Gradient Tungsten Carbide Coated Inserts

Although tungsten carbide has uniform composition and distribution and compared with other materials has many advantages, there is an inevitable contradiction that the balance between hardness and toughness. It also has been an important factor in limiting conventional carbide materials applications. Preparation and use of new technology, the traditional carbide materials exhibit gradient in the structure, can effectively reconcile the internal contradictions of this group. Gradient tungsten carbide coated inserts achieve better performance by gradient distribution, especially has a great advantage in high-performance carbide cutting tools.

After gradient treatment, alloy formation region lack toughness cubic nitrides and carbonitrides in the surface region, the corresponding binder content is higher than the nominal content of the matrix binder. On this basis, using the CVD method or PVD coating deposited on a cemented carbide substrate to get coated gradient cemented carbide. When the coating is formed the crack extended to the toughness of the gradient region, because of its good ductility and toughness, it can effectively absorb energy during crack propagation, thus effectively preventing the internal crack propagation and to improve the performance of carbide cutting tools.

The experiment shows that with the increasing content of Co, the strength, magnetic saturation has been improved, the hardness, magnetism, density of gradient carbide decreased, and the alloy composition gradient structure more obvious, gradient layer is also thicker; while with the increase of the alloy Ti (CN) content, hardness gradient alloy structure, the magnetic force is increased, reducing the strength and density occurs, reducing the thickness of the alloy graded layer; in the substrate and coating composition of the same situation, coated carbide blade cutting gradient structure without gradient structure coated carbide cutting inserts more excellent (at the same height wear conditions, cutting tool life increased nearly doubled). In addition, higher Co content gradient coated carbide cutting inserts generally better than a low Co content gradient coating blade cutting performance.

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