cBN Sintered Body Binder Composition to Suppress W2Co21B6 Chipping
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Solution Overview
Problem
High-cBN sintered bodies experience sudden chipping due to weak binding strength between cBN particles, leading to detachment and a shortened tool life, which is exacerbated by the generation of the brittle W2Co21B6 compound during sintering.
Innovation Solution
A cubic boron nitride sintered body is developed with a binder composition of WC, Co, and Al, where the generation of W2Co21B6 is suppressed by using organic cBN powder and controlling the X-ray diffraction intensity ratios (Ic/IA and Ic/IB) to minimize the presence of this compound, thereby enhancing the binding strength and reducing particle detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-cBN sintered body is used to cut sintered alloy, then cutting performance is improved, but sudden chipping occurs due to weak binding strength between cBN particles
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by specifying precise ratios of WC (10-30 wt%), Co (70-85 wt%), and Al compound (5-20 wt%). This parameter optimization ensures adequate binding strength between cBN particles while maintaining the high-cBN structure necessary for cutting performance, thereby resolving the contradiction between productivity and reliability
Solution Approach 2:
The patent creates a composite binder system combining WC, Co, and Al compound together with controlled amounts of W2Co21B6. This composite material approach leverages the strengths of each component: WC provides structural framework, Co ensures ductility and binding, Al compound enhances oxidation resistance, and controlled W2Co21B6 formation improves overall cohesion. The composite binder resolves the contradiction by providing sufficient binding strength without compromising the high-cBN cutting performance
2Ease of manufacture
If W2Co21B6 compound is generated during sintering, then sintering process is simplified, but particle detachment increases and tool life shortens
Solution Approach 1:
The patent precisely controls the formation of W2Co21B6 by optimizing sintering parameters and binder composition. By maintaining W2Co21B6 at controlled levels (5-20 wt%) rather than eliminating it completely, the patent achieves a balance where sufficient compound formation aids sintering densification and particle bonding, while excessive formation that would cause particle detachment is prevented. This parameter control resolves the contradiction between ease of manufacture and tool life
Solution Approach 2:
The patent converts the potentially harmful W2Co21B6 compound into a beneficial element by controlling its formation. The W2Co21B6 phase, which could cause particle detachment if excessive, is instead used in controlled amounts to enhance binder cohesion and sintering efficiency. This transformation resolves the contradiction by turning a harmful factor into a benefit that actually extends tool life while maintaining manufacturing simplicity
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 resulting cBN sintered body exhibits improved durability and extended tool life by minimizing the generation of W2Co21B6, resulting in a longer-lasting cutting tool.
Implementation Method 1
the binder contains WC, Co, and an Al compound
Implementation Method 2
the binder contains W2Co21B6
Implementation Method 3
when IA represents an X-ray diffraction intensity of a (111) plane of the cubic boron nitride particles, IB represents an X-ray diffraction intensity of a (100) plane of the WC, and IC represents an X-ray diffraction intensity of a (420) plane of the W2Co21B6
Data Source
AI summary
Provided is a cubic boron nitride sintered body including more than or equal to 85 volume percent and less than 100 volume percent of cubic boron nitride particles, and a remainder of a binder, wherein the binder contains WC, Co, and an Al compound, the binder contains W2Co21B6, and, when IA represents an X-ray diffraction intensity of a (111) plane of the cubic boron nitride particles, IB represents an X-ray diffraction intensity of a (100) plane of the WC, and Ic represents an X-ray diffraction intensity of a (420) plane of the W2Co21B6, a ratio IC/IA of the Ic to the IA is more than 0 and less than 0.10, and a ratio IC/IB of the IC to the IB is more than 0 and less than 0.40.