cBN Sintered Compact With WSi2 Dispersion for Crack-Resistant Cutting
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Solution Overview
Problem
Cubic boron nitride (cBN) sintered compacts face issues with reduced toughness and defect resistance due to the suppression of Ti boride phase generation and excessive diffusion reaction in the binder phase, leading to reduced adhesiveness and increased crack propagation during sintering and tool usage.
Innovation Solution
Dispersing fine WSi2 particles with an average diameter of 10 nm to 200 nm in the binder phase of the cBN sintered compact to prevent the inhibition of Ti boride phase formation and enhance crack diversion, thereby maintaining adhesiveness and increasing toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If W is contained in the sintered compact to increase binder phase strength, then binder phase strength is improved, but Ti boride phase generation is suppressed at the cBN particle-binder phase interface, reducing adhesiveness and toughness
Solution Approach 1:
Ti is introduced as an intermediary element that promotes Ti boride phase formation at the cBN particle-binder phase interface. This Ti boride phase acts as a mediator that enhances adhesiveness between cBN particles and the binder phase, counteracting the harmful effect of W on interface bonding while allowing W to maintain binder phase strength.
Solution Approach 2:
The binder phase is designed as a composite containing multiple elements (W, Ti, Al, Si, B, N) that work synergistically. W provides strength to the binder phase, Ti promotes interface adhesiveness through Ti boride formation, and Al/Si/B/N form the ceramic matrix. This composite approach allows simultaneous achievement of binder strength and interface adhesiveness.
2Stability of the object's composition
If Si content is increased to suppress excessive diffusion reaction, then diffusion reaction control is improved, but bonding force between cBN particles and binder is reduced, reducing toughness
Solution Approach 1:
The Si content is precisely controlled within a specific range (0.1-5.0 wt%) rather than being maximized. This parameter optimization allows sufficient suppression of excessive diffusion reaction while maintaining adequate bonding force. The lower Si content compared to conventional compositions prevents over-suppression of diffusion that would harm bonding.
Solution Approach 2:
Different regions of the sintered compact have different Si concentrations optimized for their specific functions. The binder phase contains controlled Si for diffusion control, while the interface region benefits from Ti boride formation. This local optimization allows Si to control diffusion where needed without compromising bonding where Ti boride forms.
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 cBN sintered compact exhibits improved toughness and defect resistance, with reduced crack propagation and enhanced wear resistance, even under high load conditions during intermittent cutting of high hardness steel.
Implementation Method 1
Ti boride phase generation at the cBN particle-binder phase interface
Implementation Method 2
the progress of cracks is finely diverted by WSi2 even during the occurrence of the cracks in the sintered compact
Implementation Method 3
cBN sintered compact having excellent toughness
Data Source
AI summary
A cBN sintered compact has cubic boron nitride particles and a ceramic binder phase, and in the sintered compact, WSi2 having an average particle diameter of 10 nm to 200 nm is dispersed such that a content thereof is 1 vol % to 20 vol %. A cutting tool has the cBN sintered compact as a tool body.