Coated Cutting Tool Laminate Structure for Oxidation and Wear Resistance
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Solution Overview
Problem
Cutting tools experience reduced wear resistance and fracture resistance during high-speed machining of difficult-to-machine materials like stainless cast steel and heat resisting steel, leading to shorter tool life due to thermal factors and oxidation, which existing coated cutting tools fail to adequately address.
Innovation Solution
A coated cutting tool with a specific laminate structure comprising alternating layers of (AlaM1-a)N and (AlbM1-b)N, where M denotes elements like Ti, Zr, or Cr, and a, b are within specific atomic ratios, ensuring optimal metal element ratios and thicknesses to enhance wear and fracture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a composite oxynitride layer is used to improve oxidation resistance, then oxidation resistance is improved, but wear resistance is reduced
Solution Approach 1:
The coating is divided into multiple functional layers: a base layer with alternating (Al,Ti)N and (Al,Cr)(O,N) layers for wear resistance, and an upper layer with alternating (Al,Ti)(O,N) and (Al,Mn)(O,N) layers for oxidation resistance. This segmentation allows each layer to optimize for its specific function without compromising the other.
Solution Approach 2:
The invention uses composite coating structures combining different material systems - titanium nitride and chromium oxynitride in the base layer, and aluminum-titanium oxynitride with aluminum-manganese oxynitride in the upper layer. These composite materials provide synergistic effects where the combination delivers both wear and oxidation resistance that individual materials cannot achieve alone.
2Productivity
If cutting speed is increased to improve machining efficiency, then productivity is improved, but tool life is reduced due to high temperature and thermal cracking
Solution Approach 1:
The invention changes the chemical composition parameters of the coating layers, specifically controlling the atomic ratios of Al, Ti, Cr, Mn, N, and O to form a multi-layer structure with optimized properties that can withstand high cutting temperatures and extend tool life during high-speed machining.
Solution Approach 2:
The multi-layer composite coating structure combines materials with different thermal and mechanical properties to create a coating system that resists thermal cracking and maintains integrity at high temperatures, enabling extended tool life during high-speed machining operations.
Data Source
AI summary
A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate, the coating layer comprising a first laminate structure and a second laminate structure, wherein: the first laminate structure has a laminate structure in which predetermined compound layers of two kinds, each having a different composition, are laminated in an alternating manner; the first laminate structure satisfies a predetermined condition; the second laminate structure has a laminate structure in which a first compound layer comprising a predetermined oxide and/or oxynitride and a second compound layer having a predetermined composition are laminated in an alternating manner; and an average thickness of each compound layer which constitutes the first laminate structure, an average thickness of each compound layer which constitutes the second laminate structure, and a thickness of the coating layer in its entirety each fall within a predetermined range.