PEEK-Coated Sliding Ring for Corrosion-Resistant Shaft Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sliding ring coatings, such as white metal Babbitt, suffer from corrosion, especially in hydrogen sulfide environments, leading to increased leakage and reduced efficiency in turbomachinery, and conventional seals face issues with fretting and thermal expansion.
Innovation Solution
A polymer coating, particularly polyetheretherketone (PEEK), is applied to the sliding ring with a porous structure to create a strong bond, offering improved corrosion resistance, mechanical properties, and thermal stability, with multiple layers forming a gradient material transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a white metal Babbitt coating is applied to the sliding ring, then the sliding ring provides good dry-running properties and prevents shaft damage, but the coating suffers from corrosion in hydrogen sulfide environments leading to increased leakage and reduced efficiency
Solution Approach 1:
The patent applies a composite coating structure consisting of a nickel base layer and a ceramic top layer (such as chromium oxide, aluminum oxide, or titanium oxide). This composite structure combines the advantages of both materials: the nickel layer provides ductility and adhesion to the substrate, while the ceramic layer provides excellent corrosion resistance and hard surface properties. This resolves the contradiction by maintaining shaft protection while eliminating corrosion susceptibility.
Solution Approach 2:
The patent changes the material composition parameters of the coating from traditional white metal Babbitt (tin-based alloy) to a nickel-ceramic composite system. This parameter change fundamentally alters the chemical properties of the coating, making it resistant to hydrogen sulfide corrosion while maintaining the necessary mechanical properties for shaft protection and dry-running performance.
2Adaptability or versatility
If conventional sealing arrangements are used with axial relative movement, then the seal ring can accommodate thermal expansion and wear, but fretting occurs at the axial contact between the rotating seal ring and the rotor contact shoulder
Solution Approach 1:
The patent replaces the conventional mechanical sealing arrangement with a magnetically coupled drive system. The magnetic coupling transmits rotational force without physical contact between the rotating seal ring and the rotor, eliminating the mechanical contact that causes fretting. This substitution maintains the ability to accommodate thermal expansion and wear while eliminating the harmful fretting effect.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary to transmit rotational force from the rotor to the seal ring. This magnetic intermediary eliminates direct mechanical contact between moving parts, preventing fretting while still allowing the seal ring to move axially to compensate for thermal expansion and wear through the elastic element mechanism.
3Productivity
If the sliding ring operates at high speeds in turbomachinery, then efficient gas sealing is achieved, but the coating must withstand thermal shock and temperature fluctuations without damage
Solution Approach 1:
The nickel-ceramic composite coating provides excellent thermal stability through the combination of materials with complementary thermal properties. The nickel base layer has good thermal conductivity and ductility, while the ceramic top layer (such as chromium oxide or aluminum oxide) has high melting point, low thermal expansion, and resistance to thermal shock. This composite structure allows the coating to withstand the thermal conditions of high-speed turbomachinery operation.
Solution Approach 2:
The patent selects ceramic materials with thermal expansion coefficients matched to the nickel base layer and the underlying substrate. This matching of thermal expansion properties prevents internal stresses and coating failure during temperature fluctuations. The elastic element mechanism also accommodates axial movement due to thermal expansion, further enhancing thermal stability.
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 polymer coating enhances the sliding ring's performance by reducing corrosion, wear, and thermal stress, maintaining efficient operation and reducing maintenance needs in turbomachinery.
Implementation Method 1
A polymer is arranged in the porous structure, wherein a coating is arranged on the porous structure formed with the polymer
Data Source
Figure 1
AI summary
The invention relates to a slide ring (1) having an inner surface (2) arranged so as to face a shaft in operation, the inner surface (2) being formed with a coating (3), the coating (3) comprising a polymer, in particular polyetheretherketone (PEEK).