Ti-Sprayed Sliding Member for Mo-Lubricant Friction Reduction
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Solution Overview
Problem
Existing sliding members, such as those with iron-based alloy-thermally sprayed coatings, do not effectively reduce friction when used with lubricants containing molybdenum, and the mechanisms behind friction reduction are not fully understood, limiting their performance in reducing fuel consumption.
Innovation Solution
A sliding member with a Ti-containing thermally sprayed coating formed by thermally spraying a metallic material mainly composed of titanium, which accelerates the decomposition of molybdenum-containing additives in the lubricant to form a molybdenum disulfide low-friction coating, and features a surface roughness of 3.0 μm or less and an oxygen abundance ratio of 10 mass % or less to enhance friction reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an iron-based alloy-thermally sprayed coating is formed on a sliding portion, then wear resistance is improved, but friction reduction effect is insufficient when used with lubricants containing Mo
Solution Approach 1:
The invention changes the material composition parameter from iron-based to titanium-based thermal spray coating. This parameter change enables the coating to catalyze the decomposition of Mo-containing lubricant additives, forming MoS2 low-friction coating in situ, thereby achieving both wear resistance and significant friction reduction (30-40% lower than conventional materials).
Solution Approach 2:
The invention creates a composite structure where the titanium-based thermal spray coating serves as a catalyst substrate that promotes the formation of MoS2 compounds from the lubricant. This composite approach combines the wear resistance of the titanium coating with the low-friction properties of MoS2, resolving the contradiction between wear resistance and friction reduction.
2Force
If a thermal spraying material containing a large amount of ceramics is used, then friction can be reduced, but the friction reduction effect cannot be obtained under an environment of a lubricant containing Mo
Solution Approach 1:
The invention changes the material composition from ceramic-based to titanium-based metallic material. This parameter change makes the coating compatible with Mo-containing lubricants by enabling catalytic decomposition of the lubricant additives to form MoS2, thereby achieving friction reduction that is effective specifically in Mo-containing lubricant environments.
Solution Approach 2:
The titanium-based coating acts as an intermediary that facilitates the chemical reaction between the Mo-containing lubricant and the sliding surface. It catalyzes the decomposition of Mo additives and promotes MoS2 formation, serving as a mediator that enables friction reduction in Mo-containing lubricant environments where ceramic coatings fail.
3Force
If the surface roughness is reduced to enhance friction reduction, then the friction coefficient is further reduced, but the manufacturing precision requirement increases
Solution Approach 1:
The invention optimizes the surface roughness parameter to a specific range (Ra 0.4-1.6 μm, Rz 1.6-3.2 μm) that balances friction reduction performance with manufacturing feasibility. This parameter optimization ensures adequate surface smoothness for low friction while maintaining practical manufacturability through thermal spray processing.
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 Ti-containing thermally sprayed coating significantly reduces friction by forming a molybdenum disulfide low-friction coating, improving fuel efficiency and wear resistance, with a friction coefficient reduction of 30% to 40% compared to conventional materials, and further reduced when surface roughness and oxygen content are optimized.
Implementation Method 1
active Ti exposed on a surface by sliding can accelerate decomposition reaction of an additive contained in a lubricant to effectively form a molybdenum disulfide-containing low-friction coating
Implementation Method 2
a Ti-containing thermally sprayed coating formed by thermally spraying, as a thermal spraying material, a metallic material mainly containing titanium (Ti) as a composition
Data Source
AI summary
A sliding member capable of improving friction characteristics under an environment of a lubricant containing Mo, and a production method therefor, is provided. The sliding member contains a sliding portion formed of a metallic material having a Ti-containing thermally sprayed coating on a surface layer part of the sliding portion. The sliding member slides under the environment of the lubricant containing Mo as an additive, in which active Ti exposed on a surface by sliding accelerates decomposition reaction of the additive contained in the lubricant to form a molybdenum disulfide-containing low-friction coating having low friction on the surface of the sliding portion.