Electric arc spraying method

A technology of arc spraying and sandblasting, which is applied in the direction of coating, fusion spraying, metal material coating process, etc. It can solve the problems that metal wires are easy to be stained with oil, dust, uneven arc spraying layer, and reduce the effect of arc spraying, etc. , to achieve the effect of eliminating residual thermal stress, uniform and compact coating, and smooth outer surface of workpiece

Pending Publication Date: 2021-01-01

上海戎实喷涂机械有限公司

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AI-Extracted Technical Summary

Problems solved by technology

[0003] In the existing technology, it is necessary to select a suitable metal wire as the raw material before spraying. However, due to the long-term exposure of the metal wire to the air, not only will an oxide layer be formed on its surface, but also the metal wire is easily stained with oil ...

Method used

In sandblasting process, arc voltage is set to 36-37V, and the distance of spray gun and workpiece surface remains on 350-400mm, and spraying moving speed remains between 0.9m/min-1.1m/min during spraying, controls spraying Temperature rise T<100℃. By adjusting the arc voltage, spraying distance, spraying moving speed and spraying temperature rise to an appropriate range, evenly distributed rough pits can be formed on the surface of the workpiece, so that the joint surface can produce micro-metallurgical bonding and improve the bonding force.

Simultaneously before electric arc spraying, the pretreatment process to metal wire rod is increased, even after the metal wire rod surface of long-term placement takes place rust, after cleaning, drying, straightening and grinding, the impurity on the metal wire rod is removed, thereby The purity of the atomized metal particles is improved to ensure that the metal particles can be evenly attached to the surface of the workpiece. After spraying, the outer surface of the workpiece is smooth, the coating is even and dense, the coating is well combined with the substrate, no blistering, no cracking, no pitting, no peeling, and the corrosion resistance and structural strength of the workpiece are improved.

The implementation principle of the present embodiment is: compared to traditional electric arc spraying, the present invention has increased the operation of surface pretreatment to be sprayed before carrying out electric arc spraying, is to carry out sandblasting treatment to the surface of workpiece, and sandblasting can Improving the surface activity of the workpiece is conducive to increasing the adsorption force between the sprayed particles and the surface of the workpiece, and improving the metallurgical bonding force between the sprayed particles and the substrate. A certain residual compressive stress is formed on the surface of the workpiece after being repeatedly impacted by sand particles, which is beneficial to improving the overall fatigue strength of the workpiece; it is also beneficial to eliminating the residual thermal stress formed during the spraying process.

Visual inspection is carried out to workpiece surface by special quality inspector, and after magnifying glass is enlarged the image of ...

Abstract

The invention relates to an electric arc spraying method. The electric arc spraying method comprises the following steps that S1, construction preparation is conducted; S2, pretreatment is conducted on the surface to be sprayed, specifically, sand blasting treatment is conducted on the surface of a workpiece through pneumatically-controlled sand blasting equipment, and the roughness of the workpiece reaches 90-120 microns; S3, pretreatment is conducted on a metal wire, specifically, the metal wire is cleaned through a rust remover, straightened through a straightening machine after being cleaned and dried, and polished after being straightened, so that the surface of the metal wire is smooth; S4, electric arc spraying is conducted; S5, coating hole sealing is conducted; and S6, coating inspection is conducted, specifically, the appearance surface obtained after spraying is inspected. According to the electric arc spraying method, the metal wire is cleaned, dried, straightened and polished before spraying, so that the outer surface of the workpiece obtained after spraying is smooth, a coating is uniform, flat and compact, the coating and a base body are well combined, bubbling, cracking, pitted surfaces and peeling are avoided, and accordingly the corrosion resistance and structural strength of the workpiece are improved.

Application Domain

Molten spray coating

Technology Topic

Corrosion preventionPre treatment +5

Image

Examples

Experimental program(1)
Effect test(1)

Example Embodiment

[0040]The present invention will be further described in detail below in conjunction with the drawings.

[0041]Referencefigure 1, Is an arc spraying method disclosed in the present invention, including the following steps:

[0042]S1: Preparation for construction, remove dust and impurities on the surface of the workpiece, and conduct all-round quality inspection on the sprayed parts of the workpiece;

[0043]S2: The surface to be sprayed is pretreated, and the surface of the workpiece is sandblasted by pneumatically controlled sandblasting equipment to make the roughness of the workpiece reach 90-120um;

[0044]S3: Metal wire pretreatment, use rust remover to clean the metal wire, after cleaning and drying, straighten the metal wire through the straightening machine, and polish the metal wire to make the surface smooth after straightening;

[0045]S4: Arc spraying, connect the air compressor and spray gun to the arc spraying power supply, install a wire feeder between the spray gun and the arc spraying power supply, connect one end of the metal wire to the wire feeder, and turn on the equipment to spray the workpiece ;

[0046]S5: Coating sealing, within 5-8 hours after spraying, spray sealing with a special high-temperature corrosion-resistant and wear-resistant sealing agent to seal the capillary pores and form a composite coating with the metal coating;

[0047]S6: Coating inspection, the total thickness of the coating is detected by the coupon method, the total thickness of the composite coating is 0.8-0.9mm, and the appearance of the surface after spraying is checked.

[0048]Before performing a sandblasting process, use masking tape and baffle objects to shield and protect the non-sprayed surface of the workpiece and form a protective layer. A transition zone of 210mm is reserved at the edge of the protective layer. This setting ensures that the surface of the workpiece during the sandblasting process Can form a smooth transition.

[0049]Among them, in S2, the pretreatment of the surface to be sprayed includes the following processes:

[0050]S2a: One-time sandblasting, using 15-16 mesh corundum sand to coarsely spray the surface of the workpiece to remove the floating dust, hard dust and rust layer on the surface, especially the adhesion in the small pits, until the metallic luster is completely exposed;

[0051]S2b: Secondary sandblasting, sandblasting the derusted surface again to roughen the surface of the workpiece to improve the bonding strength.

[0052]The purpose of a sandblasting process is to purify the surface of the workpiece and remove various pollutants on the sprayed surface, especially grease, dirt, oxide scale, rust layer, etc., so that the surface of the workpiece shows a uniform metallic luster, which is beneficial to the base material and the substrate. The adhesive bonding of the active surface (mechanical occlusion and metallurgical micro-diffusion) improves the bonding strength, and the cleanliness of the working surface reaches Sa3 level.

[0053]The purpose of the secondary sandblasting process is to roughen the surface of the workpiece. The thermal spray coating and the substrate are mainly combined mechanically. This requires that the substrate pretreatment not only removes oil and rust, but also roughens the surface so that the surface has a certain The roughness. The secondary sandblasting increases the contact area between the spray coating material and the substrate, and improves the adhesion and adsorption of the bonding surface. At the same time, the packing and embedding of the coating material and the surface of the substrate are increased to enhance the adhesion between the coating and the substrate.

[0054]In the sandblasting process, the arc voltage is set to 36-37V, the distance between the spray gun and the surface of the workpiece is maintained at 350-400mm, and the spray moving speed during spraying is maintained between 0.9m/min-1.1m/min, and the spraying temperature rise T is controlled<100°C. By adjusting the arc voltage, spraying distance, spraying moving speed and spraying temperature rise to an appropriate range, uniformly distributed rough pits can be formed on the surface of the workpiece, so that the bonding surface produces micro-metallurgical bonding and improves bonding force.

[0055]Referencefigure 1, In S4, the air pressure of the air compressor is maintained above 0.6MPa, the ambient temperature during arc spraying is between -10°C and +40°C, and the altitude is not greater than 1400m. The voltage of arc spraying is 28V-35V, the current is 160A-200A, the spraying material is L-302, CP-302A alloy wire with φ2.0mm, the spraying distance is 200mm-300mm, the spraying angle is 45-75°, particle spraying Speed>400m/s.

[0056]By adjusting the environmental parameters during arc spraying and its own working parameters, the arc spraying equipment can work normally, thereby maximizing the quality of spraying and prolonging the life of the arc spraying equipment. Furthermore, the spraying method of arc spraying adopts the “well” spraying method, layered and partitioned operations, and the local area reaches the process design thickness before moving to other areas. This setting can ensure the uniform thickness of the sprayed layer and prevent leakage. Spray phenomenon.

[0057]The interval between the sandblasting process and the arc spraying process is less than 3 hours. The sandblasting can remove the organic contamination and oxide layer on the surface of the workpiece, increase the plastic deformation of the metal surface layer grains and increase the lattice defects, so that the surface is easy The state where the chemical reaction occurs helps to promote the physical and chemical bonding between the sprayed particles and the metal surface. Therefore, spraying should be carried out as soon as possible after sandblasting. The shorter the time, the better the surface activation effect and the higher the bonding quality of the coating. The interval time is controlled within 3 hours, which can ensure the effect of arc spraying and improve the quality of spraying.

[0058]Further, in S6, the surface of the workpiece is visually inspected first, and then the visual inspection system is used to inspect the appearance of the workpiece after spraying. The visual inspection system includes a magnifying glass, a camera, and a display screen. The camera is slidably arranged above the magnifying glass, and the camera and the display screen are connected through a data cable.

PUM

Property	Measurement	Unit
Total thickness	0.8 ~ 0.9	mm

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

high purity

Electric arc spraying method

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

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Examples

Example Embodiment

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Description & Claims & Application Information

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