Cubic Boron Nitride Tool Binder Phase Enriched Layer
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Solution Overview
Problem
Hard sintered body cutting tools with cubic boron nitride suffer from reduced strength and crater wear resistance due to thermal effects during laser machining, leading to shortened tool life and increased risk of chipping or fracturing.
Innovation Solution
A tool with a sintered body containing cubic boron nitride and a binder phase enriched layer, where the binder phase comprises elements like Ti, Zr, and compounds such as TiN, TiC, and Al2O3, enhancing oxidation resistance and wear resistance, and a coating layer is applied to further improve wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser machining is used to form the tool rake surface, then the surface can be precisely formed, but cracking is generated in the surface of the sintered body due to thermal effects
Solution Approach 1:
The patent uses picosecond laser machining with specific parameters (pulse width of 1-100 ps, fluence of 0.1-10 J/cm², repetition rate of 10 kHz-10 MHz) to achieve precise surface formation while minimizing thermal damage. By controlling these parameters, the laser removes material through ablation rather than melting, preventing crack formation in the sintered body surface.
Solution Approach 2:
The patent employs pulsed laser machining with high repetition rates (10 kHz-10 MHz) to remove material in successive short pulses. This periodic action allows heat to dissipate between pulses, preventing cumulative thermal damage and crack formation while maintaining precise surface formation.
2Manufacturing precision
If laser machining is used to form the tool rake surface, then the surface can be precisely formed, but cubic boron nitride is transformed into hexagonal boron nitride due to high temperature
Solution Approach 1:
The patent uses picosecond pulse width (1-100 ps) and controlled fluence (0.1-10 J/cm²) to achieve material removal through ablation at temperatures below the transformation point of cubic boron nitride. This parameter control prevents the phase transformation from cubic to hexagonal boron nitride while maintaining surface formation precision.
Solution Approach 2:
The patent replaces conventional laser machining (which causes melting and thermal damage) with picosecond laser ablation. This substitution of the material removal mechanism eliminates the thermal effects that cause phase transformation, preserving the cubic boron nitride structure and crater wear resistance.
3Manufacturing precision
If the surface is polished with free abrasive grains, then the surface can be smoothly finished, but cubic boron nitride is removed and reaction wear progresses
Solution Approach 1:
The patent extracts and removes the binder phase from the surface layer through picosecond laser ablation, leaving behind a surface enriched with cubic boron nitride particles. This selective removal eliminates the need for conventional polishing that would remove cubic boron nitride, while the resulting surface has high crater wear resistance due to the exposed cubic boron nitride.
Solution Approach 2:
The patent creates a surface with non-uniform composition through laser ablation, where the surface layer is enriched with cubic boron nitride particles while the subsurface retains the binder phase. This local quality differentiation provides both smooth surface finish and high crater wear resistance from the cubic boron nitride-rich surface layer.
4Strength
If binder phase content is increased to improve toughness, then chipping resistance improves, but oxidation resistance decreases
Solution Approach 1:
The patent creates a surface layer enriched with binder phase through controlled laser ablation, while the bulk material maintains its original composition with adequate oxidation resistance. The binder phase-enriched surface layer provides improved toughness and chipping resistance, while the underlying material preserves oxidation resistance.
Solution Approach 2:
The patent addresses the contradiction by creating a compositional gradient through the thickness of the surface layer. The surface layer has high binder phase content for toughness, while the subsurface and bulk maintain low binder phase content for oxidation resistance. This dimensional variation in composition resolves the contradiction between chipping resistance and oxidation resistance.
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 tool exhibits improved crater wear resistance, chipping resistance, and fracture resistance, resulting in extended tool life and reduced risk of chipping or fracturing.
Implementation Method 1
irradiating a sintered body with a picosecond laser, thereby removing a binder phase from a surface layer of the sintered body
Implementation Method 2
after diamond and/or cubic boron nitride located within 20 μm in depth below the surface of the tool rake surface is transformed into a ceramic structure
Data Source
AI summary
A tool having a cutting edge that includes a sintered body containing cubic boron nitride. The sintered body integrally and inseparably includes an inner region and a binder phase enriched layer formed on at least part of a surface of the inner region. The inner region includes: 15-90 volume % of cubic boron nitride; and 10-85 volume % of a mixture of a binder phase and impurities. The binder phase enriched layer includes: 90-100 volume % of the binder phase and impurities mixture; and 0-10 volume % of cubic boron nitride; and the binder phase contains at least one kind selected from the group consisting of: at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Co, Ni and Si; and a compound of the element and at least one element selected from the group consisting of C, N, O and B.