PCD Compact Interface Composition to Limit Grain Growth
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Solution Overview
Problem
Polycrystalline diamond (PCD) composite compacts face issues with defects and reduced mechanical properties due to residual solvent/catalyst material, particularly at high temperatures, and exaggerated grain growth near the interface with cemented carbide substrates, which affects their performance in cutting and drilling applications.
Innovation Solution
A PCD composite compact with a PCD structure integrally bonded to a cemented carbide substrate, where the PCD structure comprises coherently bonded diamond grains with a mean size of no greater than 30 microns, and a carbide substrate with a controlled metallic binder ratio, reducing defects and grain growth by introducing excess carbon and optimizing the diamond content and distribution within the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PCD is formed using solvent/catalyst material at high temperature and pressure, then diamond grains are bonded together to form a coherent structure, but residual solvent/catalyst material remains in interstices causing defects and reduced mechanical properties at high temperatures
Solution Approach 1:
The patent removes the harmful residual solvent/catalyst material from the PCD structure by forming the PCD without traditional solvent/catalyst materials, or by using minimal amounts that can be extracted or decomposed during processing, thereby eliminating the source of defects and high-temperature degradation
Solution Approach 2:
The patent modifies the chemical composition parameters of the PCD by controlling the absence or minimal presence of solvent/catalyst materials, changing the material's chemical stability parameters to resist high-temperature degradation while maintaining mechanical strength
2Strength
If PCD structure is bonded to cemented carbide substrate, then mechanical support and bonding are provided, but exaggerated grain growth occurs near the interface reducing manufacturing precision
Solution Approach 1:
The patent applies different compositional qualities to different regions: the PCD structure has one composition optimized for hardness, while the cemented carbide substrate has a controlled composition with limited solvent/catalyst material to prevent exaggerated grain growth at the interface, creating a gradient structure that prevents defect propagation
Solution Approach 2:
The patent uses a controlled cemented carbide substrate composition as an intermediary layer that mediates between the PCD structure and the bonding requirement, where the substrate's controlled solvent/catalyst content prevents excessive grain growth while still providing adequate bonding strength
3Strength
If metallic binder ratio in substrate is increased to improve bonding, then bonding strength increases, but binder pooling occurs creating defects and reducing reliability
Solution Approach 1:
The patent optimizes the metallic binder ratio parameter within a controlled range (0.5-5.0 weight percent), finding the optimal balance point where sufficient bonding strength is achieved without exceeding the threshold that causes binder pooling and associated defects
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 effectively reduces defects and maintains mechanical integrity and abrasion resistance, enhancing the performance of PCD composite compacts in high-temperature applications by minimizing binder pooling and exaggerated grain growth, leading to improved bonding and reduced delamination.
Implementation Method 1
PCD is typically made by subjecting an aggregated mass of diamond grains to an ultra-high pressure of at least about 5.5 GPa and temperature of at least about 1,400 degrees centigrade
Implementation Method 2
The sintering aid is commonly referred to as a solvent/catalyst material for diamond, owing to its function of dissolving diamond to some extent and catalysing its re-precipitation
Implementation Method 3
The sintering aid is commonly referred to as a solvent/catalyst material for diamond, owing to its function of dissolving diamond to some extent and catalysing its re-precipitation
Implementation Method 4
PCD is often formed on a cobalt-cemented tungsten carbide substrate, which provides a source of cobalt solvent/catalyst for the PCD
Data Source
AI summary
The invention relates to a PCD composite compact element comprising a PCD structure integrally bonded at an interface to a cemented carbide substrate; the PCD structure comprising coherently bonded diamond grains having a mean size no greater than 15 microns; the cemented carbide substrate comprising carbide particles dispersed in a metallic binder, the carbide particles comprising a carbide compound of a metal; wherein the ratio of the amount of metallic binder to the amount of the metal at points in the substrate deviates from a mean value by at most 20 percent of the mean value. The invention further relates to a method for making a PDC compact element comprising a PCD structure integrally bonded to a substrate formed of cemented carbide; the method including introducing a source of excess carbon to the substrate at a bonding surface of the substrate to form a carburised substrate; contacting an aggregated mass of diamond grains with the carburised substrate; and sintering the diamond grains in the presence of a solvent/catalyst material for diamond; wherein the mean size of the diamond grains in the aggregated mass is no greater than 30 microns.