Method for crystallizing chemical plated Ni-P coating

Abstract

The invention relates to a method for crystallizing a chemical plated Ni-P coating, and belongs to the field of material surface modification treatment. The chemical plated Ni-P coating is crystallized by the aid of laser heat effect, the phase of the coating is transformed from an amorphous state to a crystalline state, a Ni3P hardening phase is separated out, and the hardness and the wear resistance of the coating are improved. The method is characterized in that laser is used as a heat source, the Ni-P coating absorbs energy of the laser, and the temperature can be accurately controlled. In the process of laser heat radiation treatment, the Ni3P phase starts to be formed at the temperature of 350 DEG C, further generation of the Ni3P phase is supplemented by diffusion of peripheral P atoms as P content is reduced due to generation of the Ni3P phase, the diffusion speed of the P atoms is increased by high energy density of the laser on the surface of the coating, the Ni3P phase is regenerated at the temperature of 400 DEG C, Ni3P characteristic peaks tend to be more obvious on an XRD (X-ray diffraction) spectral line, and crystallinity of single nickel is continuously improved along with temperature rise and time extension in the whole heat treatment process.

Description

technical field [0001] The invention utilizes the thermal effect of laser to carry out crystallization treatment on the electroless Ni-P coating, so that the phase changes from amorphous state to crystalline state, and Ni is precipitated. 3 The P hardening phase improves the hardness and wear resistance of the coating, and belongs to the field of material surface modification treatment. Background technique [0002] ZL113 is an Al-Si-Cu die-casting aluminum alloy. Because of its low density, high strength, and good plasticity, it is widely used in the manufacture of die-casting parts such as cylinder heads, cylinder blocks, and valve bodies. Because ZL113 aluminum The hardness of the alloy is low, only 80HB, which seriously affects the service performance and life of aluminum alloy die-casting parts; in order to improve the surface hardness and wear resistance of ZL113, it is usually necessary to carry out surface strengthening treatment on aluminum alloy; the electroless Ni...

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Problems solved by technology

[0002] ZL113 is an Al-Si-Cu die-casting aluminum alloy. Because of its low density, high strength, and good plasticity, it is widely used in the manufacture of die-casting parts such as cylinder heads, cylinder blocks, and valve bodies. Because ZL113 aluminum The hardness of the alloy is low, only 80HB, which seriously affects the service performance and life of aluminum alloy die-casting parts; in order to improve the surface hardness and wear resistance of ZL113, it is usually necessary to carry out surface strengthening treatment on aluminum alloy; the electroless Ni-P alloy coating has a relatively high High hardness, wear resistance and corrosion resistance are widely used in the surface modification treatment of aluminum alloys; in order to further improve the hardness and wear resistance of the coating, it is generally necessary to carry out crystallization heat treatment on the Ni-P alloy coating. The Ni-P coating crystallization heat treatment methods mainly include: annealing, mechanical grinding, ion beam bombardment, etc.; although the annealing treatment can obtain the maximum hardness, it will cause the softening of the substrate, and the Ni-P coating is processed by mechanical grinding. Bit mechanical treatment can crystallize the Ni-P coating and produce the expected compressive stress, but it will produce cracks or holes, which will reduce the corrosion resistance of the coating. The ion beam bombardment technology can make high-energy ions transfer energy to the coating. atoms, causing cascade collisions and thermal peak effects, increasing atomic mobility and activation ability, and helping to increase the crystallization rate; at present, ion glow discharge technology is generally used for heating annealing or tempering by ion beam bombardment, and its heating rate is slower than Fast, instantly raises the temperature of the coating and the substrate, and the temperature is difficult to control, and it is easy to damage the substrate. If the ion source is used to directly bombard the surface of the coating, the temperature rise will be very low, and the purpose of crystallization treatment will not be achieved; the patent of the invention is passed The laser thermal effect crystallizes the Ni-P coating in the as-plated state. After crystallization, the surface of the coating is smooth and smooth, with small grains and no cracks, and only produces thermal effects on the surface of the amorphous coating, without causing a significant temperature rise to the substrate. It affects the mechanical properties of the substrate, and has important engineering application significance for improving the wear resistance of Ni-P coatings

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