ZnO Coated Rolling Body Friction Reduction
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Solution Overview
Problem
Existing methods fail to form uniform and firm ZnO coatings on the spherical surfaces of rolling bodies, such as bearing elements, due to issues with coating damage and non-uniformity caused by contact and collision during the coating process, which hinders the achievement of low friction and controlled crystalline orientation.
Innovation Solution
A method involving radio frequency magnetron sputtering with a basket housing the rolling body, where the mesh size to diameter ratio is between 40% to 95%, using a mixture of oxygen and argon sputter gas with an oxygen partial pressure of 60% to 80%, and maintaining a specific vertical distance for forming a columnar ZnO coating on spherical, cylindrical, or truncated cone-shaped rolling bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the rolling body is coated while contacting another object to enable coating in all directions, then coating coverage is improved, but coating damage and non-uniformity occur due to friction and collision
Solution Approach 1:
The patent divides the coating process into multiple sequential steps, coating different regions of the spherical surface at different times. The rolling body is coated on its upper surface, then rotated 180 degrees to coat the lower surface, and finally rotated 90 degrees to coat the side surfaces. This segmentation eliminates the need for simultaneous multi-directional coating, preventing coating damage while achieving complete coverage.
Solution Approach 2:
The patent performs preliminary coating on the upper surface before rotating the rolling body to coat other regions. By completing the coating of one region before moving to the next, the coating material has time to settle and bond properly without being disturbed by subsequent handling or rotation, ensuring uniformity while preparing for complete coverage.
2Area of stationary object
If the contact point is moved to coat different surfaces, then coating coverage is improved, but friction and collision damage the coating during formation
Solution Approach 1:
The coating process is segmented into distinct phases where the rolling body is coated on its upper surface, then rotated 180 degrees to coat the lower surface, and finally rotated 90 degrees to coat the side surfaces. This segmentation allows the coating to form firmly on each region before the rolling body is moved or rotated, preventing coating damage while achieving complete coverage.
Solution Approach 2:
The patent performs preliminary coating on the upper surface before rotating the rolling body to coat other regions. By completing the coating of one region before moving to the next, the coating material has time to settle and bond properly without being disturbed by subsequent handling or rotation, ensuring uniformity while preparing for complete coverage.
3Area of stationary object
If uniform coating substance distribution is attempted on all surfaces, then coating coverage is improved, but coating conditions become difficult to control evenly
Solution Approach 1:
The patent divides the coating process into multiple sequential steps, coating different regions of the spherical surface at different times. The rolling body is coated on its upper surface, then rotated 180 degrees to coat the lower surface, and finally rotated 90 degrees to coat the side surfaces. This segmentation eliminates the need for simultaneous multi-directional coating, preventing coating damage while achieving complete coverage.
Solution Approach 2:
The patent employs dynamic rotation of the rolling body to achieve uniform coating distribution. By rotating the rolling body to specific angles (180 degrees for lower surface, 90 degrees for side surfaces) and maintaining rotation during coating, the coating material is distributed evenly across the spherical surface without requiring complex multi-positioning mechanisms.
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
This method enables the formation of uniform, firm, and specular ZnO coatings on rolling bodies, enhancing their durability and reducing friction coefficients, even under severe conditions, while maintaining the piezoelectric properties of ZnO, thus improving the reliability and longevity of bearings.
Implementation Method 1
performing ZnO sputtering while rotating a basket housing a rolling body
Implementation Method 2
a method involving radio frequency magnetron sputtering
Implementation Method 3
control of crystalline orientation of ZnO coating developed lowering of a frictional force at a nano level due to Coulomb repulsion caused by a piezoelectric effect
Data Source
AI summary
ZnO sputtering is performed while a rolling body is housed in a basket made of a metal wire and is rotated. By setting a ratio of a mesh size of the basket to a diameter of the rolling body in a range of 40 to 95%, fine and uniform ZnO coating can be formed on a surface of the rolling body. By using the rolling body with ZnO coating prepared in this manner in a bearing which is rotated at high speed in a high-load state, a friction coefficient can significantly be lowered in comparison with a case of no coating.