cBN Sintered Material Composition for Crack-Resistant Hard Turning
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Solution Overview
Problem
Conventional cubic boron nitride sintered materials have reduced tool life when used for intermittently processing hardened steel due to insufficient strength, particularly cracking issues, which is attributed to the grains' dislocation density and binder phase effectiveness.
Innovation Solution
A cubic boron nitride sintered material comprising 30% to 80% cBN grains and 20% to 70% binder phase, with specific elements like Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si, Co, and Ni, and their compounds, along with controlled dislocation density and calcium content, to enhance strength, fracture resistance, and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cBN grain content is increased to improve wear resistance, then the material hardness improves, but the strength and fracture resistance deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the dislocation density of cBN grains within the range of 3×10^17 to 1×10^20 /m². This parameter optimization allows the material to achieve both high strength and high fracture resistance, resolving the contradiction between strength and reliability that normally exists when increasing cBN content.
Solution Approach 2:
The patent uses a composite binder phase system comprising multiple components (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si, Co, Ni and their compounds) in specific proportions. This composite approach creates synergistic effects that enhance both strength and fracture resistance simultaneously, overcoming the limitations of single-phase binders.
2Reliability
If the binder phase content is increased to improve fracture resistance, then the material toughness improves, but the wear resistance deteriorates
Solution Approach 1:
The patent optimizes the dislocation density parameter of cBN grains to a specific range (3×10^17 to 1×10^20 /m²) that enables the material to achieve both high fracture resistance and high wear resistance. This parameter control allows the binder phase to enhance toughness without sacrificing the hardness and wear resistance provided by the cBN grains.
Solution Approach 2:
The multi-component binder phase system creates a composite structure where different elements contribute specific properties: some elements enhance fracture resistance while others maintain wear resistance. The synergistic interaction among Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si, Co, and Ni compounds allows the material to achieve both high reliability and high strength simultaneously.
Data Source
AI summary
A cubic boron nitride sintered material comprises 30% by volume or more and 80% by volume or less of cubic boron nitride grains and 20% by volume or more and 70% by volume or less of a binder phase, the binder phase including: a simple substance, an alloy, an intermetallic compound consisting of one or more elements selected from the group consisting of a group 4 element, a group 5 element and a group 6 element of the periodic table, aluminum, silicon, iron, cobalt and nickel; or at least one selected from the group consisting of a compound consisting of at least one element selected from the group consisting of a group 4 element, a group 5 element and a group 6 element of the periodic table, aluminum, silicon, iron, cobalt and nickel and at least one element selected from the group consisting of nitrogen, carbon, boron and oxygen, and a solid solution derived from the compound, the cubic boron nitride grains having a dislocation density of 3 × 1017/m2 or more and 1 × 102°/m2 or less.