Multilayer Hard Coating for Cutting Tools
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Solution Overview
Problem
Existing multilayer film-coated members for cutting tools and abrasion-resistant components face challenges in achieving sufficient heat resistance, abrasion resistance, and adhesion strength, especially in severe cutting environments where tools are exposed to rapid cutting speeds and high temperatures.
Innovation Solution
A multilayer film-coated member is fabricated with at least two hard coating films of different compositions, where the first composition is represented by SiaBbNcCdOe and the second composition includes elements like Al, Ti, Cr, Ni, Ce, Mg, Nb, W, Si, V, Zr, and Mo, with controlled oxygen content and B—O to B—N peak area ratios, ensuring excellent adhesion strength and resistance to heat and abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat-resistant coating film with Si (oxides of Y and Si dispersed in a glassy matrix comprising SiO2 and B2O3) is used, then heat resistance is improved, but abrasion resistance deteriorates
Solution Approach 1:
The coating is divided into multiple layers with different compositions and functions. The first layer (near substrate) has higher Si content for adhesion and heat resistance, while the second layer (outer surface) has optimized composition for abrasion resistance. This segmentation allows each layer to specialize in one property, resolving the contradiction between heat resistance and abrasion resistance.
Solution Approach 2:
Different regions of the coating have different chemical compositions tailored to local requirements. The first layer contains Si, B, N, C, O in specific ratios for heat resistance and adhesion, while the second layer has optimized composition for abrasion resistance. This local quality differentiation enables simultaneous achievement of heat resistance and abrasion resistance in different locations.
2Strength
If a (TiAl(SiC))N coating film is used, then heat resistance and abrasion resistance are improved compared to TiAlN, but the improvement effect is limited due to the TiAlN base
Solution Approach 1:
The coating uses a composite structure with TiAlN as the base layer and an outer layer with optimized composition including Si, B, C, N, O elements. This composite material approach combines the good adhesion of TiAlN with the enhanced abrasion and heat resistance of the outer layer, achieving synergistic effects that overcome the limitations of single-phase coatings.
3Strength
If a Si(BCN)-based coating film is used, then abrasion resistance and heat resistance are greatly improved, but adhesion strength deteriorates in severe cutting environments
Solution Approach 1:
The coating is segmented into two layers: the first layer (near substrate) contains Si, B, N, C, O in specific ratios optimized for adhesion to the substrate, while the second layer (outer surface) has composition optimized for abrasion and heat resistance. This segmentation resolves the contradiction by assigning different functional priorities to different layers.
Solution Approach 2:
The chemical composition parameters are changed across the coating thickness. The first layer has specific atomic ratios of Si, B, N, C, O for adhesion, while the second layer has different ratios for surface performance. This parameter gradient approach enables the coating to achieve both strong adhesion and excellent abrasion/heat resistance.
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 provides enhanced heat resistance, improved abrasion resistance, and significantly improved adhesion strength, enabling the coated tools to perform effectively in high-speed and rapid-feed cutting operations while preventing work material adhesion, thus extending tool stability and performance.
Implementation Method 1
a multilayer film-coated member fabricated by coating the surface of a substrate with at least two hard coating films having different compositions
Implementation Method 2
fabricated by coating the surface of a substrate with at least two hard coating films
Implementation Method 3
the ratio of the peak area X of B—O to the peak area Y of B—N, as obtained from the peak separation of the is orbit of B in X-ray photoelectric spectrometry
Data Source
AI summary
A multilayer film-coated member is fabricated by coating the surface of a substrate with at least two hard coating films having different compositions, wherein the first composition hard film of the outermost layer is represented by SiaBbNcCdOe with a+b+c+d+e=1, 0.1≦a≦0.5, 0.01≦b≦0.2, 0.05≦c≦0.6, 0.1≦d ≦0.7 and 0<e≦0.2, the second composition hard coating film having at least two selected from Al. Ti, Cr, Ni, Ce. Mg, Nb, W, Si, V, Zr and Mo and N and at least one selected from B, C, O and S and the oxygen content of the film at least 25 nm from the interface of the first composition hard coating film that is in contact with the underlying layer toward the surface of the first composition hard coating film is limited to a range of less than 3.5 atm. %.