Self-Lubricating Fluid Bearing Ring With Depassivated Anchor Layer
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Solution Overview
Problem
Existing self-lubrifying rings for fluid levels face issues with adhesion of the lubricating coating on alloy substrates with strong passive layers, leading to potential disassembly or plasticization due to differential dilation in high-temperature applications.
Innovation Solution
A process involving the removal of the passive layer from the alloy substrate, followed by the deposition of an anchor layer and a self-lubrifying coating, ensures sufficient adhesion and reduces differential dilation issues by using alloys compatible with the application environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a passive alloy substrate is used to reduce differential expansion, then thermal compatibility is improved, but adhesion of the self-lubricating coating deteriorates due to the strong passive layer
Solution Approach 1:
The passive layer is removed in advance through sandblasting treatment before coating deposition. This preliminary action eliminates the barrier to adhesion while maintaining the beneficial thermal compatibility of the passive alloy substrate, allowing the self-lubricating coating to bond directly to the exposed substrate surface
Solution Approach 2:
The surface properties of the substrate are changed by removing the passive layer through sandblasting, which modifies the surface energy and roughness parameters. This creates a surface that is chemically resistant in service but provides excellent adhesion for the coating during the manufacturing process
2Reliability
If stainless steel substrate is used, then coating adhesion is improved, but differential expansion increases leading to ring disassembly or plasticization
Solution Approach 1:
The substrate material parameters are changed from stainless steel to passive alloy (such as Inconel 625) that matches the thermal expansion properties of adjacent components. The sandblasting process then modifies the surface parameters to provide adequate adhesion, resolving both the dimensional stability and coating adhesion requirements
Solution Approach 2:
The substrate exhibits different properties at different locations: the bulk material provides thermal compatibility and dimensional stability, while the surface (after sandblasting) provides coating adhesion. This local differentiation allows the single substrate to satisfy multiple conflicting requirements
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 process achieves improved adhesion and reduced risk of disassembly or plasticization, enhancing the performance and reliability of self-lubrifying rings in high-temperature applications.
Implementation Method 1
In some embodiments, removing the passive layer includes sandblasting the substrate. Sandblasting not only destroys and removes the passive layer, such as naturally occurring oxides on the surface of the substrate, but also creates a roughness on the substrate that allows the anchoring layer to be mechanically anchored to the substrate.
Implementation Method 2
In some embodiments, the deposition of the anchoring layer is carried out electrolytically. The electrolytic route is relatively inexpensive and promotes interdiffusion of the materials of the anchoring layer and the substrate, which also results in better anchoring.
Implementation Method 3
In some embodiments, the deposition of the self-lubricating coating comprises sintering. The sintering, typically of a powder, creates a porous layer which can then be impregnated with a material providing the self-lubricating nature of the coating.
Implementation Method 4
The sintering, typically of a powder, creates a porous layer which can then be impregnated with a material providing the self-lubricating nature of the coating.
Data Source
Figure 1A~1E
Figure 2
AI summary
Method for manufacturing a self-lubricating ring (10) for a fluid bearing, comprising the following steps: – providing a substrate (12) made of an alloy having a passive layer (14); – at least in part removing the passive layer (14) of the said substrate so as to obtain a depassivated surface (14a); – applying an anchor layer (16) to the depassivated surface (14a); – applying a self-lubricating coating (20) to the anchor layer (16). A self-lubricating ring (10) for fluid bearing, comprising a substrate (12) made of an alloy having a passive layer, an anchor layer (16) anchored to the said substrate (12) and a self-lubricating coating (20) applied to the anchor layer (16).