Cemented Carbide Binder Phase for Heat and Fracture Resistance
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Solution Overview
Problem
Conventional cemented carbides fail to achieve both high heat resistance and fracture resistance, particularly when incorporating Al2O3 and Al intermetallic compounds, and adding Cr and Mo can decrease hardness and heat resistance.
Innovation Solution
A cemented carbide with a binder phase composition of Co content between 15% and 50% and Cr and Mo content between 15% and 40%, where Cr and Mo are present primarily as metals rather than compounds, along with a second hard phase like TiC, NbC, or TaC, to enhance heat and fracture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If Al2O3 and Al intermetallic compounds are added to improve heat resistance, then heat resistance is improved, but fracture resistance decreases due to brittleness
Solution Approach 1:
The patent changes the chemical state parameter of Cr and Mo from compound form to metallic form in the binder phase. This parameter change allows Cr and Mo to improve heat resistance through their metallic properties while avoiding the brittleness associated with intermetallic compounds, thus resolving the contradiction between heat resistance and fracture resistance
Solution Approach 2:
The patent creates a composite binder phase containing Co, Ni, Cr, and Mo metals. This composite material combines the ductility of Co and Ni with the heat-resistant properties of Cr and Mo, achieving both high heat resistance and high fracture resistance simultaneously
2Temperature
If Cr and Mo are added to improve heat resistance, then heat resistance is improved, but hardness decreases
Solution Approach 1:
The patent changes the concentration parameters of Cr and Mo in the binder phase to specific ranges (Cr: 5-20 mass%, Mo: 5-20 mass%). This optimized parameter setting ensures sufficient heat resistance while preventing excessive softening that would occur with higher concentrations, thus resolving the contradiction between heat resistance and hardness
3Temperature
If Cr and Mo content is increased to ensure heat resistance, then heat resistance is improved, but fracture resistance decreases
Solution Approach 1:
The patent optimizes the concentration parameters of Cr and Mo to specific ranges (Cr: 5-20 mass%, Mo: 5-20 mass%) rather than using excessive amounts. This parameter optimization achieves the required heat resistance while maintaining fracture resistance by preventing over-saturation that would compromise structural integrity
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 approach results in a cemented carbide with improved sinterability, heat resistance, and fracture resistance, suitable for cutting tools that can withstand high temperatures and mechanical stress, thereby extending tool life.
Implementation Method 1
a binder phase, which consists of Co, Ni, Cr, and Mo
Implementation Method 2
a shaped body is sintered to produce a cemented carbide
Data Source
Figure 1
AI summary
Provided is a cemented carbide including a first hard phase and a binder phase, the first hard phase consisting of WC, the binder phase being composed of either three elements which are Co, Ni and Cr or four elements which are Co, Ni, Cr and Mo, when a Co content of the cemented carbide is represented as M1, a total content of Cr and Mo in the cemented carbide is represented as M2, a total content of Ni, Cr, and Mo in the cemented carbide is represented as M3, and a total content of Co, Ni, Cr, and Mo in the cemented carbide is represented as M4, ratio M1/M4 being from 15 to 50%, ratio M2/M3 being from 15 to 40%, a ratio of an area of Cr/Mo-rich particles being lower than 1%, wherein the Cr/Mo-rich particles are particles constituting a region where a concentration of at least one of Cr and Mo is higher than the ratio of M1 to M4 in cross sectional elemental mapping of the cemented carbide.