Opaque Red Polycrystalline Ceramic Toughness
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Solution Overview
Problem
Existing polycrystalline ceramics used for timepiece exterior parts are unsatisfactory due to excessive pink and transparent color, and low mechanical toughness, making them inadequate for watchmaking applications.
Innovation Solution
A polycrystalline ceramic composed of alumina, chromium oxide, and magnesium oxide, with specific proportions of 0.8-1.2% chromium oxide and 0.03-0.09% magnesium oxide by total weight, achieving a toughness of at least 2.8 MPa·m1/2 and a deep red, opaque color suitable for timepiece exterior parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polycrystalline ceramic composition (alumina, chromium oxide, magnesium oxide) is used to replace monocrystalline ruby, then cost is reduced and transparency is maintained, but the color becomes excessively pink and the toughness becomes excessively low
Solution Approach 1:
The patent applies parameter changes by precisely adjusting the chemical composition parameters of the polycrystalline ceramic. Specifically, it sets chromium oxide content to 0.8-1.2% and magnesium oxide content to 0.03-0.09% by total weight, which optimizes both the toughness (≥2.8 MPa·m1/2) and color appearance (deep red, opaque) of the ceramic material.
2Reliability
If monocrystalline ruby is used for bearings, then high toughness and good mechanical characteristics are achieved, but the material is expensive and less versatile for timepiece exterior parts
Solution Approach 1:
The patent modifies the material parameters by creating a polycrystalline ceramic composition with specific oxide ratios that mimics the mechanical properties of monocrystalline ruby while enabling broader applications. The optimized composition (0.8-1.2% Cr2O3, 0.03-0.09% MgO) achieves comparable toughness and allows the material to be used for both bearings and timepiece exterior parts.
Solution Approach 2:
The patent employs composite materials by combining multiple metal oxides (alumina, chromium oxide, and magnesium oxide) in specific proportions to create a polycrystalline ceramic that integrates the advantages of individual components. This composite approach enables the material to achieve high toughness while maintaining versatility for various applications including timepiece exterior parts.
3Reliability
If additional metal oxides are added to improve appearance and mechanical characteristics, then color and toughness improve, but the composition becomes more complex and manufacturing becomes more difficult
Solution Approach 1:
The patent resolves the contradiction by identifying and optimizing specific parameter ranges for chromium oxide (0.8-1.2%) and magnesium oxide (0.03-0.09%) that simultaneously achieve the desired mechanical characteristics and appearance. This precise parameter optimization avoids the need for additional metal oxides, maintaining composition simplicity while delivering superior performance.
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 ceramic exhibits improved mechanical toughness and a desired red color, allowing for the use in timepiece exterior parts and enabling the inlay of metal inserts, while maintaining a high density and specific colorimetric characteristics.
Implementation Method 1
the invention relates to a polycrystalline ceramic solely formed based on alumina, on chromium oxide and on magnesium oxide, characterized in that the polycrystalline ceramic comprises between 0.8% and 1.2% of chromium oxide by total weight of the polycrystalline ceramic... making it possible to obtain a red ceramic
Implementation Method 2
between 0.03% and 0.09% of magnesium oxide by total weight of the polycrystalline ceramic, making it possible to obtain a red ceramic with a toughness (Kr) at least equal to 2.8 MPa·m1/2
Data Source
AI summary
A polycrystalline ceramic solely formed based on alumina, on chromium oxide and on magnesium oxide, where the polycrystalline ceramic contains between 0.8% and 1.2% of chromium oxide by total weight of the polycrystalline ceramic and between 0.03% and 0.09% of magnesium oxide by total weight of the polycrystalline ceramic, making it possible to obtain a red ceramic with a toughness (Kc) at least equal to 2.8 MPa·m1/2.