Grease Composition for Static Dissipation in Bearings
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Solution Overview
Problem
Bearings used in severe environments, such as high temperature, high speed, and high load, experience premature spalling due to hydrogen generation from grease degradation, which affects the rolling contact surface, and existing greases do not effectively address conductivity issues.
Innovation Solution
A grease composition comprising a base oil, a thickener, tungsten disulfide powder with an average particle diameter of 0.5 to 5.0 µm, and tungsten powder with an average particle diameter of 0.5 to 2.0 µm, which improves conductivity and antiwear properties, thereby reducing static electricity and extending bearing life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional grease is used in severe environments, then the bearing operates under high temperature and high load, but hydrogen is generated by grease deterioration which causes spalling of the rolling contact surface
Solution Approach 1:
The patent changes the chemical composition parameters of the grease by incorporating specific antioxidants (0.1-5.0 wt%), antiwear additives (0.1-5.0 wt%), and extreme pressure additives (0.1-5.0 wt%). These parameter changes prevent grease deterioration and hydrogen generation, thereby eliminating the harmful effect while maintaining reliability under severe conditions
Solution Approach 2:
The patent converts the harmful hydrogen generation issue into a benefit by adding metal powder (0.1-10.0 wt%) that improves electrical conductivity. The metal powder not only dissipates static electricity that would otherwise accelerate grease deterioration and hydrogen generation, but also provides antiwear protection, turning a potential harm into a protective mechanism
2Strength
If grease is used to provide lubrication under severe conditions, then antiwear property is maintained, but conductivity is insufficient and static electricity accumulates
Solution Approach 1:
The patent creates a composite grease material combining base oil, thickener, metal powder (0.1-10.0 wt%), tungsten disulfide (0.1-5.0 wt%), and various additives. This composite structure provides both antiwear properties from the metal powder and extreme pressure additives, while simultaneously achieving conductivity improvement through the conductive metal particles distributed throughout the grease matrix
Solution Approach 2:
The metal powder in the grease serves multiple functions simultaneously: it provides electrical conductivity to dissipate static electricity, offers antiwear protection through sacrificial metal transfer, and enhances extreme pressure resistance. This multi-functionality resolves the contradiction by making a single additive system achieve multiple beneficial effects
3Reliability
If metal powder is added to improve conductivity, then static electricity is removed, but particle size and amount must be controlled to maintain antiwear and extreme pressure properties
Solution Approach 1:
The patent specifies precise parameter ranges for metal powder particle diameter (0.1-10.0 µm) and content (0.1-10.0 wt%). These parameter controls ensure optimal conductivity while preventing agglomeration that would harm antiwear properties. The defined parameters transform the complexity into a controllable manufacturing specification
Solution Approach 2:
The patent applies local quality by specifying different particle size ranges for different metal powders used: aluminum powder (1-10 µm), zinc powder (1-10 µm), and tungsten disulfide (0.1-5.0 µm). Each metal powder type has optimized local particle size characteristics suited to its specific function, with finer particles for conductivity and slightly coarser particles for antiwear protection
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 grease composition provides excellent conductivity, antiwear, and extreme pressure properties, rapidly removing static electricity and suppressing spalling, resulting in a long-life bearing performance even under severe conditions.
Implementation Method 1
a grease composition which has excellent conductivity by comprising a tungsten disulfide powder with a predetermined average particle diameter and in turn can rapidly remove static electricity caused by using the bearing
Implementation Method 2
sustaining antiwear property, extreme pressure property and noise property
Data Source
Figure 1
AI summary
The present invention provides a grease composition which has excellent conductivity and can rapidly remove static electricity generated by using a bearing. The grease composition comprises a base oil, a thickener and a tungsten disulfide powder, wherein the average particle diameter of the tungsten disulfide powder is 0.5 to 5.0 µm and the amount of tungsten disulfide powder based on 100 parts by mass of the total amount of base oil and thickener is 2.0 to 4.0 parts by mass.