Multilayer Nitride Coating for Durable Coated Cutting Tools
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Solution Overview
Problem
Conventional coated cutting tools with AlCrSi nitride coatings face limitations in durability, particularly due to the presence of aluminum nitride with a hexagonal closest packed structure, which affects their wear resistance and heat resistance.
Innovation Solution
A coated cutting tool design featuring a layered coating film structure with specific composition and thickness ratios of Al-rich AlCr-based and AlTi-based nitride or carbonitride layers, reducing the amount of aluminum nitride with a hexagonal closest packed structure, and incorporating an AlCrSi-based nitride or carbonitride upper layer to enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional AlCrSi nitride coating is used, then the coating provides basic wear resistance, but the durability and heat resistance are insufficient due to the presence of brittle hexagonal AlN structure
Solution Approach 1:
The patent changes the crystal structure parameter of AlN from hexagonal to cubic form through controlled deposition conditions, and adjusts the composition parameters (Al 55-75 atom%, Cr 15-30 atom%, Si 5-20 atom%) to optimize the coating properties and eliminate the brittle hcp-AlN phase
Solution Approach 2:
The patent creates a composite nitride coating combining Al, Cr, and Si elements in specific proportions, forming a multi-element compound that leverages the beneficial properties of each element while avoiding the drawbacks of conventional AlCrSi coatings
2Strength
If the coating is made harder to improve wear resistance, then wear resistance improves, but the coating becomes more brittle and less durable under thermal stress
Solution Approach 1:
The patent changes the crystal structure from hexagonal to cubic, and optimizes composition parameters (Al 55-75 atom%, Cr 15-30 atom%, Si 5-20 atom%) to achieve a balance between hardness and thermal stability, preventing the coating from becoming excessively brittle
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 solution significantly improves the durability of the coated cutting tool by reducing the brittle aluminum nitride content and enhancing heat and wear resistance, leading to better performance under severe usage conditions.
Implementation Method 1
a layered coating film formed by alternately layering a nitride or carbonitride layer (c1) and a nitride or carbonitride layer (c2), each layer having a film thickness of 50 nm or less
Data Source
AI summary
Provided is a coated cutting tool, which includes a hard coating film containing a layer (b) formed of a nitride or a carbonitride, a layer (c) which is a layered coating film formed by alternately layering a nitride or carbonitride layer (c1) that contains 55 atom % or more and 75 atom % or less of Al, Cr having a second highest content percentage, and at least Si and a nitride or carbonitride layer (c2) that contains 55 atom % or more and 75 atom % or less of Al and Ti having a second highest content percentage, each layer having a film thickness of 50 nm or less, and a layer (d) that is a nitride or carbonitride that contains, with respect to a total amount of metal elements (including metalloid elements), 55 atom % or more and 75 atom % or less of Al, Cr having a second highest content percentage.