Fluid-Tight DLC Coating for High-Pressure Sealing Surfaces
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Solution Overview
Problem
Conventional coatings for gate and seat components in high-pressure and high-temperature applications, such as oil and gas systems, face issues with friction, wear, corrosion, and fluid leakage due to inadequate lubricity, wear resistance, and fluid impermeability, leading to sticking, galling, and deformation.
Innovation Solution
A fully-dense, fluid-tight, low-friction coating system comprising a thermal spray-fused underlying layer of tungsten carbide-based material and self-fluxing alloy (SFA) without a polymeric or non-polymeric sealant, combined with a diamond-like carbon (DLC) layer, providing improved wear resistance, lubricity, and sealing properties at elevated temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional polymeric lubricating coatings are applied to reduce friction, then lubricity is improved, but the coatings degrade over time at high temperatures and pressures, leading to increased friction and sticking
Solution Approach 1:
The patent applies a composite coating system consisting of a tungsten carbide-based wear-resistant layer combined with a diamond-like carbon (DLC) low-friction layer. This composite structure integrates the high hardness and wear resistance of tungsten carbide with the low coefficient of friction and thermal stability of DLC, achieving both improved lubricity and long-term reliability at high temperatures and pressures without degradation
Solution Approach 2:
The patent changes the material parameters by transitioning from organic polymeric coatings to inorganic coatings (tungsten carbide and DLC). This parameter change eliminates the temperature degradation issue inherent in polymers while maintaining low friction through the DLC layer's unique atomic structure and bonding characteristics
2Strength
If wear-resistant coatings like WCCrCo are applied to improve wear resistance, then wear protection is improved, but the coatings exhibit porosity and gas leakage at high pressures and temperatures
Solution Approach 1:
The patent creates a composite coating where the tungsten carbide-based layer provides wear resistance and the DLC layer provides fluid tightness. The DLC layer acts as a seamless barrier that eliminates the porosity problem inherent in conventional sprayed coatings, preventing gas and fluid leakage while maintaining wear protection
Solution Approach 2:
The DLC layer functions as a thin film barrier that conforms to the substrate surface and provides a continuous, non-porous seal. This thin film structure effectively blocks fluid and gas penetration pathways that would otherwise exist in porous wear-resistant coatings
3Strength
If conventional thermal spray coatings are applied to protect sealing surfaces, then wear resistance is improved, but frictional forces increase at high pressures requiring larger actuators
Solution Approach 1:
The patent combines tungsten carbide-based material for wear resistance with diamond-like carbon for low friction. The DLC layer has an inherently low coefficient of friction that reduces the force required to move the gate, while the tungsten carbide layer maintains wear resistance, thereby reducing actuator size requirements
Solution Approach 2:
The patent substitutes the friction-reducing mechanism by replacing conventional lubricating coatings with a DLC coating that provides low friction through its atomic structure and bonding characteristics rather than through lubrication films. This substitution eliminates the need for external lubricants and provides stable low-friction performance under high pressure
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 system achieves superior resistance to fluid leakage and maintains lubricity, wear resistance, and structural integrity at pressures up to 30,000 psi and temperatures up to 600°F, preventing sticking and galling, and ensuring a stable, impermeable seal over prolonged service life.
Implementation Method 1
a thermal spray-fused underlying layer on the substrate, said thermal spray-fused underlying layer produced from a blend comprising a tungsten carbide-based material and a self-fluxing alloy (SFA)
Implementation Method 2
a low friction layer comprising a diamond-like carbon (DLC) material extending above said thermal spray-fused underlying layer
Data Source
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AI summary
A fully-dense, fluid tight, low friction coating system is described that is characterized by fluid impermeability and a reduced coefficient of friction. The coating system includes a fully dense, fluid tight underlying layer; and a low friction layer. Unlike conventional materials requiring a sealant, the coating systems of the present invention achieves better fluid tightness and maintains said fluid tightness along one or more sealing surfaces at higher service temperatures and service pressures than previously attainable. The constituents of the fully-dense, fluid tight, low friction coating system are physically and chemically compatible so as to not adversely impact lubricity, wear resistance and corrosion resistance during the service life of a component coated with the fully-dense, fluid tight, low friction coating system.