T-type thermocouple and electrochemical spray deposition manufacturing method thereof

Abstract

The invention discloses a T-type thermocouple and an electrochemical spray deposition manufacturing method thereof. The method comprises the steps of depositing a copper inclined column, replacing electroplating liquid, depositing a copper inclined column and combining the inclined columns. Additive manufacturing of the constantan electrode and the copper electrode in the T-type thermocouple is completed through the electrochemical spray deposition process, the thermocouple with the wire diameter within hundred micrometers can be manufactured, the technical problem that in the prior art, the thermocouple with the scale is difficult to machine is effectively solved, and application and popularization are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of thermocouple preparation, and in particular relates to a T-type thermocouple and an electrochemical spray deposition manufacturing method thereof. Background Art

[0002] T-type thermocouple is a kind of low-cost metal thermocouple composed of copper and constantan (copper-nickel alloy). As it is a precision measuring tool, its accuracy is required to be very high. Due to the lack of technology, the diameter of the thermocouple wire of traditional thermocouple is relatively thick, so in actual measurement, the detection response is slow. Therefore, the use of thinner thermocouple wire to process ultrafine thermocouple is a technical improvement that can be associated with the field at present. However, when processing and manufacturing ultrafine thermocouples, there are certain technical difficulties in welding fine copper wire and constantan wire, and the product consistency is poor. In addition, the diameter of the processed thermocouple wire is usually more than 100 microns, which cannot meet the application requirements of faster response speed. Summary of the invention

[0003] The main purpose of the present invention is to provide a T-type thermocouple and an electrochemical spray deposition manufacturing method thereof, aiming to realize the manufacture of thermocouples with a wire diameter of less than 100 microns, effectively solving the technical problem that thermocouples of this scale are difficult to process in the current technology.

[0004] To this end, the present invention provides a T-type thermocouple electrochemical spray deposition manufacturing method, comprising: Step 1: Deposit copper slant columns Connect the negative electrode of the constant voltage power supply to the lead-out wire of the cathode slot, connect the positive electrode of the constant voltage power supply to the lead-out wire of the anode nozzle to form a current loop, and collect the loop current, install the substrate in the cathode slot, add constantan electroplating solution in the cathode slot, the substrate is inlaid with inlaid constantan and inlaid copper, start the electroplating solution circulation system, so that the electroplating solution is sprayed from the anode nozzle to form a spray liquid column, use a three-dimensional motion platform to drive the cathode slot and / or the anode nozzle to move according to a preset trajectory, and at the same time maintain the flow shape of the spray liquid column at the anode nozzle stable, and deposit constantan on the upper surface of the inlaid constantan of the substrate to form a constantan inclined column inclined toward the inlaid copper; Step 2: Replace the plating solution After the constantan inclined column is manufactured, the constantan electroplating solution in the cathode tank is replaced with copper electroplating solution; Step 3: Deposit copper oblique columns The cathode slot and / or the anode nozzle are driven to move along a preset trajectory by using a three-dimensional motion platform to deposit copper on the upper surface of the inlaid copper of the substrate, forming a copper oblique column whose top gradually approaches the constantan oblique column; wherein, during the deposition of the two oblique columns, the rising height of the anode nozzle is the same, the inclination angles of the constantan oblique column and the copper oblique column are the same, and the loop current value when the copper oblique column is deposited is recorded; Step 4: Merge oblique columns Turn off the power and move the anode nozzle parallel to the top of the Constantan copper inclined column. Turn on the power so that the sprayed liquid column stays and deposits only on the Constantan copper inclined column until the current value reaches the recorded value. Then move the anode nozzle to the center of the top of the Constantan copper inclined column and the copper inclined column. Use the sprayed liquid column to contact the inclined columns on both sides at the same time to induce the inclined columns to grow toward the center of the sprayed liquid column, thereby realizing the merged connection of the Constantan copper inclined column and the copper inclined column.

[0005] Specifically, the three-dimensional motion platform includes an XY motion platform and a Z-axis motion platform, the cathode tank is installed on the XY motion platform of the electrochemical spray deposition equipment, and the anode nozzle is vertically installed on the Z-axis motion platform.

[0006] Specifically, the electroplating liquid circulation system includes a circulation pipe, a peristaltic pump and a buffer bottle. The two ends of the circulation pipe are respectively connected to the anode nozzle and the cathode tank. The peristaltic pump and the buffer bottle are arranged on the circulation pipe. The inlet and outlet of the buffer bottle are detachably connected to the circulation pipe.

[0007] Specifically, the control system collects current data through a high-frequency acquisition card to monitor the loop current. As the microcolumn deposition grows higher, the loop current will increase. When the current increases to a set current threshold, the control system will control the anode nozzle to lift so that the current decreases again, and this cycle is repeated to achieve step-by-step deposition growth of the oblique column.

[0008] Specifically, the processing method of the substrate is: Copper and constantan wires were embedded in resin samples; The end of the copper wire and the constantan wire in the resin sample is polished with a grinding and polishing machine until the round cross-section of the flat copper wire and the constantan wire is exposed; The separated ends of the copper wire and the constantan wire in the resin sample are polished using a grinder and polisher until the flat circular cross-sections of the copper wire and the constantan wire are exposed.

[0009] Specifically, the constantan electroplating solution comprises: copper sulfate pentahydrate: 0.02-0.03 mol / L, nickel sulfate hexahydrate: 0.3-0.4 mol / L, citric acid monohydrate 0.4-0.5 mol / L, ethoxylated propynyl alcohol: 0.02-0.04 ml / L, ethoxylated butynediol: 0.12-0.16 ml / L, sodium propynyloxyhydroxypropane sulfonate: 0.03-0.04 ml / L, and ammonia water: the balance; The deposition conditions of the constantan electroplating solution are: pH 5.8-6.2, and deposition voltage 6-6.5V.

[0010] Specifically, the copper electroplating solution components are: copper sulfate pentahydrate: 0.7-0.9 mol / L, sulfuric acid: 1.8-2.2 mol / L, potassium chloride: 28-32 mg / L, and the copper electroplating solution deposition voltage is 7-7.2V.

[0011] The invention also provides a T-type thermocouple, which is prepared by adopting the above manufacturing method.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention realizes the automated additive manufacturing process of micro-nano three-dimensional structures by combining a three-dimensional motion platform with the principle of electrochemical spray deposition. Only by changing the components of the electroplating solution, low-cost and reliable manufacturing of micro-nano three-dimensional structures of various materials can be achieved.

[0013] 2. This method is based on the experimentally studied formula of constantan electroplating solution and deposition conditions, the micro-nano manufacturing characteristics of electrochemical spray deposition process, and combines a high-precision three-dimensional motion platform, path planning, and high-frequency current feedback motion control of the motion platform to achieve additive manufacturing of conical T-type thermocouples.

[0014] 3. The additive manufacturing of constantan electrodes and copper electrodes in T-type thermocouples is completed through the electrochemical spray deposition process with precision manufacturing characteristics, which can realize the manufacture of thermocouples with a wire diameter of less than 100 microns, effectively solving the technical problem of the difficulty in processing thermocouples of this scale in the current technology, and facilitating their promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 is a schematic diagram of a spray deposition apparatus of the present invention; Figure 2 Control software interface of spray deposition equipment of the present invention Figure 3 SEM image of the cross section of the constantan oblique column of the present invention; Figure 4 Thermocouple structural scheme of the present invention; Figure 5 Thermocouple manufacturing scheme of the present invention; Figure 6 The motion trajectory of the anode nozzle of the present invention; Figure 7 G code example of the present invention; Figure 8 SEM image of the junction between the thermocouple constantan oblique column and the copper oblique column of the present invention Fig. 9 Thermocouple manufacturing flow chart of the present invention; Fig.10 A schematic diagram of a thermocouple prepared by the present invention; Fig.11 Thermocouple response test curve prepared by the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0018] See also Figure 1 , a T-type thermocouple electrochemical spray deposition manufacturing method, comprising the following steps: Step 1: Deposit copper slant columns The cathode tank is mounted on the XY motion table of the electrochemical spray deposition equipment, and the anode nozzle is vertically mounted on the Z axis motion table of the electrochemical spray deposition equipment; Connect the negative electrode of the constant voltage power supply to the lead wire of the cathode tank, connect the positive electrode of the constant voltage power supply to the lead wire of the anode nozzle to form a current loop, and collect the loop current; The substrate is mounted in a cathode tank, and a constantan electroplating solution is added to the cathode tank, the substrate is inlaid with inlaid constantan and inlaid copper, and the electroplating solution circulation system is turned on, so that the electroplating solution is ejected from the anode nozzle to form a spray liquid column, and the upper computer controls the XY motion table and the Z axis motion table to respectively drive the cathode tank and the anode nozzle to move according to a preset trajectory, while maintaining the flow shape of the spray liquid column at the anode nozzle stable, and depositing constantan on the upper surface of the inlaid constantan of the substrate to form a constantan inclined column inclined toward the inlaid copper; Step 2: Replace the plating solution After the constantan inclined column is manufactured, the constantan electroplating solution in the cathode tank is replaced with copper electroplating solution; Step 3: Deposit copper oblique columns The host computer controls the XY motion table and the Z axis motion table to respectively drive the cathode slot and the anode nozzle to move according to the preset trajectory, depositing copper on the upper surface of the inlaid copper of the substrate to form a copper oblique column whose top gradually approaches the constantan oblique column; wherein, the rising height of the anode nozzle is the same during the two deposition processes, the inclination angles of the constantan oblique column and the copper oblique column are the same, and the loop current value when the copper oblique column is deposited is recorded; Step 4: Merge oblique columns The inventors found in their research that when the copper oblique column and the constantan oblique column are deposited, the anode nozzle is raised to the same height, but the heights of the oblique columns formed by the deposition are not consistent on both sides. This is due to the difference in materials. When the anode nozzles on both sides are raised to the same height, the heights of the deposited oblique columns on both sides are not the same, and the height of the copper side is significantly higher than that of the constantan side. If the copper oblique column and the constantan oblique column are directly merged at the central node position, they will not be able to merge and the liquid column will only grow on the copper column on the higher side. This is because the resistance of the higher side is smaller, and deposition will only occur on the higher side.

[0019] To solve the above problems, the present invention cleverly adds a copper deposition leveling process before merging, so that the lower constantan oblique column first grows to the same height as the copper oblique column and then induces merging at the center position. How to control the deposition amount of deposited copper during the leveling process so that the height of the oblique columns on both sides is the same is another key problem. The inventor further found that for jet electrodeposition, the current in the loop during deposition depends on the magnitude of the deposition voltage and the resistance of the liquid column between the cathode and the anode. Usually, constant voltage deposition is used during electrodeposition. Therefore, the current during deposition is only affected by the resistance of the jet liquid column, and the resistance of the jet liquid column is mainly affected by the distance between the cathode and the anode, that is, the loop current is affected by the distance between the cathode and the anode. This characteristic is used to achieve the growth of the constantan column on the lower side to the same height as the copper column. The method is to record the current when the liquid column contacts the copper oblique column, and then move it to contact only the top of the constantan oblique column, and the liquid column stays on this side for deposition until the current value reaches the recorded value.

[0020] The specific process is: move the liquid column to the top of the copper inclined column, turn on the power and record the current in the circuit at this time, then turn off the power and move the liquid column horizontally to the top of the constantan inclined column, set the control program to automatically disconnect the power when the current is greater than or equal to the recorded value, then turn on the power to start depositing copper and wait for the deposition to be completed. By depositing copper, the height of both sides is made consistent, which is conducive to the subsequent merging process. The ultimate goal of the merged deposition is to merge and connect the tops of the constantan inclined columns and copper inclined columns on both sides. The merging method is to use a spray liquid column to contact the tops of both sides at the same time to induce the two sides to grow toward the center of the liquid column and merge. The specific implementation method is to write a program to achieve it.

[0021] After the copper oblique column is manufactured, the present invention turns off the power and moves the anode nozzle parallel to the top of the constantan oblique column. The power is turned on so that the sprayed liquid column stays and deposits only on the constantan oblique column until the current value reaches the recorded value. Then the anode nozzle is moved to the center of the top of the constantan oblique column and the copper oblique column. The sprayed liquid column is used to contact the oblique columns on both sides at the same time to induce the oblique columns to grow toward the center of the sprayed liquid column, thereby realizing the merged connection of the constantan oblique column and the copper oblique column. The merged connection of the constantan oblique column and the copper oblique column is successfully realized.

[0022] The present invention realizes the automated additive manufacturing process of micro-nano three-dimensional structures by combining a three-dimensional motion platform with the principle of electrochemical spray deposition. Only the components of the electroplating solution need to be changed to achieve low-cost and reliable manufacturing of the hot end structure of the T-shaped thermocouple, which effectively solves the technical problem of the difficulty in processing thermocouples of this scale in the current technology and is easy to promote and use.

[0023] Reference Figure 1 The electrochemical spray deposition equipment includes a host computer, a three-dimensional motion platform, a constant voltage power supply, a data acquisition card, a peristaltic pump, a buffer bottle, an electron microscope, a cathode tank with a clamping mechanism and an anode nozzle, etc. The three-dimensional motion platform has three motion axes of X, Y, and Z. The anode nozzle can be moved to any position in the space within the axis travel by calling the driver control interface by a computer. The constant voltage power supply provides a stable voltage during the electrochemical spray deposition process, and the output voltage can be 0-30V. It communicates with the control system through a serial port. The control system can set the voltage size and switch voltage in real time. The positive terminal of the power supply is connected to the lead-out wire of the anode nozzle, and a 1000 ohm fixed value resistor is connected in series between the positive terminal and the lead-out wire. Resistance, the negative terminal of the power supply is connected to the lead-out wire of the cathode slot, the data acquisition card can collect the current value in the current loop at high frequency and save or analyze it by the control system, and through parallel connection with the fixed value resistor, the voltage value is collected and converted into the current value after processing. The peristaltic pump provides power for the circulation of the electroplating solution, and the adjustable flow rate is 4-14ml / min. It is connected in series between the inlet of the pipeline and the buffer bottle. The buffer bottle can slow down the flow rate fluctuation caused by the peristaltic pump peristalsis. The volume of the buffer bottle is 100ml, and the inlet and outlet of the buffer bottle are equipped with Luer switch interfaces, which can be threadedly connected to the pagoda head interface of the pipeline. The pipeline used in the above circulation pipeline is a silicone tube with an inner and outer diameter specification of 3.2*6.4mm.

[0024] After the peristaltic pump is turned on, the buffer bottle is pressurized, and the plating liquid with a relatively stable flow rate is output from the buffer bottle to the anode nozzle. The plating liquid is continuously pumped into the buffer bottle by the peristaltic pump at a constant flow rate, so that the pressure in the buffer bottle gradually increases until the input and output flow rates are balanced, and the liquid column ejected from the nozzle gradually becomes uniform and stable. The electrolyte ejected from the nozzle is collected in the cathode tank and pumped into the buffer bottle through the pipeline inlet by the peristaltic pump to start the circulation. The optical microscope is mainly used to monitor the deposition process and adjust the nozzle position. After connecting to the computer, real-time observation can be carried out through the built-in software.

[0025] Reference Figure 2In terms of software, in order to realize the automation of the deposition process, the above motion control, power supply setting and data acquisition functions are integrated, and a host computer control software is written. It is mainly divided into five modules, namely monitoring module (power supply status, motion status, G code), power supply control module, deposition control module, and three-dimensional motion platform control module. The main principle of the automation of the deposition process is that when the deposition starts, the voltage remains constant, and the computer collects current data through a high-frequency acquisition card to monitor the current. As the micro-column deposition grows higher, the current in the loop will increase. When the current increases to the set current threshold, the computer will control the Z axis to lift so that the current decreases again, and the cycle is realized to realize the step-by-step deposition growth of the structure. By increasing the frequency and reducing the lifting step length, the range of current variation can be reduced to achieve stable deposition. During the deposition process, the nozzle moves step by step according to the predetermined trajectory by setting the G code in advance, and the program interprets the G code to send movement instructions (motion axis, distance, direction) to the motion platform. Whether the instruction is sent each time is judged by whether the current value exceeds the current threshold.

[0026] The inventor further discovered that although there are commercial electroplating solutions that can be purchased directly on the market, commercial electroplating solutions are only suitable for electroplating thin films. Compared with thin film electroplating, the electric field of jet electrodeposition has localized characteristics, and the flow field is a high-speed flowing jet state. This change in the deposition mechanism greatly enhances the mass transfer process of metal ions, greatly improves the deposition rate, and can be deposited at a higher current density without the occurrence of concentration polarization. Due to the high deposition rate, a higher concentration of metal ions is required in the electroplating solution to ensure the continuation of the deposition process. At the same time, the electroplating solution in high-speed flow has higher requirements for chemical stability, and it is necessary to add appropriate buffers to prevent drastic changes in pH value to ensure the stability of the electroplating process. Therefore, the direct use of commercial electroplating solutions cannot meet the needs of jet electrodeposition for fast, stable, and high-quality deposition.

[0027] To this end, the inventors have determined through numerous experiments the electroplating solution formula and deposition conditions that can quickly deposit copper materials with good surface quality, as shown in Table 1, wherein M in the table represents mol / L, and the electroplating solution components use the formula in Table 1 because copper sulfate, as a source of copper ions, exceeds the range in Table 1 will directly lead to insufficient copper ion supply and non-dense grains, and although a higher concentration can optimize the surface quality, an excessively high concentration will cause copper sulfate to precipitate during the deposition process, leading to blockage of the plating solution circulation pipeline, and increasing the sulfuric acid concentration can increase the solution conductivity and thus increase the deposition rate, but a concentration exceeding the range in Table 2 will aggravate the cathode hydrogen evolution reaction, and the bursting of bubbles will destroy the flow field stability and lead to deterioration of the surface quality; although a lower deposition voltage can improve the surface quality, the deposition rate is slow, and a higher deposition voltage will cause the reduction rate of copper ions to exceed the mass transfer rate of copper ions, resulting in an unstable deposition process and a deterioration of the surface morphology.

[0028] Table 1 Copper electroplating solution composition and deposition conditions Ingredients and conditions value purity Copper sulfate pentahydrate 0.7-0.9 (M) 99.5% sulfuric acid 1.8-2.2(M) 98% Potassium chloride 28-32 (mg / L) 99.5% Voltage 7-7.2 V / temperature 25±2 ℃ / Similarly, the inventor has determined the electroplating solution formula and deposition conditions that can quickly deposit constantan with good surface quality through numerous experiments. As shown in Table 2, the inventor has found through experiments that nickel sulfate is used as a nickel source. As the concentration of nickel sulfate increases, the surface quality of the alloy column does not change significantly, but the nickel-copper ratio continues to increase; citric acid can preferentially form a complex with copper ions as a chelating agent, reduce the deposition potential of copper ions, thereby realizing the co-deposition of copper ions and nickel ions. When the concentration of citric acid is too low, copper ions are preferentially deposited, resulting in a low nickel-copper ratio, and when the concentration is too high, nickel ions will also be complexed, resulting in copper ions being preferentially deposited; pH value will affect the complex morphology of copper ions and thus affect the deposition potential. As pH increases, the nickel-copper ratio gradually increases, but when it is too high or too low, the surface quality of the alloy column is poor; the effect of deposition voltage on surface quality is the same as that of copper deposition, and as the deposition voltage increases, the nickel-copper ratio will also increase, because high potential is conducive to the reduction of nickel ions with a small deposition potential. In summary, the electroplating solution formula and voltage parameters that can quickly and stably deposit excellent surface morphology and stable alloy ratio are obtained through experimental methods. The final plating solution formula and the SEM image of the deposited constantan oblique column cross section are as follows: Figure 3 shown.

[0029] The constantan electroplating solution comprises: copper sulfate pentahydrate: 0.02-0.03 mol / L, nickel sulfate hexahydrate: 0.3-0.4 mol / L, citric acid monohydrate: 0.4-0.5 mol / L, ethoxylated propargyl alcohol: 0.02-0.04 ml / L, ethoxylated butynediol: 0.12-0.16 ml / L, sodium propargyloxyhydroxypropane sulfonate: 0.03-0.04 ml / L, and ammonia water: the balance; the deposition conditions of the constantan electroplating solution are: pH 5.8-6.2, and the deposition voltage 6-6.5 V.

[0030] See also Figure 4 The T-shaped thermocouple structure prepared by the above method is conical as a whole, and is composed of symmetrically arranged copper oblique columns and constantan oblique columns, which are merged at the top. This structure is conducive to the merging of nodes by virtue of the characteristic that the deposited layer tends to grow toward the nozzle. By staying above the node, the two sides can be induced to deposit and gradually merge together. In addition, the substrate is made of constantan wire and copper wire embedded in the resin after resin curing, and the bottom and top surfaces are polished to obtain the final substrate. The bottom surface is used to connect the compensation wire or the extension wire; the top surface is used to deposit the hot end structure of the thermocouple. The hot end structure is composed of deposited constantan oblique columns and copper oblique columns. The two oblique column connecting sections are connected by depositing copper, and the whole finally forms a conical structure.

[0031] The manufacturing scheme was designed based on the T-shaped thermocouple structure scheme, referring to Figure 5 , an anode nozzle is disposed on the substrate, wherein steps (1) (2) (3) are the deposition process of the constantan oblique column, steps (4) (5) (6) (7) are the deposition process of the copper oblique column, and steps (8) (9) (10) are the merging process.

[0032] Based on the above manufacturing scheme, the motion trajectory of the anode nozzle can be obtained. Figure 6 , and finally write the G code for the motion trajectory.

[0033] The G-code writing process is as follows: Divide the trajectory into several straight line segments; Determine the starting and ending coordinates of each straight line segment; Decompose each straight line segment according to the set step size. The smaller the step size, the closer the deposited inclined column is to the designed shape. Write the file.

[0034] The G code for the above motion trajectory was written in three files, namely the G code for the constantan inclined column ((1)~(3)), the G code for the copper inclined column ((4)~(7)) and the combined G code ((8)~(10)). During (3)~(4), the plating solution needed to be replaced and manual control was adopted.

[0035] Refer to some sample snippets of G code Figure 7 In this way, the combination of different material structures was successfully achieved. The SEM image of the combined structure is shown in Figure 2. Figure 8 shown.

[0036] See also Fig. 9 The specific steps of the above-mentioned T-type thermocouple electrochemical spray deposition manufacturing method are as follows: Step 1: Complete the preparations.

[0037] Confirm that the manufactured thermocouple wire diameter is 150um, and select a 180um diameter nozzle for standby use. The selection of wire diameter and nozzle diameter has been verified by prior experiments. Prepare two buffer bottles containing copper electroplating solution and copper-nickel alloy electroplating solution respectively; Power on the device and start the control software; Align the microscope to the substrate placement position and adjust the focus.

[0038] The substrate, cathode tank and anode nozzle were immersed in alcohol, deionized water and deionized water for ultrasonic cleaning for 5 minutes each, in order to remove the residual ions, organic matter and dust from the last preparation and avoid contamination of the electroplating solution. After cleaning, the residual water was blown dry with a hair dryer.

[0039] Install the cleaned and dried cathode tank on the corresponding installation position of the XY motion table and tighten the fixing screws; connect and clamp the negative terminal clamp of the power supply to the lead wire of the cathode tank; screw the cleaned and dried anode nozzle into the corresponding installation position of the Z-axis motion table through the threaded interface. Place the substrate in the cathode clamping mechanism with the end facing up and clamp it.

[0040] The processing method of the above substrate is: a. Take copper and constantan thermocouple wires with a diameter of 1.5 mm, sort them, and select the thermocouple wires that are smooth, without folds, cracks, and burrs for use; b. Use a square silicone mold with a specification of 8mm*8mm*8mm and a wall thickness of 3mm for later use; c. Take an appropriate amount of epoxy resin and curing agent (2:1) and put them into a disposable plastic cup. Stir evenly with a wooden stick. Put them into an ultrasonic cleaner and perform ultrasonic cleaning for 1 minute to remove the bubbles generated during the stirring process and set aside.

[0041] d. Use needle-nosed pliers to cut a 7mm copper wire and a 7mm constantan wire respectively. Put one end of the copper wire and the constantan wire together, separate the other end into a cone shape and put them into the silicone mold in b. Pour the resin in c into the resin to seal and solidify the sample.

[0042] e. Use a grinder to grind the end of the copper wire and constantan wire in the cured resin sample until the flat circular cross-section of the copper wire and constantan wire is exposed. Observe the spacing between the circular cross-sections of the copper wire and constantan wire while grinding. It is required that there is a clear spacing but the spacing cannot be too large (about 1mm).

[0043] f. Use a grinder to polish the separated ends of the copper wire and constantan wire in the cured resin sample until the flat circular cross-section of the copper wire and constantan wire is exposed.

[0044] Connect the buffer bottle filled with copper-nickel alloy electroplating solution to the circulation pipeline. The inlet and outlet of the buffer bottle are connected to the outflow and inflow of the circulation pipeline respectively. The connection method is that the inlet and outlet of the buffer bottle are external spiral Luer switches, and the inflow and outflow of the pipeline are internal spiral pagoda heads. Just twist the pagoda heads into the Luer switches accordingly.

[0045] Turn on the peristaltic pump and wait for the pressure to balance. When balanced, the liquid column ejected from the nozzle is uniform and stable, and the deposited tissue is also more uniform and regular.

[0046] Move the nozzle to the deposition starting point, enter 20000 in the speed edit box of the 3D motion platform control module in the host computer, set the platform movement speed to 20000um / s, determine the step size based on the real-time position, and control the Z axis to make the anode nozzle reach the position 300um above the constantan circular section of the substrate. During control, the position of the anode nozzle can be grasped in real time by observing the microscope monitoring interface to avoid collision between the nozzle and the substrate. Finally, click the "position set to 0" button in the deposition control module to determine this position as the starting point of deposition and prepare to start deposition.

[0047] Step 2, select the Constantan inclined column G code file in the background file and click the "Update G code" button on the host computer interface to make the motion trajectory of the platform during deposition the motion trajectory of the Constantan inclined column, click the "Start deposition" button and set the location to save the current data. Wait for the deposition to be completed.

[0048] Step 3: After the deposition of the constantan oblique column is completed, the Z axis is controlled to rise and preparations for the deposition of the copper oblique column are carried out.

[0049] Loosen the cap of the buffer bottle to release the pressure of the buffer bottle, use the peristaltic pump to pump all the remaining copper-nickel alloy electroplating solution in the cathode tank into the buffer bottle, turn off the peristaltic pump and the Luer switch at the inlet and outlet of the buffer bottle, tighten the buffer bottle cap, unscrew the spiral pagoda head connected above the Luer switch at the inlet and outlet of the buffer bottle, and store the buffer bottle containing the copper-nickel alloy electroplating solution in a suitable location. Replace an empty buffer bottle with a Luer connector, connect it to the circulation pipeline with a spiral pagoda head at the end, and turn on the peristaltic pump to introduce deionized water to clean the pipeline.

[0050] Repeat step 1 (4), take out the substrate with tweezers, clean and dry the substrate, cathode slot and the newly selected nozzle, and then repeat step 1 (5), install them to the corresponding position.

[0051] Repeat step 1 (6) and connect the buffer bottle containing the copper electroplating solution to the circulation line.

[0052] Repeat step 1 (7) to start the peristaltic pump and wait for the pressure to balance.

[0053] Following step 8 in step 1), make the anode nozzle reach 1200um above the copper circular section of the substrate and 800um on the positive Y axis of the starting point of the constantan oblique column deposition. The 1200um here is to prevent the lateral movement of the nozzle from colliding with the deposited constantan oblique column during deposition, and 800um is determined based on the lateral movement distance in the oblique column G code. After the movement is completed, click the "Set Position to 0" button.

[0054] Step 4, select the copper inclined column G code file in the background file and click the "Update G code" button on the host computer interface to make the motion trajectory of the platform during deposition the motion trajectory of the copper inclined column, click the "Start deposition" button and set the save location of the current data. Wait for the deposition to be completed.

[0055] Step 5. Select the merged G code file in the background file and click the "Update G code" button on the host computer interface to make the motion trajectory of the platform deposition a motion trajectory of the oblique column merger. Click the "Start deposition" button and set the location to save the current data. Wait for the deposition to complete.

[0056] Step 6, control the Z axis to move to a certain height, turn off the peristaltic pump, close the Luer switch of the buffer bottle, take out the deposited thermocouple sample with tweezers, then wash it in deionized water and blow dry it with a hair dryer.

[0057] Step 7, cut two copper wires of a certain length, and use electric welding to weld a copper wire to the circular cross section on the other side of the substrate as an extension wire for testing. Fig.10 , is a picture of a physical sample with the extension wire welded.

[0058] Step 8, Thermoelectric performance test Use a digital multimeter to measure whether the two even wires and the even wires and the extension wire are connected.

[0059] Fix the thermocouple sample on the response speed measurement platform, extend the wire to connect to the data amplification and acquisition system, quickly put the hot end of the thermocouple into the constant temperature thermal field, collect the thermoelectric electromotive force signal curve, analyze the curve, and judge whether the sample is qualified. Fig.11 , it can be seen that the thermoelectric thermal signal curve has an obvious step signal, and the signal rise time is within 100 ms, indicating that the sample is qualified.

[0060] The above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for manufacturing a T-type thermocouple by electrochemical spray deposition, characterized in that: The steps include: Step 1: Deposit copper slant columns Connect the negative electrode of the constant voltage power supply to the lead-out wire of the cathode slot, connect the positive electrode of the constant voltage power supply to the lead-out wire of the anode nozzle to form a current loop, and collect the loop current, install the substrate in the cathode slot, add constantan electroplating solution in the cathode slot, the substrate is inlaid with inlaid constantan and inlaid copper, start the electroplating solution circulation system, so that the electroplating solution is sprayed from the anode nozzle to form a spray liquid column, use a three-dimensional motion platform to drive the cathode slot and / or the anode nozzle to move according to a preset trajectory, and at the same time maintain the flow shape of the spray liquid column at the anode nozzle stable, and deposit constantan on the upper surface of the inlaid constantan of the substrate to form a constantan inclined column inclined toward the inlaid copper; Step 2: Replace the plating solution After the constantan inclined column is manufactured, the constantan electroplating solution in the cathode tank is replaced with copper electroplating solution; Step 3: Deposit copper oblique columns The cathode slot and / or the anode nozzle are driven to move along a preset trajectory by using a three-dimensional motion platform to deposit copper on the upper surface of the inlaid copper of the substrate, forming a copper oblique column whose top gradually approaches the constantan oblique column; wherein, during the deposition of the two oblique columns, the rising height of the anode nozzle is the same, the inclination angles of the constantan oblique column and the copper oblique column are the same, and the loop current value when the copper oblique column is deposited is recorded; Step 4: Merge oblique columns Turn off the power and move the anode nozzle parallel to the top of the Constantan copper inclined column. Turn on the power so that the sprayed liquid column stays and deposits only on the Constantan copper inclined column until the current value reaches the recorded value. Then move the anode nozzle to the center of the top of the Constantan copper inclined column and the copper inclined column. Use the sprayed liquid column to contact the inclined columns on both sides at the same time to induce the inclined columns to grow toward the center of the sprayed liquid column, thereby realizing the merged connection of the Constantan copper inclined column and the copper inclined column.

2. The method for manufacturing a T-type thermocouple by electrochemical spray deposition according to claim 1, characterized in that: The three-dimensional motion platform includes an XY motion platform and a Z-axis motion platform. The cathode tank is installed on the XY motion platform of the electrochemical spray deposition equipment, and the anode nozzle is vertically installed on the Z-axis motion platform.

3. The method for manufacturing a T-type thermocouple by electrochemical spray deposition according to claim 1, characterized in that: The electroplating liquid circulation system includes a circulation pipe, a peristaltic pump and a buffer bottle. The two ends of the circulation pipe are respectively connected to the anode nozzle and the cathode tank. The peristaltic pump and the buffer bottle are arranged on the circulation pipe. The inlet and outlet of the buffer bottle are detachably connected to the circulation pipe.

4. The method for manufacturing a T-type thermocouple by electrochemical spray deposition according to claim 1, characterized in that: The host computer collects current data through a high-frequency acquisition card to monitor the loop current. As the micro-column deposition grows higher, the loop current will increase. When the current increases to the set current threshold, the control system will control the anode nozzle to lift so that the current decreases again, and this cycle will be repeated to achieve the step-by-step deposition growth of the oblique column.

5. The method for manufacturing a T-type thermocouple by electrochemical spray deposition according to claim 1, characterized in that: The processing method of the substrate is: Copper and constantan wires were embedded in resin samples; The end of the copper wire and the constantan wire in the resin sample is polished with a grinding and polishing machine until the round cross-section of the flat copper wire and the constantan wire is exposed; The separated ends of the copper wire and the constantan wire in the resin sample are polished using a grinder and polisher until the flat circular cross-sections of the copper wire and the constantan wire are exposed.

6. The method for manufacturing a T-type thermocouple by electrochemical spray deposition according to claim 1, characterized in that: The components of the constantan electroplating solution are: copper sulfate pentahydrate: 0.02-0.03 mol / L, nickel sulfate hexahydrate: 0.3-0.4 mol / L, citric acid monohydrate 0.4-0.5 mol / L, ethoxylated propynyl alcohol: 0.02-0.04 ml / L, ethoxylated butynediol: 0.12-0.16 ml / L, sodium propynyloxyhydroxypropane sulfonate: 0.03-0.04 ml / L, ammonia water: the balance; The deposition conditions of the constantan electroplating solution are: pH 5.8-6.2, and deposition voltage 6-6.5V.

7. The method for manufacturing a T-type thermocouple by electrochemical spray deposition according to claim 1, characterized in that: The copper electroplating solution components are: copper sulfate pentahydrate: 0.7-0.9 mol / L, sulfuric acid: 1.8-2.2 mol / L, potassium chloride: 28-32 mg / L, and the copper electroplating solution deposition voltage is 7-7.2V.

8. A T-type thermocouple, characterized in that: The method is prepared by any one of claims 1 to 7.

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