Multilayer TiAlBN Hard Coating for Wear-Resistant Cutting Tools
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Solution Overview
Problem
Cutting tools experience reduced lifespan due to increased wear, breakage, and heat resistance issues under high-speed and high-load cutting processes, necessitating improved mechanical characteristics.
Innovation Solution
A cutting tool with a hard layer composed of alternately layered first and second unit layers, each defined by specific atomic ratios of Ti, Al, and B, forming a mixed crystal structure of cubic and hexagonal columnar crystals, enhancing breakage and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard coating film is formed on the substrate to improve wear resistance, then wear resistance is improved, but breakage resistance deteriorates
Solution Approach 1:
The coating film is divided into multiple alternating layers with different compositions (TiAlN layers and TiAlSiN layers) instead of using a single homogeneous layer. This segmentation allows each layer to contribute different properties, with the TiAlN layers providing hardness and wear resistance while the TiAlSiN layers providing toughness and breakage resistance, thus resolving the contradiction between wear resistance and breakage resistance
Solution Approach 2:
The coating film uses a composite structure combining different ceramic materials (TiAlN and TiAlSiN) in an alternating layered configuration. This composite material approach allows the coating to exhibit both the high hardness of TiAlN for wear resistance and the higher toughness of TiAlSiN for breakage resistance, simultaneously achieving both improved wear resistance and breakage resistance
2Reliability
If the coating film thickness is increased to improve wear resistance, then wear resistance is improved, but heat resistance deteriorates
Solution Approach 1:
The thick coating film is segmented into multiple thin alternating layers of TiAlN and TiAlSiN. This segmentation creates a multi-layered thermal management structure where the different materials provide complementary thermal properties, allowing the coating to maintain heat resistance even at greater total thickness while still providing improved wear resistance through the cumulative effect of multiple wear-resistant layers
Solution Approach 2:
The composite structure of alternating TiAlN and TiAlSiN layers provides both wear resistance and heat resistance simultaneously. The TiAlN layers contribute to wear resistance with their high hardness, while the TiAlSiN layers contribute to heat resistance with their thermal stability, allowing the coating to achieve both improved wear resistance and maintained heat resistance at optimized thicknesses
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 cutting tool exhibits excellent breakage resistance and heat resistance, with improved wear resistance when the hard layer thickness is optimized, achieving longer tool life.
Implementation Method 1
a mixed crystal of cubic columnar crystals (23) and hexagonal columnar crystals (24) is formed in the hard layer (20)
Implementation Method 2
a hard coating film layer composed of a composite nitride of Al and Ti and having a layer thickness of 0.8 to 5.0 μm is formed by vapor deposition on a surface of a tool substrate
Data Source
Figure 1~2
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Figure 5~6
AI summary
A cutting tool includes a substrate and a hard layer provided on the substrate, wherein the hard layer includes a first unit layer and a second unit layer, one or a plurality of the first unit layers and one or a plurality of the second unit layers are alternately layered in the hard layer, a thickness of each of the one or plurality of first unit layers is 2 nm or more and 100 nm or less, a thickness of each of the one or plurality of second unit layers is 2 nm or more and 100 nm or less, the first unit layer is composed of a compound represented by TiaAlbBcN, the second unit layer is composed of a compound represented by TidAleBfN, an atomic ratio a of a titanium element in the TiaAlbBcN is 0.25 or more and less than 0.45, an atomic ratio b of an aluminum element in the TiaAlbBcN is 0.55 or more and less than 0.75, an atomic ratio c of a boron element in the TiaAlbBcN is more than 0 and 0.1 or less, a total of the atomic ratio a, the atomic ratio b, and the atomic ratio c is 1, an atomic ratio d of a titanium element in the TidAleBfN is 0.35 or more and less than 0.55, an atomic ratio e of an aluminum element in the TidAleBfN is 0.45 or more and less than 0.65, an atomic ratio f of a boron element in the TidAleBfN is more than 0 and 0.1 or less, a total of the atomic ratio d, the atomic ratio e, and the atomic ratio f is 1, the atomic ratio a and the atomic ratio d satisfy 0.05≤d-a≤0.2, and the atomic ratio b and the atomic ratio e satisfy 0.05≤b-e≤0.2.