Polycrystalline Diamond Coating for Oxidation and Triboplasma Control
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Solution Overview
Problem
Existing polycrystalline diamond technologies face issues with hardness deterioration, thermal cracking, oxidation resistance, and triboplasma generation when processing ceramics or resin, particularly due to differences in thermal expansion coefficients and the water-solubility of boron oxide protective films.
Innovation Solution
A polycrystalline diamond with a water-insoluble protective film formed by incorporating boron, nitrogen, and silicon, where boron is dispersed at an atomic level in an isolated substitutional type, and nitrogen and silicon are present in isolated substitutional or interstitial types, forming a diamond single phase without a binding phase, and a graphene nanoribbon-derived protective film is created to suppress triboplasma and enhance oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a boron compound is added to polycrystalline diamond to form a protective film, then oxidation resistance is improved, but hardness deteriorates and thermal cracking occurs
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating nitrogen and silicon alongside boron in specific ratios (B: 1×10^14 to 1×10^21 atoms/cm³, N: 1×10^18 to 1×10^20 atoms/cm³, Si: 1×10^18 to 1×10^20 atoms/cm³). This parameter optimization allows formation of a protective film with improved oxidation resistance while maintaining hardness by preventing excessive boron aggregation.
Solution Approach 2:
The patent creates a composite protective film system on the diamond surface containing boron, nitrogen, and silicon elements. This composite approach forms a multi-component protective layer (including boron nitride and silicon oxide phases) that provides both oxidation resistance and maintains mechanical strength, avoiding the drawbacks of single-element boron compounds.
2Reliability
If boron compound is used to form protective film, then oxidation resistance is improved, but thermal stability worsens due to different thermal expansion coefficients
Solution Approach 1:
The patent optimizes the concentration parameters of boron, nitrogen, and silicon within specific ranges to control the thermal expansion characteristics of the protective film. By maintaining boron at ≤1×10^21 atoms/cm³ and combining it with nitrogen and silicon, the film's thermal expansion coefficient is adjusted to match diamond more closely, reducing thermal stress and preventing cracking at high temperatures.
3Productivity
If conventional nano polycrystalline diamond is used to process insulating materials, then productivity is maintained, but triboplasma generation increases causing wear and tear
Solution Approach 1:
The patent introduces nitrogen and silicon as intermediary elements that modify the surface properties of the diamond. These elements create a protective film that acts as an intermediary layer between the diamond and the workpiece, reducing direct contact and friction. This mediator effect suppresses triboplasma generation while maintaining the cutting efficiency needed for processing insulating materials like ceramics and resin.
4Reliability
If boron oxide protective film is formed, then oxidation resistance is improved, but water solubility causes loss of protective effect
Solution Approach 1:
The patent creates a composite protective film containing boron, nitrogen, and silicon that forms water-insoluble compounds. The combination of elements produces a multi-phase protective layer including boron nitride and silicon oxide, which are not water-soluble. This composite structure maintains the protective film's integrity in the presence of aqueous cutting fluids, preventing wash-off and maintaining continuous protection.
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 solution provides a polycrystalline diamond with improved isotropic hardness, reduced dynamic friction coefficient, and enhanced wear resistance, suitable for processing insulating materials like ceramics and resin, while maintaining mechanical strength and oxidation resistance.
Implementation Method 1
boron is dispersed in the crystal grains at an atomic level, and greater than or equal to 90 atomic% of all the boron is present in an isolated substitutional type
Implementation Method 2
nitrogen and silicon are present in an isolated substitutional type or an interstitial type in the crystal grains
Implementation Method 3
converting the graphite to diamond by pressure heat treatment in the vessel
Data Source
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AI summary
Provided is polycrystalline diamond having a diamond single phase as basic composition, in which the polycrystalline diamond includes a plurality of crystal grains and contains boron, at least either of nitrogen and silicon, and a remainder including carbon and trace impurities; the boron is dispersed in the crystal grains at an atomic level, and greater than or equal to 90 atomic% of the boron is present in an isolated substitutional type; the nitrogen and the silicon are present in an isolated substitutional type or an interstitial type in the crystal grains; each of the crystal grains has a grain size of less than or equal to 500 nm; and the polycrystalline diamond has a surface covered with a protective film.