Cutting Tool Coating with Gradient Oxygen Intermediate Layer
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Solution Overview
Problem
Cutting tools with existing coating layers face challenges in wear resistance and fracture resistance, especially under severe cutting conditions like heavy interrupted cutting, where chipping and peeling are common due to large impacts.
Innovation Solution
A cutting tool design featuring a coating layer structure with a lower titanium carbonitride layer, an intermediate layer comprising three sub-layers with varying oxygen content ratios, and an upper aluminum oxide layer of α-type crystal structure, enhancing adhesion and durability through specific composition and projection configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied to improve wear resistance, then wear resistance is improved, but fracture resistance deteriorates due to chipping and peeling under impact
Solution Approach 1:
The coating layer is divided into multiple functional layers: a lower layer containing titanium carbonitride, an intermediate layer with three sub-layers (first layer with TiCx1Ny1Oz1, second layer with TiCx2Ny2Oz2, third layer with TiCx3Ny3Oz3) having varying oxygen content ratios, and an upper layer containing aluminum oxide. This segmentation allows each layer to perform its specific function - the lower layer provides wear resistance, the intermediate layer with gradient composition provides transition and stress distribution, and the upper layer provides fracture resistance.
Solution Approach 2:
Different regions of the coating layer have different compositions and properties. The intermediate layer specifically has a gradient oxygen content ratio where the first layer has higher oxygen content than the third layer (z1>z3), creating local variations in material properties that optimize both wear resistance and fracture resistance in different zones.
Solution Approach 3:
The coating layer uses composite material structure combining titanium carbonitride, titanium oxycarbonitride with varying oxygen content, and aluminum oxide in a multi-layer configuration. This composite structure leverages the advantages of each material - titanium carbonitride for wear resistance, aluminum oxide for fracture resistance, and the intermediate gradient layers for stress distribution and adhesion.
2Strength
If an intermediate layer with needle-shaped particles is added to improve fracture resistance, then fracture resistance is improved, but device complexity increases
Solution Approach 1:
Instead of adding a separate intermediate layer with needle-shaped particles, this invention achieves fracture resistance by changing the compositional parameters of the intermediate layer - specifically creating a gradient oxygen content ratio across three sub-layers. The oxygen content ratio varies from the first layer (adjacent to lower layer) to the third layer (adjacent to upper layer), with z1>z3, providing stress distribution and improved adhesion without increasing structural complexity.
Data Source
AI summary
In an aspect of the disclosure, a cutting tool includes a base member and a coating layer located on a surface of the base member. The coating layer includes a lower layer, an upper layer, and an intermediate layer located between the lower layer and the upper layer. The intermediate layer includes a first layer, a second layer, and a third layer. The first layer contains TiCx1Ny1Oz1 (0≤x1<1, 0≤y1<1, 0<z1<1, and x1+y1+z1=1). The second layer contains TiCx2Ny2Oz2 (0≤x2<1, 0≤y2<1, 0<z2<1, and x2+y2+z2=1). The third layer is located between the first layer and the second layer, and contains TiCx3Ny3Oz3 (0≤x3<1, 0≤y3<1, 0≤z3<1, and x3+y3+z3=1). Here, z1>z3 and z2>z3.