Diamond-Coated WC Cutting Tool Interface for Peel-Resistant Adhesion
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Solution Overview
Problem
Diamond-coated cutting tools experience film peeling between the tool base and diamond film during high-efficiency machining of difficult-to-cut materials, leading to reduced tool life and unstable machining performance.
Innovation Solution
A coated tool with a WC-based cemented carbide base having a lower binding phase content near the surface and a controlled number of isolated WC particles at the interface with the diamond film, ensuring strong adhesion through specific surface treatments and diamond film deposition methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a diamond film is coated on a WC-based cemented carbide tool base for high-efficiency machining, then cutting performance is improved, but film peeling occurs between the base and diamond film during machining
Solution Approach 1:
The patent applies local quality by creating a gradient in binding phase content within the cemented carbide base. The surface layer has lower binding phase content (10-30 mass%) compared to the inner portion (20-40 mass%), which provides optimal adhesion conditions for the diamond film at the interface while maintaining the mechanical strength of the base. This localized compositional variation resolves the contradiction between cutting performance and film adhesion.
Solution Approach 2:
The patent changes the compositional parameter of the cemented carbide base by controlling the binding phase content to be lower at the surface than in the interior. Additionally, it controls the particle size distribution of WC grains, with the surface layer having smaller mean particle diameter (0.5-2.0 μm) compared to the inner portion (1.0-3.0 μm). These parameter changes optimize both adhesion and mechanical properties.
2Strength
If the binding phase content is increased to improve base strength, then mechanical strength is improved, but adhesion between the base and diamond film deteriorates
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatial variation in binding phase content. The surface layer contains 10-30 mass% binding phase for optimal adhesion, while the inner portion contains 20-40 mass% for mechanical strength. This gradient structure allows each region to have the binding phase content optimized for its specific function.
Solution Approach 2:
The patent segments the cemented carbide base into two distinct regions with different compositions: a surface layer (0-10 μm depth) with lower binding phase content for adhesion, and an inner portion with higher binding phase content for strength. This segmentation allows independent optimization of adhesion and mechanical properties without compromise.
3Reliability
If conventional surface treatments are applied to improve diamond film adhesion, then adhesion is improved, but isolated WC particles remain at the interface causing peeling
Solution Approach 1:
The patent applies preliminary action by performing surface treatment (acid etching with nitric acid or hydrofluoric acid, and/or alkali treatment with potassium hydroxide solution) before diamond film deposition. This pre-treatment removes binding phase from the surface and creates a morphology favorable for adhesion while eliminating isolated WC particles that would cause peeling, ensuring a clean interface for optimal film bonding.
Data Source
AI summary
A coated tool in a non-limiting embodiment of the present disclosure includes a base composed of WC-based cemented carbide including a WC particle and a binding phase, and a diamond film located on the base. In a cross section orthogonal to a surface of the coated tool, the base has a lower content of the binding phase in a surface of the base than a midportion of the base. In an interface region between the base and the diamond film, a WC particle located away from the base is an isolated WC particle, and the number of the isolated WC particle present per interface length of 10 μm is 4 or less. A cutting tool in a non-limiting embodiment of the present disclosure includes the above coated tool.