Multilayer Hard Coating for Tool Wear and Welding Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hard film coatings for cutting tools, such as end mills, fail to provide sufficient abrasion resistance for cutting carbon steel, alloy steel, and heat-treated steel, and also lack adequate welding resistance.
Innovation Solution
A hard film is formed by alternately laminating layers of AlTiCr nitride, AlTiCr carbonitride, and AlCr(SiC) nitride or carbonitride with nano-order thickness, using a physical vapor deposition method, to achieve a total film thickness of 0.5 to 20 µm, enhancing abrasion and welding resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a TiAlN-based/TiCrN-based hard film is used, then the coating provides basic hardness, but sufficient abrasion resistance cannot be achieved when used for cutting of carbon steel, alloy steel, or heat-treated steel
Solution Approach 1:
The patent applies composite materials by creating a multilayer hard film structure consisting of alternating layers of AlTiCr nitride, AlTiCr carbonitride, and AlCr(SiC) nitride or carbonitride. Each layer contributes different properties: AlTiCr nitride provides hardness, AlTiCr carbonitride enhances toughness and abrasion resistance, and AlCr(SiC) nitride/carbonitride layers provide welding resistance and heat resistance. This composite structure resolves the contradiction by combining multiple materials with complementary properties to achieve both high abrasion resistance and reliable cutting performance on carbon steel.
Solution Approach 2:
The patent applies segmentation by dividing the hard film into multiple thin alternating layers with different compositions and functions. Instead of using a single homogeneous coating, the film is segmented into nanometer-thin layers (each layer 0.5-500 nm thick) that alternate between different material systems. This segmentation allows each layer to perform its specific function while collectively providing superior overall performance, resolving the contradiction between hardness and abrasion resistance.
2Reliability
If an AlCrN- and TiSiN-based multilayer structure is used, then the coating provides basic welding resistance, but sufficient performance cannot be achieved due to insufficient welding resistance when used for cutting work of carbon steel, alloy steel, or heat-treated steel
Solution Approach 1:
The patent enhances welding resistance by incorporating AlCr(SiC) nitride and carbonitride layers into the composite structure. The AlCr(SiC) composition specifically addresses welding resistance concerns while maintaining cutting performance. The alternating structure ensures that the welding-resistant layers are distributed throughout the film thickness, providing consistent protection against welding issues during cutting of alloy steel and heat-treated steel.
Solution Approach 2:
The patent applies local quality by assigning specific functions to specific layers within the multilayer structure. The AlCr(SiC) nitride and carbonitride layers are specifically designed to provide welding resistance at the interfaces where welding issues occur, while the AlTiCr nitride and carbonitride layers provide hardness and abrasion resistance in the bulk. This localized functional assignment resolves the contradiction between welding resistance and cutting performance.
3Duration of action of stationary object
If a single-layer or simple multilayer hard film is used, then the coating process is simpler, but the tool life is shorter due to insufficient combined abrasion and welding resistance
Solution Approach 1:
The patent uses segmentation to create a multilayer structure with 5-50 alternating layers, each only 0.5-500 nm thick. While the number of layers increases complexity, the nanometer-scale thickness of each layer and the systematic alternation pattern keep the overall structure manageable. The segmentation allows each layer to be optimized for its specific function while maintaining a relatively simple overall architecture that can be deposited using standard PVD equipment.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the thickness of each layer (0.5-500 nm) and the total film thickness (0.5-20 µm), as well as the composition ratios of elements within each layer. These parameter optimizations ensure that the complex multilayer structure achieves maximum performance with minimal material usage and processing time, resolving the contradiction between tool life extension and coating complexity.
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 resulting hard film coating significantly improves the tool's lifespan by providing high hardness, toughness, and lubricity, effectively addressing the limitations of previous coatings in cutting and welding applications.
Implementation Method 1
a hard film formed by alternately laminating a layer A of AlTiCr nitride, a layer B of AlTiCr carbonitride, and an alternating layer of a nanolayer A or nanolayer B having the same composition as the layer A or the layer B and a nano-order thickness and a nanolayer C of AlCr(SiC) nitride or AlCr(SiC) carbonitride having a nano-order thickness
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A hard film 24 for coating a surface of a tool base material 30 is configured to have a film thickness of 0.5 to 20 µm by using a physical vapor deposition method to alternately laminate a layer A 34, a layer B 36, and a nanolayer-alternating layer 40 in which a nanolayer A 37 or a nanolayer B 38 having the same composition as the layer A or the layer B and a layer C 39 are alternately laminated to a nano-order thickness; the layer A 34 has a composition formula of (AlaTibCrcαd)N and has a thickness of 0.5 to 1000 nm; the layer B 36 has a composition formula of (AleTifCrgβh)CxN1-X and has a thickness of 0.5 to 1000 nm; the nanolayer-alternating layer 40 has a thickness of 1 to 1000 nm; the layer C 39 has a composition formula of [AliCrj(SiC)kγl]CYN1-Y; and the nanolayer A 37 or the nanolayer B and the layer C 39 have a thickness of 0.5 to 500 nm.