Cemented Carbide Composition With Lattice-Strained WC Grains
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Solution Overview
Problem
Cemented carbides used in cutting tools face challenges in maintaining toughness and strength, particularly in cutting processes involving difficult-to-cut materials like steel and titanium, necessitating improved properties to extend tool life.
Innovation Solution
A cemented carbide composition comprising 80% or more tungsten carbide grains and a binder phase, with specific atomic ratios of first metal elements (titanium, niobium, or tantalum) distributed across the grain surface and interior regions, generating lattice strain for enhanced toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional cemented carbide composition is used, then manufacturing simplicity is maintained, but toughness and strength are insufficient for cutting difficult materials
Solution Approach 1:
The patent applies local quality by creating distinct regions within the tungsten carbide grain structure: a surface region (0-50nm from surface) with high first metal element concentration (R1 ratio) and an interior region (second region) with lower concentration (R2 ratio). This spatial differentiation of composition optimizes both surface toughness and overall grain strength, resolving the contradiction between improved toughness and composition simplicity.
Solution Approach 2:
The patent uses composite materials by combining tungsten carbide grains with a binder phase containing cobalt and other metal elements. The multi-phase composite structure (WC grains + binder phase with specific metal elements) provides both the hardness of carbide and the toughness of metallic binder, addressing the strength limitation while maintaining manufacturability through established composite material processing.
2Strength
If binder phase content is increased to improve toughness, then strength is enhanced, but hardness and wear resistance deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the binder phase content within 0.1-20 volume% and the first metal element ratios (R1: 0.70-1.30 times R2, where R2 is 2.0-10.0%). This optimized parameter range ensures sufficient toughness from the binder phase while maintaining adequate hardness and wear resistance, preventing the deterioration that would occur with higher binder content.
3Strength
If uniform metal element distribution is used, then manufacturing is simplified, but lattice strain and toughness are insufficient
Solution Approach 1:
The patent implements local quality through non-uniform metal element distribution: the surface region (first region) contains a higher concentration of first metal elements (R1 ratio) compared to the interior region (R2 ratio), with R1 being 0.70-1.30 times R2. This localized concentration gradient generates the necessary lattice strain to enhance toughness while providing clear compositional targets for manufacturing control.
Solution Approach 2:
The patent applies dimensional change by considering the radial dimension from the grain surface inward, defining two distinct regions (surface region 0-50nm and interior region) with different compositional characteristics. This spatial dimensioning of element distribution enables lattice strain optimization without requiring complex multi-step manufacturing processes.
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 composition achieves significant improvements in toughness and strength, enabling longer tool life and better performance in challenging cutting processes.
Implementation Method 1
each of the first region and the second region includes a first metal element, a ratio R1 of the number of atoms of the first metal element to a total of the number of atoms of the first metal element and the number of atoms of a tungsten element in the first region is 0.70 time or more and less than 1.30 times as large as a ratio R2 of the number of atoms of the first metal element to a total of the number of atoms of the first metal element and the number of atoms of a tungsten element in the second region, the R2 is 2.0% or more and 10.0% or less
Data Source
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AI summary
A cemented carbide includes a tungsten carbide grain and a binder phase, wherein the cemented carbide includes 80 volume% or more of the tungsten carbide grain and the binder phase in total, the cemented carbide includes 0.1 volume% or more and 20 volume% or less of the binder phase, the tungsten carbide grain is composed of a first region and a second region, the first region is a region of 0 nm or more and 50 nm or less from a surface of the tungsten carbide grain, the second region is a portion of the tungsten carbide grain other than the first region, each of the first region and the second region includes a first metal element, the first metal element is at least one selected from a group consisting of titanium, niobium, and tantalum, a ratio R1 of the number of atoms of the first metal element to a total of the number of atoms of the first metal element and the number of atoms of a tungsten element in the first region is 0.70 time or more and less than 1.30 times as large as a ratio R2 of the number of atoms of the first metal element to a total of the number of atoms of the first metal element and the number of atoms of the tungsten element in the second region, the R2 is 2.0% or more and 10.0% or less, and the binder phase includes cobalt.