cBN Cutting Tool Ceramic Coating for Peeling-Resistant Machining
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Solution Overview
Problem
Conventional cutting tools with cubic boron nitride sintered materials experience coating film peeling issues when machining steel, hardened steel, or difficult-to-cut cast steel, leading to inadequate machining precision and efficiency.
Innovation Solution
A cutting tool with a ceramic coating film having an oxygen content of less than or equal to 0.040 mass percent, formed using a physical vapor deposition method in a chamber with controlled oxygen and water partial pressures, is used. The base material is a cubic boron nitride sintered material with a binder composition that enhances adhesion and peeling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic coating film is formed on a cBN sintered material using conventional methods, then the coating film provides basic protection, but the coating film peels off easily during machining of steel and hardened steel
Solution Approach 1:
The patent applies parameter changes by严格控制 the oxygen partial pressure (≤1×10^-3 Pa) and water partial pressure (≤1×10^-3 Pa) during PVD coating formation, and controlling the oxygen content in the coating film to ≤0.040 mass percent. These parameter changes prevent oxygen-induced adhesion reduction and microfractures, resolving the contradiction between coating adhesion and machining efficiency
Solution Approach 2:
The patent uses an inert atmosphere (vacuum environment with controlled partial pressures of oxygen and water) during the PVD coating formation process. This inert environment prevents oxidation and contamination of the coating film and base material interface, thereby improving coating adhesion and preventing peeling during machining operations
2Reliability
If the oxygen content in the coating film is reduced to ≤0.040 mass percent, then adhesion and peeling resistance are improved, but the manufacturing process becomes more complex requiring controlled partial pressures
Solution Approach 1:
The patent replaces complex chemical coating processes with a simplified PVD (physical vapor deposition) process operating under controlled vacuum conditions. By using physical vapor deposition with controlled oxygen and water partial pressures, the patent achieves low oxygen content (≤0.040 mass percent) in the coating film through a more straightforward physical process rather than complex chemical reactions
Solution Approach 2:
The patent simplifies the manufacturing process by focusing on controlling key parameters (oxygen partial pressure ≤1×10^-3 Pa, water partial pressure ≤1×10^-3 Pa during PVD) rather than managing complex chemical compositions. This parameter-based control approach achieves the desired low oxygen content (≤0.040 mass percent) and high peeling resistance through a streamlined process
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 improves the adhesion and peeling resistance of the coating film, resulting in enhanced machining precision and tool longevity by reducing oxygen-induced adhesion reduction and microfractures, thereby achieving better wear resistance and machining accuracy.
Implementation Method 1
forming a ceramic coating film on the surface of the base material placed within the chamber using a physical vapor deposition method
Implementation Method 2
emitting inert gas ions onto a surface of the base material, and thereby cleaning the surface of the base material
Data Source
AI summary
A cutting tool includes a base material, and a coating film covering the base material in contact with the base material. The base material is a cubic boron nitride sintered material. The coating film is a ceramic. An amount of oxygen in the coating film is less than or equal to 0.040 mass percent.