Cemented Carbide Composition for Stable CFRP Cutting Tool Coatings
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Solution Overview
Problem
Cutting tools with cemented carbide bases experience reduced sharpness and surface quality when processing carbon fiber reinforced plastics (CFRPs), leading to unstable tool performance over time.
Innovation Solution
A cemented carbide composition comprising a first hard phase of tungsten carbide grains with specific grain size distributions, a binder phase with 50% or more cobalt by mass, and a controlled volume percentage and area distribution of second hard phases such as TaNbC, TaNbN, and TiCN, which improves adhesiveness with coating films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard film is formed on a cemented carbide base body for cutting CFRPs, then initial cutting performance is improved, but tool life is reduced due to coating film peeling and sharpness deterioration
Solution Approach 1:
The patent changes the physical and chemical parameters of the cemented carbide base body by controlling the grain size distribution of tungsten carbide (D10≥0.40μm, D90≤2.00μm) and the content/distribution of second hard phases (0.30-1.60% by volume, median area 0.90-1.20μm²). These parameter changes create an optimized microstructure that enhances coating adhesion and prevents peeling, thereby extending tool life when cutting CFRPs
Solution Approach 2:
The patent creates a composite microstructure within the cemented carbide by combining tungsten carbide grains with specific grain size distribution and second hard phases (TaNbC, TaNbN, TaNbCN, TiCN, TiNbC, TiNbN, or TiNbCN). This composite structure at the micro-level improves the overall performance by enhancing coating film adhesion while maintaining the base body's mechanical properties, leading to extended tool life
2Strength
If the grain size of tungsten carbide is increased to improve toughness, then resistance to impact is improved, but hardness and wear resistance deteriorate
Solution Approach 1:
The patent applies local quality by creating different grain size regions within the cemented carbide structure. By specifying D10≥0.40μm and D90≤2.00μm, the patent ensures that smaller grains (providing hardness) and larger grains (providing toughness) coexist in specific proportions and distributions. This local variation in grain size allows the material to simultaneously achieve both toughness and hardness/wear resistance
3Reliability
If the content of second hard phases is increased to improve coating adhesion, then coating film stability is improved, but the base body strength may deteriorate
Solution Approach 1:
The patent optimizes the content parameter of second hard phases to 0.30-1.60% by volume, which is a specific range that balances coating adhesion improvement with base body strength maintenance. Additionally, by controlling the median area (0.90-1.20μm²) and coefficient of variation (0.50-1.20) of second hard phase distribution, the patent ensures uniform dispersion that prevents local weakening while providing sufficient nucleation sites for coating adhesion
Data Source
AI summary
A cemented carbide consisting of a first hard phase, second hard phases, and a binder phase, wherein the first hard phase is composed of tungsten carbide grains, a D10 and a D90 of grain sizes of the tungsten carbide grains are 0.40 sm or more and 2.00 sm or less respectively, the second hard phases are composed of at least one first compound selected from the group consisting of TaNbC, TaNbN, TaNbCN, TiCN, TiNbC, TiNbN, and TiNbCN, the cemented carbide includes 0.30 to 1.60% by volume of the second hard phases, a median of areas of the second hard phases is 0.90 to 1.20 μm2, a coefficient of variation of the areas of the second hard phases is 0.50 to 1.20, the binder phase includes 50% by mass or more of cobalt, and the cemented carbide includes 8.0 to 12.0% by volume of the binder phase.