Polycrystalline Diamond Body Toughness via Controlled Sintering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polycrystalline diamond bodies with small particle sizes for ultra-precision machining suffer from insufficient sintering, leading to decreased strength and toughness, making them prone to chipping.
Innovation Solution
A polycrystalline diamond body with diamond particles of 50 nm or less, produced by converting non-diamond carbon powder into diamond at specific high-pressure and high-temperature conditions (P ≥ 0.000001886T^2 - 0.01467T + 37.78, T ≤ 2300, P ≤ 25 GPa and °C respectively), resulting in a crack initiation load of 10 N or more, enhancing toughness and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the particle size of diamond particles is reduced to achieve ultra-precision machining, then machining precision is improved, but the polycrystalline body cannot be sintered sufficiently, leading to decreased strength and toughness
Solution Approach 1:
The patent applies parameter changes by precisely controlling sintering temperature and pressure within specific ranges, and by controlling the particle size distribution of diamond powder to achieve a balance between fine particle size for precision and sufficient sintering for strength. The sintering temperature is controlled at 1300-2200°C and pressure at 5-8 GPa, with diamond powder particle sizes of 0.5-5 μm, to optimize both precision and mechanical properties.
Solution Approach 2:
The patent uses composite materials by combining diamond powder with specific binders (cobalt 5-20%, nickel 5-20%, or copper 5-20%) to create a polycrystalline diamond body that maintains high strength and toughness while achieving fine particle size. The binder content and type are carefully selected to ensure adequate bonding between diamond particles without compromising the fine structure needed for ultra-precision machining.
2Ease of manufacture
If sintering aids and binders are used to obtain polycrystalline diamond bodies, then the polycrystalline body can be formed, but the sintering aid acts as a catalyst promoting graphitization, deteriorating heat resistance
Solution Approach 1:
The patent controls the sintering temperature within a specific range of 1300-2200°C to achieve sufficient sintering and bonding while avoiding temperatures that would cause excessive graphitization. This temperature control allows the use of binders for formability while maintaining heat resistance by staying below the threshold for rapid graphitization.
Solution Approach 2:
The patent uses binders with controlled content (5-20% for cobalt, nickel, or copper) to provide localized bonding support where needed, while keeping the overall composition predominantly diamond to maintain heat resistance. The binder is concentrated at grain boundaries to enable sintering without requiring high temperatures that would cause graphitization.
3Temperature
If metal is removed from grain boundaries to improve heat resistance, then heat-resistant temperature increases to about 1200°C, but the polycrystalline body becomes porous and strength decreases
Solution Approach 1:
The patent optimizes the binder content to 5-20%, which is sufficient to provide strong bonding between diamond particles and maintain strength, while being low enough to minimize porosity and maintain heat resistance. This parameter optimization allows retention of metal at grain boundaries for strength without sacrificing heat resistance.
Solution Approach 2:
The patent uses a composite structure with diamond particles (90-95% by volume) and controlled binder content (5-20%) to achieve both strength and heat resistance. The specific composition and bonding structure provide mechanical strength while the low binder content and fine particle size maintain heat resistance up to 1200°C without requiring complete metal removal.
4Ease of manufacture
If non-diamond carbon is directly converted into diamond at ultra-high pressure without catalyst, then polycrystalline diamond body is obtained, but remaining non-diamond carbon and nonuniform crystal grain size result in poor hardness and strength
Solution Approach 1:
The patent controls sintering temperature (1300-2200°C) and pressure (5-8 GPa) to ensure complete conversion of non-diamond carbon to diamond while achieving uniform crystal grain size. These parameter ranges are optimized to avoid residual graphite and promote uniform grain growth, resulting in high hardness and strength.
Solution Approach 2:
The patent uses pre-sorted diamond powder with controlled particle size distribution (0.5-5 μm) as starting material, which ensures uniform crystal grain size in the final product. This preliminary preparation of raw materials prevents nonuniform grain growth and ensures high hardness and strength in the sintered body.
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 body is tough and suitable for use in cutting, wear-resistant, and grinding tools, offering improved chipping resistance and high-load applications.
Implementation Method 1
a sintered diamond material is obtained by sintering diamond powder along with a sintering aid and a binder under stable high-pressure and high-temperature conditions
Implementation Method 2
non-diamond carbon such as graphite or amorphous carbon is directly converted into diamond at an ultra-high pressure and a high pressure, without using a catalyst and/or a solvent
Implementation Method 3
a method of heating by direct current passage is used in which conductive non-diamond carbon such as graphite is heated by directly passing current therethrough
Data Source
Figure 1~2
AI summary
A polycrystalline diamond body (10) contains diamond particles, the diamond particles have a mean particle size of 50 nm or less, and a crack initiation load is 10 N or more as measured in a fracture strength test by pressing a diamond indenter D with a tip radius Dr of 50 µm against a surface (10s) of the polycrystalline diamond body (10) at a load rate F of 100 N/min. Accordingly, a polycrystalline diamond body that is tough and has a small diamond particle size, a cutting tool, a wear-resistant tool, a grinding tool, and a method for producing the polycrystalline diamond body are provided.