Dry Gas Seal Coating for Low Friction and Wear Resistance
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Solution Overview
Problem
Existing dry gas seals face challenges in achieving low friction and wear resistance, particularly in high-pressure and high-temperature conditions, where friction between silicon carbide surfaces leads to wear and downtime, and existing lubricant systems fail to maintain adhesion effectively.
Innovation Solution
A method involving a coating composition of molybdenum disulfide and graphene oxide, optionally with polydopamine, applied to silicon carbide substrates using air-spray coating, forming a homogenous mixture that achieves ultralow friction and wear resistance by encapsulating molybdenum disulfide flakes in graphene oxide, reducing shear strength and protecting against oxygen and moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DLC or carbon-derived coatings are applied to reduce wear, then friction and wear are reduced, but the coating process is time and capital-intensive
Solution Approach 1:
The patent changes the deposition parameters by using solution-based spray coating instead of conventional PVD/CVD methods, enabling rapid, low-cost application while maintaining coating performance
Solution Approach 2:
The patent uses inexpensive carbonaceous materials (sugar, starch, cellulose) as coating precursors that can be readily deposited and discarded, replacing expensive DLC coating processes
2Reliability
If DLC coating is applied to provide solid lubrication, then friction is reduced, but the coating fails to remain bound to the rotating ring and primary ring
Solution Approach 1:
The patent creates a composite coating system combining carbonaceous material with binder materials that adhere to both the rotating ring and primary ring surfaces, maintaining lubricity while ensuring stable bonding
Solution Approach 2:
The patent introduces binder materials as intermediaries between the carbonaceous coating and the metal surfaces, ensuring the coating remains bound during operation
3Reliability
If friction between SiC-SiC surfaces is reduced, then wear is reduced, but high heat and pressure are generated causing downtime
Solution Approach 1:
The patent converts the harmful friction between SiC surfaces into beneficial low-friction sliding by introducing carbonaceous coatings, thereby reducing both wear and heat generation
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 coating achieves significant reductions in coefficient of friction and wear, maintaining ultralow friction and wear resistance even at elevated temperatures and high loads, with 80% torque reduction and 85% wear reduction observed in tests, and demonstrates improved adhesion and longevity compared to baseline coatings.
Implementation Method 1
forming a homogenous mixture of molybdenum disulfide, graphene oxide, and optional polydopamine (e.g. by sonicating)
Implementation Method 2
evaporating the carrier liquid to form a dry coating layer
Data Source
AI summary
A dry gas seal assembly for use with a rotating machine that includes a rotating shaft, the seal assembly comprises a seal face bears a solid coating comprising molybdenum disulfide, graphene oxide, and optionally polydopamine, preferably wherein the graphene oxide to molybdenum disulfide ratio is 8:10 to 10:8. A method for making a dry gas seal assembly comprises coating a homogeneous dispersion of graphene oxide and molybdenum disulfide on a seal face.