Nickel-Based Alloy Passivation via Low-Temp Oxidation
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Solution Overview
Problem
Nickel-based alloys face challenges in forming a stable, uniform, and dense passivation layer due to surface contaminants and the need for high-temperature heat treatments, which are energy-intensive and can affect the alloy's microstructure and mechanical properties.
Innovation Solution
A method involving immersion in neutral or alkaline solutions to remove surface contaminants and form functional groups, followed by a low-temperature heat treatment in an oxygen and protective gas environment to form a passivation layer with specific surface roughness and thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional high-temperature heat treatment is used to form a passivation layer, then the passivation layer can be formed, but energy consumption increases and the alloy's microstructure and mechanical properties are adversely affected
Solution Approach 1:
The patent changes the temperature parameter from traditional high-temperature heat treatment to low-temperature treatment (25-60°C) combined with chemical solutions (NaOH, H2O2, NH4OH) to form the passivation layer, thereby reducing energy consumption while avoiding adverse effects on the alloy's microstructure and mechanical properties
Solution Approach 2:
The patent introduces chemical intermediaries (alkaline solutions containing NaOH, H2O2, NH4OH) that mediate the formation of functional groups on the alloy surface, which then facilitate passivation layer formation at low temperatures, replacing the need for high-temperature thermal energy
2Reliability
If traditional high-temperature heat treatment is used to form a passivation layer, then the passivation layer can be formed, but the alloy's microstructure and mechanical properties are adversely affected
Solution Approach 1:
The patent changes the temperature parameter from high-temperature heat treatment to low-temperature treatment (25-60°C) combined with chemical solutions to form the passivation layer, thereby preserving the alloy's original microstructure and mechanical properties while still achieving effective passivation
3Productivity
If surface contaminants are present, then the alloy can be processed quickly, but the passivation layer formation is hindered and corrosion resistance decreases
Solution Approach 1:
The patent performs preliminary cleaning action by immersing the alloy in alkaline solution (NaOH) followed by H2O2 treatment to remove surface contaminants and form functional groups before the actual passivation process, ensuring a clean surface that facilitates uniform passivation layer formation
Solution Approach 2:
The patent replaces mechanical cleaning methods with chemical cleaning using alkaline solutions and hydrogen peroxide, which more effectively remove organic residues and surface contaminants without causing mechanical damage to the alloy 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 method effectively enhances the corrosion resistance of nickel-based alloys by forming a stable and uniform passivation layer, while being energy-efficient and preserving the alloy's inherent properties.
Implementation Method 1
the nickel-based alloy undergoes a low-temperature heat treatment process in an environment containing oxygen and a protective gas to form a passivation layer on at least one surface of the alloy
Data Source
AI summary
A method for the surface treatment of a corrosion-resistant nickel-based alloy and the resulting surface structure of the treated alloy is disclosed. The method includes immersing a nickel-based alloy in a first neutral or alkaline solution to remove surface contaminants, followed by immersing the cleaned alloy in a second neutral or alkaline solution to form functional groups on its surface. Subsequently, a low-temperature heat treatment is performed to form a passivation layer on the surface of the nickel-based alloy. The passivation layer has a surface roughness of less than 0.04 microns and a thickness ranging from 5 nanometers to 200 nanometers. The resulting corrosion-resistant nickel-based alloy comprises a substrate made of the nickel-based alloy and a passivation layer established on at least one surface of the substrate. The nickel content of the alloy is greater than 50%, and the alloy may also contain additional metallic components such as chromium (Cr) and manganese (Mn). The passivation layer may be a layer of nickel oxide, manganese oxide, chromium oxide, or a combination thereof.