cBN Sintered Material Composition for Low Resistivity Cutting Tools
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Solution Overview
Problem
Sintered materials with high cubic boron nitride content rates have high volume resistivity, limiting their conductive properties and toughness, which is a challenge in the development of cutting tools.
Innovation Solution
A cubic boron nitride sintered material with a binder phase containing aluminum nitride and aluminum diboride, where the cubic boron nitride particles have a specific particle size distribution and content proportion, achieving a volume resistivity of 5×10−3 Ωcm or less and improved toughness by suppressing void generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content rate of cubic boron nitride particles is increased to improve hardness, then the volume resistivity increases and conductive properties deteriorate
Solution Approach 1:
The patent uses a composite binder phase consisting of aluminum nitride and aluminum diboride in specific proportions (AlN:AlB2 = 3:7 to 7:3 by mass). This composite material approach allows the binder to provide both mechanical binding and electrical conductivity, resolving the contradiction between high cBN content for hardness and sufficient conductivity for reliability.
Solution Approach 2:
The patent changes the chemical composition parameters of the binder phase by specifying aluminum nitride and aluminum diboride with controlled mass ratios, and adjusts the sintering temperature (1000-1500°C) and pressure (4-7 GPa) parameters to achieve optimal density and conductivity while maintaining high cBN content (70-97 vol%).
2Reliability
If the binder phase composition is changed to improve conductive properties, then the manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-mixing aluminum nitride and aluminum diboride powders in the specified mass ratio before sintering. This pre-prepared composite binder phase simplifies the manufacturing process by eliminating the need for complex post-sintering treatments or multiple processing steps to achieve the desired conductivity.
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 material exhibits excellent conductive properties and cutting performance, including breakage resistance, making it suitable for use in cutting tools with enhanced durability and wear resistance.
Implementation Method 1
sintering the precursor at a sintering pressure of 4 GPa or higher and 7 GPa or lower and a sintering temperature of 1000° C. or higher and 1500° C. or lower
Data Source
AI summary
A cBN sintered material comprising cBN particles and a binder phase, in which the binder phase contains AlN and AlB2, a content proportion of cBN particles is 70 to 97 vol %, cBN sintered material has a volume resistivity up to 5×10−3 Ωcm, a rate of a peak intensity derived from Al with respect to a peak intensity derived from cBN particles is less than 1.0%, cBN particles include fine particles and coarse particles, coarse particles optionally include ultra-coarse particles, with respect to the entire cBN particles, a content proportion α of fine particles is from 10 vol %, a content proportion β of coarse particles is from 30 vol %, a content proportion γ of ultra-coarse particles is 25 vol % or less, and a total of the content proportion α of fine particles and the content proportion β of coarse particles is 50 to 100 vol %.