Al2O3-Coated Cutting Tool Structure for Chipping Resistance
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Solution Overview
Problem
Coated tools used in heavy intermittent cutting processes face issues with chipping and peeling of the Al2O3 coating layer due to large impacts, necessitating improvements in fracture resistance alongside wear resistance.
Innovation Solution
A coated tool design featuring a base with a coating layer comprising an intermediate Ti layer and an Al2O3 layer, where the intermediate layer includes a plurality of first protrusions, at least one of which is a composite protrusion with second protrusions intersecting the primary protrusions, optimizing film forming properties and adhesion.
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 under heavy intermittent cutting conditions
Solution Approach 1:
The coating layer is segmented into multiple functional layers (bonding layer, intermediate layer, wear-resistant layer) with each layer having specific protrusion structures. The intermediate layer contains first protrusions extending toward the wear-resistant layer, while the bonding layer contains second protrusions extending toward the base, creating a segmented architecture that improves both wear resistance and fracture resistance by distributing stress across multiple interfaces.
Solution Approach 2:
The coating layer uses composite material structure with different functional layers made of different materials (TiN, TiCN, Al2O3, CrN) with specific protrusion configurations. This composite structure allows each layer to contribute its specific properties: the bonding layer provides strong adhesion to the base, the intermediate layer provides transition and stress distribution, and the wear-resistant layer provides hardness and wear resistance, collectively resolving the contradiction between wear resistance and fracture resistance.
2Strength
If protrusions with obtuse angle tips are used to improve fracture resistance, then fracture resistance is improved, but film forming properties deteriorate
Solution Approach 1:
Different regions of the coating layer have different local structures optimized for their specific functions. The bonding layer has second protrusions with obtuse angle tips optimized for fracture resistance and adhesion to the base. The intermediate layer has first protrusions with acute angle tips optimized for film forming properties and adhesion to the wear-resistant layer. This local quality differentiation allows each region to excel at its specific function without compromising the other.
Solution Approach 2:
The invention adds dimensional complexity by creating protrusions in multiple directions and layers. Instead of simple surface protrusions, the structure extends through the thickness of the coating layer with first protrusions from the intermediate layer and second protrusions from the bonding layer, creating a three-dimensional architecture that simultaneously improves film forming properties and fracture resistance through multi-directional stress distribution.
Data Source
AI summary
A coated tool in the present disclosure includes a base and a coating layer located on a surface of the base. The coating layer includes an intermediate layer including Ti, and an Al2O3 layer. The Al2O3 layer is located in contact with the intermediate layer at a position further away from the base than the intermediate layer. The intermediate layer includes a plurality of first protrusions protruding toward the Al2O3 layer. At least one of the plurality of first protrusions is a composite protrusion including second protrusions protruding in a direction intersecting with a protruding direction of the first protrusions. An average number of the second protrusions in the composite protrusion is 1.4 or less. A cutting tool in the present disclosure includes a holder which is extended from a first end toward a second end and includes a pocket on a side of the first end, and the coated tool located in the pocket.