Gradient AlCr/AlTi Coating Structure for Wear-Resistant Cutting Tools
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Solution Overview
Problem
Existing coated tools for cutting processes face issues with adhesion and wear resistance due to high Cr content degrading toughness and low Cr content degrading hardness in the B layer, leading to coating separation and wear.
Innovation Solution
A coated tool with a laminate structure comprising AlTi and AlCr layers, where the AlCr layers have a higher Cr content ratio farther away from the base member, enhancing adhesion and wear resistance by gradual changes in chromium content ratios to avoid stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform Cr content is used in all AlCr layers, then manufacturing is simplified, but stress concentration occurs and coating separation is likely
Solution Approach 1:
The patent applies local quality by creating a gradient Cr content distribution within the AlCr layers. The Cr content is lower in AlCr layers adjacent to the tool base member (maintaining toughness for adhesion) and progressively higher in AlCr layers farther from the base member (enhancing wear resistance for surface protection). This spatial variation in composition resolves the contradiction between toughness and wear resistance.
Solution Approach 2:
The patent employs beforehand cushioning by placing AlCr layers with lower Cr content (higher toughness) adjacent to the tool base member before the higher Cr content layers. This gradient structure acts as a cushion that absorbs and distributes thermal and mechanical stresses, preventing stress concentration and coating separation while maintaining manufacturing feasibility through controlled composition gradients.
Data Source
AI summary
A coated tool may include a base member and a coating layer located on the base member. The coating layer may include a plurality of AlTi layers and a plurality of AlCr layers. The AlTi layers may include at least one kind selected from nitride, carbide or carbonitride, each including aluminum and titanium. The AlCr layers may include at least one kind selected from nitride, carbide or carbonitride, each including aluminum and chromium. The coating layer may include a laminate structure in which the AlTi layers and the AlCr layers are alternately laminated one upon another. The AlCr layers may include a first AlCr layer and a second AlCr layer located farther away from the base member than the first AlCr layer. A content ratio of chromium in the second AlCr layer may be higher than a content ratio of chromium in the first AlCr layer.