Two-step hot and cold mounting method for metallographic specimens

Abstract

The invention discloses a cold and hot two-step mounting method for metallographic samples, and relates to the field of metallographic structure analysis. The method first uses a clamp to clamp the sample, adjusts the angle of the sample and puts it into a cold mounting mold; then cold mounting is performed to obtain a cold mounting sample; then hot mounting is performed to obtain a hot mounting sample; then grinding and polishing are performed in sequence, and inspection and analysis are performed. The invention has the advantages of combining the advantages of cold mounting and hot mounting, and can realize fast, accurate and simple mounting of irregular-shaped samples at any angle without damaging the sample.

Description

Technical Field

[0001] The invention relates to the field of metallographic structure analysis, in particular to a cold and hot two-step embedding method for metallographic samples. Background Art

[0002] When identifying the cause of an electrical fire, the melt mark (melt bead) samples extracted from the fire scene are often of different sizes and irregular shapes, and need to be mounted and then ground and polished to prepare metallographic specimens for inspection and analysis. Commonly used mounting methods include cold mounting and hot press mounting. The cold mounting method is carried out at room temperature and is flexible and easy to operate, but it takes a long time to completely solidify, and can only be ground and polished after it is completely solidified. The hot press mounting method is carried out under a certain pressure and temperature in the mounting machine, with a short molding time, and can be directly ground and polished.

[0003] For samples with irregular shapes, it is difficult to place the desired observation position on the bottom surface of the mounting mold stably during the mounting process. If the sample is attached to the bottom surface of the mounting mold with double-sided tape or 502 glue, the residual adhesive will affect the quality of subsequent grinding and polishing processes.

[0004] Patent document with announcement number CN109708937B discloses a method for inlaying products with a diameter or thickness of less than 2 mm. The sample after the first inlay is longitudinally sectioned by a cutting machine, and the longitudinally sectioned sample is erected for secondary inlaying to expose the cross section of the thin plate or wire drawing. This patent is only applicable to thin plates or wire drawing with a diameter or thickness of less than 2 mm, and is not applicable to samples with irregular shapes. In addition, longitudinal sectioning may cause damage to the sample.

[0005] Patent document with announcement number CN203148756U discloses a metallographic sample mounting box, in which a sample pit is provided on the bottom wall of the bottom cover, and the metallographic sample is directly placed in the sample pit to fix the orientation when in use. The sample pit in the patent has a fixed shape and size, and the fixing angle of the sample is limited by the position, size and depth of the sample pit.

[0006] Patent document with announcement number CN111089775B discloses a vertical cold embedding device and embedding method for small ceramic-based composite materials, which uses a telescopic tube and a slider to clamp the sample and can fix the sample vertically. This patent is only applicable to cylindrical and slender samples, and the sample must be able to pass through the vertical through hole. It is not applicable to samples with irregular shapes, and the sample is fixed vertically, and the placement angle is limited.

[0007] Patent document with announcement number CN204988845U discloses a metallographic cold mounting device with adjustable sample mounting position and angle, which uses a claw-shaped fixture to clamp the sample and insert it into the mounting mold for mounting, and the mounting position and angle can be freely adjusted. The claw-shaped fixture of the patent remains inside the mounting block, and the sample needs to be pulled out of the fixture, which is complicated to operate and may cause damage to the sample. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a metallographic sample cold and hot two-step mounting method which can mount irregular-shaped samples at any angle without causing damage to the samples.

[0009] The present invention solves the above technical problems by the following technical means: a metallographic sample cold and hot two-step mounting method, comprising the following steps:

[0010] Step 1, using a clamp to clamp the sample, adjusting the angle of the sample to place it in a cold mounting mold, making the predetermined observation position of the sample contact with the bottom surface of the cold mounting mold, and leaving a gap between the clamping position of the clamp and the bottom surface of the cold mounting mold;

[0011] Step 2, adding cold mounting material into the cold mounting mold, the height of the cold mounting material immersing the sample is lower than the clamping point, and the cold mounting material is solidified to obtain a cold mounting specimen including the sample and the cold mounting block;

[0012] Step 3, taking out the cold mounting sample from step 2 from the cold mounting mold, placing it into the mounting machine with its predetermined observation position facing the mounting machine bottom mold, and removing the fixture;

[0013] Step 4, adding hot mounting material into the mounting machine for hot mounting, to obtain a hot mounting specimen including a sample, a cold mounting block and a hot mounting block;

[0014] Step 5: Grind, polish, inspect and analyze the hot-mounted samples in step 4.

[0015] As an optimized technical solution, the cold mounting mold is a flat-bottomed container, the longest dimension of the bottom surface of which is smaller than the diameter of the bottom mold of the mounting machine.

[0016] As an optimized technical solution, the cold mounting mold is made of silicone rubber or plastic.

[0017] As an optimized technical solution, in step two, the cold mounting material uses denture base resin powder and denture base resin liquid or epoxy resin and curing agent.

[0018] As an optimized technical solution, in step four, the hot embedding material uses hot embedding powder, which is a mixture of bakelite powder, phenolic plastic powder and electric jade powder.

[0019] As an optimized technical solution, in step 4, the hot mounting temperature is 135-150°C, and the hot mounting holding time is 3-5 minutes.

[0020] As an optimized technical solution, in the hot-mounted sample of step four, the cold-mounted block is located at the outer circle of the sample, and the hot-mounted block is located at the outer circle of the cold-mounted block.

[0021] The invention has the advantages of combining the advantages of cold mounting and hot mounting, and can quickly, accurately and conveniently mount irregularly shaped samples at any angle without damaging the samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a process flow chart of a metallographic specimen cold and hot two-step mounting method.

[0023] Figure 2 It is a schematic diagram of the cold mounting step of an embodiment of the present invention.

[0024] Figure 3 Schematic diagram of the hot mounting step of an embodiment of the present invention.

[0025] Figure 4 It is a bottom-up schematic diagram of a metallographic sample obtained after the metallographic sample cold and hot two-step mounting method is completed in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] like Figures 1 to 4 As shown, the metallographic specimen cold and hot two-step mounting method includes the following steps:

[0028] Step 1, use the clamp 2 to clamp the sample 1, adjust the angle of the sample 1 and place it in the cold mounting mold 3, make the predetermined observation position of the sample 1 contact with the bottom surface of the cold mounting mold 3, and leave a distance of about 3mm between the clamping position of the clamp 2 and the bottom surface of the cold mounting mold 3; the cold mounting mold 3 is a flat-bottomed container, and the longest dimension of its bottom surface is smaller than the diameter of the bottom mold 5 of the mounting machine, and the cold mounting mold 3 is made of silicone rubber or a plastic material that does not adhere to the cured cold mounting block 4.

[0029] Step 2, adding cold mounting material to the cold mounting mold 3, the height of the cold mounting material immersing the sample 1 is about 1.5 mm, which is lower than the clamping point. After the cold mounting material is cured, a cold mounting specimen including the sample 1 and the cold mounting block 4 is obtained; the cold mounting material can be made of denture base resin powder and denture base resin liquid or epoxy resin and curing agent. In this embodiment, 8.8g of denture base resin powder and 4mL of denture base resin liquid are mixed and stirred evenly. After it becomes viscous, take an appropriate amount and pour it into the cold mounting mold 3.

[0030] Step three, take out the cold mounting sample prepared in step two from the cold mounting mold 3, put it into the mounting machine with its predetermined observation position facing the mounting machine bottom mold 5 with a diameter of 30 mm, and remove the fixture 2.

[0031] Step 4, adding 13g of hot mounting material into the mounting machine for hot mounting, and obtaining a hot mounting sample including sample 1, cold mounting block 4 and hot mounting block 6; in the hot mounting sample, the cold mounting block 4 is located at the outer circle of sample 1, and the hot mounting block 6 is located at the outer circle of the cold mounting block 4; the hot mounting material adopts hot mounting powder, and the hot mounting powder can be a mixture of bakelite powder, phenolic plastic powder and electric jade powder; the hot mounting temperature is 135-150°C, and the hot mounting holding time is 3-5min, and in this embodiment, it is 145°C for 3min.

[0032] Step 5: Grind, polish, inspect and analyze the hot-mounted sample prepared in step 4 in accordance with the preparation process of the metallographic sample.

[0033] The principle of the cold and hot two-step mounting method for metallographic samples of the present invention is: cold-hot two-step mounting is performed in sequence, firstly the advantage of the flexible and simple operation of cold mounting is utilized, and the mounting angle of the sample 1 is adjusted and fixed in combination with the clamp 2, and then the advantage of the high molding efficiency of hot mounting is utilized to quickly mold the sample 1 with a fixed angle; the method combines the advantages of cold mounting and hot mounting, has no requirements on the shape of the sample 1, the placement angle of the sample 1 is not restricted, and does not involve destructive processes such as cutting and extraction, thereby realizing fast, accurate and convenient mounting of irregularly shaped samples 1 at any angle without damaging the sample 1.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A two-step hot and cold mounting method for metallographic specimens, characterized in that: The following steps are involved: Step 1: clamp the sample with a clamp, adjust the angle of the sample and place it in a cold mounting mold, make the predetermined observation position of the sample contact with the bottom surface of the cold mounting mold, and leave a gap between the clamping position of the clamp and the bottom surface of the cold mounting mold; the cold mounting mold is a flat-bottomed container, and the longest dimension of its bottom surface is smaller than the diameter of the bottom mold of the mounting machine; Step 2, adding cold mounting material into the cold mounting mold, the height of the cold mounting material immersing the sample is lower than the clamping point, and the cold mounting material is solidified to obtain a cold mounting specimen including the sample and the cold mounting block; Step 3, taking out the cold mounting sample from step 2 from the cold mounting mold, placing it into the mounting machine with its predetermined observation position facing the mounting machine bottom mold, and removing the fixture; Step 4, adding hot mounting material to a mounting machine for hot mounting, to obtain a hot mounting specimen including a sample, a cold mounting block and a hot mounting block; in the hot mounting specimen of step 4, the cold mounting block is located at the outer circle of the sample, and the hot mounting block is located at the outer circle of the cold mounting block; Step 5: Grind, polish, inspect and analyze the hot-mounted samples in step 4.

2. The metallographic specimen cold and hot two-step mounting method according to claim 1, characterized in that: The cold mounting mold is made of silicone rubber or plastic.

3. The metallographic specimen cold and hot two-step mounting method according to claim 1, characterized in that: In step 2, the cold mounting material uses denture base resin powder and denture base resin liquid or epoxy resin and curing agent.

4. The metallographic specimen cold and hot two-step mounting method according to claim 1, characterized in that: In step 4, the hot embedding material adopts hot embedding powder, which is a mixture of bakelite powder, phenolic plastic powder and electric jade powder.

5. The metallographic specimen cold and hot two-step mounting method according to claim 1, characterized in that: In step 4, the hot mounting temperature is 135-150° C., and the hot mounting holding time is 3-5 min.

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