cBN Cutting Insert Binder Phase Composition
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Solution Overview
Problem
Cubic boron nitride (cBN)-based cutting tools face challenges in achieving balanced bonding between phases, leading to either reduced wear resistance or edge failure, and often contain undesirable impurities like Fe and Cu, which affect their performance in machining hard materials.
Innovation Solution
A cutting tool insert composed of a composite comprising a cBN-phase and a binder phase with a titanium carbonitride and TiB2 phase, where the peak height ratio of TiB2 to cBN is carefully controlled, and the titanium carbonitride phase exhibits a broad compositional range, minimizing the presence of Fe and Cu, to achieve balanced bonding and enhanced resistance to wear and edge failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If strong bonding between cBN grains and ceramic binder is achieved, then wear resistance is improved, but edge toughness decreases due to straight crack propagation
Solution Approach 1:
The patent changes the chemical composition parameters of the binder phase by introducing reactive elements (Ti, Al, B) that form specific compounds (TiB2, TiN, TiC) during sintering. This controlled parameter change creates an intermediate bonding strength that allows crack deflection while maintaining wear resistance, resolving the contradiction between strong bonding and edge toughness.
Solution Approach 2:
The patent creates a composite binder phase consisting of multiple compounds (TiB2, TiN, TiC) formed from reactive elements. This composite structure provides balanced bonding characteristics - strong enough to resist wear but with controlled interfaces that enable crack deflection, thereby simultaneously improving wear resistance and maintaining edge toughness.
2Reliability
If high cBN content (40-80% by volume) is used, then edge failure resistance is improved for interrupted cutting, but wear resistance decreases in continuous cutting
Solution Approach 1:
The patent changes the binder phase composition by incorporating reactive elements (Ti, Al, B) in specific proportions. This parameter optimization allows the binder to provide adequate support for high cBN content structures while maintaining sufficient bonding strength for wear resistance, enabling the tool to perform well in both interrupted and continuous cutting.
Solution Approach 2:
The patent creates local quality variations in the binder phase through the formation of different compounds (TiB2, TiN, TiC) with distinct properties. This local differentiation allows specific regions to provide structural support while other regions provide bonding strength, enabling the material to handle both edge failure and wear challenges.
3Reliability
If intermediate adhesion phase is added to increase chipping resistance, then edge toughness improves, but manufacturing complexity increases
Solution Approach 1:
The patent employs self-service by incorporating reactive elements (Ti, Al, B) into the binder phase that automatically form the desired intermediate compounds (TiB2, TiN, TiC) during the sintering process. This self-organizing approach creates the necessary intermediate adhesion phase without requiring additional manufacturing steps, thereby improving chipping resistance while avoiding increased manufacturing complexity.
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 solution results in improved wear and edge failure resistance, allowing for higher cutting speeds and depths while maintaining reduced impurity levels, thereby enhancing productivity and cost-effectiveness in machining operations.
Implementation Method 1
cBN-based ceramics sintered under high pressure and high temperature
Implementation Method 2
The bonding phase is formed due to a chemical reaction between cBN or B 2 O 3 residuals coating the cBN grains and the ceramic binder forming TiB 2
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
A cutting tool insert which can, for example, be used for machining of hardened steel, hot and cold working tool steel, die steel, case hardened steel, high speed steel and ductile grey cast iron and composed of a composite comprising a cBN-phase and a binder phase comprising a titaniumcarbonitride phase and a TiB2 phase is disclosed. In the XRD pattern from the composite using CuKa-radiation, the peak height ratio of the strongest (101) TiB2 peak and the strongest cBN (111) peak is less than 0.06, the (220) peak from the titanium carbonitride phase in the XRD-pattern intersects both vertical lines of the PDF-lines of TiC (PDF 32-1383) and TiN (PDF 38-1420) and the lowest intersected point height is at least 0.15 of the maximum (220) peak height of the ceramic binder phase. The insert is made by powder metallurgical methods milling, pressing and sintering, the sintering being performed at lowest possible temperature for shortest possible time necessary to obtain a dense structure.