Cubic Boron Nitride Sintered Body With Stronger Grain Binding
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Solution Overview
Problem
High-cBN sintered materials used in cutting tools are prone to chipping due to weak binding strength between cubic boron nitride grains, leading to a short tool life and increased costs.
Innovation Solution
A production method involving the use of a binder comprising WC, Co, and Al, with carbon uniformly distributed between cubic boron nitride grains to enhance binding strength through a catalyst function, promoting neck growth between grains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-cBN sintered material is used to increase hardness for cutting sintered alloy, then cutting capability is improved, but binding strength between grains becomes weak causing sporadic chipping
Solution Approach 1:
The invention applies local quality by creating a carbon-enriched interface region specifically at the grain boundaries between cubic boron nitride grains. This localized carbon distribution (0.1-10 nm width) provides enhanced binding strength at the critical interface regions without compromising the overall high hardness of the bulk material. The carbon acts as a binding agent locally at the grain boundaries while the bulk maintains its cBN grain structure for hardness.
Solution Approach 2:
The invention creates a composite structure by combining cubic boron nitride grains with a binder system comprising WC, Co, and Al compound. This composite material approach allows the cBN grains to provide hardness while the binder matrix provides binding strength. The carbon-enriched interface region further enhances this composite structure by creating a transitional zone that strengthens the grain-to-grain bonding.
2Reliability
If carbon is added to enhance binding strength between grains, then binding strength is improved, but excessive carbon may reduce hardness
Solution Approach 1:
The invention applies parameter changes by precisely controlling the carbon concentration and distribution parameters. The carbon width D is limited to 0.1-10 nm and maximum carbon content M is limited to 0.1-5.0 atom%. These parameter constraints ensure that carbon is present in sufficient quantity to enhance binding strength but in limited amounts to maintain the high hardness characteristic of cBN materials. The narrow interface region prevents excessive carbon from forming large graphite structures that would reduce hardness.
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 produces a cubic boron nitride sintered material with increased binding strength, resulting in a longer tool life and reduced grain falling, thus extending the cutting tool's lifespan.
Implementation Method 1
carbon uniformly distributed between cubic boron nitride grains to enhance binding strength through a catalyst function, promoting neck growth between grains
Implementation Method 2
A production method involving the use of a binder comprising WC, Co, and Al, with carbon uniformly distributed between cubic boron nitride grains
Data Source
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AI summary
A method of producing a cubic boron nitride sintered material includes: forming an organic cubic boron nitride powder by attaching an organic substance onto a cubic boron nitride source material powder; preparing a powder mixture including more than or equal to 85 volume% and less than 100 volume% of the organic cubic boron nitride powder and a remainder of a binder source material powder by mixing the organic cubic boron nitride powder and the binder source material powder, the binder source material powder including WC, Co and Al; and obtaining the cubic boron nitride sintered material by sintering the powder mixture.