DLC-Coated Bearing Rolling Elements With Nitrided Delamination Resistance
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Solution Overview
Problem
Rolling element bearing assemblies face issues with coating delamination due to contamination and substrate deformation, as the coatings are more brittle than the underlying substrate, leading to chipping or flaking.
Innovation Solution
A diamond-like carbon (DLC) coating is bonded directly onto a hardened nitrided layer of metal substrates in rolling element bearings, enhancing the substrate's robustness and resistance to hard particle damage through a surface hardening process involving heat treatment and nitriding, followed by DLC coating application using methods like PVD or CVD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is applied to the substrate, then wear resistance and friction resistance are improved, but the coating is prone to delamination, chipping, or flaking due to brittleness and substrate deformation
Solution Approach 1:
The patent applies a multi-layer composite structure consisting of a metal substrate, a nitrided surface layer, and a DLC coating. The nitrided layer acts as an intermediate layer that combines the ductility of metal with the hardness required to support the brittle DLC coating, preventing delamination while maintaining wear resistance
Solution Approach 2:
The patent changes the physical and chemical parameters of the substrate surface through nitriding, creating a hardened surface layer with different mechanical properties than the base metal. This surface hardening increases the substrate's ability to withstand deformation without causing coating failure
2Strength
If the substrate is hardened through surface treatment, then resistance to hard particle damage is improved, but the surface becomes more brittle and prone to coating delamination
Solution Approach 1:
The patent applies surface hardening (nitriding) only to the specific regions of the substrate that require enhanced resistance to hard particle damage, while maintaining the ductility of the bulk material. The controlled depth and distribution of the nitrided layer provide localized strength without overall brittleness
Solution Approach 2:
The combination of the ductile metal substrate and the hardened nitrided surface layer creates a composite structure where each layer performs its specific function: the base metal provides toughness and ductility, while the nitrided layer provides hardness and particle resistance
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 significantly improves the tribological properties of bearing components by providing a harder surface that resists wear and friction, reducing the likelihood of coating delamination and enhancing the bearing's durability and performance.
Implementation Method 1
at least a portion of the surface layer includes a hardened nitrided layer
Implementation Method 2
DLC coating application using methods like PVD or CVD
Implementation Method 3
DLC coating application using methods like PVD or CVD
Data Source
AI summary
A rolling element for a roller bearing. The rolling element may include a metal substrate having a surface layer. A portion of the surface layer may include a hardened nitrided layer. A diamond-like carbon (DLC) coating may be bonded directly on at least a portion of the hardened nitrided layer.