Intermetallic Watch Shaft Material for Magnetic and Corrosion Resistance
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Solution Overview
Problem
Existing watch shaft materials face challenges in machinability, resistance to corrosion, impact, fracture, and magnetic interference, necessitating a material that is non-magnetic and meets these criteria simultaneously.
Innovation Solution
A watch shaft composed of at least 20% by mass of non-magnetic intermetallic material with a hardness of at least 400 HV, preferably 450 HV, utilizing binary metal or metalloid combinations like AuTi, CoAl, CuTi, IrTi, MoAl, NiAl, and ZrAl, with specific manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If martensitic steel is used for the watch shaft, then adequate strength properties are achieved, but susceptibility to magnetism and corrosion increases
Solution Approach 1:
The patent employs intermetallic compounds (such as NiAl, CoAl, TiAl) which are composite materials combining metallic elements with specific ordered crystal structures. These materials provide both mechanical strength and resistance to magnetism and corrosion, resolving the contradiction between strength and harmful factor resistance.
Solution Approach 2:
The patent changes the material parameters by selecting intermetallic compounds with specific compositional ranges (e.g., Ni-20-30 wt% Al, Co-25-35 wt% Al) and controlled microstructures. This parameter optimization allows achieving adequate strength while eliminating magnetic susceptibility and improving corrosion resistance.
2Object-affected harmful factors
If ceramic materials are used for the watch shaft, then resistance to corrosion and magnetism is improved, but brittleness under repeated impacts increases
Solution Approach 1:
The patent uses intermetallic compounds that combine the corrosion and magnetic resistance of ceramic-like materials with the ductility and impact resistance of metallic materials. These intermetallics provide a balanced performance that neither pure metal nor pure ceramic can achieve alone.
Solution Approach 2:
By controlling the composition (e.g., Ni-20-30 wt% Al, Co-25-35 wt% Al) and microstructure of the intermetallic materials, the patent optimizes the balance between hardness, strength, and toughness, achieving adequate impact resistance while maintaining corrosion and magnetic field resistance.
3Strength
If multiple thermal and mechanical treatments are applied to achieve required strength properties, then material strength is improved, but manufacturing complexity and processing time increase
Solution Approach 1:
The intermetallic materials possess inherent high strength properties due to their ordered crystal structures and strong atomic bonding, eliminating the need for extensive post-manufacturing heat treatments or mechanical processing to achieve required strength. The material self-provides the necessary mechanical properties.
Solution Approach 2:
The patent selects intermetallic compositions (NiAl, CoAl, TiAl with specific weight percentages) that naturally exhibit adequate strength properties, allowing simplification of manufacturing processes by reducing or eliminating complex thermal and mechanical treatment steps.
Data Source
Figure 1
AI summary
The present invention relates to a watch axis comprising more than 20% by mass of non-magnetic intermetallic material having a hardness greater than 400 HV.