CVD Diamond Tool Working Surface for Fine Finish and Wear Resistance
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Solution Overview
Problem
Current diamond tools, particularly those made from polycrystalline CVD diamond, fail to provide a combination of fine surface finish and large working surface dimensions at a reasonable cost, as they suffer from grain chipping and poor quality surfaces compared to single crystal diamond tools.
Innovation Solution
A polycrystalline CVD synthetic diamond tool with a working surface formed from a processed nucleation face, having smaller diamond grains and low sp2 carbon content, is used, which is mounted in a holder to expose the nucleation face for improved surface finish and wear resistance, while maintaining large dimensions and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polycrystalline CVD diamond material is used to fabricate diamond tools, then the tools can be produced at lower cost and in larger sizes, but the surface finish quality deteriorates compared to single crystal diamond tools
Solution Approach 1:
The patent applies local quality by orienting the polycrystalline CVD diamond material such that the nucleation face, which possesses superior surface finish characteristics, is positioned to form the working surface of the tool. This selective orientation allows different regions of the material to serve different functions: the nucleation face provides high-quality surface finish where it contacts the workpiece, while the bulk material provides structural support and cost-effectiveness. This resolves the contradiction by achieving single-crystal-like surface quality on a polycrystalline, cost-effective substrate.
2Strength
If the growth face of polycrystalline CVD diamond is used as the working surface, then the material has better inter-grain bonding and higher toughness, but the surface finish quality deteriorates
Solution Approach 1:
The patent inverts the conventional approach by using the nucleation face instead of the growth face as the working surface. Conventionally, the growth face is used because it has better inter-grain bonding and higher toughness. However, the invention discovers that the nucleation face, while having slightly different mechanical properties, provides superior surface finish quality. This inversion allows the tool to achieve the primary function of high-quality surface finishing, with the understanding that the bulk material still provides adequate structural support.
3Manufacturing precision
If single crystal diamond material is used, then the surface finish quality is excellent, but the tool cost increases significantly and available sizes are limited
Solution Approach 1:
The patent uses polycrystalline CVD diamond material as a 'copy' or substitute for single crystal diamond, achieving similar surface finish quality characteristics. By selectively orienting the nucleation face of the polycrystalline material to form the working surface, the invention replicates the surface quality benefits of single crystal diamond while avoiding the high cost and size limitations. This allows manufacturers to produce larger tools at lower costs while maintaining excellent surface finish capability.
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 achieves a high-quality surface finish comparable to single crystal diamond tools, with improved wear resistance and larger sizes, addressing the limitations of existing polycrystalline CVD diamond tools in industrial applications.
Implementation Method 1
polycrystalline CVD synthetic diamond material which comprises a plurality of diamond grains directly bonded together via diamond-to-diamond bonding as a result of the CVD growth method
Implementation Method 2
diamond grains directly bonded together via diamond-to-diamond bonding as a result of the CVD growth method, without the use of any metal solvent
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(d)
AI summary
A polycrystalline CVD synthetic diamond work piece for use in a polycrystalline CVD synthetic diamond tool, the polycrystalline CVD synthetic diamond work piece comprising: a working surface; and a rear mounting surface; wherein an average lateral grain size of the rear mounting surface is no less than 10 μm, and wherein the working surface comprises: (a) smaller diamond grains than the rear mounting surface; (b) an average lateral grain size in a range 10 nm to 15 μm; and (c) a Raman signal generated by a laser focused on the working surface which exhibits one or more of the following characteristics: (1) an sp3 carbon peak at 1332 cm-1 having a full width half-maximum of no more than 8.0 cm-1, (2) an sp2 carbon peak at 1550 cm-1 having a height which is no more than 20% of a height of an sp3 carbon peak at 1332 cm-1 after background subtraction when using a Raman excitation source at 633 nm; and (3) an sp3 carbon peak at 1332 cm-1 is no less than 10% of local background intensity in a Raman spectrum using a Raman excitation source at 785 nm.