Delta-Phase MoN Coating Sliding Wear Reduction
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Solution Overview
Problem
There is a lack of clarity on the most suitable molybdenum nitride layer phase and hardness for sliding elements, with existing methods being expensive and time-consuming for post-treatment, particularly for complex shapes like piston pins and piston rings, and existing molybdenum nitride layers do not consistently achieve optimal sliding properties and wear reduction.
Innovation Solution
A molybdenum nitride layer with a hexagonal delta phase (δ-MoN) is deposited using PVD techniques, with a Vickers hardness between 2600 HV and 3700 HV, and internal stresses between -1 GPa and -9 GPa, followed by a brushing process for post-treatment to achieve improved sliding properties and reduced counter-body wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If molybdenum nitride layers with high hardness (e.g., 5085 HV) are used, then wear resistance is improved, but sliding properties deteriorate due to excessive friction and difficulty in post-treatment
Solution Approach 1:
The patent applies parameter changes by precisely controlling deposition conditions (nitrogen pressure between 1.2-1.8 Pa, substrate temperature between 450-500 °C, bias voltage between -50 to -150 V) to achieve the desired delta phase structure with optimal hardness and sliding properties
Solution Approach 2:
The patent utilizes phase transitions by controlling the crystal structure of molybdenum nitride to form the delta phase (δ-MoN) with hexagonal structure, which inherently provides both high hardness and good sliding properties, eliminating the need for extreme hardness values
2Manufacturing precision
If conventional polishing processes are used for post-treatment, then surface quality is improved, but manufacturing cost and time increase significantly for complex shapes
Solution Approach 1:
The patent employs a brushing process as a simpler, more cost-effective alternative to conventional polishing methods. This mechanical brushing technique can be applied to complex geometries like piston pins and piston rings without requiring expensive specialized equipment or extensive manual intervention
Solution Approach 2:
The patent replaces the complex mechanical polishing system with a simpler brushing mechanism that uses abrasive brushes to achieve adequate surface quality. This substitution maintains functional performance while dramatically reducing manufacturing complexity and cost for complex components
3Ease of operation
If molybdenum nitride layers with optimal sliding properties are used, then friction is reduced, but hardness decreases below the required threshold for wear resistance
Solution Approach 1:
The patent creates a composite structure at the crystal level by forming the delta phase of molybdenum nitride, which combines hard molybdenum atoms with nitrogen atoms in a hexagonal arrangement. This phase composition inherently provides both the hardness needed for wear resistance (2000-5000 HV) and the sliding properties needed for low friction
Solution Approach 2:
The patent achieves the dual requirement of hardness and sliding properties by optimizing deposition parameters: nitrogen pressure (1.2-1.8 Pa), substrate temperature (450-500 °C), and bias voltage (-50 to -150 V). These parameter combinations produce the delta phase with the specific properties needed to satisfy both contradictory requirements simultaneously
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 provides a cost-effective and efficient method for achieving optimal sliding properties and reduced wear, with the molybdenum nitride layers exhibiting excellent tribological performance, including reduced counter-body wear and suitable surface roughness for industrial applications.
Implementation Method 1
A molybdenum nitride layer with a hexagonal delta phase (δ-MoN) is deposited using PVD techniques
Implementation Method 2
followed by a brushing process for post-treatment
Data Source
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AI summary
The invention relates to a coating and a method for the production thereof, said coating comprising at least one Mo-N-based layer of hard material which at least predominantly contains the hexagonal phase of the molybdenum nitride δ-ΜοΝ, the intensity ratio of the two peaks (δ-ΜοΝ 220)/(δ-ΜοΝ 200) being ≥ 3, preferably ≥ 10, especially preferably ≥ 30.