TiCN Coated Cutting Tool Crystal Orientation
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Solution Overview
Problem
Conventional cutting tools with hard coating layers suffer from chipping and flaking under severe cutting conditions, such as heavy interrupted cutting, leading to reduced tool life due to inadequate fracture resistance and wear resistance.
Innovation Solution
A surface coated member with a hard coating layer containing a TiCN layer on a substrate, where the ratio of peak strengths on the (422)-crystal plane to other crystal planes is controlled to enhance adhesion, toughness, and wear resistance, and a cutting tool design with a TiN and TiCN layer laminate for improved fracture and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coating layer is formed on a cutting tool substrate, then wear resistance is improved, but fracture resistance deteriorates under severe cutting conditions
Solution Approach 1:
The hard coating layer is divided into multiple layers with different compositions and functions. The lower layer (near substrate) has higher toughness and adhesion to prevent delamination, while the upper layer has higher hardness for wear resistance. This segmentation allows each layer to optimize its properties without compromising the other.
Solution Approach 2:
The coating system uses composite material structure combining different ceramic materials (e.g., TiCN, TiN, Al2O3) with distinct properties. The composite structure integrates the adhesion benefits of TiCN with the wear resistance of Al2O3 and the toughness of TiN, achieving overall improved performance.
2Strength
If the hard coating layer is made thicker to prevent early wear, then wear resistance is improved, but chipping and flaking occur more easily under shock
Solution Approach 1:
Different regions of the coating layer have different properties tailored to their specific functions. The lower layer near the substrate has higher toughness and ductility to absorb shock and prevent chipping, while the upper layer has higher hardness to resist wear. This local differentiation of material properties resolves the contradiction between thickness and shock resistance.
Solution Approach 2:
The coating structure is designed to dynamically respond to different loading conditions. Under normal cutting conditions, the hard upper layer provides wear resistance. Under shock loading, the tougher lower layer and intermediate layers provide flexibility and energy absorption, preventing catastrophic failure.
3Reliability
If multiple coating layers are added to improve adhesion and suppress crack extension, then fracture resistance is improved, but wear resistance of the second layer deteriorates
Solution Approach 1:
The multi-layer structure is designed with each layer having a specific thickness and composition optimized for its position. The second layer's thickness and material composition are carefully controlled to provide crack suppression without excessive thickness that would cause wear problems. Each layer's properties are segmented and optimized independently.
Solution Approach 2:
The multi-layer coating uses composite material selection where each layer contributes specific properties. The second layer uses a material composition that balances adhesion enhancement and wear resistance, different from the layers above and below it. This composite approach allows each layer to fulfill its specific function without compromising others.
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 a cutting tool with enhanced fracture resistance and wear resistance, extending tool life even under severe cutting conditions, including interrupted cutting of metals like cast iron, by optimizing the crystal plane ratios and layer construction.
Implementation Method 1
A ratio r in a region on an outer surface side is larger than a ratio r in a region on an inner surface side, wherein r is a ratio of a peak strength I(422) of a (422)-crystal plane to a peak strength I(111) of a (111)-crystal plane, namely (I(422)/I(111)), in an X-ray diffraction analysis of the TiCN layer.
Data Source
AI summary
A surface coated member comprises a substrate composed of a hard material, and a hard coating layer containing at least a TiCN layer on a surface of the substrate. A ratio r in a region of an outer surface side is larger than a ratio r in a region of an inner surface side, wherein r is a ratio of a peak strength I(422) of a (422)-crystal plane to a peak strength I(111) of a (111)-crystal plane, namely (I(422)/I(111)), in an X-ray diffraction analysis of the TiCN layer. The surface coated member has excellent adhesion between the substrate and the hard coating layer, and it also has excellent fracture resistance and wear resistance. Further provided is a cutting tool that includes a rake face and a flank formed on the substrate in the above surface coated member, and a cutting edge formed on a cross ridge portion between the rake face and the flank. Still further provided is a method for manufacturing a work piece to perform cutting process by applying the cutting edge of this cutting tool, to a work material.