Nickel Substrate Coating Removal via Acid Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for removing metallic coatings from nickel substrates in repair processes can cause chemical etching, making it challenging to restore airfoils and other components without damaging the substrate.
Innovation Solution
A method involving a nitric acid solution with a molarity of 0.07M - 0.8M at 65°F - 160°F followed by a hydrochloric acid solution with a molarity of 0.65M - 0.85M at 120°F - 180°F is used to remove protective metallic coatings from nickel-based substrates, minimizing chemical etching and ensuring the substrate's integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional acid stripping methods are used to remove protective coatings from nickel substrates, then coating removal is achieved, but chemical etching of the substrate occurs causing damage
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molarity concentrations of nitric acid (0.07M-0.8M) and hydrochloric acid (0.65M-0.85M), as well as temperature parameters (first solution: 65°F-160°F, second solution: 120°F-180°F) and exposure times (first solution: 1-24 hours, second solution: 1-6 hours). These controlled parameter changes enable effective coating removal while minimizing substrate etching damage.
Solution Approach 2:
The patent segments the coating removal process into two distinct sequential stages: first treating with a nitric acid solution to remove portions of the protective coating, then treating with a hydrochloric acid solution to remove remaining coating portions. This segmentation allows each solution to target specific coating components, achieving complete removal while reducing overall substrate exposure to aggressive chemicals.
2Productivity
If strong acid solutions are used to accelerate coating removal, then productivity increases, but substrate integrity deteriorates due to increased etching
Solution Approach 1:
The patent optimizes productivity while preserving substrate integrity by establishing specific molarity ranges for nitric acid (0.07M-0.8M) and hydrochloric acid (0.65M-0.85M), along with temperature ranges (first solution: 65°F-160°F, second solution: 120°F-180°F). These controlled parameter changes enable accelerated coating removal without excessive etching of the nickel substrate.
Solution Approach 2:
The segmented two-solution approach improves productivity by dividing the removal task: the nitric acid solution addresses portions of the coating first, then the hydrochloric acid solution completes the removal. This segmentation prevents any single aggressive acid from being applied at full strength for extended periods, thereby maintaining substrate integrity while achieving efficient overall removal.
3Reliability
If extended exposure time to acid solutions is used to ensure complete coating removal, then removal completeness improves, but substrate damage increases
Solution Approach 1:
The patent ensures complete coating removal while limiting cumulative damage by segmenting the process into two sequential treatments with controlled durations (first solution: 1-24 hours, second solution: 1-6 hours). Each solution targets specific coating portions, and the sequential arrangement ensures complete removal without requiring any single solution to act for excessively long periods.
Solution Approach 2:
The patent controls cumulative etching damage while ensuring complete removal by precisely managing exposure time parameters for each solution stage. The nitric acid exposure is limited to 1-24 hours followed by hydrochloric acid exposure of 1-6 hours, with these time parameters optimized to achieve complete coating removal while minimizing total substrate exposure to aggressive chemical environments.
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
This method effectively removes protective metallic coatings with minimal chemical etching of the nickel substrate, allowing for safe restoration and re-coating of airfoils and other components, maintaining their structural integrity.
Implementation Method 1
subjecting a substrate coated with a protective metallic coating to a nitric acid solution... to remove the protective metallic coating from the substrate
Implementation Method 2
subjecting the substrate with the protective metallic coating to a hydrochloric acid solution to remove the protective metallic coating from the substrate
Data Source
Figure 1
AI summary
A method for a repair process includes the steps of subjecting a substrate coated with at least one protective metallic coating to a nitric acid solution (12) and then subjecting the substrate with the at least one protective metallic coating to a hydrochloric acid solution (14) to remove the at least one protective metallic coating from the substrate. The substrate includes about 5 wt% - 15wt% chromium, about 2 wt% - 8wt% cobalt, about 2 wt% - 6wt% tungsten, about 0.5 wt% - 2.5wt% titanium, about 8 wt% - 16wt% tantalum, about 2 wt% - 8wt% aluminum, hafnium in an amount no greater than 1wt%, and a remainder of nickel.