Binder-Free Diamond Polycrystal for Crack-Resistant Cutting Tools
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Solution Overview
Problem
Conventional diamond polycrystals used in cutting tools suffer from breakage resistance and cracking issues due to the presence of sintering aids and binders, which compromise their mechanical properties and heat resistance.
Innovation Solution
A diamond polycrystal is produced by converting non-diamond-like carbon materials into diamond grains under specific high-pressure and high-temperature conditions, eliminating the need for sintering aids and binders, and incorporating a ratio of cubic and 6H type hexagonal diamonds to enhance breakage and cracking resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sintering aid or binder is used to produce diamond polycrystal, then the diamond polycrystal can be obtained through sintering process, but the mechanical properties such as hardness and strength or heat resistance decrease
Solution Approach 1:
The invention extracts and removes the harmful sintering aids and binders from the diamond polycrystal production process. By using pure diamond powder without any sintering aid or binder, the patent eliminates the source of mechanical property degradation while still achieving successful sintering through direct carbon phase conversion under high pressure and temperature conditions.
Solution Approach 2:
The invention changes the sintering parameters to enable direct conversion from non-diamond carbon phase to diamond phase. By applying extremely high pressure (5-8 GPa) and high temperature (1300-2200°C), the process bypasses the need for sintering aids, directly transforming the carbon structure into diamond crystalline form through phase transition.
2Temperature
If sintering aid is removed by acid treatment to improve heat resistance, then heat resistance improves, but hardness and strength decrease
Solution Approach 1:
The invention performs preliminary action by preventing the incorporation of sintering aids in the first place. Instead of adding sintering aids and then removing them through acid treatment, the process uses pure diamond powder from the beginning, eliminating the need for post-processing removal steps that damage mechanical properties.
3Ease of manufacture
If non-diamond-like carbon material is directly converted to diamond without sintering aid, then no binder is needed, but the conversion requires very high pressure and temperature
Solution Approach 1:
The invention utilizes phase transition of carbon from non-diamond forms (amorphous carbon, graphite, glassy carbon, or carbon black) to diamond crystalline structure. By applying high pressure and temperature, the carbon atoms reorganize into the diamond lattice structure directly, achieving conversion without requiring sintering aids or binders.
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 diamond polycrystal exhibits excellent breakage resistance, high hardness, and improved cracking resistance, making it suitable for high-load and precision cutting tools without the drawbacks of binder-induced mechanical property degradation.
Implementation Method 1
converting non-diamond-like carbon materials into diamond grains under specific high-pressure and high-temperature conditions
Implementation Method 2
a diamond polycrystal is obtained by sintering a diamond powder, which is a source material, together with a sintering aid or a binder at high pressure and high temperature
Data Source
AI summary
A diamond polycrystal includes diamond grains, the diamond polycrystal including a cubic diamond and a 6H type hexagonal diamond, wherein the cubic diamond and the 6H type hexagonal diamond exist in the same or different diamond grains, and a ratio Ab1/Ab2 is more than or equal to 0.4 and less than or equal to 1, Ab1 representing a maximum value of absorption in a range of more than or equal to 1200 cm−1 and less than or equal to 1300 cm−1 in an infrared absorption spectrum, Ab2 representing a maximum value of absorption in a range of more than or equal to 1900 cm−1 and less than or equal to 2100 cm−1.