cBN Sintered Material Composition for Crack-Resistant Hardened Steel Cutting
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Solution Overview
Problem
Conventional cubic boron nitride sintered materials have reduced tool life when used for intermittently processing hardened steel due to insufficient strength, particularly cracking issues, which is attributed to low dislocation density in the cubic boron nitride grains.
Innovation Solution
A cubic boron nitride sintered material with a dislocation density of 3×10^17/m² or more and 1×10^20/m² or less, comprising 30% to 80% by volume of cubic boron nitride grains and 20% to 70% by volume of a binder phase, including specific elements and compounds, enhances strength and thermal conductivity, leading to improved wear resistance and fracture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content of cubic boron nitride grains is increased to improve hardness, then the strength and fracture resistance deteriorate due to reduced binder phase content
Solution Approach 1:
The patent changes the dislocation density parameter of cubic boron nitride grains from low (conventional) to high (3×10^17/m² or more), which fundamentally alters the material properties. This parameter change enables the cBN grains to maintain high strength while allowing sufficient binder phase content (20-70 vol%) to preserve fracture resistance and toughness.
2Strength
If the dislocation density of cubic boron nitride grains is increased to improve strength, then the manufacturing complexity increases
Solution Approach 1:
The patent achieves high strength by changing the dislocation density parameter to 3×10^17/m² or more, which can be controlled through synthesis conditions such as temperature, pressure, and catalyst selection during the cubic boron nitride formation process, without requiring complex post-processing or specialized manufacturing equipment.
3Reliability
If the binder phase content is increased to improve fracture resistance, then the hardness deteriorates due to reduced cubic boron nitride grain content
Solution Approach 1:
By changing the dislocation density parameter of cBN grains to high levels (3×10^17/m² or more), the patent enables the maintenance of high hardness even with reduced cBN content (30-80 vol%), while simultaneously allowing increased binder phase content (20-70 vol%) to ensure adequate fracture resistance and toughness.
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 enhanced material provides extended tool life during high-speed processing of hardened steel by maintaining thermal conductivity and reducing crater wear, thus increasing the longevity of cutting tools.
Implementation Method 1
the cubic boron nitride grains having a dislocation density of 3×10^17/m² or more and 1×10^20/m² or less
Implementation Method 2
maintaining thermal conductivity
Data Source
AI summary
A cubic boron nitride sintered material comprises 30% by volume or more and 80% by volume or less of cubic boron nitride grains and 20% by volume or more and 70% by volume or less of a binder phase, the cubic boron nitride grains having a dislocation density of 3×1017/m2 or more and 1×1020/m2 or less.