CN104858792A - Method for rapidly removing thermal spraying coating - Google Patents

Abstract

The invention discloses a method for rapidly removing a thermal spraying coating. A sand blasting material adopts alloy sand with diameters being 0.5-5.0 mm, special-shaped alloy sand with the ratio of length to width being 1.0-5.0 as well as 10-50-mesh ceramic sand, wherein the mass ratio of the alloy sand to the special-shaped alloy sand to the ceramic sand is (1-4):(1-4):1; before sand blasting, three raw materials are uniformly poured into an iron barrel simultaneously, mixing of the raw materials is facilitated, the mixed sand in the iron barrel is poured into a sand tank for sand blasting, and the air source pressure for sand blasting is 0.5-0.9 MPa. The sand composition is optimized and improved, the air source pressure is increased, the removal time of an old coating is greatly shortened, and compared with the time for old coating removal through single ceramic sand blasting, the time is shortened by 60%-75%; meanwhile, the production cost is reduced, the old coating is economically and efficiently removed, and the method is suitable for removing various metal coatings, alloy coatings and metal ceramic coatings.

Description

A kind of method of quick removal hot-spraying coating

Technical field

The invention belongs to field of surface engineering technique, be specifically related to a kind of method of quick removal hot-spraying coating.

Background technology

Power system parts adopt plasma spray technology to carry out anti-protection to its surface more and more.In coal-burning power plant, hydroelectric power plant, GTCC power plant, in order to improve the service life of equipment, extending the unit maintenance cycle, usually adopting plasma spray technology to being corroded, wearing and tearing, water erosion, cavitation erosion etc. parts carry out surfacecti proteon.The actual operating mode in different power station and conditional decision such as tungsten carbide, chromium carbide, metal or alloy coating etc. there will be damage in various degree.For the parts that coating damage is comparatively serious, need again to spray coating.In order to ensure the quality of new spray-on coating, before enforcement spraying protection, need to remove work thoroughly to the old coating of area to be sprayed and periphery.

Removal at present for old hot-spraying coating has mechanical grinding and traditional sandblasting two kinds of methods usually.Namely mechanical rubbing method adopts angle grinding machine old coating polishing to be removed, and the surface smoothness that this method polish, uniformity, cleannes are poor, and is not suitable for surface quality requirements higher part part.The method labour intensity of mechanical grinding is large simultaneously, efficiency is low, when the old coating area needing to remove is larger, and the method long construction period.

Namely tradition blasting method adopts sand-blasting machine and compressed air that the sand grains (as quartz sand, ceramic sand etc.) of high rigidity is ejected into surface of the work thus makes the method for old coating shedding.Comparatively mechanical grinding mode is compared, and the method is destroyed less to parts surface uniformity, improves the speed of old coating removal.But for the removal of the old coating of large area, this conventional method efficiency is still low.

For the economical and efficient realizing old coating is removed, need to optimize further current blasting method.

Summary of the invention

For solving the problem, the object of the present invention is to provide a kind of method of quick removal hot-spraying coating, solving the present situation that existing blasting method efficiency is low, the cycle is long, labour intensity is large.

For achieving the above object, the technical solution adopted in the present invention is:

A method for quick removal hot-spraying coating, comprises the steps:

Step 1: sand-blast material adopt particle diameter be 0.5-5.0mm alloy sand, length-width ratio in the special-shaped alloy sand of 1.0-5.0 and 10-50 object ceramic sand, the mass ratio of described alloy sand, special-shaped alloy sand and ceramic sand three kinds of raw materials is (1 ~ 4): (1 ~ 4): 1;

Step 2: before sandblasting, first evenly poured in metal bucket by three kinds of raw materials, to help the mixing between raw material, then pour in sand tank by the mixed sand in metal bucket, carry out sandblasting, sandblasting bleed pressure is 0.5-0.9MPa simultaneously.

Compared to the prior art, tool of the present invention has the following advantages:

1) sand grains composition is optimized improvement by the present invention, is mixed by multiple sand-blast material, improves air source pressure intensity, effectively shorten the old coating removal time, compared with removing old coating with single ceramic abrasion blasting, time decreased 60 ~ 80%, achieves the efficient removal of old coating.Reduce production cost simultaneously.

2) alloy sand and special-shaped alloy sand can recycle.

3) can be used for removing multiple coating, as coatings such as metal, alloy, cermets, be particularly useful for the removal of Large area coatings.

Detailed description of the invention

Below in conjunction with specific embodiment, the present invention is described in further details.

Embodiment one

After the impeller that certain power station sprays entirely runs the several years, the old tungsten carbide coating on surface needs all to remove then again to spray, and this impeller diameter is 3.7m, and its inner flow passage all coats coating.Under arms, original coating failure, again before spraying need old coating all to remove, old coating accounts for 80% of original spray area, is about 68 square meters, and adopt the present invention to carry out sandblasting to it, process is as follows.

First alloy sand, special-shaped alloy sand, ceramic sand are mixed in the ratio of 2:1:1, then pour mixed sand into sand-spraying pot.Adjustment bleed pressure makes it reach 0.75MPa, and start sandblasting, traditional blasting craft needs about 22 day time, and adopt the present invention, its blast time shortens to 7 day time, substantially reduces the removal work of old impeller tungsten carbide coating.Simultaneously, after each sandblasting is complete, the sand of shot blast cabinet can be carried out recycling, sand grains runs off less, and whole sandblasting procedures substantially no longer needs to add new sand, has saved the sandblasting cost of raw material, in addition, the whole sandblasting cycle shortens greatly, also saves artificial grade for production cost, thus achieves the removal of the high-efficiency and economic of old coating.

Embodiment two

Certain power station is after the impeller of spraying protection runs the several years, and the nickel-based filler metal on surface needs all to remove then again to spray, and this impeller diameter is about 1.8m, and blade surface all coats nickel-based filler metal.Under arms after the several years, original coating failure, again before spraying need old coating all to remove, old coating accounts for 70% of original spray area, is about 12 square meters, and adopt the present invention to carry out sandblasting to it, process is as follows.

First alloy sand, special-shaped alloy sand, ceramic sand are mixed in the ratio of 4:4:1, then pour mixed sand into sand-spraying pot.Adjustment bleed pressure makes it reach 0.90MPa, and start sandblasting, traditional blasting craft needs about 5 day time, and adopt the present invention, its blast time shortens to 1 day time, substantially reduces the removal work of the old nickel-based filler metal of impeller.

Embodiment three

Certain combustion engine power station is after the gas turbine passage component of spraying protection runs about 12000 hours, and the nickel base superalloy coating on surface needs all to remove then again to spray, and blade quantity to be removed is 10, and adopt the present invention to carry out sandblasting to it, process is as follows.

First alloy sand, special-shaped alloy sand, ceramic sand are mixed in the ratio of 1:1:1, then pour mixed sand into sand-spraying pot.Adjustment bleed pressure makes it reach 0.50MPa, starts sandblasting, adopts traditional blasting craft sandblasting, individual blade coating removal required time is about 2 hours, adopt the present invention, its blast time shortens to 15min, substantially reduces the removal work of the old nickel base superalloy coating of impeller.And after coating removal, blade surface quality is better, there will not be the destructions such as the distortion of blade.

Claims (1)

1. remove a method for hot-spraying coating fast, it is characterized in that, comprise the steps:

Step 1: sand-blast material adopt particle diameter be 0.5-5.0mm alloy sand, length-width ratio in the special-shaped alloy sand of 1.0-5.0 and 10-50 object ceramic sand, the mass ratio of described alloy sand, special-shaped alloy sand and ceramic sand three kinds of raw materials is (1 ~ 4): (1 ~ 4): 1;

Step 2: before sandblasting, first evenly poured in metal bucket by three kinds of raw materials, to help the mixing between raw material, then pour in sand tank by the mixed sand in metal bucket, carry out sandblasting, sandblasting bleed pressure is 0.5-0.9MPa simultaneously.