Preparation method for tungsten carbide reinforced nickel-based composite coating

Abstract

The invention provides a preparation method for a tungsten carbide reinforced nickel-based composite coating and belongs to the technical field of laser cladding metal ceramic composites. According tothe reparation method, during laser cladding, a broad beam rectangular spot is used for laser input, the broad beam is large in beam spot area and even in energy distribution, a large-area cladding layer without an overlapping joint area is easy to achieve, coating thermal stress can be effectively relieved, cracks are reduced, and the large-area laser cladding layer can be prepared and is uniform and compact in structure and free of cracks, pores, inclusions or other defects. According to the preparation method, composite powder is fed into the surface of a substrate through a synchronous powder feeding method, and structure uniformity of the composite coating can be ensured. Process parameters of laser cladding and the adding amount of tungsten carbide in the composite powder (claddingmaterials) are controlled precisely, cracks, pores, non-molten parts and other macroscopic defects can be avoided, the problems that a cladding layer is uneven in structure, the structure of an overlapped area is worsened, and bonding strength is lowered can be solved, and thus the structure and comprehensive performance of the coating are improved.

Description

technical field [0001] The invention relates to the technical field of laser cladding metal-ceramic composite materials, in particular to a preparation method of a tungsten carbide-reinforced nickel-based composite coating. Background technique [0002] With the development of industrial technology, the technological process and working environment tend to be more complex, and the surface of many engineering materials has different degrees of wear, corrosion, fatigue and other phenomena during the service process, which greatly reduces the functional accuracy of the original design of the components. Make the components fail prematurely and reduce the service life. [0003] As an emerging surface modification technology, the scope of use of laser cladding technology is gradually expanding. Laser cladding (Laser Cladding), also known as laser cladding, adds cladding materials to the surface of the substrate and uses a high-energy-density laser beam to fuse it with the thin l...

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Problems solved by technology

However, due to the large gap between the melting point, linear expansion coefficient, elastic modulus, and thermal conductivity of the ceramic material and the metal matrix, when the amount of the ceramic phase is not added, it is easy to cause a large thermal stress during the cladding process, making the melting The coating is prone to defects such as pores, cracks and inclusions

In addition, the process method of laser cladding also has a great influence on the quality of the cladding layer, which may aggravate the occurrence of defects

If the laser cladding powder material is sent into the molten pool by the preset method, the binder introduced by the preset method will pollute the surface of the substrate, and at the same time, the binder is likely to generate gas during the heating process. If it cannot be discharged in time, the cladding layer will be damaged. porosity

When no adhesive is used, the cladding powder is loose and easy to slide on the substrate, which is not conducive to cladding

Secondly, at present, when performing laser cladding, circular beam spots are widely used to obtain large-area laser cladding layers by overlapping. However, the energy of this kind of spot is similar to Gaussian distribution, which will cause a steep temperature distribution in the molten pool, and even more It is easy to cause the cladding layer to increase in stress and cause cracking, and at the same time, the structure of the overlapping area will be deteriorated due to the secondary remelting effect of the laser

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