Casting micropore self-healing repairing method

Abstract

The invention discloses a casting micropore self-healing repairing method which comprises the following steps that an iron casting with casting micropore gas leakage is subjected to powder sherardizing treatment, metal zinc and an iron matrix form a zinc-iron alloy, and the zinc-iron alloy grows towards a near space and occupies the original space of micropore channels until the micropore channels are closed. The method has the beneficial effects that the zinc-iron alloy grows towards the near space, the iron casting with the micropores is subjected to zinc impregnation treatment, the zinc impregnation treatment is simple and rapid, the limitation of the internal space of the valve body can be ignored, meanwhile, residues are not left in the valve body, the micropores are efficiently repaired, and leakage is avoided after the micropores are repaired.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal casting repair, and particularly relates to a casting micro-hole self-healing repair method. BACKGROUND

[0002] Many valve products are used in railway brake systems, such as cast iron valve products, which play an important role in railway transportation safety. During the steel casting process, small pores are often produced, which do not affect the mechanical properties of the product, but can cause valve leakage. Especially, the braking system of a railway freight car is powered by compressed air, and leakage can cause brake failure. During production, the valve is usually subjected to air tightness test, and the leaking products are selected for repair or scrap, but the leakage of the valve internal chamber partition cannot be handled.

[0003] The repair of the casting product leakage micro-hole currently has repair methods such as laser cladding, welding, heat-cured impregnation, and air-cured paste. Due to the complex space structure and small space, the repair methods such as laser cladding, welding, and air-cured paste are difficult to implement for internal valve repair. Heat-cured impregnation is easy to remain in the valve, and the repair method has defects. Therefore, it is urgent to find a better repair method for casting micro-holes. SUMMARY

[0004] The purpose of the present application is to provide a casting micro-hole self-healing repair method, which solves the problem of rapid and convenient repair of cast iron parts.

[0005] The purpose of the present application is achieved by the following technical solutions: A casting micro-hole self-healing repair method, comprising the following steps: performing powder zinc impregnation treatment on a cast iron part with casting micro-hole gas leakage, forming a zinc-iron alloy between the metal zinc and the iron matrix, and growing the zinc-iron alloy towards the adjacent space, occupying the original space of the micro-hole channel, until the micro-hole channel is closed.

[0006] Further, the diameter of the micro-hole of the cast iron part is less than or equal to 140 microns.

[0007] Further, the thickness of the zinc-iron alloy is less than or equal to 100 microns.

[0008] Further, the growth thickness of the zinc-iron alloy is 0.5-0.7 times the thickness of the zinc alloy.

[0009] Further, the zinc impregnation treatment is: the mixture of zinc powder, aluminum oxide and zinc chloride is connected with the cast iron part with micro-hole leakage and is loaded into a tank, and the tank is heated.

[0010] Further, the zinc powder in the mixture is 50%~60%, the aluminum oxide is 37%~48%, and the zinc chloride is 2%~3% by weight.

[0011] Further, the heating temperature is 420~440℃.

[0012] Further, the heating time is 3~5h.

[0013] Further, the heating mode is to rotate the tank body.

[0014] The beneficial effects of the present application: using the characteristics of zinc-iron alloy growth in the near space, the zinc infiltration treatment is simple and fast, and the space limitation in the valve body can be ignored, and the residual in the valve body is not performed, the micro-hole repair is efficiently realized, and the micro-hole repair is no longer leaked.

[0015] The foregoing main scheme of the present application and each further selected scheme can be freely combined to form multiple schemes, all of which are the schemes that can be adopted and claimed by the present application; and the present application, the (each non-conflict selection) selection and the other selection can also be freely combined. Those skilled in the art can understand that there are many combinations according to the prior art and common knowledge after understanding the schemes of the present application, all of which are the technical schemes claimed by the present application, and are not enumerated here. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram before repair of the present application.

[0017] Figure 2 is a schematic diagram in the repair of the present application.

[0018] Figure 3 is a schematic diagram after repair of the present application.

[0019] Figure 4 is a metallographic diagram after repair of the present application.

[0020] Figure 5 is Figure 4 a partial enlarged view. DETAILED DESCRIPTION

[0021] The following non-limiting examples are used to illustrate the present application.

[0022] Example Referring to Figures 1-3 , a cast micro-hole self-healing repair method includes the following steps: powder zinc infiltration treatment is performed on the cast iron piece with cast micro-hole gas leakage, zinc and iron matrix form zinc-iron alloy, zinc-iron alloy grows in the near space, occupies the original space of the micro-hole channel, and until the micro-hole channel is closed.

[0023] When the growth thickness of zinc-iron alloy δ1 is greater than or equal to the micro-hole diameter Φ of the cast iron piece, the hole port is naturally healed to achieve plugging. The micro-hole diameter Φ of the cast iron piece is less than or equal to 140 microns, that is, the repair method is suitable for the cast iron piece with the size, and the cast iron piece with a size greater than the size cannot be repaired by micro-growth due to the larger micro-hole.

[0024] The thickness δ of the zinc-iron alloy is less than or equal to 100 microns, and the thickness of the zinc-iron alloy includes the thickness of the zinc element penetrating into the iron matrix and the thickness of the zinc-iron alloy growing on the outer surface of the iron matrix (i.e. δ1). The zinc-iron alloy with the size is easy to be treated by zinc penetration, which can simplify the processing difficulty. The growth thickness δ1 of the zinc-iron alloy is 0.5-0.7 times the thickness δ of the zinc alloy, and the multiple is controlled by the processing parameters, and the zinc penetration material is comprehensively adjusted to ensure that the final growth thickness can meet the closure requirement.

[0025] The zinc penetration treatment is that a mixture of zinc powder, aluminum oxide and zinc chloride is loaded into a tank together with the cast iron piece with a micro-hole leakage, and the tank is heated. According to the weight parts, the zinc powder in the mixture is 50%-60%, the aluminum oxide is 37%-48%, and the zinc chloride is 2%-3%. The heating temperature is 420-440℃. The heating time is 3-5h. The heating mode is to rotate the tank.

[0026] The thickness of the zinc-iron alloy is controlled by the proportion of zinc powder and heating time. The higher the proportion of zinc powder, the faster the penetration and growth speed, the deeper the penetration layer, and the longer the heating holding time, the thicker the penetration layer.

[0027] Experimental case Based on the experimental operation of the embodiment.

[0028] The cast iron bar is turned into a test piece with a diameter of Φ18*2cm, and a hole with a diameter of 0.1mm and 0.05mm is formed in the center of the test piece by laser perforation. The test piece is placed in a special airtight test device, compressed air is introduced and soap water is brushed, and the observation port is observed to produce soap bubbles. The test shows that the test piece is leaking.

[0029] After the zinc element is penetrated into the test piece, the zinc element and the iron matrix form a zinc-iron alloy. Since the zinc-iron alloy layer grows to the adjacent space, the original space of the micro-hole channel is occupied, and when the zinc-iron alloy layer grows to a certain extent, the channel is naturally healed, thereby realizing micro-hole repair, so that the micro-hole is no longer leaking after repair.

[0030] The test piece after the zinc element is penetrated is subjected to leakage test, and after the compressed air is introduced and the soap water is brushed, no soap bubbles are observed in the observation port, and the test shows that the micro-hole of the test piece is healed and plugged.

[0031] Reference Figure 4 and Figure 5As shown, the test piece after zinc infiltration is cut along the laser perforation position, and the metallographic test shows that in the process of zinc-iron alloy growing inward and outward, the hole port is gradually closed and healed by zinc-iron alloy, and the hole disappears.

[0032] The foregoing basic examples and each further selected example of the present application can be freely combined to form a plurality of embodiments, all of which are embodiments that can be adopted and claimed by the present application. In the present application scheme, each selected example can be arbitrarily combined with any basic example and selected example.

[0033] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for self-healing repair of casting micropores, characterized in that, The process includes the following steps: applying a powder zinc infiltration treatment to cast iron parts with micropore gas leakage, where metallic zinc forms a zinc-iron alloy with the iron matrix, and the zinc-iron alloy grows into the adjacent space, squeezing out the original space of the micropore channels until the micropore channels are sealed.

2. The self-healing repair method for casting micropores according to claim 1, characterized in that: The diameter of the micropores in cast iron parts is less than or equal to 140 micrometers.

3. The self-healing repair method for casting micropores according to claim 1, characterized in that: The thickness δ of zinc-iron alloy is less than or equal to 100 micrometers.

4. The self-healing repair method for casting micropores according to claim 1 or 3, characterized in that: The growth thickness δ1 of the zinc-iron alloy is 0.5 to 0.7 times the thickness δ of the zinc alloy.

5. The self-healing repair method for casting micropores according to claim 1, characterized in that: The zinc diffusion process involves loading a mixture of zinc powder, alumina, and zinc chloride, along with a microporous, leaky cast iron component, into a tank and then heating the tank.

6. The self-healing repair method for casting micropores according to claim 5, characterized in that: By weight, the mixture contains 50% to 60% zinc powder, 37% to 48% alumina, and 2% to 3% zinc chloride.

7. The self-healing repair method for casting micropores according to claim 5, characterized in that: The heating temperature is 420~440℃.

8. The self-healing repair method for casting micropores according to claim 5 or 6, characterized in that: The heating time is 3 to 5 hours.

9. The self-healing repair method for casting micropores according to claim 5, characterized in that: The heating method involves rotating the tank for heating.

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