Coated Cemented Carbide Description II

At present, coated cemented carbide has some tendency in diverse composition, multi-layer structure, diverse combination of process and gradient structure of matrix, etc.

1. Diverse coating composition:

Due to big differences of crystal lattice, the hardness, modulus of elasticity and coefficient of thermal expansion between the single layer coated matrix and coating material, the adhesion becomes weaker. If add some new elements in single coating layer, the comprehensive properties of tungsten carbide will be remarkably improved, such as silicon (Si) is beneficial for the hardness promoting and chemical diffusion resistance, the rare earth element Y can improve the resistance to oxidation and the adding Zr, V, Hf will improve the wear resistance.

2. Multi-layer coating structure:

Multi-layer coating structure is one of the main trends of coated cemented carbide, which uses different combination of layers to adapt to different situation. And the layer becomes thinner and tends to nano scale.

3. Diverse combination of process:

Diverse combination of process is suitable for the complicate working conditions in modern industry, such as combined CVD with PVD, which makes CVD-TiCN coating with high wear resistance, and substrate and bonding strength between the coating greatly improved, and PVD-TiN coating having a compressive residual stress effect, two who make carbide cutting tools combined with a better comprehensive performance.

4. Gradient structure of matrix

Gradient matrix structure refers to the cemented carbide substrate gradient process, thereby effectively prevents the cracks internal alloy from expanding.

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