Preparation and use method of an on-site metallographic coating block

Abstract

The present invention provides a method for preparing an on-site metallographic coating block and a method for using the same. The method for preparing the on-site metallographic coating block comprises: (1) coating the wall; (2) filling; (3) melting; (4) cooling; and (5) demoulding. The present invention adopts green and degradable polymer materials to prepare the metallographic coating block and perform metallographic coating operations, thereby avoiding the disadvantage of using acetone as a solvent, and has the advantages of convenient operation, short time, no pollution, no harm to the human body, reusability, and good coating effect.

Description

Technical Field

[0001] The invention belongs to the technical field of metallographic testing, and in particular relates to a preparation method of an on-site metallographic coating block and a use method thereof. Background Art

[0002] On-site metallographic experiments are metallographic experiments conducted under non-experimental conditions. They are usually used for online inspection of pressure pipes, non-destructive inspection of large castings and forgings, and other scenarios where sampling is not suitable for metallographic testing. The main method is to directly select a small area on the workpiece for relevant metallographic inspection. Due to the existence of high-altitude work, weighted climbing, or limited working space, it is often necessary to coat the prepared metallographic inspection surface, and replicate the metallographic structure morphology on the workpiece on the "film" and bring it back to the laboratory for observation.

[0003] The usual operation of metallographic inspection is: use the coating material AC paper (generally 0.5mm thick, acetate fiber component) or acrylic plate (thickness 1-2mm), drop a drop of acetone on the metallographic inspection surface, and then use tweezers to stick a certain size of AC paper or acrylic plate to the part with acetone. During the operation, it is necessary to ensure that the bubbles on the contact surface are as much as possible. After pressing and fixing, it is necessary to wait for more than 20 minutes. After the acetone is completely evaporated, use tweezers to remove the film. Metallographic inspection usually requires acetone. This chemical is extremely volatile and has certain toxicity. It will damage the human central nervous system. It is a drug-making chemical with strict management. If used in a relatively sealed space (inside a pressure vessel), it will cause greater damage to the human body; and acetone is a liquid, which will be very difficult to operate on the inspection surface of the upward-looking workstation. During the operation, special techniques are required to remove the air on the contact surface. It takes a long time to wait for the acetone to completely evaporate. In addition, the coating is small, not easy to preserve, and easy to lose. Therefore, it is urgently needed in the field of metallographic testing technology to invent a metallographic coated block which is simple in preparation method, safe in use, easy to operate, and easy to preserve after coating. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a simple method for preparing a metallographic coated block and a method for using the same. The present invention is easy to operate and safe to use during on-site metallographic testing, and the coated metallographic coated block is easy to store.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing an on-site metallographic coating block comprises the following steps:

[0007] (1) Wall coating: Apply vaseline on the inner wall of the tempered glass tube and place it on a flat tempered glass plate coated with vaseline;

[0008] (2) Filler: Pour polycaprolactone particles into the tempered glass tube obtained in step (1);

[0009] (3) Melting: Heat the tempered glass tube filled with polycaprolactone together with the tempered glass plate below until the polycaprolactone is completely melted;

[0010] (4) Cooling: After melting, take out the mixture and place it in a dry environment to cool naturally;

[0011] (5) Demolding: After cooling to room temperature, take out the prepared coated block.

[0012] Furthermore, in step (2), the height of the polycaprolactone particles is greater than 3 / 4 of the height of the tempered glass tube.

[0013] Furthermore, in step (3), the heating temperature is 120-180°C.

[0014] The method for using the on-site metallographic coating block includes the following steps:

[0015] (1) heating the surface of the coated block until the surface of the coated block becomes transparent;

[0016] (2) The baked coated surface is then pressed onto the prepared metallographic inspection surface, and the coated block is cooled to ambient temperature, and the junction between the coated block surface and the metallographic inspection surface completely turns milky white;

[0017] (3) Separate the coating block from the inspection surface;

[0018] (4) Remove the coated block and seal it for storage.

[0019] By adopting the above technical solution, the beneficial effects of the present invention are:

[0020] The preparation of the metallographic coating block in the present invention can be completed by using general equipment in metallographic laboratories, and the size and thickness of the coating block can be adjusted to meet the needs of different detection situations; vaseline is applied to the wall of the steel pipe to make demoulding easier; the polycaprolactone used to prepare the metallographic coating block is a green and environmentally friendly material, which is environmentally friendly and will not affect the environment even if it is lost on site; the operation process of on-site metallographic coating does not require the use of acetone, will not cause harm to the human respiratory tract, and also meets the control requirements of easily-made-drug chemicals; the operation process of on-site metallographic coating no longer requires special techniques to eliminate bubbles and the waiting time for the coating to cool is short, so that the on-site metallographic coating time is greatly shortened; because the coating surface will become soft during baking, it can be reused; the metallographic coating block prepared according to the present invention is large in size, not easy to lose, easy to preserve, and can be preserved for a long time, meeting the needs of laboratory sample preservation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is the organizational morphology of the steel pipe under a metallographic microscope.

[0022] Figure 2 for Figure 1 The microstructure of the coated block corresponding to the medium steel pipe.

[0023] Figure 3 This is the organizational morphology of the gear under a metallographic microscope.

[0024] Figure 4 for Figure 3 The tissue morphology on the coating block corresponding to the middle gear. DETAILED DESCRIPTION

[0025] Example 1

[0026] A method for preparing an on-site metallographic coating block and using the same comprises the following steps:

[0027] 1. Preparation of metallographic coating blocks:

[0028] (1) Wall coating: In the laboratory, vaseline was applied on the inner wall of a tempered glass tube with a height of 20 mm, a diameter of 25 mm, and a wall thickness of 1 mm, and the tube was placed on a 150×150 mm flat tempered glass plate. The area on the plate was also evenly coated with vaseline.

[0029] (2) Filler: Pour polycaprolactone 6800 particles into a tempered glass tube, with the particle stacking height being 3 / 4 of the height of the tempered glass tube;

[0030] (3) Melting: Put the tempered glass tube filled with polycaprolactone 6800 together with the tempered glass plate below into an oven at a temperature of 150°C for 8 minutes. After all the polycaprolactone 6800 particles are melted, take out the device together.

[0031] (4) Cooling: The melted polycaprolactone obtained in step (3) and the tempered glass plate are placed in a dry environment and cooled to room temperature.

[0032] (5) Demolding: Take out the milky white coated block cooled in step (4).

[0033] 2. Prepare a metallographic inspection surface on a gas pipeline at the production site:

[0034] (1) Use an angle grinder to prepare the metallographic inspection surface. The prepared surface should be no less than 30 mm × 50 mm. Install a shutter grinding wheel on the angle grinder and grind with a No. 260 grinding wheel, a No. 400 grinding wheel, a No. 600 grinding wheel, a No. 800 grinding wheel, and a No. 1000 grinding wheel in sequence. Each time the grinding is performed, the grinding marks of the previous grinding must be removed;

[0035] (2) Install a wool wheel on the angle grinder and use a metallographic polishing agent to perform polishing operations. During the operation, it is necessary to continuously spray water for lubrication. The polishing is completed when the inspection area is a mirror surface;

[0036] (3) Use the corresponding corrosive agent to perform metallographic etching operation on the polished inspection area. After the etching is completed, wash it with water and blow dry it with a hair dryer;

[0037] (4) Use a metallographic microscope to observe the metallographic inspection surface on the gas pipeline, such as Figure 1 shown.

[0038] 3. Metallographic coating:

[0039] (1) Hold the edge of the coated block with one hand and use a lighter with the other hand to bake the coated surface of the coated block until the coated surface becomes transparent and slightly melted;

[0040] (2) Press the baked coated surface slightly onto the metallographic inspection surface and then release it;

[0041] (3) When the coated block cools to ambient temperature, the junction between the coated surface of the coated block and the metallographic inspection surface turns completely milky white, and then it is removed by hand;

[0042] (4) Use a metallographic microscope to observe the metallographic coating block corresponding to the metallographic inspection surface on the gas pipeline, such as Figure 2 shown.

[0043] like Figure 1 and Figure 2 As shown, it can be clearly seen that the metallographic surface microscopic morphology shown in the two figures is the same, from which it can be known that the metallographic coating block prepared by the present invention can well replicate the microscopic morphology of the metallographic surface.

[0044] Example 2

[0045] A method for preparing and using an on-site metallographic coating block comprises the following steps:

[0046] 1. Preparation of metallographic coating

[0047] (1) Wall coating: In the laboratory, vaseline was applied on the inner wall of a tempered glass tube with a height of 20 mm, a diameter of 25 mm, and a wall thickness of 1 mm, and the tube was placed on a 150 × 150 mm flat tempered glass plate. The placement area on the plate was also evenly coated with vaseline;

[0048] (2) Filling: Pour polycaprolactone 6800 particles into a tempered glass tube, with the stacking height of the particles flush with the height of the tempered glass tube;

[0049] (3) Melting: Put the tempered glass tube filled with polycaprolactone 6800 together with the tempered glass plate into an oven at 160°C for 10 minutes. When all the polycaprolactone 6800 particles are melted, take out the device.

[0050] (4) Cooling: placing the melted polycaprolactone obtained in step (3) and the tempered glass plate together in a dry environment to cool to room temperature;

[0051] (5) Demolding: Take out the milky white coated block cooled in step (4).

[0052] 2. Prepare a metallographic inspection surface on the end face of a large gear manufactured at the production site:

[0053] (1) Use an angle grinder to prepare the metallographic inspection surface. The prepared surface should be no less than 30 mm × 50 mm. Install a shutter grinding wheel on the angle grinder and grind with a No. 260 grinding wheel, a No. 400 grinding wheel, a No. 600 grinding wheel, a No. 800 grinding wheel, and a No. 1000 grinding wheel in sequence. Each time the grinding is performed, the grinding marks of the previous grinding must be removed;

[0054] (2) Install a wool wheel on the angle grinder and use a metallographic polishing agent to perform polishing operations. During the operation, it is necessary to continuously spray water for lubrication. The polishing is completed when the inspection area is a mirror surface;

[0055] (3) Use the corresponding corrosive agent to perform metallographic etching operation on the polished inspection area. After the etching is completed, wash it with water and blow dry it with a hair dryer;

[0056] (4) Use a metallographic microscope to observe the metallographic inspection surface of the large gear end face, such as Figure 3 shown.

[0057] 3. Metallographic coating:

[0058] (1) Hold the edge of the coated block with one hand and use a lighter with the other hand to bake the coated surface of the coated block until the coated surface becomes transparent and slightly melted;

[0059] (2) Press the baked coated surface slightly onto the metallographic inspection surface and then release it;

[0060] (3) When the coated block cools to ambient temperature, the junction between the coated surface of the coated block and the metallographic inspection surface turns completely milky white, and then it is removed by hand;

[0061] (4) Use a metallographic microscope to observe the metallographic coating block corresponding to the metallographic inspection surface of the end face of the large gear, such as Figure 4 shown.

[0062] like Figure 3 and Figure 4As shown, it can be clearly seen that the metallographic surface microscopic morphology shown in the two figures is the same, from which it can be known that the metallographic coating block prepared by the present invention can well replicate the microscopic morphology of the metallographic surface.

[0063] Therefore, the metallographic coating block produced by the present invention can be well utilized in on-site metallographic testing.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for using an on-site metallographic coating block, characterized in that: The following steps are involved: (1) heating the surface of the coated block until the surface of the coated block becomes transparent; (2) The heated coated surface is then pressed onto the prepared metallographic inspection surface, and the coated block is cooled to ambient temperature, and the junction between the coated block surface and the metallographic inspection surface completely turns milky white; (3) Separate the coating block from the inspection surface; (4) Remove the film block and seal it for storage; Wherein, the method for preparing the on-site metallographic coating block comprises the following steps: (1) Wall coating: Apply vaseline on the inner wall of the tempered glass tube and place it on a flat tempered glass plate coated with vaseline; (2) Filler: Pour polycaprolactone particles into the tempered glass tube obtained in step (1); (3) Melting: Heat the tempered glass tube filled with polycaprolactone together with the tempered glass plate below until the polycaprolactone is completely melted; (4) Cooling: After melting, take out the mixture and place it in a dry environment to cool naturally; (5) Demolding: After cooling to room temperature, take out the prepared coated block.

2. The method for using the on-site metallographic coating block according to claim 1, characterized in that: The height of the polycaprolactone particles filled in step (2) of the method for preparing an on-site metallographic coated block is greater than 3 / 4 of the height of the tempered glass tube.

3. The method for using the on-site metallographic coating block according to claim 1, characterized in that: In step (3) of the method for preparing the on-site metallographic coated block, the heating temperature is 120-180°C.

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