Cemented Carbide Toughness via WC/WC Interface Co Enrichment
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Solution Overview
Problem
Cemented carbides used in cutting tools lack sufficient toughness, especially when processing complex and difficult-to-cut workpieces, leading to issues with thermal shock and mechanical impact resistance.
Innovation Solution
A cemented carbide composition with a high ratio of WC/WC interfaces having a specific atomic percentage of Co, combined with a second hard phase containing tungsten and specific metal elements, enhances adhesion strength and toughness, balancing hardness and toughness for improved cutting tool performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional cemented carbide composition is used, then hardness is maintained, but toughness is insufficient
Solution Approach 1:
The patent creates a non-uniform distribution of Co atoms at WC/WC interfaces, where the atomic percentage of Co is specifically controlled to be 0.5-2.0 times the average value in the binder phase. This local enrichment of Co at interfaces enhances adhesion strength between WC particles without compromising the overall hardness of the cemented carbide, thereby improving toughness and resistance to thermal shock and mechanical impact.
Solution Approach 2:
The patent utilizes a composite structure consisting of WC hard phase particles embedded in a Co binder phase, with specific attention to the interface region. By controlling the atomic percentage of Co at WC/WC interfaces to be within a specific range (0.5-2.0 times the average), the material achieves a balanced composite structure that provides both the hardness from WC particles and the toughness from optimized Co distribution at interfaces.
Data Source
AI summary
A cemented carbide comprising a first hard phase composed of tungsten carbide particles and a binder phase including Co, the cemented carbide having a ratio Nt/Na of 0.9 or more, where, in any surface or any cross section of the cemented carbide, a region in which there is a distance X of 5 nm or less between surfaces respectively of tungsten carbide particles adjacent to each other, the surfaces facing each other along a length L of 100 nm or more, is referred to as a WC/WC interface, and Na represents a total number of WC/WC interfaces and Nt represents a number of WC/WC interfaces having distance X of 1 nm or more and 5 nm or less and having therein an atomic percentage of Co higher than an average value of atomic percentages of Co in the tungsten carbide particles.