Polyimide Lubricating Coating for CO2 Compressor Sliding Members
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Solution Overview
Problem
Existing lubricating compositions for swash plate-type compressors face challenges in forming uniform and effective coatings due to variations in solvent ratio and viscosity, leading to issues with abrasion resistance, seizure resistance, and lubricating properties, especially when using CO2 as a refrigerant.
Innovation Solution
A lubricating coating composition comprising a thermosetting or thermoplastic polyimide-based resin, polytetrafluoroethylene (PTFE) as a solid lubricant, silicon carbide or alumina as fillers, and a silane coupling agent, with a controlled solvent mixture of N-methyl-2-pyrrolidone, xylene, dimethylacetamide, and methyl ethyl ketone, to achieve improved adhesion and lubricating properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the amount of solvent in lubricating composition is increased, then the composition becomes easier to apply, but it becomes difficult to form a uniform and thin coating layer
Solution Approach 1:
The patent optimizes the solvent content parameter within a specific range (60-80 wt%) to balance application ease and coating uniformity. This parameter change resolves the contradiction by finding the optimal point where the composition is sufficiently fluid for application but maintains enough viscosity to form uniform coatings.
Solution Approach 2:
The patent uses a composite lubricating composition containing multiple components including solid lubricants (PTFE, MoS2, graphite), binder resins, and solvents in specific ratios. This composite structure allows the composition to maintain both good flowability for application and sufficient viscosity for uniform coating formation.
2Speed
If the viscosity of lubricating composition is decreased, then the composition flows better, but it becomes difficult to form a coating layer of desired thickness due to low adhesion
Solution Approach 1:
The patent optimizes viscosity parameters by controlling solvent content (60-80 wt%) and solid content (20-40 wt%) to achieve a balance between flowability and adhesion. The composition maintains sufficient viscosity to adhere to substrates while remaining fluid enough for proper coating formation.
Solution Approach 2:
The composite formulation includes binder resins (polyester, polyamide, epoxy) that provide adhesion to substrates, solid lubricants for lubricating properties, and solvents for flowability. This composite structure resolves the contradiction by combining materials with complementary properties.
3Reliability
If the ratio of solid lubricant in composition is changed, then the lubricating properties improve, but the adhesion to substrate and other physical properties are affected
Solution Approach 1:
The patent optimizes the solid lubricant content parameter within specific ranges (PTFE: 5-20 wt%, MoS2: 3-10 wt%, graphite: 5-15 wt%) to balance lubricating properties with adhesion and other physical properties. This parameter optimization resolves the contradiction by finding the optimal concentration for each component.
Solution Approach 2:
The patent uses a composite system combining multiple solid lubricants (PTFE, MoS2, graphite) with binder resins in specific ratios. This composite approach allows the solid lubricants to provide excellent lubricating properties while the binder resins ensure adequate adhesion to substrates, resolving the contradiction between lubrication and adhesion.
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 composition ensures excellent abrasion resistance, seizure resistance, and lubricating ability, even in CO2 environments, by maintaining a specific solid content and viscosity range, resulting in a durable and reliable lubricating layer.
Implementation Method 1
a silane coupling agent for increasing abrasion resistance or adhesion to a substrate
Implementation Method 2
a solid lubricant such as PTFE, MoS2, WS2 or crystalline graphite
Implementation Method 3
dispersed in various solvents to prepare slurry-state lubricating compositions
Data Source
AI summary
The present invention relates to a lubricating coating composition and a compressor including a sliding member coated with the lubricating coating composition. The lubricating coating composition comprises a thermosetting or thermoplastic polyimide-based resin as a binder, a solid lubricant, various solvents and other additives at a controlled ratio so as to improve the abrasion resistance, seizure resistance, lubricating ability, heat resistance, adhesion to a substrate, and flexibility of the composition, and thus does not cause seizure even when CO2 gas is used as a refrigerant.