Nickel Alloy Coating for Turbo-Machine Corrosion
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Solution Overview
Problem
Components in subsea or offshore environments, particularly those made of carbon steel, low-alloy steel, or stainless steel, are prone to corrosion from wet CO2 and chlorides, leading to damage and pitting, and existing solutions are costly and ineffective for complex-shaped components.
Innovation Solution
A multi-layer nickel-based coating is applied using electroplating and electroless plating techniques, followed by thermal treatment, to create a durable and cost-effective anti-corrosion layer with specific thickness and properties, allowing the use of less expensive materials like carbon or low-alloy steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon steel or low-alloy steel is used as substrate material, then cost is reduced, but corrosion resistance deteriorates in wet CO2 environments
Solution Approach 1:
The patent applies a multi-layer composite coating system consisting of electroplated nickel layers and electroless nickel-phosphorus alloy layers. This composite structure combines the advantages of different deposition methods to provide superior corrosion resistance against wet CO2 while maintaining cost-effectiveness through the use of carbon steel or low-alloy steel substrates.
Solution Approach 2:
The patent utilizes thermal treatment at controlled temperatures (150-300°C) to modify the microstructure and properties of the nickel-based coating. By adjusting treatment temperature and duration, the coating achieves optimal hardness, ductility, and corrosion resistance, transforming the coating's properties to withstand aggressive environments.
2Reliability
If stainless steel is used as substrate material, then corrosion resistance to chlorides is improved, but cost increases
Solution Approach 1:
The patent replaces expensive stainless steel substrates with more economical carbon steel or low-alloy steel substrates. The corrosion protection function is transferred to a specifically designed nickel-based coating system, allowing the use of cheaper base materials while maintaining adequate corrosion resistance through the protective coating layers.
Solution Approach 2:
The patent applies a specialized multi-layer nickel coating system specifically tailored for wet CO2 corrosion environments. This localized protective measure concentrates corrosion resistance where it is most needed (at the substrate-coating interface and outer surface) rather than requiring the entire substrate material to be corrosion-resistant.
3Reliability
If multi-layer nickel coating is applied, then corrosion protection is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the coating process into distinct segments: electroplating steps and electroless plating steps, with thermal treatment in between. This segmentation allows each process step to be optimized independently and performed by standard equipment, making the complex multi-layer structure manufacturable through routine industrial processes.
Solution Approach 2:
The patent incorporates a preliminary thermal treatment step after the initial electroplating and electroless plating layers are deposited. This pre-treatment prepares the coating structure for subsequent layers, ensuring proper adhesion, microstructure, and properties before final coating completion, which simplifies the overall process control.
4Reliability
If coating thickness is increased, then corrosion resistance is improved, but ductility deteriorates
Solution Approach 1:
The patent applies thermal treatment at optimized temperatures (150-300°C) for specific durations to modify the microstructure of the nickel-based coating. This thermal processing transforms the coating's physical properties, achieving an optimal balance where sufficient thickness provides corrosion resistance while thermal treatment restores and optimizes ductility by relieving stresses and refining the microstructure.
Solution Approach 2:
The multi-layer composite structure with alternating electroplated and electroless plating layers creates a nuanced microstructure where each layer contributes different properties. The combined structure, when thermally treated, achieves both adequate thickness for corrosion protection and maintained ductility through the synergistic effect of different layer compositions and structures.
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 provides a structurally homogeneous and resistant coating with optimal hardness and ductility, effectively preventing corrosion in humid environments with aggressive contaminants, eliminating the need for additional scrubbers and filters in turbo-machines.
Implementation Method 1
a first deposition step of depositing a first metallic layer on said substrate by electroplating
Implementation Method 2
a second deposition step of depositing at least a second layer of a nickel alloy on said first layer by electroless plating
Implementation Method 3
at least one thermal treatment step after said deposition steps, said thermal treatment being applied at a temperature and for a time depending on the overall thickness of said layers
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5
AI summary
Method (100) for preventing corrosion in a component (1) of a turbo-machine having a metal substrate (5) made of carbon steel, low alloy steel and stainless steel includes: -a first deposition step (110) of depositing a first metallic layer (2a) on the substrate (5) by electroplating; -a second deposition step (120) of depositing at least a second layer (2b) of a nickel alloy on the first layer (2a) by electroless plating; -at least one thermal treatment (140) step after the deposition steps (110, 120), said thermal treatment (140) being applied at a temperature (T) and for a time (t) depending on the overall thickness of the layers (2a, 2b), the value of said temperature (T) being directly proportional to the thickness, the value of said time (t) being inversely proportional to the temperature (T).