Laminated Nitride Coating for Chipping-Resistant Intermittent Cutting
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Solution Overview
Problem
Conventional surface-coated cutting tools experience chipping and reduced wear resistance when used in heavy intermittent cutting of alloy steel, leading to short tool life due to intermittent and impacting heavy loads.
Innovation Solution
A surface-coated cutting tool with a hard coating layer formed in an alternating laminated structure, comprising a (Ti, Al)N layer as the A layer and a (Cr, Al, M)N layer as the B layer, with specific compositional and structural parameters to enhance adhesion strength, chipping resistance, and wear resistance, including a lattice constant and peak intensity ratio within predetermined ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional hard coating layer is used on cutting tools, then wear resistance is provided, but chipping resistance deteriorates under heavy intermittent cutting loads
Solution Approach 1:
The hard coating layer is divided into multiple sub-layers with different compositions and functions. The gradient structure segments the coating into regions with varying Al content and crystal orientations, allowing each segment to address specific requirements: surface hardness, impact resistance, and adhesion to the substrate.
Solution Approach 2:
The coating structure utilizes controlled variations in compositional parameters (Al content gradient from 20-80 at%), crystallographic parameters (preferred orientation angles), and microstructural parameters (grain size distribution) to achieve optimal balance between chipping resistance and wear resistance throughout the coating thickness.
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 tool exhibits excellent chipping resistance and wear resistance over long periods, effectively attenuating impact loads during heavy intermittent cutting, ensuring extended tool life and improved cutting performance.
Implementation Method 1
a coated tool formed by coating a hard coating layer constituted by a complex nitride ((Cr, Al)N) layer of Cr and Al or a complex nitride ((Ti, Al)N) layer of Ti and Al on a surface of a body (hereinafter, these are generally referred to as a tool body) constituted by a tungsten carbide (hereinafter, represented by WC)-based cemented carbide, a titanium carbonitride (hereinafter, represented by TiCN)-based cermet or a cubic boron nitride sintered material (hereinafter, represented by cBN) through an arc ion plating method
Data Source
AI summary
Provided is a surface-coated cutting tool including: a tool body (3) and a hard coating layer on the tool body (3). The hard coating layer has an alternate laminate structure of A (1) and B layers (2). The A layer (1) is a Ti and Al complex nitride layer satisfying a compositional formula: (Ti1-zAlz)N, 0.4≤z≤0.7. The B layer (2) is a Cr, Al and M complex nitride layer satisfying a compositional formula: (Cr1-x-yAlxMy)N, 0.03≤x≤0.4 and 0≤y≤0.05. The value of a ratio tB/tA of the average layer thickness of the B layer (2) to the average layer thickness of the A layer (1) satisfies 0.67 to 2.0. The lattice constant a(Å) of crystal grains of the hard coating layer satisfies 4.10≤a≤4.20. The ratio of I(200) to I(111) satisfies 2.0≤I(200)/I(111)≤10.