TiSiCN Coating Gradient for Crack-Resistant Cutting Tools
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Solution Overview
Problem
Conventional cutting tools with a TiSiCN film exhibit excellent wear resistance but suffer from cracks during milling of die steel, leading to reduced tool life.
Innovation Solution
A cutting tool with a hard particle layer composed of titanium, silicon, and nitrogen, featuring a first region and a second region with varying silicon content and a periodic silicon concentration, providing enhanced wear and toughness to prevent crack propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a TiSiCN film is formed on the base material to improve wear resistance, then wear resistance is improved, but cracks occur in the coating during milling of die steel, leading to reduced tool life
Solution Approach 1:
The coating is designed with spatially varying silicon content: the first region (near the base material) has higher silicon content (Xb) for wear resistance, while the second region (outer surface) has lower silicon content (Xs) for toughness and crack resistance. This gradient structure (Xb - Xs ≥ 0.01) allows each region to perform its specific function optimally, resolving the contradiction between wear resistance and crack resistance
Solution Approach 2:
The coating forms a composite structure with two distinct regions having different compositions (Ti(1-Xb)SiXbCN and Ti(1-Xs)SiXsCN). This composite architecture combines the wear-resistant properties of high-silicon regions with the tough, crack-resistant properties of low-silicon regions, achieving both improved wear resistance and extended tool life
Data Source
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AI summary
A cutting tool comprising a base material and a coating disposed on the base material, wherein the coating comprises a hard particle layer, the hard particle layer is formed from a plurality of hard particles consisting of titanium, silicon, carbon, and nitrogen, the hard particle layer comprises a first region and a second region, the first region is a region sandwiched between a first main surface of the hard particle layer facing forward the base material and a virtual surface S1 at a distance of 0.5 µm from the first main surface toward the hard particle layer, the second region is a region sandwiched between a second main surface of the hard particle layer opposite to the first main surface and a virtual surface S2 at a distance of 0.5 µm from the second main surface toward the hard particle layer, a composition of the first region is Ti(1-Xb)SiXbCN, a composition of the second region is Ti(1-Xs)SiXsCN, the Xs and the Xb satisfy relationships of Xb - Xs ≥ 0.01 and 0 < Xs < Xb ≤ 0.10, the hard particles have a cubic crystal structure, and in the hard particles, a concentration of the silicon changes periodically along a first direction going from the first main surface to the second main surface.