TiSiCN Coating Structure for Cutting Tools to Suppress Welding
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Solution Overview
Problem
Cutting tools with a TiSiCN film exhibit high abrasion resistance but suffer from welding issues during continuous machining of chromium molybdenum steel due to high affinity between silicon and iron, leading to reduced tool life.
Innovation Solution
A cutting tool with a coating comprising a first layer of hard particles made of titanium, silicon, and nitrogen, having a cubic crystal structure and a columnar structure, with specific atomic ratios and a stacked layer configuration, enhances hardness, slidability, and suppresses welding by alternating unit layers with varying silicon and carbon content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a TiSiCN film is used on the substrate, then abrasion resistance is improved, but welding occurs during continuous machining of chromium molybdenum steel due to high affinity between silicon and iron
Solution Approach 1:
The coating is divided into multiple layers with different compositions and functions. The first layer contains hard particles with specific TiSiCN composition for abrasion resistance, while the second layer has different composition to prevent welding. This segmentation allows each layer to perform its specific function without interfering with the other.
Solution Approach 2:
Different regions of the coating have different chemical compositions tailored to specific requirements. The first layer has higher silicon content for hardness, while the second layer has optimized composition to reduce silicon-iron affinity and prevent welding. This local quality variation resolves the contradiction between needing silicon for hardness and avoiding silicon for welding prevention.
2Strength
If silicon content is increased to improve hardness, then abrasion resistance is improved, but affinity with iron increases causing welding
Solution Approach 1:
The coating is divided into multiple layers with different compositions and functions. The first layer contains hard particles with specific TiSiCN composition for abrasion resistance, while the second layer has different composition to prevent welding. This segmentation allows each layer to perform its specific function without interfering with the other.
Solution Approach 2:
Different regions of the coating have different chemical compositions tailored to specific requirements. The first layer has higher silicon content for hardness, while the second layer has optimized composition to reduce silicon-iron affinity and prevent welding. This local quality variation resolves the contradiction between needing silicon for hardness and avoiding silicon for welding prevention.
Data Source
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AI summary
A cutting tool, comprising a substrate and a coating disposed on the substrate, wherein the coating comprises a first layer, the first layer consists of multiple hard particles, the hard particles consist of titanium, silicon, carbon, and nitrogen, the hard particles have a cubic crystal structure, the first layer has a columnar structure, in the first layer, the average of the ratio of the number of silicon atoms NSi to the sum of the number of titanium atoms NTi and the number of silicon atoms NSi, NSi/(NTi + NSi), is 0.01 or more and 0.10 or less, in the first layer, the average of the ratio of the number of carbon atoms Nc to the sum of the number of carbon atoms Nc and the number of nitrogen atoms NN, Nc/(Nc + NN), is 0.60 or more and 0.85 or less, the hard particles have a stacked structure in which first unit layers and second unit layers are stacked alternately, the first unit layers and the second unit layers each consist of titanium, silicon, carbon, and nitrogen, the ratio of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the first unit layers, x1, is higher than the ratio of the number of silicon atoms to the sum of the number of titanium atoms and the number of silicon atoms in the second unit layers, x2, and the ratio of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the first unit layers, y1, is higher than the ratio of the number of carbon atoms to the sum of the number of carbon atoms and the number of nitrogen atoms in the second unit layers, y2.