HCP Seeded PDC Cutters for Deep Catalyst Leaching

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Solution Overview

Problem

Polycrystalline diamond compact (PDC) cutting elements in drill bits face thermal instability and reduced impact resistance due to cobalt catalyst removal, limiting leaching depth and increasing leaching time, especially with smaller diamond grain sizes, as existing leaching methods are hindered by material breakdown and increased density.

Innovation Solution

Incorporating a hexagonal close-packed (HCP) crystalline seed material into the PDC structure allows for faster and deeper catalyst removal, enabling deeper leaching and improved leach geometry, particularly with finer diamond particles, by exploiting differing leach rates across seeded and unseeded regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If cobalt catalyst is removed from PDC to improve thermal stability, then thermal instability is reduced, but impact resistance decreases

Engineering Contradiction:

Improvethermal stabilityVSAvoidimpact resistance

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent applies local quality by selectively removing cobalt catalyst from specific regions of the PDC structure rather than uniformly throughout. The leached region is concentrated near the working surface where thermal stability is most critical, while retaining cobalt in the bulk material to maintain impact resistance and structural integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The PDC structure is segmented into distinct regions: a leached region near the working surface depleted of cobalt catalyst for thermal stability, and an unleached bulk region retaining cobalt for mechanical strength. This segmentation allows different regions to optimize for different performance requirements.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If leaching depth is increased to remove more catalyst, then thermal stability improves, but leaching time increases

Engineering Contradiction:

Improvethermal stabilityVSAvoidleaching time

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The patent concentrates the leaching process locally near the working surface rather than uniformly throughout the entire PDC. This localized approach achieves sufficient catalyst removal for thermal stability while minimizing the overall leaching time and depth required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by removing cobalt catalyst only to the extent necessary near the working surface, rather than completely removing it from the entire structure. This partial leaching achieves the required thermal stability improvement without the excessive time and material loss of complete removal.

Inventive Principle:

Principle #16Partial or excessive action

3Strength

If diamond grain size is reduced to improve cutting performance, then abrasion resistance improves, but leaching depth is limited

Engineering Contradiction:

Improveabrasion resistanceVSAvoidleaching depth

Core Design Contradiction:

StrengthVSLength of stationary object

Solution Approach 1:

The patent applies local quality by concentrating the leached region near the working surface where it is most needed, rather than attempting uniform deep leaching throughout the entire PDC structure. This allows fine diamond grains to be effectively treated without requiring excessive leaching depth.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the leaching parameters (depth, time, intensity) to be optimized for fine diamond grain sizes. By adjusting these parameters and concentrating the leaching action locally, the patent overcomes the natural limitation of shallow leaching depths associated with fine grains while maintaining effective catalyst removal.

Inventive Principle:

Principle #35Parameter changes

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

This approach enhances leaching depth and efficiency, maintaining structural integrity and increasing fracture toughness and abrasion resistance, making it practical to leach to depths exceeding previous limitations, even with nano-sized diamond particles.

Implementation Method 1

Methodology Applied

Scientific EffectDifferential leaching:

Implementation Method 2

a sintered polycrystalline diamond structure, which has been seeded with an HCP seed material prior to sintering, is leached to remove catalyst

Methodology Applied

Scientific EffectCatalyst removal:

Implementation Method 3

a polycrystalline diamond compact is made by mixing the polycrystalline diamond in powder form with one or more powdered metal catalysts and other materials, forming the mixture into a compact, and then sintering it using high heat and pressure or microwave heating

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS10711528B2Diamond cutting elements for drill bits seeded with HCP crystalline material

Publication Date: 2020.07.14 ULTERRA DRILLING TECHNOLOGIES LP

AI summary

A polycrystalline diamond compact (PDC), which is attached or bonded to a substrate to form a cutter for a drill bit, is comprised of sintered polycrystalline diamond interspersed with a seed material which has a hexagonal close packed (HCP) crystalline structure. A region of the sintered polycrystalline diamond structure, near one or more of its working surfaces, which has been seeded with an HCP seed material prior to sintering, is leached to remove catalyst. Selectively seeding portions or regions of a sintered polycrystalline diamond structure permits differing leach rates to form leached regions with differing distances or depths and geometries.