Polycrystalline Diamond Pick Tool Tip Fracture Resistance
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Solution Overview
Problem
There is a need for pick tools with polycrystalline diamond (PCD) tips that have high resistance to fracture while maintaining wear resistance.
Innovation Solution
A PCD tip structure with a thickness of at least 3mm, containing filler materials like cobalt, iron, or nickel, where the filler material content is greater than 5 weight percent near the strike surface, and a method involving sintering diamond grains with a catalyst material under high pressure and temperature to form a robust PCD structure bonded to a cemented metal carbide substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the PCD structure thickness is increased to improve fracture resistance, then the tip becomes more resistant to fracture, but the wear resistance may be compromised due to potential catalyst migration and grain growth
Solution Approach 1:
The patent applies local quality by creating distinct regions within the PCD structure with different catalyst concentrations. The first region near the strike surface has a first catalyst concentration optimized for wear resistance, while the second region has a second catalyst concentration optimized for fracture resistance. This spatial variation in material properties allows each region to perform its specific function optimally without compromising the other.
Solution Approach 2:
The patent creates a composite PCD structure with two distinct regions having different catalyst concentrations. This composite approach combines the benefits of low-catalyst material (superior wear resistance) in the first region with high-catalyst material (superior fracture resistance) in the second region, achieving a balance between conflicting performance requirements that cannot be obtained with a uniform composition.
2Strength
If filler material content is increased to improve fracture toughness, then the PCD structure becomes more resistant to cracking, but the wear resistance decreases due to softer filler material
Solution Approach 1:
The patent implements local quality by varying the filler material content and type in different regions of the PCD structure. The first region has a filler content and composition optimized for wear resistance, while the second region has increased filler content optimized for fracture toughness. This regional differentiation allows the structure to exhibit both wear resistance and fracture toughness without the trade-off that would occur in a uniform material.
Solution Approach 2:
The patent creates a composite structure with two regions having different filler material characteristics. The first region uses minimal filler or filler optimized for wear resistance, while the second region incorporates increased filler material content to enhance fracture toughness. This composite approach allows the overall structure to achieve both wear resistance and fracture toughness by combining regions with complementary properties.
3Reliability
If a non-planar interface is used between PCD and substrate to reduce stress concentrations, then shear failures are reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by creating a non-planar interface with specific geometric features tailored to stress distribution requirements. The interface includes regions of varying curvature and thickness that locally adapt to reduce stress concentrations at critical locations. This targeted approach to interface geometry reduces shear failures without requiring complete complexity throughout the entire interface structure.
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 enhances the fracture toughness and wear resistance of the pick tool tips, potentially extending their working life by reducing the risk of cracks and stress concentrations, and minimizing the complexity of the interface, thus reducing shear failures and residual stresses.
Implementation Method 1
providing an aggregation comprising a plurality of diamond grains combined with a source of catalyst material for diamond
Implementation Method 2
subjecting the pre-sinter assembly to a pressure and temperature at which the diamond grains can be sintered together in the presence of the catalyst material
Data Source
AI summary
A tip for a pick tool, comprising a polycrystalline diamond (PCD) structure joined to a substrate body. The PCD structure has a strike surface including an apex opposite a boundary with the substrate body. At least an outer volume of the PCD structure contains filler material between diamond grains, the content of the filler material being more than 5 weight per cent of the PCD material in the outer volume. The outer volume is proximate at least an area of the strike surface including the apex, and the thickness of the PCD structure between the apex and the boundary with the substrate body is at least 2.5 mm.