Selective Primer Removal on Titanium Alloy Substrates
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Solution Overview
Problem
Existing methods for removing bonding primer from titanium or titanium alloy reinforcement in composite fan vanes are ineffective, leading to damage of the substrate and inability to check for primer residues, particularly due to alkaline chemical pickling's aggressive nature and limited applicability.
Innovation Solution
A method involving a thermal treatment at 250-350°C in an oxidizing atmosphere to form a protective titanium oxide layer, followed by alkaline chemical pickling for selective primer removal and residue detection, minimizing substrate attack and preserving material thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkaline chemical pickling is used to remove the bonding primer, then the primer removal effectiveness is improved, but the titanium alloy substrate is damaged and thickness is lost
Solution Approach 1:
The method applies a thermal treatment step before the alkaline chemical pickling to pre-oxidize the titanium alloy substrate surface. This preliminary oxidation creates a protective oxide layer that reduces the aggressiveness of the subsequent alkaline pickling, thereby protecting the substrate while still allowing effective primer removal.
Solution Approach 2:
The thermal oxidation process acts as an intermediary between the primer and the alkaline pickling solution. By creating a modified surface layer through thermal treatment, the method mediates the interaction between the aggressive chemical pickling and the substrate, reducing direct damage while maintaining primer removal capability.
2Reliability
If alkaline chemical pickling is used to remove the bonding primer, then the primer removal effectiveness is improved, but the ability to detect primer residues is lost
Solution Approach 1:
The thermal treatment step causes the titanium alloy substrate to develop a characteristic oxide layer with distinct visual properties. This color/visual change provides a reference state that makes it easier to detect any remaining primer residues, as the contrast between the oxidized substrate and any residual primer becomes more apparent.
3Loss of substance
If mechanical dry pickling with plastic media is used to remove the bonding primer, then the substrate is protected from chemical attack, but the primer removal effectiveness is insufficient
Solution Approach 1:
The method changes the parameters of the chemical pickling process by pre-oxidizing the substrate surface through thermal treatment. This parameter change (creating an oxide layer) modifies the surface properties to reduce chemical attack on the substrate while maintaining or enhancing the effectiveness of primer removal in the subsequent alkaline pickling step.
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 allows for selective primer removal with minimal substrate attack, enabling repair on titanium alloy parts with tighter geometric tolerances and visual detection of primer residues, thus improving the surface treatment process for composite fan vanes.
Implementation Method 1
subjecting the metallic reinforcement to a thermal treatment performed at a temperature of between 250 and 350° C. for a period of between 1 hour and 10 hours in an oxidising atmosphere
Implementation Method 2
subjecting the metallic reinforcement, after the thermal treatment in step A), to chemical pickling in an alkaline bath
Data Source
AI summary
A method for treating the surface of a titanium or titanium alloy metal reinforcement of a blade made of composite material enables selective removal of a bonding primer with respect to the titanium or titanium alloy reinforcement. The method includes subjecting the metallic reinforcement to a thermal treatment performed at a temperature of between 250 and 350° C. for a period of between 1 hour and 10 hours in an oxidizing atmosphere. The method further includes subjecting the metallic reinforcement, after the thermal treatment, to a chemical pickling in an alkaline bath.