TiCNO-Al2O3 Coating Structure for Fracture-Resistant Cutting Tools
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Solution Overview
Problem
Cutting tools with Al2O3 coatings face issues with fracture resistance under heavy intermittent cutting conditions, leading to chipping or peeling, which existing techniques have not adequately addressed.
Innovation Solution
A coated tool design featuring a TiCNO layer with multiple protrusions and beams that connect them, forming a strong adhesion with the Al2O3 layer, enhancing the bonding strength and preventing peeling, while maintaining homogeneous compositions and specific dimensions to improve fracture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a coating layer with Al2O3 is formed on the base member 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 layers (bonding film, TiCNO layer, Al2O3 layer) with distinct functions. The TiCNO layer is further segmented into protrusions and beams, creating a hierarchical structure that simultaneously provides wear resistance and fracture resistance by distributing stress across different layers and structural elements.
Solution Approach 2:
The patent uses composite material structure with TiCNO (titanium carbon oxynitride) and Al2O3 (alumina) layers. The TiCNO layer serves as an intermediate composite between the metallic base member and the ceramic Al2O3 layer, providing both adhesion and fracture resistance while the Al2O3 layer provides wear resistance.
2Strength
If the coating layer is made thicker to improve wear resistance, then wear resistance is improved, but adhesion between layers deteriorates
Solution Approach 1:
The TiCNO layer has local quality variations with protrusions having different compositions and structures from the beam portions. The protrusions provide strong adhesion to Al2O3 while the beams provide fracture resistance, allowing the coating to maintain both adhesion and wear resistance even at greater thicknesses.
Solution Approach 2:
The coating structure transitions from a two-dimensional planar layer to a three-dimensional structure with protrusions and beams extending in multiple directions. This dimensional change creates additional bonding interfaces and stress distribution pathways, maintaining adhesion strength while allowing increased overall coating thickness for wear resistance.
3Force
If a bonding film and Al2O3 layer are formed sequentially to improve adhesion, then adhesion is improved, but fracture resistance deteriorates under large impacts
Solution Approach 1:
The intermediate TiCNO layer is segmented into protrusions and beams that create a hierarchical structure. This segmentation allows the layer to accommodate impact forces by distributing stress across multiple structural elements rather than concentrating it at a single interface, thereby improving fracture resistance while maintaining adhesion.
Solution Approach 2:
The TiCNO layer with its protrusion-beam structure acts as a cushioning layer between the rigid Al2O3 coating and the base member. This structure absorbs and dissipates impact energy before it reaches the Al2O3 layer, preventing catastrophic failure while maintaining strong adhesion bonds.
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 design significantly enhances the fracture resistance and adhesion of the TiCNO and Al2O3 layers, reducing the likelihood of peeling and improving the tool's performance in severe cutting conditions.
Implementation Method 1
a bonding film and an Al2O3 layer are formed sequentially, and a dendrite extending toward the Al2O3 layer side and a branched protrusion extending from the dendrite are provided on the bonding film, thereby enhancing the adhesion between the bonding film and the Al2O3 layer
Implementation Method 2
a coating layer formed by laminating an Al2O3 layer is formed on a surface of a base member such as a cemented carbide, a cermet or a ceramic through a bonding film
Implementation Method 3
after the formation of the dendrite, the flow of a source gas is stopped once, and while the temperature is maintained, the pressure and the type of the source gas are changed to form the dendrite having a composition different from that of the dendrite
Data Source
AI summary
A coated tool of the present disclosure is provided with a base member and a coating layer located on a surface of the base member. The coating layer includes a TiCNO layer and an Al2O3 layer. The Al2O3 layer is located in contact with the TiCNO layer at a position farther from the base member than the TiCNO layer is. The TiCNO layer includes a plurality of first protrusions that project toward the Al2O3 layer, and a beam that extends in a direction intersecting a direction in which the first protrusions project, to connect the first protrusions. A cutting tool of the present disclosure is provided with: a holder extending from a first end toward a second end and including a pocket on a side of the first end; and the above-described coated tool located in the pocket.