Mechanical Seal DLC Coating Against Silicate Deposition
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Solution Overview
Problem
Mechanical seals used in water-cooling engines and devices handling chemicals and oils face issues with deposition of silicate compounds on sealing faces, leading to reduced smoothness and leakage, especially when using silicon carbide as the sliding material, as it has a high affinity with silicate-containing fluids.
Innovation Solution
A sliding component with an annular stationary and rotating seal ring, where at least one of the sealing faces is coated with a diamond-like carbon film formed using a hydrocarbon gas containing no silicon compound, with a silicon content of 1.5 at% or less, to prevent silicate deposition and maintain smoothness and prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon carbide is used as the sliding material of the mechanical seal, then corrosion resistance and wear resistance are improved, but silicate compound deposition on the sealing face occurs due to high affinity with silicate-containing fluids
Solution Approach 1:
The patent applies a diamond-like carbon (DLC) coating on the sealing face of the silicon carbide-based seal ring. This creates a composite structure where the silicon carbide substrate provides mechanical strength, corrosion resistance, and wear resistance, while the DLC coating layer provides low silicate affinity and prevents deposition. The coating thickness is controlled at 1 μm to 10 μm to ensure effective protection while maintaining the underlying substrate properties.
Solution Approach 2:
The invention applies the DLC coating only on the sealing face surface where contact with silicate-containing fluids occurs, rather than treating the entire seal ring. This localized treatment targets the specific area where silicate deposition is problematic, while preserving the excellent mechanical properties of the silicon carbide substrate in other regions.
2Object-generated harmful factors
If DLC coating is applied on the sealing face, then silicate deposition is prevented, but machining property remains poor due to substrate material characteristics
Solution Approach 1:
The patent combines silicon carbide substrate with DLC coating to create a composite seal ring structure. The silicon carbide provides excellent corrosion and wear resistance, while the DLC coating (1-10 μm thick) applied on the sealing face provides low silicate affinity and prevents deposition, thereby overcoming the poor machining property issue through surface engineering rather than bulk material change.
3Loss of energy
If fluid lubrication state is maintained by dynamic pressure generation, then friction is reduced, but sealing property may be compromised due to fluid film formation
Solution Approach 1:
The patent optimizes the DLC coating thickness parameter to 1 μm to 10 μm, which is sufficient to prevent silicate deposition while maintaining appropriate surface properties for fluid lubrication. This controlled thickness ensures that the coating is thin enough to allow effective sealing contact while thick enough to prevent deposition, thereby balancing friction reduction and sealing property.
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 solution effectively prevents silicate compound deposition on the sealing faces, maintaining smoothness and preventing leakage of the sealed fluid, even when using silicon carbide as the substrate material, while also generating dynamic pressure for low friction and low leakage operation.
Implementation Method 1
an amorphous carbon film formed in plasma CVD using a hydrocarbon gas containing no organic silicon compound gas
Implementation Method 2
a method of reducing friction can be achieved by providing a dynamic pressure generation mechanism between sealing faces by rotation, and sliding in a state where a liquid film is interposed, a so-called fluid lubrication state
Implementation Method 3
it has a lower affinity with silicate, and it is possible to prevent deposition of a silicate compound contained in the sealed fluid on the sealing face
Data Source
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AI summary
[Technical Problem] The present invention is to prevent leakage due to deposition of a silicate compound in a sliding component such as a mechanical seal that seals a silicate-containing sealed fluid such as LLC to which silicate is added. [Solution to Problem] A sliding component includes an annular stationary side seal ring 5 fixed to the stationary side and an annular rotating side seal ring 3 to be rotated together with a rotating shaft, in which by relatively rotating opposing sealing faces S of the stationary side seal ring 5 and the rotating side seal ring 3, a silicate-containing sealed fluid present on one side in the radial direction of the relatively rotating sealing faces S is sealed, wherein an amorphous carbon film 8 formed by using a hydrocarbon gas containing no silicon compound is provided on at least any one of the sealing faces S of the stationary side seal ring 5 and the rotating side seal ring 3, and content of silicon of the amorphous carbon film 8 is 1.5 at% or less.