cBN Sintered Material With Carbon-Mediated Grain Binding
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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 method of producing a cubic boron nitride sintered material by forming an organic cubic boron nitride powder with an attached organic substance, mixing it with a binder source material powder including WC, Co, and Al, and sintering the mixture, which results in increased binding strength between the cubic boron nitride grains through a catalyst function of carbon, suppressing grain falling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-cBN sintered material is used to increase hardness and reduce wear, then cutting tool performance is improved, but sporadic chipping occurs due to weak binding strength between grains
Solution Approach 1:
The patent introduces carbon as an intermediary substance at the grain boundaries between cubic boron nitride grains. This carbon layer acts as a mediator that enhances the binding strength between the hard cBN grains, preventing sporadic chipping while maintaining the high hardness and wear resistance of the material.
Solution Approach 2:
The patent creates a composite material structure by combining cubic boron nitride grains with carbon at the grain boundaries. This composite approach allows the material to simultaneously exhibit the high hardness of cBN and the enhanced binding strength provided by the carbon interfacial layer, resolving the contradiction between hardness and reliability.
2Duration of action of moving object
If the content ratio of cubic boron nitride grains is increased to improve wear resistance, then tool life should be extended, but binding strength between grains decreases leading to grain falling
Solution Approach 1:
Carbon is introduced as an intermediary at the grain boundaries to maintain binding strength even when the cBN grain content is increased to 85-100 volume %. This intermediary carbon layer ensures that the high grain content does not compromise the binding strength, thereby extending tool life without causing grain falling.
Solution Approach 2:
The patent changes the chemical composition parameter at the grain boundaries by introducing carbon. This parameter change allows the material to maintain adequate binding strength even at high cBN grain content levels (85-100 volume %), thereby achieving extended tool life without the detrimental effect of grain falling.
3Reliability
If binder content is increased to improve binding strength, then grain falling is suppressed, but the high-cBN characteristic is compromised
Solution Approach 1:
Carbon serves as an intermediary that provides binding strength enhancement without requiring increased binder content. This allows the material to maintain its high-cBN characteristic (85-100 volume %) and associated cutting efficiency while still suppressing grain falling through the carbon-mediated grain boundary bonding.
Solution Approach 2:
The patent effectively replaces the traditional binder-based binding mechanism with a carbon-based interfacial layer. This copying of the binding function through a different mechanism (carbon at grain boundaries instead of bulk binder) allows high binding strength with minimal binder content, preserving the high-cBN characteristic and cutting efficiency.
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 a longer life and improved binding strength, reducing grain falling and extending the cutting tool's lifespan.
Implementation Method 1
increased binding strength between the cubic boron nitride grains through a catalyst function of carbon
Implementation Method 2
forming an organic cubic boron nitride powder by attaching an organic substance onto a cubic boron nitride source material powder
Data Source
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.