Metal Ring Laminate Oxidation for Uniform Nitriding Hardness
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Solution Overview
Problem
The existing method for manufacturing metal ring laminates results in a significant difference in surface hardness between the outer and inner metal rings, leading to uneven nitriding and reduced fatigue strength due to inadequate nitrogen gas penetration during nitriding treatment.
Innovation Solution
An oxidizing treatment is performed on the metal ring laminate at a temperature between 350°C and the aging treatment temperature, followed by nitriding, to promote even nitriding and maintain desired strength levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nitriding treatment is performed on the metal ring laminate, then the surface hardness of metal rings is improved, but the difference in surface hardness between outer and inner metal rings becomes large
Solution Approach 1:
An oxidizing treatment is performed as a preliminary step before nitriding treatment. This oxidizing treatment creates a uniform oxide layer on all metal rings in the laminate, including inner rings that would otherwise be inaccessible to nitrogen gas. The preliminary oxidation enables subsequent uniform nitriding across all rings.
Solution Approach 2:
An oxidizing atmosphere (such as air or oxygen-containing gas) is introduced as an intermediary medium to facilitate the nitriding process. The oxidizing treatment modifies the surface of all metal rings to enable uniform nitrogen penetration during the subsequent nitriding step, acting as a mediator between the nitriding gas and the metal surfaces.
2Reliability
If nitriding treatment is performed on the metal ring laminate, then the fatigue strength is enhanced, but nitrogen gas penetration to inner metal rings is insufficient
Solution Approach 1:
The oxidizing treatment is performed beforehand to modify the surface condition of all metal rings, including inner rings. This preliminary surface modification enables nitrogen gas to penetrate uniformly to all rings during the subsequent nitriding treatment, ensuring adequate nitrogen penetration throughout the laminate.
3Manufacturing precision
If each metal ring is nitrided individually, then uniform nitriding is achieved, but the size of the nitriding treatment apparatus becomes large
Solution Approach 1:
Multiple metal rings that would traditionally require separate nitriding treatments are merged into a single laminate structure and treated together as one unit. The oxidizing treatment enables this combined treatment to achieve uniform nitriding across all rings, eliminating the need for multiple separate apparatuses.
Solution Approach 2:
An oxidizing atmosphere serves as an intermediary that enables uniform nitriding to be achieved in a compact apparatus. The oxidizing treatment modifies the entire laminate structure, allowing nitrogen to reach inner rings even in a space-constrained environment, thus enabling combined treatment in a smaller apparatus.
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 reduces the surface hardness difference between outer and inner metal rings, ensuring uniform nitriding and maintaining the desired strength of the metal rings while reducing the size of the nitriding treatment apparatus.
Implementation Method 1
an oxidizing treatment is performed after the aging treatment but before the nitriding treatment
Implementation Method 2
a nitriding treatment is performed on the metal ring laminate
Implementation Method 3
nitrogen gas such as ammonia enters the metal rings
Implementation Method 4
maraging steel, which is ultra-high strength steel hardened by precipitation
Data Source
AI summary
A method for manufacturing a metal ring laminate includes: performing an aging treatment on a metal ring laminate in which a plurality of metal rings made of maraging steel are laminated; and performing a nitriding treatment on the metal ring laminate that has been nitrided. Oxidizing treatment is performed after the aging treatment but before the nitriding treatment at a temperature equal to or higher than 350° C. and lower than an aging treatment temperature.