Carbonate PCD Cutting Elements Without Substrate Bonding
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Solution Overview
Problem
Conventional cutting elements with diamond surfaces bonded to tungsten carbide substrates experience high residual compressive stress, leading to breakage and delamination during drilling due to mismatched thermal expansion coefficients, compromising wear resistance and service life.
Innovation Solution
A diamond-bonded body is sintered under HPHT conditions using a carbonate material without a substrate, creating a carbonate polycrystalline diamond (PCD) body with intercrystalline bonding and interstitial regions, which is then mechanically coupled with a matrix casting to form a cutting element, reducing residual stress and enhancing wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a diamond layer is bonded to a tungsten carbide substrate using HPHT process, then wear resistance and abrasion resistance are improved, but residual compressive stress increases leading to breakage and delamination
Solution Approach 1:
The invention separates the diamond layer formation from the substrate attachment process. The diamond layer is first sintered as a standalone PCD body, then mechanically coupled to the substrate via a matrix casting process, eliminating the thermal stress issues of direct HPHT bonding while maintaining wear resistance
Solution Approach 2:
The invention changes the bonding mechanism from direct thermal-chemical bonding (HPHT) to mechanical coupling through matrix casting. This parameter change in the attachment process eliminates residual compressive stress while preserving the diamond layer's wear resistance properties
2Reliability
If residual tensile stress is reduced at the diamond layer-substrate interface, then breakage and delamination are minimized, but wear resistance and crack initiation resistance are compromised
Solution Approach 1:
By separating the diamond layer sintering from substrate attachment, the invention allows independent optimization of each component. The diamond layer can be sintered with minimal stress, then mechanically coupled to the substrate, maintaining both low residual stress and high wear resistance
Solution Approach 2:
The matrix casting acts as an intermediary between the diamond layer and substrate, providing a mechanical coupling mechanism that reduces residual stress while maintaining the structural integrity and wear resistance of the diamond surface
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 approach significantly reduces residual stress in cutting elements, improving fracture resistance, wear resistance, and impact resistance, thereby extending the operational service life while maintaining or exceeding the wear and impact resistance of conventional PCD cutting elements.
Implementation Method 1
a diamond-bonded body that is sintered under HPHT conditions in the presence of a carbonate material, where the body includes a matrix phase of intercrystalline bonded diamond
Data Source
AI summary
Cutting elements include a carbonate diamond-bonded body that is sintered under HPHT conditions in the presence of a carbonate material, where the body includes a matrix phase of intercrystalline bonded diamond with interstitial regions including the carbonate material, where the diamond-bonded body is sintered without a substrate. A matrix casting is formed and mechanically coupled to the body after the body is sintered, and a portion of the body surface is exposed along a surface of the matrix casting. The exposed body surface is thereafter intentionally treated to induce a compressive residual surface stress that is greater than a remaining portion of the body. The compressive residual surface stress is less than about 500 MPa, and from about 100 to 500 MPa, and a remaining region the body may have a residual stress of less than about 300 MPa, and less than about 100 MPa.