Diamond Hard Material Coating Adhesion Oxidation Resistance
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Solution Overview
Problem
Diamond-coated tools face issues with oxidation and chemical wear, especially when processing iron-containing materials, and existing coatings lack effective oxidation resistance and adhesion promotion.
Innovation Solution
A coated body comprising a substrate with a diamond layer applied using CVD, followed by a hard material layer via PVD, including an adhesive layer formed by metal atom implantation or diffusion, and a transition layer to enhance adhesion and oxidation resistance, with specific compositions like Ti-Al-N and Ti-Si-N to reduce roughness and prevent chemical wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a diamond layer is applied to provide wear protection and high hardness, then the tool exhibits exceptionally high hardness and wear resistance, but oxidation occurs at high temperatures and chemical wear occurs when machining ferrous materials
Solution Approach 1:
A multi-layer coating system is introduced between the diamond layer and the substrate, consisting of an adhesive layer (e.g., TiN, CrN), an intermediate layer (e.g., TiAlN, TiSiN), and a hard material layer (e.g., TiN, CrN). These intermediary layers provide oxidation resistance while maintaining the diamond layer's hardness, as the diamond layer remains chemically inert while the metallic layers protect against oxidation and chemical wear.
Solution Approach 2:
The tool surface is constructed as a composite structure combining diamond (for hardness and wear resistance) with oxidation-resistant ceramic coatings (e.g., TiAlN, TiSiN, CrN) and adhesive layers. This composite material system leverages the complementary properties of each material: diamond provides mechanical hardness, while the ceramic layers provide oxidation and chemical wear resistance.
2Reliability
If multiple layers are applied to improve oxidation resistance and adhesion, then the tool's service life and oxidation resistance are enhanced, but the coating process complexity increases
Solution Approach 1:
The coating system is segmented into functionally distinct layers: an adhesive layer for bonding, an intermediate layer for oxidation protection and stress management, and a hard material layer for wear resistance. Each layer has a specific thickness and composition optimized for its function, allowing the complex performance requirements to be divided into manageable functional segments.
Solution Approach 2:
The coating process utilizes controlled variations in deposition parameters (temperature, pressure, gas composition, deposition rate) to achieve different layer properties. By changing parameters during deposition, the system transitions between forming adhesive layers, intermediate layers, and hard material layers, enabling multi-functional coatings through a single integrated 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 layer structure significantly enhances the tool's oxidation resistance, reduces chemical wear, and improves adhesion, leading to increased service life and reduced thermal stress, while maintaining high hardness and thermal conductivity.
Implementation Method 1
CVD processes can be used to create various layers and layer systems on the surface of a substrate. Synthetic diamond layers, which are deposited from an atmosphere containing carbon and hydrogen, play a special role in this process.
Implementation Method 2
an adhesive layer which is formed by implantation or diffusion of metal atoms in an outer zone of the diamond layer
Implementation Method 3
an adhesive layer which is formed by implantation or diffusion of metal atoms in an outer zone of the diamond layer
Implementation Method 4
a hard material layer above the diamond layer which is applied by vapor deposition
Data Source
Figure 1~3
AI summary
The invention relates to a coated body and to a method for coating a body. The coated body comprises at least a substrate (22), a layer of diamond (24) having a thickness of 1-40 µm, and a layer of hard material (26), which is arranged further outside on the body (10) than the layer of diamond (24). The layer of hard material (26) comprises at least one metal element and at least one non-metal element. An adhesive layer (32) having a thickness of 2-80 nm is provided between the layer of diamond (24) and the layer of hard material (26). The adhesive layer (32) contains carbon and at least one metal element. The layer of diamond (24) can be applied by mans of a CVD method. The layer of hard material can be applied by means of a PVD method. The adhesive layer (32) between the layer of diamond (24) and the layer of hard material (26) can be produced in that, before the layer of hard material (26) is applied, the surface of the layer of diamond (24) is pretreated by means of HIPIMS metal ion etching, wherein ions are implanted into or diffuse into the surface of the layer of diamond (24) by means of metal ion etching.