cBN Sintered Tool Material Balancing Hardness and Breakage Resistance
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Solution Overview
Problem
Existing cubic boron nitride sintered materials do not provide adequate tool life during high-efficiency machining of high-hardness steel, necessitating improvements in abrasion and breakage resistance.
Innovation Solution
A cubic boron nitride sintered material comprising specific compositions and structures, including cubic boron nitride particles, a binder phase with certain elements and compounds, and a first phase containing cobalt and tungsten, enhancing the binding force between particles to improve tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content of cubic boron nitride particles is increased to improve hardness, then abrasion resistance is improved, but toughness and breakage resistance deteriorate
Solution Approach 1:
The patent optimizes the content of cubic boron nitride particles within a specific range (25-80% by volume) rather than maximizing it to 100%. This parameter optimization balances hardness and breakage resistance, preventing excessive brittleness while maintaining sufficient abrasion resistance for high-hardness steel machining.
Solution Approach 2:
The patent creates a composite sintered material containing cubic boron nitride particles, binder phase particles, and a W-Co phase. This composite structure combines the high hardness of cBN with the toughness and binding capability of the W-Co phase, resolving the contradiction between hardness and breakage resistance.
2Strength
If the content of cubic boron nitride particles is increased to improve abrasion resistance, then tool life is improved, but the material becomes more brittle
Solution Approach 1:
The patent specifies that cubic boron nitride particle content should be 25-80% by volume, optimizing the balance between abrasion resistance and toughness. This parameter control prevents excessive brittleness while ensuring sufficient resistance to crater abrasion during high-speed machining.
Solution Approach 2:
The W-Co phase acts as an intermediary between the cubic boron nitride particles and the binder phase. It provides a ductile matrix that absorbs stress and prevents crack propagation, thereby maintaining toughness even with high cBN content for improved abrasion resistance.
3Strength
If a binder phase is used to improve binding force between particles, then toughness is improved, but hardness and abrasion resistance may deteriorate
Solution Approach 1:
The W-Co phase serves as an intermediary binding phase that provides both toughness and hardness. The cobalt and tungsten elements create a strong metallic bond between cBN particles while maintaining a hard structure, avoiding the hardness loss that would occur with softer traditional binder phases.
Solution Approach 2:
The patent controls the total content of cobalt and tungsten within 1.0-6.0% by mass, optimizing the binding force while preventing excessive softening. This parameter control ensures the binder phase provides sufficient toughness without compromising the overall hardness of the sintered material.
Data Source
AI summary
cBN sintered material, including cBN particles; a binder phase; and a first phase,wherein the content of the cBN particles in the cBN sintered material is 25% to 80% by volume,the binder phase contains either or both ofone or more first compounds, anda solid solution derived from the first compound,the first phase contains cobalt, tungsten, and at least one first element selected from the group consisting of the elements contained in the binder phase,the total content of cobalt and tungsten in the cBN sintered material is 1.0% to 6.0% by mass,the binder phase consists of multiple binder phase particles containing 50% or more of first binder phase particles on a number basis,surfaces of the first binder phase particles include 50% by area or more of a first region which is in contact with the first phase.