Composite Sliding Layer for Scratch-Resistant Low-Torque Bearings
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Solution Overview
Problem
Conventional sliding members in rotary devices, such as oil pumps, suffer from increased torque due to scratches and breakage from metallic foreign matter, and lack sufficient wear resistance and abrasion resistance, especially with the increasing demand for higher engine speeds and improved fuel efficiency.
Innovation Solution
A sliding member comprising a sliding layer with a synthetic resin, solid lubricant, and additive, where the resin is polyimide, polyamide-imide, etc., the lubricant is polytetrafluoroethylene or molybdenum disulfide, and the additive is bentonite or smectite clay mineral, with specific volume percentages and particle sizes to enhance hardness, wear resistance, and torque reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fluororesin coating is applied to the sliding member, then the sliding member achieves basic lubrication properties, but the coating film becomes soft and susceptible to scratching and breakage from metallic foreign matter
Solution Approach 1:
The patent creates a composite coating film by dispersing inorganic particles (silica, alumina, zirconia, titania, or carbon) within the fluororesin matrix. This composite structure combines the low friction properties of fluororesin with the high hardness and scratch resistance of inorganic particles, resolving the contradiction between softness and scratch resistance
Solution Approach 2:
The patent modifies the physical and chemical parameters of the coating by controlling particle size (0.1-10 μm), particle concentration (1-50 wt%), and surface treatment of inorganic particles. These parameter changes optimize both the hardness provided by particles and the flexibility provided by the fluororesin binder
2Productivity
If the engine speed is increased to improve fuel efficiency, then the productivity increases, but the wear and abrasion resistance of the sliding member becomes insufficient
Solution Approach 1:
The composite coating with inorganic particles embedded in fluororesin provides enhanced wear and abrasion resistance compared to pure fluororesin coatings, enabling the sliding member to withstand higher engine speeds and longer operating conditions
Solution Approach 2:
The coating is applied in advance to the sliding member surface before operation, creating a pre-formed protective layer that reduces friction and wear from the outset, allowing immediate operation at higher speeds without break-in period
3Loss of energy
If the solid lubricant content is increased to improve lubrication, then the torque reduction improves, but the coating film strength and hardness decrease
Solution Approach 1:
The inorganic particles act as intermediaries that transfer and distribute mechanical stress throughout the coating film, preventing stress concentration that would otherwise occur in pure fluororesin coatings with high solid lubricant content. This allows higher lubricant content while maintaining film integrity
Solution Approach 2:
The composite structure allows optimization of the lubricant-to-hardness ratio by incorporating inorganic particles that provide structural support while fluororesin provides lubrication, achieving both low torque and adequate film strength
Data Source
AI summary
A sliding member according to the present disclosure contains, in a sliding layer, a synthetic resin, a solid lubricant, and an additive. The synthetic resin is a polyimide, a polyamide imide, a polybenzimidazole, a polyphenyl sulfone, a polyether sulfone, a polyether ether ketone, or a combination thereof. The solid lubricant is a polytetrafluoroethylene, a tetrafluoroethylene-perfluoroalkoxyethylene copolymer, molybdenum disulfide, a tetrafluoroethylene-hexafluoropropylene copolymer, or a combination thereof. The contained amount of the solid lubricant in the sliding layer is 5.0-40.0 vol. %. The additive is bentonite, smectite clay mineral, silica, a polyamide, or a combination thereof. The contained amount of the additive in the sliding layer is 0.1-9.0 vol. %.