TiC Coated Timepiece with Graded Elastic Modulus
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Solution Overview
Problem
Decorative articles made from metals like platinum and silver are prone to scratching and deterioration due to their low hardness, and existing solutions like nitriding result in a roughened surface that compromises their appearance and provides inadequate protection against strong external forces.
Innovation Solution
A decorative article with a substrate of Ti or stainless steel coated with a multi-layered TiC coating, where the elastic modulus varies through the thickness to enhance hardness and self-repairing capabilities, making it resistant to scratches and indentations while maintaining a polished appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nitriding process is applied to increase hardness, then resistance to weak external forces is improved, but surface roughening occurs and polished appearance is lost
Solution Approach 1:
The coating is divided into multiple layers with different carbon content: a first layer with high carbon content (40-60 wt%) for hardness and scratch resistance, and a second layer with lower carbon content (10-30 wt%) for maintaining polished appearance and elastic modulus. This segmentation allows each layer to fulfill different functions simultaneously.
Solution Approach 2:
Different regions of the coating have different properties: the outer layer has high carbon content for hardness and scratch resistance, while the inner layer has lower carbon content for elasticity and appearance. This local differentiation of material properties resolves the contradiction between hardness and surface finish.
2Strength
If nitriding process is applied to increase hardness, then resistance to scratching by weak forces is improved, but protection against strong external forces remains inadequate
Solution Approach 1:
The invention uses a composite coating structure with two distinct layers having different compositions and properties. The high-carbon outer layer provides scratch resistance while the low-carbon inner layer provides elasticity and impact resistance, together offering comprehensive protection against both weak and strong external forces.
Solution Approach 2:
The carbon content parameter is changed through the thickness of the coating, with high carbon content (40-60 wt%) in the outer layer for hardness and low carbon content (10-30 wt%) in the inner layer for elasticity. This parameter gradient allows the coating to resist both scratching and indentation from strong forces.
3Ease of manufacture
If uniform carbon content is used throughout the coating, then manufacturing is simplified, but self-repairing effect is reduced
Solution Approach 1:
The coating is segmented into layers with different carbon contents to enable the self-repairing effect. The inner layer with lower carbon content acts as a reservoir that can flow into scratches and indentations in the outer layer, automatically repairing damage without complex manufacturing processes.
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 decorative article that is highly resistant to scratches and indentations, with the self-repairing properties ensuring that any damage from strong external forces becomes inconspicuous, maintaining the article's appearance and durability.
Implementation Method 1
a coating made of primarily TiC and disposed on the substrate. The coating has at least a first region, and a second region disposed on the substrate side of the first region. The elastic modulus of the second region being greater than the elastic modulus of the first region.
Implementation Method 2
The C content of the first region is preferably greater than or equal to 45 wt % and less than or equal to 60 wt %. This configuration increases the hardness of the outside surface of the coating
Implementation Method 3
The elastic modulus of the second region being greater than the elastic modulus of the first region. This configuration increases the hardness of the entire coating, and enhances the self-repairing effect of the second region.
Data Source
AI summary
An external part of a timepiece has a substrate that includes a base layer and a surface layer, the surface layer including Ti or stainless steel; and a coating disposed on the substrate. The coating includes an outermost layer formed primarily of TiC defining an external surface, and an interior layer formed primarily of TiC positioned between the substrate and the outermost layer. An elastic modulus of the interior layer is greater than the elasticmodulus of the outermost layer.