Three-Layer Hard Coating Film for Tool Base Material
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Solution Overview
Problem
Hard coating films on tool base materials suffer from inadequate bonding strength, leading to peeling and wear issues, especially when cutting stainless steel or materials with lower hardness, resulting in reduced cutting performance and tool life.
Innovation Solution
A three-layer hard coating film structure is developed, comprising a first layer of (Cr1-a-bBa(SiC)b)(CcOdN1-c-d), a second layer of AlCrN or AlCrDN, and a third layer of nitride, carbon nitride, or carbide of metals like Al, Ti, Zr, Hf, V, Nb, Ta, Cr, and W, with specific atomic ratios and film thickness ranges, and mixed layers formed at boundary portions to enhance bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-layer hard coating film (layer A with wear resistance, layer B with adhesion resistance) is formed on a tool base material, then wear resistance and adhesion resistance are improved, but bonding strength between the coating film and the tool base material remains inadequate
Solution Approach 1:
The coating film is divided into three distinct layers: a third layer (nitride, carbonitride, or carbide) that provides strong bonding to the tool base material, a second layer (AlCrN or AlCrDN) that provides wear resistance, and a first layer that provides adhesion resistance. This segmentation allows each layer to specialize in one function, resolving the contradiction by ensuring strong bonding through the third layer while maintaining wear and adhesion resistance through the other layers.
Solution Approach 2:
The invention uses composite material structure with three different compositional layers, where each layer is made of specific material combinations (nitride/carbonitride/carbide in third layer, AlCrN/AlCrDN in second layer). This composite approach enables the coating film as a whole to achieve both strong bonding strength and excellent wear/adhesion resistance that cannot be achieved with a single material composition.
2Reliability
If a hard coating film is formed to achieve excellent wear resistance and adhesion resistance, then cutting performance is improved, but the coating film peels or chips early due to inadequate bonding strength
Solution Approach 1:
By segmenting the coating into three layers with the third layer specifically designed for strong bonding to the tool base material, the invention prevents early peeling and chipping that would otherwise occur. This ensures the coating film remains intact throughout the tool's service life, enabling sustained wear and adhesion resistance over extended periods.
Solution Approach 2:
The third layer is formed first as a bonding foundation before applying the second and first layers. This preliminary action of creating a strong bonding interface ensures that subsequent layers adhere properly and remain intact during tool operation, preventing early failure modes like peeling and chipping.
3Ease of manufacture
If the coating film structure is simplified to reduce manufacturing complexity, then ease of manufacture is improved, but bonding strength and coating performance deteriorate
Solution Approach 1:
While the coating is segmented into three layers, each layer can be formed using the same PVD or CVD deposition process, maintaining manufacturing simplicity. The segmentation is achieved by adjusting deposition parameters and sequence rather than requiring fundamentally different manufacturing techniques, thus preserving ease of manufacture while achieving superior bonding strength.
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 stable and extended wear resistance and adhesion resistance, suppressing peeling and wear due to chipping, and improving cutting performance and tool life, especially when cutting materials with high hardness, by increasing surface hardness and bonding strength.
Implementation Method 1
Possible methods for forming the hard coating film include a PVD (physical vapor deposition) method such as an arc ion plating method or a sputtering method, and a CVD (chemical vapor deposition) method.
Data Source
AI summary
A hard coating film formed on a surface of a predetermined member and having excellent wear resistance and adhesion resistance, the hard coating film includes: a three-layer structure composed of a third layer formed in contact with the surface of the predetermined member, a second layer formed on the third layer, and a first layer formed on the second layer to constitute the surface; the first layer being made of (Cr1-a-bBa(SiC)b)(CcOdN1-c-d) [provided that SiC is silicon carbide, and a, b, c and d are atomic ratios in ranges of 0≦a≦0.2, 0.01≦b≦0.2, 0≦c≦0.5 and 0≦d≦0.3, respectively; the second layer being made of AlCrN or AlCrDN [provided that D includes either one kind of elements of a Group IVa, a Group Va and a Group VIa (except Cr) of a Periodic Table of Elements and Y, or SiC (silicon carbide)]; and the third layer being made of nitride, carbon nitride or carbide of metals including elements of one kind or more kinds of Al, Ti, Zr, Hf, V, Nb, Ta, Cr and W.