Diamond Composite Polycrystal With Graphite for Longer Tool Life
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Solution Overview
Problem
Diamond polycrystals used in abrasion-resistant tools and cutting tools face issues with increased pull-out resistance, wire breaking during wire drawing, and shortened tool life due to local abrasion and thermal expansion caused by metal oxides or carbides, leading to reduced durability.
Innovation Solution
A composite polycrystal containing polycrystalline diamond with dispersed compressed graphite, where the diamond grains are directly bonded and have a continuous three-dimensional phase, and the graphite has specific grain size and concentration, enhancing abrasion resistance and Knoop hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal oxides or carbides are added to diamond polycrystals, then sintering aid effect is improved, but thermal expansion and local abrasion increase causing reduced tool life
Solution Approach 1:
The patent changes the chemical composition parameter by replacing metal oxides/carbides with specific non-metallic substances (boron nitride, silicon oxide, silicon carbide, boron carbide) that have different thermal expansion characteristics and chemical properties, thereby eliminating thermal expansion issues while maintaining sintering aid functionality
Solution Approach 2:
The patent uses carbon-based materials (amorphous carbon, graphite) as sintering aids that can be consumed or transformed during the sintering process without causing long-term thermal expansion problems, effectively replacing durable but problematic metal-based aids
2Strength
If diamond grain size is reduced to increase hardness, then abrasion resistance is improved, but pull-out resistance increases causing wire breaking
Solution Approach 1:
The patent optimizes the diamond grain size parameter to a specific range (5-50 μm) that balances hardness and pull-out resistance, rather than simply minimizing grain size, and combines this with specific binder phase composition to achieve both high hardness and wire drawing durability
3Strength
If binder phase content is increased to improve bonding, then strength is improved, but abrasion resistance decreases due to local abrasion
Solution Approach 1:
The patent optimizes the binder phase content parameter to a specific range (2-20 mass%) and changes its chemical composition to include elements like Ti, Zr, Hf, V, Nb, Ta, Cr, Mo in controlled amounts, which reduces local abrasion while maintaining adequate bonding strength
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 composite polycrystal exhibits improved abrasion resistance, preventing tool life shortening and prolonging service life by maintaining tool durability and reducing friction and thermal expansion issues.
Implementation Method 1
a composite polycrystal containing polycrystalline diamond formed of diamond grains that are directly bonded mutually
Implementation Method 2
improved abrasion resistance, preventing tool life shortening
Data Source
Figure 1
AI summary
A composite polycrystal contains polycrystalline diamond formed of diamond grains that are directly bonded mutually, and compressed graphite dispersed in the polycrystalline diamond.