Composition-Modulated (Al,Cr,Si,Cu)N Coating for Crack-Resistant Cutting Tools
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Solution Overview
Problem
Coated tools used for cutting high-hardness steels under high-speed intermittent conditions suffer from cracking and wear due to high-temperature heat and intermittent loads, leading to reduced tool life.
Innovation Solution
A hard coating layer composed of (Al,Cr,Si,Cu)N with a composition modulated structure, where the Cr and Cu concentrations periodically change in phase, enhancing toughness and wear resistance, is applied to the cutting tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a hard coating layer is applied to improve wear resistance, then wear resistance is improved, but cracking resistance deteriorates under high-temperature and high-impact conditions
Solution Approach 1:
The coating layer introduces a composition modulated structure with periodic variation in Cr and Cu concentrations, creating regions of alternating hardness and toughness. The highest Cr content points provide high hardness and wear resistance, while the lowest Cr content points (with higher Cu content) provide toughness and cracking resistance, allowing the coating to simultaneously exhibit both wear resistance and cracking resistance through spatially varying local properties.
2Strength
If Cr content is increased to improve high-temperature toughness and strength, then high-temperature strength is improved, but wear resistance deteriorates due to reduced Al content
Solution Approach 1:
The coating layer employs a composition modulated structure where Cr and Cu concentrations periodically vary along the layer thickness direction. This periodic modulation creates alternating regions: highest Cr content points (providing high-temperature strength) and lowest Cr content points (providing wear resistance through higher Al and Cu content). The periodic distribution allows both high-temperature strength and wear resistance to be achieved without requiring a uniform high Cr content throughout the entire layer.
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 (Al,Cr,Si,Cu)N layer exhibits excellent chipping resistance and wear resistance, extending the tool's service life during high-speed intermittent cutting of high-hardness steels by preventing cracking and wear progression.
Implementation Method 1
a hard coating layer which includes at least the (Al,Cr,Si,Cu)N layer, in which a composition modulated structure is formed, having highest Cr content points and lowest Cr content points alternately arranged in a layer thickness direction
Implementation Method 2
the Cr component concentration in the (Al,Cr,Si,Cu)N layer periodically changes along the layer thickness direction, and highest Cr content points and lowest Cr content points are present
Data Source
Figure 1A~1B
Figure 1C~2
Figure 3A
AI summary
At least a (Al1-a-b-cCraSibCuc)N (where 0.15≤a≤0.40, 0.05≤b≤0.20, and 0.005≤c≤0.05) layer is provided on a surface of a tool body, a Cr concentration or a Cu concentration periodically changes in a layer thickness direction, a concentration Crmax in a highest content point of Cr is in a range of a<Crmax≤1.3a, a concentration Crmin in a lowest content point of Cr is in a range of 0.50a≤Crmin<a, and optionally in a case where a Cu composition at one point z along the layer thickness direction is represented by cz and a Cr composition at the point z is represented by az, (cz/az)/(c/a) is 0.7 to 1.5 over the layer thickness direction entirely.