W-Enriched Interfacial Phase Cermet for Cutting Tools
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Solution Overview
Problem
Conventional cermets used in cutting tools suffer from poor fracture resistance, making it difficult to achieve a longer tool lifetime and efficient cutting processing.
Innovation Solution
A cermet with an interfacial phase containing a higher amount of W than the hard phase, comprising Ti-based carbides, nitrides, and carbonitrides, and a binder phase with iron group metals, which improves fracture and wear resistance by forming a layered complex carbonitride interfacial phase with a specific W atomic ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional cermet is used, then wear resistance is improved, but fracture resistance deteriorates
Solution Approach 1:
The patent applies local quality by creating distinct regions within the hard phase with different W concentrations. The interfacial phase at grain boundaries has high W content (3-10 atomic%) for fracture resistance, while the inner hard phase maintains lower W content for wear resistance. This spatial differentiation of composition resolves the contradiction between wear resistance and fracture resistance.
Solution Approach 2:
The patent creates a composite structure within the hard phase consisting of an interfacial phase (high W content) and an inner hard phase (lower W content). This composite arrangement combines the crack-arresting capability of W-rich regions with the wear-resistant properties of Ti-based carbonitride, simultaneously achieving both wear resistance and fracture resistance.
2Duration of action of stationary object
If cutting tool lifetime is extended, then processing efficiency is improved, but tool defect frequency increases
Solution Approach 1:
The patent implements beforehand cushioning by pre-forming an interfacial phase enriched with W at the grain boundaries of hard phases before the tool encounters operational stresses. This pre-positioned W-rich phase acts as a cushion that arrests cracks and prevents defect propagation, enabling extended tool lifetime without increasing defect frequency.
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 cermet exhibits enhanced fracture resistance and wear resistance, inhibiting crack progression and extending the tool's lifetime and processing efficiency.
Implementation Method 1
a diffusion barrier layer for preventing material interdiffusion
Implementation Method 2
the coating layer and the diffusion barrier layer may each be formed by a physical vapor deposition process, a chemical vapor deposition process
Implementation Method 3
the coating layer and the diffusion barrier layer may each be formed by a physical vapor deposition process, a chemical vapor deposition process
Data Source
AI summary
The present invention is to provide a cermet which comprising a hard phase which contains W and nitrogen, and comprises at least one selected from a carbide, nitride and carbonitride of a metal comprising Ti as a main component, and a binder phase comprising an iron group metal as a main component, wherein a W amount contained in the whole cermet is 5 to 40% by weight, an interfacial phase comprising a complex carbonitride with a larger W amount than a W amount of the hard phase being present between the hard phase and the hard phase, and when a W amount contained in the interfacial phase based on the whole metal element is represented by Wb (atomic %), and a W amount contained in the hard phase based on the whole metal element is represented by Wh (atomic %), then, an atomic ratio of Wb to Wh (Wb/Wh) being 1.7 or more, which is excellent in fracture resistance and wear resistance.