Titanium Sintered Body Luster and Weather Resistance
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Solution Overview
Problem
Titanium sintered bodies produced by powder metallurgy methods often lack high design properties due to reflecting raw material properties, and alloys with added elements like iron suffer from poor weather resistance, leading to surface deterioration over time.
Innovation Solution
A titanium sintered body with an average crystal grain diameter of 30 μm to 500 μm, Vickers hardness of 300 to 800, and a balanced α-phase and β-phase structure, along with optimized oxygen content, is developed to enhance luster, polishing properties, and wear resistance, maintaining a high design property over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If iron powder and molybdenum powder are added to titanium powder to achieve desired specularity, then the titanium alloy obtains α+β two-phase structure and specularity for exterior components, but the titanium alloy contains iron which causes poor weather resistance and surface deterioration over time
Solution Approach 1:
The invention removes iron powder from the raw material composition while retaining molybdenum powder (0.1-4.0 wt%) to achieve the desired α+β two-phase structure and specularity. By extracting the harmful iron component that causes poor weather resistance and surface deterioration, the invention maintains the aesthetic properties while improving long-term reliability and corrosion resistance.
Solution Approach 2:
The invention changes the compositional parameters by eliminating iron and optimizing molybdenum content within 0.1-4.0 wt%, along with controlling sintering conditions (1200-1350°C) to achieve the desired crystal grain structure and phase composition. This parameter optimization allows obtaining specularity without the detrimental effects of iron addition.
2Productivity
If powder metallurgy method is used to produce titanium sintered body with shape close to final shape, then secondary processing can be omitted or reduced and components can be efficiently produced, but the titanium sintered body reflects raw material powder properties and it is difficult to obtain appearance with high design property
Solution Approach 1:
The invention optimizes multiple parameters including molybdenum content (0.1-4.0 wt%), sintering temperature (1200-1350°C), and crystal grain size (30-500 μm) to achieve both production efficiency and high design property. By controlling these parameters, the invention obtains excellent luster and polishing properties while maintaining the advantages of powder metallurgy for near-net-shape production.
Solution Approach 2:
The invention achieves high design property by controlling the local crystal grain structure on the surface, obtaining an average crystal grain diameter of 30-500 μm with appropriate α+β phase distribution. This local optimization of microstructure provides excellent luster and polishing properties in the critical surface region while maintaining overall production efficiency.
3Illumination intensity
If crystal grain diameter is increased to improve luster and polishing property, then titanium sintered body obtains excellent luster and favorable polishing property, but mechanical strength may be reduced
Solution Approach 1:
The invention optimizes crystal grain diameter within the range of 30-500 μm to balance luster and mechanical strength. By controlling the crystal grain size in this specific range and maintaining the α+β two-phase structure with molybdenum addition, the invention achieves excellent luster and polishing properties while preventing excessive grain growth that would compromise mechanical strength.
Solution Approach 2:
The invention creates a composite microstructure with α+β two-phase distribution controlled by molybdenum addition (0.1-4.0 wt%). This composite phase structure allows the material to exhibit both the luster and polishing properties associated with appropriate crystal grain size and the mechanical strength provided by the dual-phase microstructure.
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 titanium sintered body achieves excellent luster, polishing smoothness, and long-term design property retention with improved wear and corrosion resistance, suitable for ornaments and timepieces.
Implementation Method 1
a titanium sintered body having a shape close to the final shape can be easily produced
Implementation Method 2
the titanium sintered body has an excellent luster and a favorable polishing property
Data Source
AI summary
A titanium sintered body has an average crystal grain diameter on the surface of more than 30 μm and 500 μm or less, and a Vickers hardness on the surface of 300 or more and 800 or less. In the titanium sintered body, it is preferred that crystal structures on the surface have an average aspect ratio of 1 or more and 3 or less. Further, in the titanium sintered body, it is preferred that the oxygen content on the surface is 2000 ppm by mass or more and 5500 ppm by mass or less. Further, in the titanium sintered body, it is preferred that titanium is contained as a main component, and an α-phase stabilizing element and a β-phase stabilizing element are also present.