Mo-N Hard Layer System for Wear Reduction
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Solution Overview
Problem
Carbon-based hard material coatings used in tribological applications face limitations due to complex and expensive coating processes, insufficient chemical resistance to modern lubricants, loss of structural and chemical stability at elevated temperatures, and poor oxidation resistance, especially under increased mechanical and thermal loads.
Innovation Solution
The controlled adjustment of PVD layer deposition process parameters, such as nitrogen partial pressure and bias voltage, allows for targeted manipulation of Mo-N hard material layer microstructure, influencing tribological performance and counter-body wear without adverse effects on chemical and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon-based hard material coatings are used for tribological applications, then friction reduction and wear protection are achieved, but chemical resistance to modern lubricant additives and oxidation resistance at elevated temperatures deteriorate
Solution Approach 1:
The patent applies composite material principles by combining multiple layers with different compositions and functions. The coating system includes a base layer (e.g., CrN, CrC, or Mo-based) providing chemical stability and adhesion, overlaid with carbon-based tribological layers (DLC, WC/C) for friction reduction. This composite structure allows each layer to perform its specialized function, resolving the contradiction between tribological performance and chemical/oxidation resistance.
Solution Approach 2:
The patent employs parameter changes by modifying the composition, thickness, and deposition conditions of coating layers. By adjusting carbon content, hybridization state (sp2/sp3), and layer thickness parameters, the coating achieves optimal balance between low friction and chemical stability. Process parameters such as deposition temperature, pressure, and gas flow ratios are controlled to produce layers with tailored properties that resist both wear and chemical degradation.
2Reliability
If carbon-based coatings are applied to protect components, then wear protection is improved, but coating process complexity and maintenance requirements increase due to hydrophilicity
Solution Approach 1:
The patent extracts and addresses the hydrophilicity issue by incorporating specific process steps that modify the coating surface properties. Plasma treatment, chemical vapor deposition, or controlled oxidation steps are introduced to reduce hydrophilicity and improve coating stability, thereby simplifying overall system maintenance while preserving wear protection benefits.
Solution Approach 2:
The patent employs inert atmosphere techniques during coating deposition and storage to prevent unwanted chemical reactions and reduce hydrophilicity. By controlling the atmospheric environment (using inert gases like nitrogen or argon), the coating maintains its intended properties without requiring complex post-processing or maintenance, thus reducing device complexity while preserving protective functions.
3Power
If operating temperature of components is increased, then performance under mechanical load is improved, but structural and chemical stability of carbon-based coatings deteriorates at elevated temperatures
Solution Approach 1:
The patent uses composite material structures where a thermally stable base layer (such as CrN, CrC, or Mo-based alloys) is combined with carbon-based tribological layers. The base layer acts as a thermal barrier and structural support that maintains stability at elevated temperatures, while the carbon layers provide friction reduction. This composite approach allows the component to operate at higher temperatures without compromising coating integrity.
Solution Approach 2:
The patent applies parameter changes by optimizing the deposition temperature, layer thickness, and composition ratios to enhance thermal stability. By controlling the sp3 hybridization content and reducing residual stresses through adjusted deposition parameters, the coating maintains its structural integrity at elevated operating temperatures, enabling higher power transmission while preserving chemical 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
This approach results in improved tribological performance, including reduced counter-body wear and consistent friction coefficients, with a performance increase of approximately 20% under dry conditions, and potential for further enhancement with longer test durations.
Implementation Method 1
at least one hard material layer system comprising molybdenum nitride is applied to a surface of a body by means of PVD layer deposition
Implementation Method 2
Self-lubricating properties are reported with the formation of molybdenum oxide even at room temperature in tribological contact
Implementation Method 3
Self-lubricating properties are reported with the formation of molybdenum oxide even at room temperature in tribological contact
Data Source
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AI summary
The present invention relates to a method for improving the wear of a body in tribological contact with steel and ceramic, characterized in that at least one system of hard material layers comprising molybdenum nitride is applied to the surface of a body by means of PVD layer deposition, wherein the system of hard material layers comprises at least one hard material layer of molybdenum nitride, characterized in that the molybdenum-nitride hard material layer comprises the cubic phase of the molybdenum nitride γ- Mo2N, which has an intensity ratio of the two associated peaks 200/111 of less than 10, preferably less than 2.3, and has an absolute half width at the 200 peak of 0.94 - 1.24, preferably of 1.09 - 1.19.