Polycrystalline Diamond Grain Mixture for Graphite-Free Bonding

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Solution Overview

Problem

Conventional polycrystalline diamond (PCD) materials face reduced strength and wear resistance due to graphite areas at grain boundaries, which are trapped during high-pressure sintering and remain in the final product, affecting bonding and durability.

Innovation Solution

The solution involves a mixture of fine-sized partially graphitized diamond grains and coarse-sized non-graphitized diamond grains, subjected to high pressure/high temperature conditions with a sintering aid, resulting in enhanced intercrystalline bonding and minimized graphite presence at grain boundaries, thereby improving structural uniformity and wear resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional high pressure/high temperature sintering is used to form PCD materials, then wear resistance is improved, but graphite areas are trapped at grain boundaries reducing strength

Engineering Contradiction:

ImprovestrengthVSAvoidgraphite areas at grain boundaries

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-graphitizing the fine-sized diamond grains before the main sintering process. This preliminary graphitization converts the harmful graphite-forming tendency of fine grains into a controlled process, allowing the graphite to form during sintering rather than being trapped as defects, thereby eliminating graphite areas at grain boundaries while maintaining strength

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter of diamond grain size distribution by using a bimodal mixture of fine-sized (0.01-6 micrometers) and coarse-sized (>6 micrometers) diamond grains. This parameter change allows different grain sizes to serve different functions: fine grains provide wear resistance while coarse grains provide structural strength, and the size difference prevents graphite trapping at grain boundaries

Inventive Principle:

Principle #35Parameter changes

2Reliability

If fine-sized diamond grains are used to improve wear resistance, then wear resistance is improved, but graphite formation at grain boundaries reduces bonding strength

Engineering Contradiction:

Improvewear resistanceVSAvoidbonding strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by creating different functional zones within the PCD material: fine-sized diamond grains are concentrated in regions requiring wear resistance, while coarse-sized diamond grains are concentrated in regions requiring structural strength. The bimodal size distribution creates local variations in grain characteristics that optimize both wear resistance and bonding strength simultaneously

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining two different diamond grain size populations (fine-sized and coarse-sized) in a single PCD construction. This composite approach allows the material to exhibit both the wear resistance of fine grains and the bonding strength of coarse grains, resolving the contradiction between these two properties

Inventive Principle:

Principle #40Composite materials

3Strength

If graphite is present at grain boundaries during sintering, then bonding occurs, but graphite remains in final product reducing durability

Engineering Contradiction:

ImprovebondingVSAvoiddurability

Core Design Contradiction:

StrengthVSDuration of action of stationary object

Solution Approach 1:

The patent converts the harmful effect of graphite formation into a beneficial process by controlling the graphitization to occur during sintering rather than before. The fine-sized diamond grains are pre-prepared to graphitize, and this graphitization is harnessed as a beneficial mechanism that promotes bonding while preventing graphite from remaining as harmful trapped areas in the final product, thereby improving durability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 the strength and wear resistance of PCD materials by eliminating graphite at grain boundaries and promoting more intense bonding between diamond grains, leading to improved mechanical properties.

Implementation Method 1

The resulting polycrystalline diamond construction includes bonded-together diamond grains

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 2

The fine-sized diamond grains are partially graphitized

Methodology Applied

Scientific EffectGraphitization: Phase Change

Data Source

PatentUS11761062B2Polycrystalline diamond constructions

Publication Date: 2023.09.19 SCHLUMBERGER TECH CORP

AI summary

Polycrystalline diamond constructions are formed from a mixture of diamond grains including a first volume of fine-sized diamond grains, and a second volume of coarse-sized diamond grains. The fine-sized diamond grains are partially graphitized, and the coarse-sized diamond grains are not graphitized. The mixture of diamond grains is subjected to high pressure/high temperature sintering process conditions in the presence of a sintering aid thereby forming polycrystalline diamond. Contact areas between coarse-sized diamond grains in the polycrystalline diamond construction are substantially free of graphite.