing workflows
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 increases the chromium/iron ratio and passive layer thickness, significantly improving corrosion resistance and reducing the adhesion of contaminants, thereby enhancing the longevity and safety of medical instruments.
Implementation Method 1
a passive layer present on the surface of the steel is strengthened. This strengthening can be achieved by increasing the chromium/iron ratio in the passive layer, by increasing the thickness of the passive layer
Data Source
Figure 1
AI summary
A method for strengthening the passive layer on the surface of a chromium-containing steel, preferably by increasing the chromium/iron ratio in the passive layer or by increasing the thickness of the passive layer, characterized in that it comprises at least stage (ii) and optionally, prior to or concurrently with stage (ii), stage (i): (i) cleaning the surface; (ii) contacting the surface of the steel with an acid-containing aqueous solution, wherein the acid is selected from one or more of the following compounds: maleic acid, maleic anhydride, maleic half-ester, itaconic acid, itaconic half-ester, water-soluble copolymer of maleic acid or maleic anhydride or itaconic acid.