AlCrTiN Coated Cutting Tool for Thick Wear-Resistant Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Coated cutting tools with high compressive stress and cubic crystal hard films suffer from peeling and limited thickness, leading to insufficient wear resistance and short tool life.
Innovation Solution
A coated cutting tool with a substrate and a coating layer containing a compound layer with a specific composition (AlxCryTi1−x−y)N, where 0.70≤x≤0.95, 0.04≤y≤0.21, and 1−x−y>0, and having a columnar crystal structure, an average thickness of 2.0 μm to 10.0 μm, and residual stress between −10.0 GPa and −2.0 GPa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard film with high Al content (80% or more) and cubic crystal structure is formed using cathode arc ion plating with bias voltage of -100V to -150V and substrate temperature of 330°C to 370°C, then the hardness and wear resistance are improved, but the compressive stress becomes very high causing peeling and limiting film thickness
Solution Approach 1:
The patent changes multiple parameters simultaneously: reduces bias voltage from -100V to -150V to -50V to -100V, reduces substrate temperature from 330°C to 370°C to 200°C to 300°C, and optimizes Al content to 70-90% and Cr content to 5-15%. This combination of parameter changes achieves the desired balance between hardness and compressive stress
Solution Approach 2:
The patent uses a composite coating layer containing AlCrTiN compound with specific atomic ratios (Al: 70-90%, Cr: 5-15%, Ti: balance), combining multiple elements to achieve both high hardness and reduced compressive stress, preventing peeling while maintaining wear resistance
2Duration of action of moving object
If the thickness of the hard film is increased to improve wear resistance, then the tool life is extended, but the high compressive stress causes peeling and makes it difficult to increase thickness
Solution Approach 1:
By changing the deposition parameters (bias voltage to -50V to -100V, substrate temperature to 200°C to 300°C) and composition (Al: 70-90%, Cr: 5-15%), the patent reduces compressive stress in the film, enabling formation of thicker coatings (5-20 μm) without peeling, thus extending tool life while maintaining reliability
Solution Approach 2:
The AlCrTiN composite coating with optimized element ratios creates a more stable film structure with reduced internal stress, allowing thicker deposits that maintain adhesion and prevent peeling, thereby achieving both extended tool life and improved reliability
3Strength
If the Al content in the AlCrN layer is increased to 70% or more to achieve high hardness, then the wear resistance should be improved, but hexagonal crystals are included which reduce hardness and wear resistance
Solution Approach 1:
The patent optimizes Al content to 70-90% (rather than ≥70%) and combines it with controlled Cr content (5-15%) and substrate temperature (200°C to 300°C) to stabilize the cubic crystal structure and prevent hexagonal phase formation, maintaining both hardness and compositional stability
Solution Approach 2:
By creating an AlCrTiN composite system with specific ratios (Al: 70-90%, Cr: 5-15%, Ti: balance), the patent stabilizes the cubic crystal structure even at high Al content, preventing hexagonal phase formation and maintaining consistent hardness and wear resistance
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 coated cutting tool exhibits improved wear resistance, fracture resistance, and extended tool life due to increased hardness, high-temperature strength, and enhanced adhesion of the compound layer.
Implementation Method 1
the crystal system of the hard film produced by the film forming method described in Patent Publication JP-A-2020-109210 is a cubic crystal system
Implementation Method 2
the compressive stress is very high, peeling occurs after the hard film is formed
Data Source
AI summary
A coated cutting tool includes a substrate and a coating layer formed on the substrate, wherein the coating layer comprises a compound layer containing a compound having a composition represented by (AlxCryTi1−x−y)N (in the formula (1), x represents an atomic ratio of an Al element to a total of the Al element, a Cr element and a Ti element and satisfies 0.70≤x≤0.95, and y represents an atomic ratio of a Cr element to a total of an Al element, the Cr element and a Ti element and satisfies 0.04≤y≤0.21, and 1−x−y>0); a ratio (Cr/Ti) of the Cr element and the Ti element in the compound layer is 1.0 or more and 2.5 or less; and an average thickness of the compound layer is 2.0 μm or more and 10.0 μm or less.