Cherry Blossom Pink Decorative Coating via Segmented Carbonitride and Gold Alloy Layers

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Solution Overview

Problem

Current decorative members cannot achieve a cherry blossom pink color and lack sufficient scratch resistance, particularly for applications like watch bands where durability is essential.

Innovation Solution

A decorative member is created by layering a carbonitride undercoat layer composed of Ti and Nb or Ta on a base, followed by a thin Au alloy finishing layer, which provides the desired color and enhanced scratch resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional decorative coatings are formed on metal bases, then decorative appearance is achieved, but scratch resistance is insufficient

Engineering Contradiction:
Improvescratch resistanceVSAvoidcolor accuracy
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The decorative coating is divided into multiple functional layers: a hard undercoat layer (Ti, Zr, or Hf carbonitride) providing scratch resistance, and a top decorative layer (Au alloy or Pd alloy) providing the cherry blossom pink color. This segmentation allows each layer to specialize in one function, resolving the contradiction between durability and color accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses composite material structures combining different metals and compounds. The undercoat layer uses carbonitride compounds of hard metals (Ti, Zr, Hf) mixed with Nb and Ta for enhanced hardness, while the top layer uses Au-Cu-Pd or Au-Ag-Pd alloys. This composite approach achieves both high scratch resistance and precise color rendering.

Inventive Principle:
Principle #40Composite materials

2Strength

If hard carbonitride layers are used for scratch resistance, then durability is improved, but the ability to achieve cherry blossom pink color is reduced

Engineering Contradiction:
Improvescratch resistanceVSAvoidcolor formation capability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The coating is segmented into an undercoat layer for hardness and a top layer for color. The undercoat uses Ti, Zr, or Hf carbonitride with Nb/Ta for scratch resistance, while the top layer uses Au-Cu-Pd or Au-Ag-Pd alloys specifically formulated to achieve cherry blossom pink color through controlled composition and thickness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention controls specific parameters including the composition ratios (Au:Cu:Pd or Au:Ag:Pd), layer thicknesses (undercoat 0.5-5.0μm, top layer 0.05-2.0μm), and deposition conditions to achieve the precise cherry blossom pink color while maintaining scratch resistance. By adjusting these parameters, the manufacturing process becomes more precise and reproducible.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If multi-layer structures are implemented to achieve both hardness and color, then scratch resistance and color accuracy are improved, but manufacturing complexity increases

Engineering Contradiction:
Improveoverall performanceVSAvoidlayering process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The coating structure is segmented into two main layers with clear functional differentiation, simplifying the design logic despite the multi-material composition. The undercoat layer handles mechanical protection while the top layer handles aesthetics, making the manufacturing process more systematic and controllable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

By establishing specific parameter ranges for composition and thickness, the invention creates standardized manufacturing parameters that reduce process complexity. The undercoat layer thickness of 0.5-5.0μm and top layer thickness of 0.05-2.0μm, along with defined alloy compositions, provide clear manufacturing guidelines that simplify the overall process.

Inventive Principle:
Principle #35Parameter changes

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 decorative member achieves a cherry blossom pink appearance while offering excellent scratch resistance and corrosion protection, suitable for use in items like watch bands.

Implementation Method 1

a decorative member comprising a base and a decorative coating formed on the base

Methodology Applied
Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

the finishing layer is a Au alloy layer composed of an alloy containing Au, a metal having a silver color, and Cu

Methodology Applied
Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Data Source

PatentEP3441501B1Cherry blossom pink decorative member and production method therefor
Publication Date: 2022.11.09 CITIZEN WATCH CO LTD
  • EP3441501B1 patent drawingFigure 1~4
  • EP3441501B1 patent drawingFigure 5~7
  • EP3441501B1 patent drawingFigure 8~9

AI summary

To provide a decorative member having a cherry blossom pink color. A cherry blossom pink decorative member of the present invention includes a base and a decorative coating formed on the base, wherein the decorative coating is formed by layering an undercoat layer and a finishing layer from the base side, the undercoat layer is a carbonitride layer composed of a carbonitride of a metal containing Ti and at least one selected from Nb and Ta, and the finishing layer is a Au alloy layer composed of an alloy containing Au, a metal having a silver color, and Cu.