Super-hard Construction Bonding via Thermal Pressure Cycling
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Solution Overview
Problem
Super-hard constructions, such as those made from PCD and PCBN materials, often experience cracking issues due to thermal expansion and Young's modulus mismatches between materials, leading to structural instability and reduced durability.
Innovation Solution
A method involving the formation of a super-hard construction by joining two structures with differing thermal expansion coefficients and Young's moduli, using a binder material to bond them together, and subjecting the assembly to controlled temperature and pressure cycles to ensure the super-hard material remains thermodynamically stable, thereby reducing the likelihood of cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If super-hard materials are joined using conventional methods, then bonding is achieved, but cracking occurs due to thermal expansion and Young's modulus mismatches
Solution Approach 1:
The patent applies parameter changes by carefully controlling pressure and temperature parameters during the bonding process. The method subjects the assembly to a first pressure at which the super-hard material is thermodynamically stable at a sufficiently high temperature, then reduces pressure to a second pressure while maintaining temperature, and finally reduces temperature to solidify the binder. This controlled parameter sequence prevents cracking while achieving strong bonding.
Solution Approach 2:
The patent uses a composite material approach by employing a binder material that comprises metal and acts as a matrix to bond the super-hard material to other structures. The binder material is selected to be compatible with the super-hard material and other materials being joined, creating a composite structure that accommodates thermal expansion differences and mechanical property mismatches between the joined components.
2Ease of manufacture
If pressure is reduced after sintering, then the construction is formed, but cracking occurs due to residual stress
Solution Approach 1:
The patent applies preliminary action by maintaining the assembly at a sufficiently high temperature throughout the entire pressure reduction process from the first pressure to the second pressure. This ensures the binder material remains in a ductile, molten state that can accommodate volume changes and stress relief during decompression, preventing crack formation. Only after pressure reduction is complete is the temperature reduced to solidify the binder.
3Strength
If temperature is reduced to solidify binder, then bonding is completed, but thermal stress causes cracking
Solution Approach 1:
The patent applies preliminary action by completing all pressure reduction and stress relief operations while the binder is still in the molten state at sufficiently high temperature. Only after the pressure has been fully reduced to the second pressure does the method reduce the temperature to solidify the binder. This sequence ensures that thermal stress is minimized because the binder remains ductile during the critical pressure transition phase.
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 method effectively reduces the frequency and likelihood of cracking in super-hard constructions, particularly during heating processes, by managing residual stress and maintaining structural integrity through precise thermal and pressure management.
Implementation Method 1
subjecting the assembly to a sufficiently high temperature for the binder material to be in the liquid state
Implementation Method 2
a first pressure at which the super-hard material is thermodynamically stable
Implementation Method 3
reducing the temperature to solidify the binder material
Implementation Method 4
the first CTE and the second CTE being substantially different from each other
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method for making a super-hard construction comprising a first structure comprising a first material joined to a second structure comprising a second material, in which the coefficient of thermal expansion (CTE) and Young's moduli of the materials of each material are substantially different from each other. The method includes forming an assembly comprising the first material, the second material and a binder material arranged to be capable of bonding the first and second materials together, the binder material comprising metal; subjecting the assembly to a sufficiently high temperature for the binder material to be in the liquid state and to a first pressure at which the super-hard material is thermodynamically stable; reducing the pressure to a second pressureat which the super-hard material is thermodynamically stable, the temperature being maintained sufficiently high to maintain the binder material in the liquid state; reducing the temperature to solidify the binder material; and reducing the pressure and the temperature to an ambient condition to provide the super-hard construction.