Molybdenum Sliding Surface Coating for Harsh Lubrication Conditions
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Solution Overview
Problem
Existing surface treatment methods for sliding members fail to provide sufficient slidability under harsh conditions such as high-speed sliding and high surface pressure, with lubricating oils breaking down and molybdenum disulfide coatings being brittle and costly to form and maintain.
Innovation Solution
A surface treatment method involving shot peening to create micronized surface structures and arc-shaped concavities, followed by forming a molybdenum coating as a precursor, which reacts with sulfur or oxygen to create a solid lubricant coating, enhancing adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricating oil is used for high-speed sliding contact, then lubrication is provided, but the lubricating oil breaks down under high temperature and pressure conditions
Solution Approach 1:
A molybdenum coating is applied as an intermediary layer between the sliding surfaces. This coating reacts with sulfur or oxygen to form molybdenum disulfide or molybdenum oxide, which act as solid lubricants. The solid lubricant coating mediates the sliding contact, preventing direct metal-to-metal contact and reducing the breakdown of lubricating oil under high temperature and pressure conditions.
Solution Approach 2:
The surface treatment changes the chemical composition and physical properties of the sliding surface. By forming a molybdenum coating and converting it to a solid lubricant coating, the friction coefficient and temperature resistance parameters are improved, allowing the system to withstand harsher operating conditions without lubricating oil breakdown.
2Reliability
If molybdenum disulfide coating is formed directly by ejecting particles, then solid lubricant coating is created, but the coating is brittle and costly to form and maintain
Solution Approach 1:
A molybdenum coating is formed first as a precursor layer before converting it to the final solid lubricant coating. This preliminary molybdenum coating provides a stable base that is easier and less costly to form than direct molybdenum disulfide coating. The conversion to solid lubricant occurs through controlled reaction with sulfur or oxygen, reducing manufacturing complexity and cost.
Solution Approach 2:
The invention uses reusable molybdenum or molybdenum alloy particles for forming the precursor coating. These particles can be reused multiple times, reducing material costs compared to direct use of molybdenum disulfide particles. The cost-effective approach allows for economical formation and maintenance of the solid lubricant coating.
3Productivity
If punching speed is increased to improve productivity, then electromagnetic steel sheets are processed faster, but sliding members experience harsher sliding conditions
Solution Approach 1:
The sliding members are pre-treated with shot peening to create micronized surface structures and arc-shaped concavities before use. This preliminary surface treatment prepares the surfaces to withstand high-speed sliding by creating oil reservoirs and improving surface properties, enabling the system to handle increased punching speeds without compromising durability.
Solution Approach 2:
The solid lubricant coating acts as an intermediary protective layer on the sliding members. This coating reduces friction and wear during high-speed sliding contact, allowing the system to operate at higher punching speeds while maintaining component durability and reliability.
4Weight of moving object
If electromagnetic steel sheets are miniaturized to reduce material use, then weight is reduced, but sliding members must withstand higher rotational speeds
Solution Approach 1:
Sliding members are pre-treated with shot peening to create micronized surface structures and arc-shaped concavities that serve as oil reservoirs. This preliminary surface preparation enables the sliding members to withstand higher rotational speeds by improving lubrication retention and surface durability, compensating for the increased speed demands from miniaturized electromagnetic steel sheets.
Solution Approach 2:
The solid lubricant coating serves as an intermediary protective layer that reduces friction and wear during high-speed operation. This coating enables the sliding members to handle the increased rotational speeds required by miniaturized electromagnetic steel sheets while maintaining reliability and preventing seizure.
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 method improves slidability and adhesion strength of the solid lubricant coating, allowing it to withstand harsh conditions and reduce maintenance costs by using reusable molybdenum or molybdenum alloy particles.
Implementation Method 1
ejecting shots onto the sliding portion to form arc-shaped concavities on the surface of the sliding portion and obtain a micronized surface structure
Implementation Method 2
forming arc-shaped concavities on the surface of the sliding portion and obtain a micronized surface structure by ejecting shots
Implementation Method 3
forming a molybdenum coating as a precursor, which reacts with sulfur or oxygen to create a solid lubricant coating
Data Source
Figure 1A~1B
Figure 1C~2C
Figure 3A~3B
AI summary
The present invention involves forming a solid lubricant coating material having high adhesion strength on the surface of a sliding portion of a sliding member at low cost. Specifically, a molybdenum coating 30 is formed on the surface of a sliding portion 11 of a sliding member 10 by spraying, on the sliding portion 11 to cause collision with the same, spray particles 22 containing molybdenum having a particle size of #100 to #800 or a molybdenum alloy at a spray pressure of at least 0.2 MPa to cause molybdenum in the spray particles 22 to diffuse and penetrate the sliding portion. Because of the heat generated due to sliding of the sliding portion 11 against a counterpart member with a lubricating oil therebetween when the sliding member 10 is used, the molybdenum coating 30, which serves as a precursor, reacts with sulfur and oxygen contained in the lubricating oil and the counterpart member to form a solid lubricant coating containing molybdenum disulfide and molybdenum oxide.