cBN Sintered Material With Oxygen-Bonded Grain Interfaces
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Solution Overview
Problem
High-cBN sintered materials used in cutting tools tend to experience sporadic chipping due to weak binding strength between cubic boron nitride grains, leading to a short tool life and increased costs.
Innovation Solution
A cubic boron nitride sintered material with a binder composition of WC, Co, and an Al compound, where oxygen exists on the interface between grains in a controlled region (0.1 nm to 10 nm) is produced by removing oxygen from the source material and attaching an organic substance, such as hexylamine, to enhance binding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-cBN sintered material is used to achieve high hardness, then cutting performance is improved, but binding strength between grains becomes weak leading to sporadic chipping
Solution Approach 1:
The patent applies local quality by introducing oxygen specifically at the grain boundaries and interfaces between cBN grains, rather than uniformly throughout the material. This localized oxygen presence (0.1-10 nm width at interfaces) creates strong bonding zones exactly where needed to prevent grain detachment, while maintaining the high hardness of the bulk cBN grains. The binder composition is also optimized locally at the grain boundary regions.
Solution Approach 2:
The patent changes the chemical composition parameters of the binder system by incorporating WC, Co, and Al compound in specific proportions. Additionally, the oxygen concentration at grain boundaries is controlled within specific ranges (0.1-10 nm width), representing parameter changes that optimize both hardness and binding strength simultaneously.
2Strength
If the content ratio of cubic boron nitride grains is increased to improve cutting performance, then material hardness increases, but binding strength decreases causing grain falling
Solution Approach 1:
By concentrating oxygen at the grain boundaries (local region) rather than distributing it uniformly, the patent enables high cBN grain content (85-100 volume %) while maintaining strong inter-grain bonding. The local oxygen presence creates effective bonding zones that prevent grain detachment even at high grain densities.
Solution Approach 2:
The patent creates a composite structure consisting of cBN grains embedded in a binder matrix containing WC, Co, and Al compound, with oxygen specifically positioned at grain boundaries. This composite approach allows the material to exhibit both the high hardness of cBN and the strong bonding capability of the optimized binder system.
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 results in a cubic boron nitride sintered material with improved binding strength, reducing grain falling and extending the life of cutting tools, while maintaining high hardness and toughness.
Implementation Method 1
oxygen exists on a whole or part of the interface, and a width D of a region in which the oxygen exists is more than or equal to 0.1 nm and less than or equal to 10 nm
Implementation Method 2
forming an organic cubic boron nitride powder by removing oxygen of cubic boron nitride source material powder
Implementation Method 3
attaching an organic substance onto the cubic boron nitride source material powder
Implementation Method 4
obtaining the cubic boron nitride sintered material by sintering the powder mixture
Data Source
AI summary
A cubic boron nitride sintered material includes: more than or equal to 85 volume % and less than 100 volume % of cubic boron nitride grains; and a remainder of a binder, wherein the binder includes WC, Co and an Al compound, and when a TEM-EDX is used to analyze an interface region including an interface at which the cubic boron nitride grains are adjacent to each other, oxygen exists on a whole or part of the interface, and a width D of a region in which the oxygen exists is more than or equal to 0.1 nm and less than or equal to 10 nm.