Micromechanical Assembly Tribological Coating
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Solution Overview
Problem
The Diamond vs Diamond pair in micromechanical assemblies experiences adhesion issues due to the creation of carbon bonds, leading to friction instabilities and tribological instability over short periods without sufficient humidity.
Innovation Solution
Functionalizing the diamond layer with a compound of sulfur and fluorine, creating a second layer on top of the diamond layer, which modifies the tribological properties and reduces adhesion between diamond surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If diamond surfaces are used in direct contact, then hardness and wear resistance are improved, but adhesion and friction instability occur due to carbon bond formation
Solution Approach 1:
The invention applies a composite structure consisting of a diamond layer combined with an outer layer containing oxygen, fluorine, and sulfur atoms. This composite material approach allows the diamond layer to provide hardness and wear resistance while the outer layer prevents adhesion by modifying the surface chemistry, thereby eliminating carbon bond formation between contacting surfaces.
Solution Approach 2:
The invention changes the chemical composition parameters of the surface layer by incorporating specific elements (oxygen, fluorine, sulfur) in controlled amounts. This parameter modification transforms the surface properties to reduce adhesion while maintaining the underlying diamond's mechanical properties, resolving the contradiction between hardness and tribological stability.
2Reliability
If humidity is increased to reduce adhesion, then friction is reduced, but long-term tribological stability cannot be guaranteed
Solution Approach 1:
The outer layer with oxygen, fluorine, and sulfur atoms provides self-lubricating properties by creating a low-adhesion surface that reduces friction without requiring external humidity or lubricants. This self-service mechanism maintains low friction and high tribological stability over long periods independent of environmental conditions.
Solution Approach 2:
The outer layer acts as an intermediary between the diamond surface and the contacting counterpart, preventing direct carbon-carbon bond formation. This intermediary layer mediates the interaction by providing a chemically inert surface that reduces adhesion while maintaining mechanical performance over time.
3Reliability
If environmental humidity is maintained at 50% RH or higher, then adhesion is reduced, but the tribological conditions become difficult to maintain
Solution Approach 1:
The functionalized diamond surface with oxygen, fluorine, and sulfur atoms provides inherent adhesion reduction properties that do not depend on environmental humidity. This self-service capability eliminates the need to maintain specific environmental conditions, making the system easier to operate while maintaining low adhesion.
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 sulfur and fluorine functionalization improves the tribological behavior of diamond surfaces, allowing for stable operation of micromechanical assemblies like watch escapements without lubrication, maintaining performance equivalent to standard references over extended periods.
Implementation Method 1
the diamond layer is functionalized with a compound of sulfur and fluorine... the S allowing to protect against the appearance of bonds (CC) when the relative humidity is no longer sufficient to play this role
Implementation Method 2
the method of functionalizing diamond by reactive ion etching... by using very low power reactive ion etching equipment
Implementation Method 3
reactive ion etching is generally used for deep etching on silicon... it is possible to synthesize this compound of S and F on a part
Data Source
Figure 1~3
Figure 4~5a
Figure 5b~6
AI summary
The present invention relates to a functional assembly (1) of micromechanics comprising at least a first part (2) with a first functional surface (2a) intended to come into frictional contact with a second functional surface (3a), said second functional surface belonging either to said first part (2) or to at least a second part (3) constituting with said first part (2) said functional assembly (1), said functional assembly (1) being characterized in that the first functional surface (2a) and the second functional surface (3a) are formed of a first layer (9a) comprising ultrananocrystalline, nanocrystalline or microcrystalline diamond, said first layer (9a) being surmounted by a second layer (9b) comprising S and F atoms. It also relates to the process of functionalizing diamond.