Cubic Boron Nitride Sintered Body Binder Phase Optimization
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Solution Overview
Problem
Current cubic boron nitride sintered bodies used in cutting tools lack sufficient Co3W3C content and exhibit weakened binding strength due to imbalanced X-ray diffraction intensity ratios, leading to inadequate wear resistance and fracture resistance, especially during high-speed processing of sintered metals.
Innovation Solution
A cubic boron nitride sintered body with a composition of 85-95% cubic boron nitride and 5-15% binder phase, containing Co3W3C, W2Co21B6, and an Al compound, with specific X-ray diffraction intensity ratios (I_B/I_A, I_C/I_A, and I_C ≥ I_D) to enhance binding strength and fracture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the binder phase contains high WC content to improve binding strength, then the binding strength improves, but the fracture resistance deteriorates due to imbalanced phase composition
Solution Approach 1:
The patent changes the compositional parameters of the binder phase by specifying precise ratios of WC (10-30 mass%), Co (60-75 mass%), and W2Co21B6 (5-20 mass%), along with controlling X-ray diffraction intensity ratios (Ic/Ia ≥ 0.1, Ib/Ia ≤ 0.08). This parameter optimization balances binding strength and fracture resistance by ensuring appropriate phase distribution and crystalline structure.
Solution Approach 2:
The patent creates a composite binder phase combining multiple materials (WC, Co, W2Co21B6, and Al compound) in specific proportions. This composite structure leverages the complementary properties of each component: WC provides hardness and binding strength, Co provides ductility and toughness, W2Co21B6 enhances fracture resistance, and Al compound improves thermal stability, achieving both strong binding and high fracture resistance.
2Reliability
If the cubic boron nitride content is increased to improve wear resistance, then the wear resistance improves, but the toughness deteriorates leading to reduced fracture resistance
Solution Approach 1:
The patent optimizes the cBN content parameter to 85-95 volume%, balancing wear resistance and toughness. Additionally, it controls the binder phase content at 5-15 volume% and specifies the crystalline phase ratios through X-ray diffraction intensity control, ensuring the material maintains sufficient toughness while achieving high wear resistance.
Solution Approach 2:
The patent creates a composite structure with cBN particles embedded in an optimized binder matrix. The specific composition ratios and crystalline phase control ensure that the hard cBN particles provide wear resistance while the tailored binder phase (with ductile Co and reinforced W2Co21B6) provides toughness and fracture resistance, preventing catastrophic failure.
3Strength
If the binder phase composition is optimized for binding strength, then the binding strength improves, but the tool life deteriorates due to insufficient fracture resistance in high-speed processing
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: binder phase composition (WC 10-30 mass%, Co 60-75 mass%, W2Co21B6 5-20 mass%), X-ray diffraction intensity ratios (Ic/Ia ≥ 0.1, Ib/Ia ≤ 0.08), and phase content ratios. This multi-parameter optimization ensures both strong binding for durability and high fracture resistance for maintaining performance during high-speed processing, thereby extending tool life.
Solution Approach 2:
The patent employs a composite binder phase combining WC, Co, W2Co21B6, and Al compound in precise proportions. This composite structure provides synergistic effects: strong binding from WC-Co matrix, enhanced fracture resistance from W2Co21B6 reinforcement, and thermal stability from Al compound, enabling the tool to maintain performance and resist failure during extended high-speed processing operations.
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 optimized composition significantly improves wear resistance and fracture resistance, extending tool life by inhibiting cBN particle drop-off and crack propagation, while maintaining hardness and toughness.
Implementation Method 1
the binder phase comprises Co 3 W 3 C, W 2 Co 21 B 6 , and an Al compound
Implementation Method 2
I A denotes an X-ray diffraction peak intensity of a (111) plane of the cubic boron nitride, I B denotes an X-ray diffraction peak intensity of a (400) plane of the Co 3 W 3 C
Data Source
AI summary
A cubic boron nitride sintered body including cubic boron nitride and a binder phase, wherein: a content ratio of the cubic boron nitride is 85 volume% or more and 95 volume% or less, a content ratio of the binder phase is 5 volume% or more and 15 volume% or less, the binder phase contains Co3W3C, W2Co21B6, and an Al compound, and IB/IA is 0.02 or more and 0.15 or less, IC/IA is 0.02 or more and 1.00 or less, and Ic ≥ ID, where IA denotes an X-ray diffraction peak intensity of a (111) plane of the cubic boron nitride, IB denotes an X-ray diffraction peak intensity of a (400) plane of the CosWsC, Ic denotes an X-ray diffraction peak intensity of a (420) plane of the W2Co21B6, and ID denotes an X-ray diffraction peak intensity of a (001) plane of WC.