Binder-Free Polycrystalline Diamond With High Dislocation Density
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Solution Overview
Problem
Conventional polycrystalline diamond tools suffer from low toughness and hardness due to the presence of sintering aids and binders, which affect their mechanical properties and thermal resistance, and existing methods for improving these properties have limitations in achieving optimal performance for cutting and machining applications.
Innovation Solution
A polycrystalline diamond composition with diamond particles exceeding 99% by volume, a median diameter of 10 nm to 200 nm, and a dislocation density of 2.0×10^15 m^-2 to 4.0×10^16 m^-2, without a binder phase, is developed, incorporating boron for slidability and electrical conductivity, and optimized to enhance toughness and hardness.
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 or heat resistance deteriorate
Solution Approach 1:
The invention extracts and removes the harmful binder phase from the polycrystalline diamond structure. By using a unique sintering method that directly sinters diamond powder without conventional binder materials, the resulting product contains no binder phase, thereby eliminating the deterioration of mechanical properties caused by binders while maintaining sintering feasibility
Solution Approach 2:
The invention changes the sintering parameters to achieve binder-free sintering. By controlling pressure, temperature, and holding time within specific ranges, and using a unique atmosphere control method, the diamond powder sinters directly without requiring conventional binder materials, thus improving hardness and strength
2Temperature
If acid treatment is used to remove sintering aid, then heat resistance improves, but hardness and strength decrease
Solution Approach 1:
The invention performs preliminary action by preventing the formation of harmful binder phases during the sintering process itself, rather than requiring subsequent acid treatment to remove them. The sintering conditions are optimized from the outset to produce a binder-free structure, eliminating the need for damaging post-treatment processes
3Temperature
If heat-resistant SiC is used as binder material, then heat resistance improves, but hardness and strength decrease
Solution Approach 1:
The invention completely extracts and eliminates the binder material (including heat-resistant SiC) from the polycrystalline diamond structure. By using a unique sintering method that achieves direct sintering of diamond powder, the resulting product is a pure diamond structure without any binder phase, thereby achieving both heat resistance and high mechanical 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 resulting polycrystalline diamond exhibits superior toughness, hardness, wear resistance, and chipping resistance, making it suitable for high-speed machining of various materials without the drawbacks of binder-induced property deterioration.
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
Implementation Method 2
Polycrystalline diamond can be produced by directly converting the non-diamond phase to the diamond phase and simultaneously performing sintering
Data Source
AI summary
A polycrystalline diamond comprising diamond particles, wherein: the content of the diamond particles is more than 99% by volume based on the total volume of the polycrystalline diamond; the median diameter d50 of the diamond particles is 10 nm or more and 200 nm or less; and the dislocation density of the diamond particles is 2.0×1015 m−2 or more and 4.0×1016 m−2 or less.