An apparatus and method for measuring the hydrogen content in aluminum and aluminum alloys.

Abstract

The application discloses a device and method for measuring hydrogen content in aluminum and aluminum alloy, and relates to the technical field of hydrogen sensing; the device comprises a decompression container, a sampler, a first pressure transmitter, a first gas circuit, a first vacuum valve, a buffer cylinder, a second pressure transmitter, a second gas circuit, a second vacuum valve, a three-way valve, a vacuum pump, a controller, a sealing cover, a sealing ring and a heat preservation base; the vacuum degree of the decompression container is rapidly reduced to a target value through the buffer cylinder, and interference is reduced; the vacuum degree of the decompression container is stably controlled at the target value through dynamic control of the buffer cylinder and the vacuum valve, and test accuracy is improved. The heat preservation base is adopted to prolong the solidification time of liquid in the sample, the hydrogen evolution time is long, the hydrogen content detection limit is lower, and the test result is accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen measurement, in particular to a device and method for measuring hydrogen content in aluminum and aluminum alloy. BACKGROUND

[0002] In the production process of high-performance aluminum and aluminum alloy materials, the quality control of aluminum melt is one of the key factors, and the hydrogen content is an important parameter of the quality of aluminum melt.

[0003] The hydrogen saturation solubility of liquid aluminum is much higher than that of solid aluminum. During the solidification process of aluminum melt, hydrogen tends to precipitate from the aluminum melt, which will lead to loose, irregular pores and pinholes in the aluminum alloy, resulting in hydrogen-induced defects in the aluminum alloy, which significantly reduces the mechanical properties or physical and chemical properties of the aluminum alloy, greatly affecting the density, fatigue limit, strength, plasticity, corrosion resistance, electrical conductivity and thermal conductivity of the aluminum alloy. Therefore, it is necessary to quickly test the hydrogen content in aluminum during production to control product quality.

[0004] The reduced pressure solidification method is a commonly used method for measuring hydrogen in the production of aluminum alloy. This method takes a sample of liquid aluminum and places it in a sealed container. After vacuumizing, the liquid aluminum sample gradually solidifies under negative pressure. Due to the difference in hydrogen saturation solubility between solid and liquid aluminum, hydrogen in aluminum is precipitated during the solidification process of the melt under the driving of negative pressure, resulting in pores in the solidified aluminum sample. The pore rate of the test sample can represent the hydrogen content in aluminum. Therefore, a stable negative pressure / vacuum degree must be provided during the decompression process to ensure test accuracy. The general test process requires a vacuum degree of 2kPa, while the vacuum source is usually a rotary vane vacuum pump, and the ultimate vacuum degree is generally 2Pa. In addition, factors such as external power supply, vacuum oil quality, vacuum pump aging, vacuum pump sealing degree, pipeline sealing degree, and decompression container sealing degree all affect the vacuum degree of the decompression container. Due to the design defects of existing methods and devices, and the uncontrollable factors, the vacuum degree of the decompression container cannot be stably controlled. Therefore, the vacuum degree is extremely unstable during the solidification and decompression process, and the test results are inaccurate. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a device and method for measuring hydrogen content in aluminum and aluminum alloy, which can quickly and accurately measure the hydrogen content in aluminum and aluminum alloy.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is:

[0007] In one aspect, the present application provides a device for measuring the hydrogen content in aluminum and aluminum alloys, which comprises a decompression container, a sampler, a first pressure transmitter, a first gas path, a first vacuum valve, a buffer cylinder, a second pressure transmitter, a second gas path, a second vacuum valve, a three-way valve, a vacuum pump, a controller, a sealing cover, a sealing ring and a heat preservation base; wherein the sampler is placed in the heat preservation base, and both are placed in the sealed decompression container; the top of the decompression container is provided with a sealing ring and covers an openable sealing cover; the decompression container is connected with the buffer cylinder through the first gas path and the first vacuum valve; the buffer cylinder is connected with the vacuum pump through the second gas path and the second vacuum valve; the first pressure transmitter and the second pressure transmitter respectively test the vacuum degree of the decompression container and the buffer cylinder; the controller is used to control the opening and closing of the first vacuum valve and the second vacuum valve, and adjust the vacuum degree of the decompression container.

[0008] The material of the decompression container is one of steel, copper and nickel and alloys of multiple thereof.

[0009] The material of the sampler is one of boron nitride, graphite, silicon carbide, corundum, steel, copper and nickel and alloys of multiple thereof.

[0010] When the material of the sampler is one of corundum, steel, copper and nickel and alloys of multiple thereof, the surface of the sampler needs to be coated with a boron nitride release agent.

[0011] The first pressure transmitter and the second pressure transmitter are pressure transmitters.

[0012] The material of the first gas path and the second gas path is one of stainless steel, copper and polytetrafluoroethylene.

[0013] The first vacuum valve and the second vacuum valve are solenoid valves.

[0014] The material of the buffer cylinder is one of steel, copper, nickel and alloys of multiple thereof or polytetrafluoroethylene.

[0015] The three-way valve is a three-way vacuum ball valve, and the material thereof is one of stainless steel, copper and nylon.

[0016] The vacuum pump is a rotary vane vacuum pump.

[0017] The controller is an industrial computer.

[0018] The material of the sealing cover is one of polytetrafluoroethylene, glass and quartz or one of steel, copper, nickel and alloys of multiple thereof.

[0019] The material of the sealing ring can be one of silicone rubber, fluororubber and polytetrafluoroethylene.

[0020] The material of the outer shell of the heat preservation base is stainless steel, and the inside is a mixed salt of NaCl-KaCl.

[0021] In another aspect, the application also provides a method for measuring hydrogen content in aluminum and aluminum alloy, which is realized by using the device for measuring hydrogen content in aluminum and aluminum alloy and comprises the following steps:

[0022] S1: open the sealing cover, take out the sampler and the heat preservation base, and preheat together;

[0023] S2: adjust the three-way valve to be connected with the buffer cylinder, close the first vacuum valve, and open the second vacuum valve;

[0024] S3: start the vacuum pump, when the vacuum degree of the buffer cylinder measured by the second pressure transmitter reaches a preset threshold, close the second vacuum valve; when the vacuum degree is higher than the preset threshold, open the second vacuum valve;

[0025] S4: place the sampler containing the aluminum melt sample into the heat preservation base and place it in the decompression container, and close the sealing cover;

[0026] S5: open the first vacuum valve, when the vacuum degree reaches the preset threshold, close the first vacuum valve, and when the vacuum degree is higher than the preset threshold, open the first vacuum valve;

[0027] S6: after the aluminum sample is solidified, take out the aluminum sample, test its relative density, calculate the porosity and hydrogen content of the aluminum sample, and the calculation process is shown in formula (1) and formula (2):

[0028] L = 1 - A (1)

[0029]

[0030] Wherein, L is the porosity, A is the relative density, x is the hydrogen content in aluminum, f(x) is the porosity of the solidified sample, M P is the solubility of hydrogen in aluminum, G C is the growth control constant, L P is the minimum porosity of the sample to be tested under a certain pressure, P I is the maximum turning point of the relationship between the porosity of the solidified sample and the hydrogen content, and r is the average turning point of the relationship between the porosity of the solidified sample and the hydrogen content.

[0031] The preset threshold is 2.0 kPa, and the error is ±0.2 kPa;

[0032] The preheating temperature is 600-700 DEG C.

[0033] The beneficial effects generated by the above technical scheme are:

[0034] 1. The device and method for rapidly measuring the hydrogen content in aluminum and aluminum alloy can rapidly reduce the vacuum degree of the decompression container to the target value through the buffer cylinder, reduce interference, and improve the test accuracy.

[0035] 2、The application provides a device and method for rapidly measuring hydrogen content in aluminum and aluminum alloy, which can stabilize and control the vacuum degree of a decompression container at a target value through a buffer cylinder and dynamic control of a vacuum valve, thereby improving test accuracy.

[0036] 3、The application provides a device and method for rapidly measuring hydrogen content in aluminum and aluminum alloy, which adopts a heat preservation base to prolong the liquid solidification time in the sample, prolongs the hydrogen evolution time, lowers the hydrogen content detection limit, and is accurate in test results. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A device for measuring hydrogen content in aluminum and aluminum alloy is provided in the embodiment of the application;

[0038] Figure 2 A method for measuring hydrogen content in aluminum and aluminum alloy is provided in the embodiment of the application;

[0039] In the figure, 1 is a decompression container, 2 is a sampler, 3 is an aluminum sample, 4 is a first pressure transmitter, 5 is a first gas path, 6 is a first vacuum valve, 7 is a buffer cylinder, 8 is a second pressure transmitter, 9 is a second gas path, 10 is a second vacuum valve, 11 is a three-way valve, 12 is a vacuum pump, 13 is a controller, 14 is a sealing cover, 15 is a sealing ring, and 16 is a heat preservation base. DETAILED DESCRIPTION

[0040] The specific implementation of the application will be further described in combination with the drawings and embodiments.

[0041] On one hand, the embodiment provides a device for measuring hydrogen content in aluminum and aluminum alloy, as shown in the figure, the device comprises a decompression container 1, a sampler 2, an aluminum sample 3, a first pressure transmitter 4, a first gas path 5, a first vacuum valve 6, a buffer cylinder 7, a second pressure transmitter 8, a second gas path 9, a second vacuum valve 10, a three-way valve 11, a vacuum pump 12, a controller 13, a sealing cover 14, a sealing ring 15, and a heat preservation base 16. Figure 1 The sampler 2 containing the aluminum sample 3 is placed in the heat preservation base 16 and is placed together in the sealed decompression container 1, the decompression container 1 has the sealing ring 15 on the top and covers the openable sealing cover 14; the decompression container is connected with the buffer cylinder 7 through the first gas path 5 and the first vacuum valve 6, the buffer cylinder is connected with the vacuum pump 12 through the gas path B and the second vacuum valve 10, the first pressure transmitter 3 and the second pressure transmitter 9 respectively test the vacuum degrees of the decompression container 1 and the buffer cylinder 7, the controller 13 is used for controlling the opening and closing of the first vacuum valve 6 and the second vacuum valve 10, and the vacuum degree of the decompression container 1 is adjusted and controlled.

[0042] The material of the pressure reducing container 1 is one of steel, copper and nickel and alloys of multiple thereof.

[0043] The material of the sampler 2 is one of boron nitride, graphite, silicon carbide, corundum, steel, copper and nickel and alloys of multiple thereof.

[0044] When the material of the sampler 2 is one of corundum, steel, copper and nickel and alloys of multiple thereof, the surface of the sampler 2 needs to be coated with boron nitride release agent.

[0045] The first pressure transmitter 4 and the second pressure transmitter 8 are pressure transmitters, and in the embodiment, pressure transmitters with a range of 0-100 kPa and an accuracy of 0.2% FS are adopted.

[0046] The material of the first gas path 5 and the second gas path 9 is one of stainless steel, copper and polytetrafluoroethylene.

[0047] The first vacuum valve 6 and the second vacuum valve 10 are normally closed electromagnetic valves, and in the embodiment, normally closed electromagnetic valves with a pressure range of 0-0.5 MPa are adopted.

[0048] The material of the buffer cylinder 7 is one of steel, copper, nickel and alloys of multiple thereof or polytetrafluoroethylene.

[0049] The three-way valve 11 is a three-way vacuum ball valve, and the material thereof is one of stainless steel, copper and nylon.

[0050] The vacuum pump 12 is a rotary vane vacuum pump.

[0051] The controller 13 is an industrial computer.

[0052] The material of the sealing cover 14 is one of polytetrafluoroethylene, glass and quartz or one of steel, copper and nickel and alloys of multiple thereof.

[0053] The material of the sealing ring 15 can be one of silicone rubber, fluororubber and polytetrafluoroethylene.

[0054] The material of the outer shell of the heat preservation base 16 is stainless steel, and the inside is a mixed salt of NaCl and KaCl.

[0055] On the other hand, the embodiment also proposes a method for measuring the hydrogen content in aluminum and aluminum alloy, which is realized by using the device for measuring the hydrogen content in aluminum and aluminum alloy, as shown in Figure 2 The method comprises the following steps:

[0056] S1: open the sealing cover, take out the sampler and the heat preservation base, and preheat to 600-700°C;

[0057] S2: adjust the three-way valve to connect the vacuum pump and the buffer cylinder, close the first vacuum valve, and open the second vacuum valve;

[0058] S3: open the vacuum pump, when the second pressure transmitter measures the vacuum degree of the buffer cylinder to the preset threshold, close the second vacuum valve; when the vacuum degree is higher than the preset threshold, open the second vacuum valve;

[0059] In this embodiment, the preset threshold is 2.0kPa, and the error is ±0.2kPa;

[0060] S4: place the sampler containing the aluminum melt sample into the heat preservation base and place it in the pressure reduction container, and close the sealing cover;

[0061] S5: open the first vacuum valve, when the vacuum degree reaches the preset threshold, close the first vacuum valve, when the vacuum degree is higher than the preset threshold, open the first vacuum valve;

[0062] S6: after the aluminum sample is solidified, take out the aluminum sample, test its relative density, calculate the porosity and hydrogen content of the aluminum sample, and the calculation process is shown in formula (1) and formula (2):

[0063] L=1-A (1)

[0064]

[0065] Wherein, L is the porosity, A is the relative density, x is the hydrogen content in aluminum, f(x) is the porosity of the solidified sample, M P is the solubility of hydrogen in aluminum, G C is the growth control constant, L P is the minimum porosity of the sample to be tested under a certain pressure, P I is the maximum turning point of the relationship between the porosity of the solidified sample and the hydrogen content, and r is the average turning point of the relationship between the porosity of the solidified sample and the hydrogen content.

Claims

1. An apparatus for measuring the hydrogen content in aluminum and aluminum alloys, characterized by, The device comprises a decompression container, a sampler, a first pressure transmitter, a first gas path, a first vacuum valve, a buffer cylinder, a second pressure transmitter, a second gas path, a second vacuum valve, a three-way valve, a vacuum pump, a controller, a sealing cover, a sealing ring and a heat preservation base; wherein the sampler is put into the heat preservation base and is placed together in the sealed decompression container, the top of the decompression container is provided with a sealing ring and covers an openable sealing cover; the decompression container is connected with the buffer cylinder through the first gas path and the first vacuum valve, the buffer cylinder is connected with the vacuum pump through the second gas path and the second vacuum valve, the first pressure transmitter and the second pressure transmitter respectively test the vacuum degree of the decompression container and the buffer cylinder, the controller is used to control the opening and closing of the first vacuum valve and the second vacuum valve, and the vacuum degree of the decompression container is adjusted and controlled.

2. The apparatus for measuring the hydrogen content in aluminum and aluminum alloys according to claim 1, wherein The material of the decompression container is one of steel, copper and nickel and an alloy of multiple thereof.

3. The apparatus for measuring the hydrogen content in aluminum and aluminum alloys according to claim 1, wherein The material of the sampler is one of boron nitride, graphite, silicon carbide, corundum, steel, copper and nickel and an alloy of multiple thereof.

4. The apparatus for measuring the hydrogen content in aluminum and aluminum alloys according to claim 3, wherein When the material of the sampler is one of corundum, steel, copper and nickel and an alloy of multiple thereof, the surface of the sampler needs to be coated with a boron nitride release agent.

5. The apparatus for measuring the hydrogen content in aluminum and aluminum alloys according to claim 1, wherein The material of the first gas path and the second gas path is one of stainless steel, copper and polytetrafluoroethylene.

6. The apparatus for measuring the hydrogen content in aluminum and aluminum alloys according to claim 1, wherein The first vacuum valve and the second vacuum valve are electromagnetic valves. The material of the buffer cylinder is one of steel, copper, nickel and an alloy of multiple thereof or polytetrafluoroethylene. The three-way valve is a three-way vacuum ball valve, and the material thereof is one of stainless steel, copper and nylon. The vacuum pump is a rotary vane vacuum pump. The controller is an industrial computer.

7. The apparatus for measuring the hydrogen content in aluminum and aluminum alloys according to claim 1, wherein The material of the sealing cover is one of polytetrafluoroethylene, glass and quartz or one of steel, copper, nickel and an alloy of multiple thereof. The material of the sealing ring can be one of silicone rubber, fluororubber and polytetrafluoroethylene. The material of the outer shell of the heat preservation base is stainless steel, and the inside is a mixed salt of NaCl-KaCl.

8. A method for measuring the hydrogen content in aluminum and aluminum alloy, which is realized by using the device for measuring the hydrogen content in aluminum and aluminum alloy according to claim 1 and comprises the following steps: S1: open the sealing cover, take out the sampler and the heat preservation base, and preheat together; S2: adjust the three-way valve to connect the vacuum pump and the buffer cylinder, close the first vacuum valve, and open the second vacuum valve; S3: start the vacuum pump, close the second vacuum valve when the vacuum degree of the buffer cylinder measured by the second pressure transmitter reaches a preset threshold, and open the second vacuum valve when the vacuum degree is higher than the preset threshold; S4: place the sampler containing the aluminum melt sample into the heat preservation base and put it into the decompression container, and close the sealing cover; S5: open the first vacuum valve, close the first vacuum valve when the vacuum degree reaches the preset threshold, and open the first vacuum valve when the vacuum degree is higher than the preset threshold; S6: after the aluminum sample solidifies, take out the aluminum sample, test the relative density, calculate the porosity and hydrogen content of the aluminum sample, and the calculation process is shown in formula (1) and formula (2): （1） （2） wherein L is the porosity, A is the relative density, x is the hydrogen content in the aluminum, f(x) is the porosity of the solidification sample, M P is the solubility of hydrogen in the aluminum, G C is the growth control constant, L P is the minimum porosity of the sample to be tested at a certain pressure, P I is the maximum transition point of the porosity of the solidification sample versus the hydrogen content, and r is the average transition point of the porosity of the solidification sample versus the hydrogen content.

9. The apparatus for measuring the hydrogen content in aluminum and aluminum alloys as claimed in claim 8, wherein The preheating is to 600-700°C.

10. The apparatus for measuring the hydrogen content in aluminum and aluminum alloys as claimed in claim 8, wherein The preset threshold is 2.0 kPa, and the error is ±0.2 kPa.

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