CN103234872B - Equipment for measuring metal melt diffusion by using multi-layer translation shearing unit method - Google Patents

Abstract

The invention discloses equipment for measuring metal melt diffusion by using a multi-layer translation shearing unit method. The equipment is characterized in that a frame is arranged in a vacuum cavity; a diffusion table made of graphite is fixed in the frame; a heater is arranged at the periphery of the diffusion table; a first sample post cavity, a second sample post cavity and a preset sample post cavity are respectively arranged in the diffusion table; the first sample post cavity and the second sample post cavity are arranged in the manner that the first sample post cavity is at an upper position, the second sample post cavity is at a lower position and both the first sample post cavity and the second sample post cavity are located the same vertical axis position; the preset sample poke cavity is located at the left side of the first sample post cavity; and the diffusion table is respectively provided with a preheating state position, a fusion state position and a cooling state position. By adopting the equipment for measuring metal melt diffusion, precision measurement of a metal melt diffusion coefficient by using a shearing unit method is achieved, and reliable support is provided for conducting relevant metal research and casting.

Description

A device for measuring the diffusion of molten metal by multilayer translational shear element method

technical field

The invention relates to a multilayer translational shear unit method for measuring the diffusion of metal melt, which is used for measuring the interdiffusion coefficient of binary or multi-element alloys or other non-metallic materials in molten state.

Background technique

A lot of research has been done on the liquid diffusion at room temperature, such as the diffusion of copper sulfate solution in water. However, due to the limitation of technical conditions, there is no better diffusion equipment for high-temperature molten metal alloy melts so far.

The diffusion behavior of metal melt plays an important role in the solidification process of the melt, and is a key kinetic parameter affecting the crystal nucleation and growth process. In the research of some alloy systems, it is found that changing the diffusion coefficient of the melt can directly change the composition distribution and microscopic morphology of the solidified structure. Therefore, the diffusion coefficient of the metal melt is also one of the necessary parameters for the design of metal materials. Considering that metal melt is a special kind of disordered structure system, its structure is relatively simple and can be described by the hard spherical close-packing model, so studying the mass transport properties of such a system is helpful for in-depth understanding of the disordered state system The general law of the mass transfer process. For some unique alloy systems, the diffusion behavior of the melt is correspondingly special. For example, in the bulk metallic glass alloy melt, the diffusion coefficient is 2-3 orders of magnitude smaller than that of the general simple metal melt, showing Therefore, the study of the diffusion coefficient of the melt is also an important aspect to understand the properties of the alloy melt. Since the discovery of Fick's diffusion law in 1855 and Einstein's paper on Brownian motion in 1905, people have studied the phenomenon of liquid diffusion for more than 100 years, but people have only studied the diffusion behavior of liquid metals. For decades, measurement techniques and theories are immature. For example, the diffusion coefficient of the same system measured by different methods is often very different, and some differences even exceed 1 times. The shear element method is considered to be one of the more accurate methods. The main idea is to separate the two diffusion samples before reaching the preset holding temperature to avoid atomic diffusion during the heating process. Diffusion couples are separated into small units to avoid atomic diffusion during cooling. In the existing shear element method, the method of rotation is adopted, and the constructed model has a great relationship with the selected material, and since the center of the constructed diffusion table is occupied by the central axis, there are many problems in the experimental process. It is beneficial for in-situ measurement of X-ray testing equipment.

Contents of the invention

In order to avoid the shortcomings of the above-mentioned prior art, the present invention provides a device for measuring the diffusion of molten metal by a multi-layer translational shear element method, in order to accurately measure the diffusion coefficient of molten metal by using the shear element method. The measurement provides a reliable basis for the relevant metal research and casting.

The present invention adopts following technical scheme for solving technical problems:

The structural characteristics of the equipment for measuring the diffusion of molten metal by the multilayer translational shearing element method of the present invention are:

A frame is arranged in the vacuum cavity, and a diffusion table made of graphite is fixedly arranged in the frame, and a heater is arranged on the periphery of the diffusion table; a first sample column chamber, a first sample column chamber, The second sample column cavity and the preset sample column cavity, the first sample column cavity and the second sample column cavity are located at the same vertical axis position with the first sample column cavity on the top and the second sample column cavity on the bottom above, the preset sample column cavity is on the left side of the first sample column cavity;

The diffusion table is composed of horizontal long graphite sheets laminated layer by layer, including: a group of right-moving graphite sheets that can be moved to the right, a group of fixed graphite sheets that are fixedly arranged, and a piece of graphite that can be independently pushed to the right fused graphite sheet;

The fused graphite sheet is in the middle of the diffusion table, and adjacent to the fused graphite sheet up and down is a right-moving graphite sheet. Above and below the fused graphite sheet, each piece of right-moving graphite sheet and each fixed graphite sheet slice-by-interval setting;

Vertical through holes are respectively arranged on the right-moving graphite sheet, fixed graphite sheet and welded graphite sheet, including: one left and one right are respectively provided with left vertical through-holes on the right-moving graphite sheet and the fixed graphite sheet. hole and the vertical through hole on the right side, a left vertical through hole is only set on the left side on the fused graphite sheet; the first sample column cavity, the second sample column cavity and the preset sample column cavity are formed by The vertical through-holes respectively arranged on the corresponding positions on the right-moving graphite sheet, the fixed graphite sheet and the welded graphite sheet are formed in series;

The diffusion table has three status bits:

Preheating state position: the left vertical through holes in the right-moving graphite sheet, fixed graphite sheet and welded graphite sheet are aligned and penetrated at the same vertical position to form a preset sample column cavity; the right-moving graphite sheet and fixed graphite sheet The vertical through holes on the right side of the graphite sheet are aligned at the same vertical position, and the middle part is blocked by a fused graphite sheet to form a first sample column cavity and a second sample column cavity;

Welding state position: the right-moving graphite sheet and the fixed graphite sheet are kept in the preheating state position, and the fused graphite sheet connects the first sample column cavity and the second sample column cavity through the vertical through hole on the left side. welding state;

Cooling state position: the fixed graphite sheet and the welded graphite sheet remain on the welded state position, and the vertical through holes in the right-moving graphite sheet are misaligned with the vertical through holes in the fixed graphite sheet and the welded graphite sheet, so that The first sample column cavity and the second sample column cavity are vertically divided into column cavities isolated from each other.

The structural characteristics of the equipment for measuring the diffusion of molten metal by the multi-layer translational shear element method of the present invention also lie in:

The fixed graphite sheets are connected in series on the right column, and the right-moving graphite sheets are connected in series on the left column, wherein the right column is fixed, and the left column can drive the right-moving graphite sheets under the push of the "C" frame. The slice moves to the right in sync.

A horizontal push rod is arranged on the left side of the fused graphite sheet to push the fused graphite sheet to move horizontally.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The present invention enables the method of the shear unit to be realized. On the one hand, before the two diffusion samples reach the preset holding temperature, they are separated from each other, so as to avoid atomic diffusion in the heating process; on the other hand, after completing the holding process, the The diffusion couple is separated into multiple sample segments, which effectively avoids the diffusion of atoms during the cooling process, making the subsequent measurement of the diffusion coefficient of the diffused sample more accurate and reasonable.

2. The present invention adopts a horizontal movement method, which can ensure that the sample is always in the center of the heating system, so that the temperature of the diffusion couple is uniform and stable during the diffusion process. Moreover, in the experimental measurement process, it is convenient to use X-rays for in-situ measurement.

3. In the shear element method of the prior art rotation method, due to the need to rotate the rotary vane, a 3-4mm thick graphite sheet is usually used for the experiment, which reduces the accuracy of the diffusion analysis sample. The invention adopts the mode of horizontal movement, and the thickness of the parallel moving graphite sheet can be reduced to 1mm or even less than 1mm, which improves the accuracy of the diffusion analysis sample.

4. The device of the present invention is simple and easy to implement, and can be widely used in various occasions such as teaching, experiment, scientific research and production.

Description of drawings

Fig. 1 is the test system schematic diagram that constitutes with the present invention;

Fig. 2 is a schematic diagram of the structure of the diffusion table of the present invention;

Figure 3a is a schematic diagram of the assembly of the diffusion table in the present invention;

Fig. 3 b is a schematic diagram of the graphite sheet structure in the present invention;

Figure 4a is a schematic diagram of the first status bit of the diffusion station in the present invention;

Fig. 4b is a schematic diagram of the second status bit of the diffusion station in the present invention;

Fig. 4c is a schematic diagram of the third status bit of the diffusion station in the present invention;

Numbers in the figure: 1 vacuum cavity; 2 frame; 3 heating device; 4 diffusion platform; 5 left column; 6 right column; 7a first sample column cavity; 7b second sample column cavity; 7c preset sample column cavity; 8 welded graphite sheet; 9 is "L" type bracket; 9a blind hole; 10 is fixed corundum tube; 11 is "C" type frame; 12 horizontal push rod; 13 vacuum port; 14 temperature controller; 15 cooling gas inlet port ; 16 cylinders; 17 vacuum pumps.

Detailed ways

Referring to Fig. 1 and Fig. 2, in the present embodiment, the structural form of the equipment for measuring the diffusion of metal melt by multilayer translational shear element method is:

A frame 2 is arranged in the vacuum chamber 1, and a diffusion table 4 made of graphite is fixedly installed in the frame 2, and a heater 3 is arranged on the periphery of the diffusion table 4; first sample column chambers 7a are respectively arranged in the diffusion table , the second sample column cavity 7b and the preset sample column cavity 7c, the first sample column cavity 7a and the second sample column cavity 7b are based on the first sample column cavity 7a on the top and the second sample column cavity 7b on the bottom On the same vertical axis position, the preset sample column cavity 7c is on the left side of the first sample column cavity 7a;

As shown in Figure 3a and Figure 3b, the diffusion table 4 is composed of horizontal long graphite sheets laminated layer by layer, including: a group of right-moving graphite sheets 4a that can be pushed to the right, and a group of fixed graphite sheets that are fixedly arranged. 4b, and a piece of fused graphite sheet 8 that can independently move to the right;

The fused graphite sheet 8 is located in the middle of the diffusion table, and adjacent to the fused graphite sheet 8 is a right-moving graphite sheet 4a. Above and below the fused graphite sheet 8, each sheet moves to the right graphite sheet 4a and each fixed graphite sheet 4b one by one interval setting;

Vertical through holes are respectively arranged on the right-moving graphite sheet 4a, the fixed graphite sheet 4b and the welded graphite sheet 8, including: one left and one right are respectively arranged on the right-moving graphite sheet 4a and the fixed graphite sheet 4b. Vertical through hole and vertical through hole on the right side, a left side vertical through hole is only set on the left side on the fused graphite sheet 8; the first sample column cavity 7a, the second sample column cavity 7b and the preset sample column The chamber 7c is formed in series by vertical through-holes respectively arranged on the corresponding positions on the right-moving graphite sheet 4a, the fixed graphite sheet 4b and the welded graphite sheet 8, between the preset sample column cavity 7c and the first sample column cavity 7a The horizontal interval is not less than 3 times the diameter of the first sample column cavity 7a;

The Diffusion Station has three status bits:

The preheating state position shown in Fig. 4a: the left vertical through holes in the graphite sheet 4a, the fixed graphite sheet 4b and the welded graphite sheet 8 are aligned and penetrated at the same vertical position to form a preset sample column cavity 7c; The vertical through holes on the right side of the moving graphite sheet 4a and the fixed graphite sheet 4b are aligned at the same vertical position, and the middle part is blocked by a welded graphite sheet 8 to form the first sample column cavity 7a and the second sample column cavity 7b respectively;

The welding state position shown in Fig. 4b: moving right graphite sheet 4a and fixing graphite sheet 4b are kept on the preheating state position, and welding graphite sheet 8 connects the first sample column chamber 7a and the second sample column cavity 7a with the vertical through hole on its left side. The sample column cavity 7b is in a welded state;

The cooling state position shown in Figure 4c: the fixed graphite sheet 4b and the welded graphite sheet 8 remain on the welded state position, and the vertical through hole in the graphite sheet 4a and the vertical through hole in the fixed graphite sheet 4b and the welded graphite sheet 8 are moved to the right. The through holes are misaligned so that the first sample column cavity 7a and the second sample column cavity 7b are vertically divided into column cavities isolated from each other.

The corresponding settings in the specific implementation also include:

Each fixed graphite sheet 4b is connected in series on the right column 6, and each right-moving graphite sheet 4a is connected in series on the left column 5, wherein the right column 6 is fixed, and the left column 5 can drive each column under the push of the "C" frame 11. Move the graphite sheet 4a to the right and move to the right synchronously. A horizontal push rod 12 is arranged on the left side of the fused graphite sheet 8 to push the fused graphite sheet 8 to move horizontally.

As shown in Figure 2, a pair of "L"-shaped brackets 9 are interlocked to form a rectangular inner cavity, and the diffusion table 4 fits into the rectangular inner cavity, and axial clamping grooves are evenly distributed on the "L"-shaped brackets 9, The heating device 3 is positioned in each axial slot for heating the diffusion table, and a blind hole 9a is provided in the "L"-shaped bracket 9 along the axial direction for fixing the L-shaped bracket. Small holes are provided at different positions on the side wall of the "L"-shaped bracket 9 for placing thermocouples for temperature measurement.

As shown in Figure 1, a vacuum port 13 and a cooling gas inlet port 15 are respectively provided at the bottom of the vacuum chamber 1, and the vacuum chamber 1 is vacuumed through the vacuum port 13 under the control of the vacuum pump group 17; The bottle 16 injects cooling gas into the vacuum chamber 1 through the cooling gas introduction port 15 .

The temperature controller 14 is used to control the heating, heat preservation and cooling of the diffusion platform according to the set temperature control curve, and record the temperature change curve, record the heat preservation time and the cooling time of the residual temperature of the diffusion.

The first sample and the second sample are both Φ1.5mm rod-shaped metal materials to be tested, which are made by vacuum arc melting suction casting furnace, with accurate and uniform composition;

The method for preparing the diffusion sample in the present embodiment is to carry out as follows:

Step 1: Set the diffusion table to the preheating state, place the two first samples in the first sample chamber 7a and the preset sample chamber 7c respectively, and place the second sample in the second sample chamber 7b; The diffusion table is heated under certain process conditions, so that the first sample and the second sample respectively located in the first sample chamber 7a, the preset sample chamber 7c and the second sample chamber 7b are melted into a liquid state;

Step 2: Push the welded graphite sheet 8 to the right, so that the diffusion table is in the welded state, and the first sample melted into a liquid state in the preset sample chamber 7c is used by the welded graphite sheet 8 by the left side of the welded graphite sheet 8 The side vertical through hole is transferred between the first sample chamber 7a and the second sample chamber 7b, so that the first sample and the second sample are vertically docked to form a diffusion couple; the diffusion table is kept warm according to the set process conditions , so that the first sample and the second sample complete the diffusion;

Step 3: After the diffusion process is over, push the graphite sheet 4a to the right to make the diffusion table in the cooling state, and the diffusion couple is therefore vertically divided into separate sample sections; and then to the vacuum chamber 1 The cooling gas is introduced to cool and solidify each sample section to obtain the diffusion sample. The cooling gas uses high-purity nitrogen with a volume percentage of 99.99% to prevent sample oxidation and graphite combustion.

Claims (3)

1. A multi-layer translational shear element method measures the equipment for the diffusion of molten metal, said equipment comprising: a frame (2) is set in the vacuum chamber (1), fixedly arranged in the frame (2) A diffuser (4) made of graphite is provided with a heater (3) on the periphery of the diffuser (4); it is characterized in that: A first sample column cavity (7a), a second sample column cavity (7b) and a preset sample column cavity (7c) are respectively arranged in the diffusion stage, and the first sample column cavity (7a) and the second sample column cavity The sample column cavity (7b) is on the same vertical axis position with the first sample column cavity (7a) on the top and the second sample column cavity (7b) on the bottom, and the preset sample column cavity (7c) is at The left side of the first sample column cavity (7a); The diffusion platform (4) is composed of horizontal long graphite sheets laminated layer by layer, including: a group of right-moving graphite sheets (4a) that can be moved to the right, a group of fixed graphite sheets (4b) that are fixedly arranged , and a piece of fused graphite sheet (8) that can independently move to the right; The fused graphite sheet (8) is in the middle of the diffusion table, and adjacent to the fused graphite sheet (8) up and down is a right-moving graphite sheet (4a), above and below the fused graphite sheet (8) , each sheet moves to the right graphite sheet (4a) and each sheet fixed graphite sheet (4b) is arranged at intervals one by one; Vertical through holes are respectively arranged on the right-moving graphite sheet (4a), the fixed graphite sheet (4b) and the welded graphite sheet (8), including: moving rightward at the graphite sheet (4a) and the fixed graphite sheet ( 4b) are respectively provided with a left vertical through hole and a right vertical through hole on the left side and a right side, and only a left vertical through hole is set on the left side on the said fused graphite sheet (8); The first sample column cavity (7a), the second sample column cavity (7b) and the preset sample column cavity (7c) are respectively arranged on the right-moving graphite sheet (4a), the fixed graphite sheet (4b) and the fused graphite The vertical through holes on the corresponding positions on the sheet (8) are formed in series; The diffusion table has three status bits: Preheating state position: the left vertical through holes in the right-moving graphite sheet (4a), fixed graphite sheet (4b) and welded graphite sheet (8) are aligned and penetrated at the same vertical position to form a preset sample column cavity (7c); each vertical through hole on the right side in the described right-moving graphite sheet (4a) and the fixed graphite sheet (4b) is aligned on the same vertical position, and the middle part forms the first respectively with the welding graphite sheet (8) barrier A sample column cavity (7a) and a second sample column cavity (7b); Welding status position: the right-moving graphite sheet (4a) and the fixed graphite sheet (4b) remain on the preheating status position, and the welding graphite sheet (8) connects the first sample column with its left vertical through hole The cavity (7a) and the second sample column cavity (7b) are connected in a welded state; Cooling state position: the fixed graphite sheet (4b) and the welded graphite sheet (8) are kept on the welded state position, and the vertical through hole in the right-moving graphite sheet (4a) is connected with the fixed graphite sheet (4b) and welded The vertical through holes in the graphite sheet (8) are misaligned, so that the first sample column cavity (7a) and the second sample column cavity (7b) are vertically divided into separate column cavities. 2. the multilayer translational shear element method according to claim 1 measures the equipment of molten metal diffusion, it is characterized in that: described each fixed graphite sheet (4b) is connected in series on the right column (6), sets described Each right-moving graphite sheet (4a) is connected in series on the left column (5), wherein the right column (6) is fixed, and the left column (5) can drive each right-moving graphite sheet under the push of the "C"-shaped frame (11). The slice (4a) moves to the right synchronously. 3. the multilayer translational shear element method according to claim 1 measures the equipment that molten metal spreads, it is characterized in that: horizontal push rod (12) is set on the left side of described welding graphite sheet (8), uses To push the fused graphite sheet (8) to move horizontally.