Cemented Carbide Fracture Resistance via Uniform Second Hard Phase
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Solution Overview
Problem
Cemented carbides used in cutting tools face challenges in achieving high fracture resistance, especially with increasing complexity in cutting processes and shapes of workpieces, requiring enhanced toughness and wear resistance.
Innovation Solution
A cemented carbide composition with a uniform second hard phase dispersed throughout, composed of compounds containing tungsten and metallic elements from groups 4, 5, and 6, along with carbon, nitrogen, oxygen, and boron, which forms strong interfaces with the primary tungsten carbide phase, improving binding strength and fracture resistance. The second hard phase has a uniform grain size and is uniformly dispersed to enhance the overall strength and toughness of the cemented carbide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If WC grains are tightly bound to improve plastic deformation resistance, then plastic deformation resistance is improved, but fracture resistance deteriorates
Solution Approach 1:
The invention uses a composite hard phase structure consisting of WC grains combined with composite compound grains (containing W and other metallic elements). This composite structure allows the material to simultaneously achieve high plastic deformation resistance through tight binding while maintaining fracture resistance through the synergistic properties of the composite grains and controlled grain size distribution.
2Reliability
If fracture resistance is improved by adding composite compounds, then fracture resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The invention controls the grain size distribution of the second hard phase within specific ranges (D10: 0.5-2.0 μm, D90: 3.0-6.0 μm, and D10/D90 ratio: 0.16-0.33) to optimize fracture resistance. By precisely controlling these parameters during sintering, the invention achieves high fracture resistance while maintaining manageable manufacturing complexity through defined process parameters.
3Strength
If grain size of second hard phase is reduced to improve toughness, then toughness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies precise grain size parameters for the second hard phase (D10: 0.5-2.0 μm, D90: 3.0-6.0 μm, D10/D90: 0.16-0.33) to achieve optimal toughness. These controlled parameter ranges enable the material to gain enhanced toughness while maintaining manufacturability through defined sintering process parameters.
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 cemented carbide exhibits high fracture resistance and extended tool life under severe cutting conditions, with the uniform dispersion of the second hard phase increasing the number of contacts between grains, promoting strong binding and improved wear resistance.
Implementation Method 1
Elements can more easily interdiffuse at an interface between a first hard phase grain and a second hard phase grain than at an interface between first hard phase grains
Implementation Method 2
DE102011053740A1 relates to preparing a hard material tool component, e.g. a full hard metal tool, comprising transforming and/or pressing or extruding a hard material, a sintering agent such as carbon monoxide, and/or binding agent to slug, and then sintering
Data Source
Figure 1~2
AI summary
A cemented carbide including a hard phase, a binding phase, and inevitable impurities. The hard phase satisfies a first hard phase composed mainly of tungsten carbide, and a second hard phase composed mainly of a compound. The compound contains multiple types of metallic elements including tungsten and at least one element selected from carbon, nitrogen, oxygen, and boron. The second hard phase satisfies D10/D90 < 0.4, wherein D10 denotes a cumulative 10% grain size in an area-based grain size distribution on a surface or cross section of the cemented carbide, and D90 denotes a cumulative 90% grain size in the area-based grain size distribution, and satisfies σ2 < 5.0, wherein σ2 denotes the variance of the distance between the centroids of the nearest two of the second hard phases. The average grain size DW of the first hard phase ranges from 0.8 to 4.0 µm and satisfies DM/DW < 1.0, wherein DM denotes the average grain size of the second hard phase.