Polycrystalline Diamond Composite Without Sintering Aids
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Solution Overview
Problem
Conventional polycrystalline diamond tools have limitations in hardness and slidability, which hinder their performance in high-speed machining and wire drawing applications, particularly due to the presence of sintering aids and binders that degrade mechanical properties and introduce directional anisotropy.
Innovation Solution
A polycrystalline composite comprising diamond particles and non-diamond carbon, with a high volume percentage of diamond (>99%), optimized dislocation density, and minimal impurities, which eliminates the need for sintering aids and binders, enhancing hardness and slidability through direct bonding of diamond particles and non-diamond carbon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sintering aid or binder material is used to produce polycrystalline diamond, then the diamond can be sintered under high pressure and high temperature, but the mechanical properties such as hardness and strength deteriorate
Solution Approach 1:
The invention extracts and removes the sintering aid from the polycrystalline diamond structure through acid treatment, eliminating the harmful component while preserving the diamond particles. This resolves the contradiction by removing the element that causes mechanical property deterioration while maintaining the sintered structure's integrity
Solution Approach 2:
The invention creates a composite structure where diamond particles are directly bonded to each other without traditional binder materials. The direct diamond-to-diamond bonding forms a composite material with superior mechanical properties, eliminating the need for sintering aids that compromise hardness and strength
2Temperature
If heat-resistant SiC is used as binder material, then heat resistance is improved, but hardness and strength decrease
Solution Approach 1:
The invention completely removes the SiC binder material from the polycrystalline diamond structure through acid treatment, eliminating the compromise between heat resistance and mechanical strength. The resulting structure relies on direct diamond bonding rather than binder materials
Solution Approach 2:
The invention changes the bonding mechanism from binder-mediated (SiC) to direct diamond-to-diamond bonding. This parameter change in the bonding interface eliminates the need for heat-resistant binders while achieving superior mechanical properties through the inherent strength of diamond bonds
3Ease of manufacture
If conventional polycrystalline diamond is produced with sintering aid, then the material can be manufactured, but directional hardness and cleavage are introduced
Solution Approach 1:
The invention removes the sintering aid that causes directional anisotropy and cleavage planes. By eliminating this foreign material, the resulting polycrystalline diamond achieves isotropic properties without directional hardness variations or cleavage weaknesses
Solution Approach 2:
The invention achieves a homogeneous structure where diamond particles are uniformly distributed and directly bonded without foreign sintering aid materials. This homogeneity eliminates directional properties and cleavage, creating isotropic mechanical behavior in all directions
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 achieves superior hardness and slidability, leading to improved wear resistance and machining performance without the drawbacks of directional properties or thermal expansion issues, making it suitable for high-speed machining and wire drawing.
Implementation Method 1
Such a non-diamond carbon material as graphite, glassy carbon, amorphous carbon and onion-like carbon can be directly converted into diamond under ultra-high pressure and high temperature without sintering aid or the like used
Data Source
AI summary
A polycrystalline composite comprising diamond particles and non-diamond carbon, wherein: the sum of the content Vd of the diamond particles and the content Vg of the non-diamond carbon is more than 99% by volume based on the total volume of the polycrystalline composite; the median diameter d50 of the diamond particles is 10 nm or more and 200 nm or less; the dislocation density of the diamond particles is 1.0×1013 m−2 or more and 1.0×1016 m−2 or less; and the content Vd of the diamond particles and the content Vg of the non-diamond carbon satisfy the relationship represented by the formula 1:0.01<Vg/(Vd+Vg)≤0.5 Formula 1.