Magnesium alloy ignition point testing device and method under different atmosphere environments

Abstract

The invention discloses a magnesium alloy ignition point test device and method under different atmosphere environments, comprising a bracket, a sample hanging basket and an air duct, wherein a heating furnace is installed on the upper part of the bracket, a resistance belt is installed on the inner wall of the heating furnace, the sample hanging basket is installed at the center of the heating furnace, the bottom of the sample hanging basket is used to place the ignition point test sample, a thermocouple group for monitoring the temperature change of the ignition point test sample is installed on the upper part of the sample hanging rod, a first thermocouple for monitoring the temperature change inside the heating furnace is also installed inside the heating furnace, the first thermocouple is connected to a temperature control module, the thermocouple group is connected to a data recording module, one end of the air duct is connected to the heating furnace, the other end of the air duct is connected to a gas cylinder, and a flow meter for controlling the atmosphere flow is installed on the air duct.

Description

Technical Field

[0001] The invention relates to the field of testing technology, and in particular to a device and method for testing the ignition point of a magnesium alloy under different atmospheres. Background Art

[0002] Magnesium alloy has the characteristics of low density, high specific strength and specific stiffness, good casting and machining performance, electromagnetic shielding performance, and good recyclability. It is known as the lightest engineering structural material and can partially or completely replace structural materials such as steel and aluminum. In recent years, with the increasing awareness of environmental protection and energy conservation, the requirements for lightweight industrial products have been put forward both internationally and domestically. As the lightest engineering structural material, magnesium alloy has been increasingly used in various industrial fields.

[0003] TSO-C127 "Rotor and Transport Aircraft Seating Systems" issued by the FAA (Federal Aviation Administration) in 1992 has always used the seat standards set by the Society of Automotive Engineers, which clearly prohibits the use of magnesium alloy seats. However, in recent years, with the requirements for lightweight aerospace components, magnesium alloys have broken the deadlock with their high specific strength and specific stiffness, high electromagnetic shielding, high damping, good dimensional stability, thermal conductivity, and excellent casting, cutting performance and easy recycling. In June 2014, the FAA issued TSO-C127b, which has been updated and refined on the original basis. In order to reduce weight, the use of magnesium alloy seats has been relaxed. Up to now, although the mechanical properties of magnesium alloys have been continuously improved, their flame retardant properties have not been effectively improved because it is difficult to form a dense and uniform oxide film with a protective effect on the surface of magnesium alloys when oxidized at high temperatures and there is no high-temperature melting point phase with good heat resistance in the magnesium alloy matrix. Once the magnesium alloy burns, it will be violent and uncontrollable. This feature has brought great difficulties to the preparation, production and subsequent processing of magnesium alloys such as welding, forging, rolling, etc., restricting the widespread promotion and application of magnesium alloys in the industrial field.

[0004] Improving the flame retardancy and high temperature oxidation resistance of magnesium alloys and proving their safety in commercial applications through a series of tests will attract widespread attention in the application of magnesium alloys. Among them, the test of the ignition point of magnesium alloys is essential, but the ignition point test devices currently used are as follows: (1) flame jet ignition point test device; (2) cone calorimeter ignition point test device; (3) resistance furnace ignition point test device, etc. Although the above ignition point test devices can be used to test the ignition point of magnesium alloys, they have certain disadvantages. For example, the flame jet ignition point test device simulates the heating conditions of magnesium alloy at the fire scene to a certain extent, but because the alloy is directly exposed to the air when it is sprayed, the surface temperature of the alloy is greatly affected by external factors, so the measured ignition point of the magnesium alloy has a large error; the cone calorimeter ignition point test device is a new generation of material combustion performance tester based on the principle of oxygen consumption. It obtains a variety of combustion parameters when the magnesium alloy burns, including heat release rate, total heat release, effective combustion heat, ignition time, smoke and toxicity parameters and mass change parameters, but its structure is complex, the operation is cumbersome and the price is expensive. It is often used as an auxiliary experimental instrument for magnesium alloy ignition point and combustion performance testing; the resistance furnace ignition point test device is a common device for most magnesium alloy ignition point and high temperature oxidation performance researchers. It has a simple structure, convenient operation and flexible use, but the problem is that when the temperature in the furnace is high during the test, the air in the furnace is thin and cannot be replenished, the environment of the sample deviates from the actual environment, and the measured magnesium alloy ignition point deviates from the true value to a large extent. In addition, the above ignition point test devices can only perform ignition point tests on magnesium alloys in air environments, which has great limitations.

[0005] Therefore, it is necessary to provide a magnesium alloy ignition point testing device and method under different atmosphere environments to solve the problems raised in the above background technology. Summary of the invention

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a magnesium alloy ignition point test device under different atmosphere environments, comprising a bracket, a sample hanging basket and an air duct, a heating furnace is installed on the upper part of the bracket, a resistance belt is installed on the inner wall of the heating furnace, the sample hanging basket is installed at the center of the heating furnace, the bottom of the sample hanging basket is used to place the ignition point test sample, a thermocouple group for monitoring the temperature change of the ignition point test sample is installed on the upper part of the sample hanging rod, a first thermocouple for monitoring the temperature change inside the heating furnace is also installed inside the heating furnace, the first thermocouple is connected to the temperature control module, the thermocouple group is connected to the data recording module, one end of the air duct is connected to the heating furnace, the other end of the air duct is connected to the gas cylinder, and a flowmeter for controlling the atmosphere flow is installed on the air duct.

[0007] As a preferred technical solution of the present invention, a radiation tube located outside the sample hanging basket is installed inside the heating furnace, an outer ring cavity is formed between the radiation tube and the heating furnace, the upper end of the outer ring cavity is connected to the upper end of the tube cavity of the radiation tube, the air guide tube includes a branch bronchus connected to the lower end of the outer ring cavity, and the bottom of the heating furnace is provided with a through hole connected to the tube cavity of the radiation tube.

[0008] As a preferred technical solution of the present invention, a rotatable stirring blade is provided in the annular cavity between the upper end outer wall of the radiation tube and the upper end of the outer annular cavity.

[0009] As a preferred technical solution of the present invention, the inner wall of the upper end of the radiation tube is installed with vertical flow diversion baffles distributed in a circumference.

[0010] As a preferred technical solution of the present invention, the first thermocouple is arranged inside the tube cavity of the radiation tube.

[0011] As a preferred technical solution of the present invention, a center hole is provided in the middle of the ignition point test sample, and the thermocouple group includes a second thermocouple and a third thermocouple. The second thermocouple is used to monitor the temperature change of the outer surface of the ignition point test sample, and the third thermocouple is used to be inserted into the center hole to monitor the internal temperature change of the ignition point test sample, and a heat-conducting roller belt is also installed on the second thermocouple.

[0012] As a preferred technical solution of the present invention, the depth of the central hole is half of the height of the ignition point test specimen.

[0013] As a preferred technical solution of the present invention, the heat-conducting roller belt includes a hanging plate, which is installed on the monitoring end of the second thermocouple, and a rotating roller one symmetrically distributed up and down is installed on the hanging plate, and a rotating roller two symmetrically distributed up and down is provided on the outer side of the vertical rotating roller one, and the outer sides of the two groups of rotating rollers are covered with a heat-conducting sheet for conducting temperature with the ignition point test sample, and the inner belt of the heat-conducting sheet is tightly attached to the outer surface of the ignition point test sample. The two groups of rotating rollers are pressed on the outer belt of the heat-conducting sheet, so that the inner belt of the heat-conducting sheet and the outer belt of the heat-conducting sheet are in contact with each other, and the belt surface of the outer belt of the heat-conducting sheet is in contact with the monitoring end of the second thermocouple, and the second thermocouple is installed on the collecting plate, and a lifting rod for controlling the lifting and lowering movement of the collecting plate is installed on the outside of the heating furnace.

[0014] As a preferred technical solution of the present invention, a collection box is provided below the through hole.

[0015] A method for testing a magnesium alloy ignition point test device under different atmosphere environments, comprising the following steps:

[0016] S1: Prepare the fire point test specimen required for the fire point test;

[0017] S2: The surface of the ignition point test sample is polished with sandpaper, then cleaned with acetone and blown dry;

[0018] S3: placing the ignition point test sample into a sample hanging basket;

[0019] S4: Set the heating rate of the ignition point test;

[0020] S5: The atmosphere required for the ignition point test is supplied by a gas cylinder;

[0021] S6: Turn on the power of the equipment, start the ignition point test under the action of atmosphere, observe the changes on the surface of the sample, and pay attention to the temperature data.

[0022] Compared with the prior art, the present invention provides a magnesium alloy ignition point test device and method under different atmosphere environments, which has the following beneficial effects:

[0023] 1. The present invention enables the magnesium alloy to be tested in various atmospheres during the test of the magnesium alloy ignition point, and the atmosphere can be continuously replenished, and the temperature in the heating furnace can fluctuate evenly, so that the magnesium alloy can obtain sufficient and uniform heat conduction, which greatly broadens the scope of magnesium alloy ignition point testing and can greatly expand researchers' understanding of magnesium alloy properties.

[0024] 2. This device adopts a thermal radiation heating method, which has uniform heating and good controllability of the heating rate. It also guides the flow direction of the atmosphere to make it flow evenly to the surface of the magnesium alloy, so that the surface of the magnesium alloy shows uniform changes. By simultaneously monitoring the temperature changes on the surface and inside of the magnesium alloy, the inflection point of the ignition point data obtained is more accurate. In addition, the heat conduction contact method of the heat conduction roller is adopted, so that the surface of the magnesium alloy and the surface of the contact area can interact with the atmosphere, thereby further improving the accuracy of the inflection point of the ignition point data. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of a magnesium alloy ignition point testing device under different atmosphere environments of the present invention;

[0026] Figure 2 It is a schematic diagram of the internal structure of the heating furnace of the present invention;

[0027] Figure 3 for Figure 2 Local structure diagram Figure 1 ;

[0028] Figure 4 for Figure 2 Local structure diagram Figure 2 ;

[0029] Figure 5 It is a schematic diagram of the heat-conducting roller structure of the present invention;

[0030] Figure 6 This is a schematic diagram of the temperature curve of AZ80 ignition point test in air environment;

[0031] Figure 7 This is a schematic diagram of the temperature curve of AZ80 ignition point test in oxygen environment;

[0032] In the figure: 1. flow meter; 2. air duct; 3. gas cylinder; 4. bracket; 5. temperature control module; 6. data recording module; 7. ignition point test sample; 21. shunt bronchial tube; 41. heating furnace; 42. collecting box; 43. resistance belt; 44. radiation tube; 45. stirring fan blade; 46. shunt baffle; 47. through hole; 51. first thermocouple; 61. sample hanging basket; 62. thermocouple group; 63. heat-conducting roller belt; 64. lifting rod; 65. loading plate; 621. second thermocouple; 622. third thermocouple; 631. hanging plate; 632. roller one; 633. roller two; 634. heat-conducting belt sheet; 71. center hole. DETAILED DESCRIPTION

[0033] Reference Figure 1-5 The present invention provides a technical solution: a magnesium alloy ignition point test device under different atmosphere environments, comprising a bracket 4, a sample hanging basket 61 and an air duct 2, characterized in that a heating furnace 41 is installed on the upper part of the bracket 4, a resistance belt 43 is installed on the inner wall of the heating furnace 41, the sample hanging basket 61 is installed at the center of the heating furnace 41, the bottom of the sample hanging basket 61 is used to place the ignition point test sample 7, a thermocouple group 62 for monitoring the temperature change of the ignition point test sample 7 is installed on the upper part of the sample hanging rod 61, a first thermocouple 51 for monitoring the temperature change inside the heating furnace 41 is also installed inside the heating furnace 41, the first thermocouple 51 is connected to the temperature control module 5, the thermocouple group 62 is connected to the data recording module 6, one end of the air duct 2 is connected to the heating furnace 41, the other end of the air duct 2 is connected to the gas cylinder 3, and a flowmeter 1 for controlling the atmosphere flow is installed on the air duct 2;

[0034] In this embodiment, the resistance belt 43 is a resistance belt containing 80% nickel and 20% chromium;

[0035] In this embodiment, the first thermocouple and the thermocouple group are both K-type thermocouples.

[0036] In this embodiment, a radiation tube 44 located outside the sample hanging basket 61 is installed inside the heating furnace 41, and an outer ring cavity is formed between the radiation tube 44 and the heating furnace 41. The upper end of the outer ring cavity is connected to the upper end of the tube cavity of the radiation tube 44. The air guide pipe 2 includes a shunt bronchial pipe 21 connected to the lower end of the outer ring cavity. The bottom of the heating furnace 41 is provided with a through hole 47 connected to the tube cavity of the radiation tube 44. In addition, the air outlet of the shunt bronchial pipe is inclined upward, and a plurality of air outlets are provided to supply atmosphere to the lower end of the outer ring cavity, so that the atmosphere entering the outer ring cavity rises steadily and passes through the resistance belt 43 at the first time, and then enters from the upper end of the tube cavity of the radiation tube 44, and flows to the side of the ignition point test sample in the tube cavity of the radiation tube 44, and combines the heating method of thermal radiation and thermal radiation conduction to make the flow of the atmosphere more regular, improve the controllability of the temperature control rate of the heating environment and the stability of the heat distribution, and at the same time, also make the monitoring accuracy of the heating environment is improved;

[0037] The annular cavity between the upper outer wall of the radiation tube 44 and the upper end of the outer annular cavity is provided with a rotatable stirring blade 45 to further accelerate the mixing rate of the heat conduction mixing of the atmosphere;

[0038] Among them, the inner wall of the upper end of the radiation tube 44 is installed with a vertical circularly distributed diversion baffle 46 to further improve the balance rate of the heat distribution of the atmosphere continuously flowing in the heating furnace, so that the ignition point test sample can be heated by uniform and stable heat conduction in the environment of continuously flowing atmosphere.

[0039] In this embodiment, the first thermocouple 51 is disposed inside the tube cavity of the radiation tube 44 .

[0040] In this embodiment, a central hole 71 is provided in the middle of the ignition point test sample 7, and the thermocouple group 62 includes a second thermocouple 621 and a third thermocouple 622. The second thermocouple 621 is used to monitor the outer surface temperature change of the ignition point test sample 7, and the third thermocouple 622 is used to be inserted into the central hole to monitor the internal temperature change of the ignition point test sample 7, and a heat-conducting roller belt 63 is also installed on the second thermocouple; the outer surface temperature change and internal temperature change data of the ignition point test sample 7 are obtained by the second thermocouple 621 and the third thermocouple 622, so that the ignition point temperature data information of the ignition point test sample 7 is more accurate;

[0041] In addition, the data recording module collects the temperature data of the second thermocouple and the third thermocouple, and calculates the average value of the temperature data of the two for recording and analysis.

[0042] The depth of the central hole 71 is half of the height of the ignition point test specimen 7 .

[0043] In this embodiment, the heat-conducting roller belt 63 includes a hanging plate 631, which is installed at the monitoring end of the second thermocouple 621. A roller 1 632 symmetrically distributed up and down is installed on the hanging plate 631. A roller 2 633 symmetrically distributed up and down is provided on the outer side of the vertical roller 1 632. The outer sides of the two groups of rollers 2 633 are covered with a heat-conducting sheet 634 for conducting temperature with the ignition point test sample 7. The inner belt of the heat-conducting sheet 634 is tightly attached to the outer surface of the ignition point test sample 7. The two groups of rollers 1 632 are rolled on the outer belt of the heat-conducting sheet 634, so that the inner belt of the heat-conducting sheet 634 and the outer belt of the heat-conducting sheet 634 are in contact with each other, and the belt surface of the outer belt of the heat-conducting sheet 634 is in contact with the monitoring end of the second thermocouple 621, and the second thermocouple 621 is installed on the carrier plate 65. The outside of the heating furnace 41 is equipped with a device for controlling the lifting and lowering of the carrier plate 65. The lifting rod 64 is movable; because the atmosphere will undergo a certain oxidation reaction with the ignition point test sample under the action of heating, a certain oxide is formed on the surface of the ignition point test sample, and the contact area of ​​the current ignition point test sample is in real-time contact with the contact area of ​​the ignition point test sample during the process from the beginning of the test to the end of the test, thereby affecting the reaction change between the atmosphere and the ignition point test sample, resulting in inaccurate temperature change data of the measured ignition point test sample. Therefore, by controlling the lifting and moving of the carrier plate through the lifting rod, the heat conductive sheet can be driven to continuously roll on the surface of the ignition point test sample, thereby exposing the contact area with the ignition point test sample, so that the surface of the ignition point test sample is fully affected by the atmosphere, and the heat is transferred to the second thermocouple in the form of high-conductivity heat of the heat conductive sheet, thereby obtaining accurate temperature changes of the outer surface of the ignition point test sample;

[0044] When the second thermocouple collects temperature data of the outer surface of the ignition point test sample, the lifting rod stops running, so as to facilitate the measurement of the temperature data of the second thermocouple.

[0045] In this embodiment, a collection box 42 is provided below the through hole 47 to ensure safety before the test is completed and to clean up after the test is completed.

[0046] In specific implementation, it includes the following steps:

[0047] S1: Prepare the burning point test sample required for the burning point test; cut the burning point test sample and process it into corresponding specifications, the specifications of the burning point test sample are 15mm long×15mm wide×20mm high, and a central hole of Φ2mm is opened;

[0048] S2: The surface of the ignition point test sample is polished with sandpaper, then cleaned with acetone and blown dry; wherein the surface of the ignition point test sample is treated with 200#, 400#, 800#, 1000#, 2000# and 3000# sandpaper respectively;

[0049] S3: Put the ignition point test sample into the sample hanging basket; place the second thermocouple close to the outer surface of the ignition point test sample and evenly place it on both sides of the sample, insert the third thermocouple into the central hole of the ignition point test sample, install the first thermocouple inside the radiation tube, and monitor the change of the ambient temperature of the ignition point test sample; the data recording module reads the temperature data (the average value of the temperatures measured by the second thermocouple and the third thermocouple) once per second, and draws it into a temperature (T)-time (t) curve;

[0050] S4: Set the heating rate of the ignition point test; the heating rate of the ignition point test sample is set at 1℃-25℃ / min;

[0051] S5: The atmosphere required for the ignition point test is supplied by a gas cylinder;

[0052] S6: Turn on the power of the equipment, start the ignition point test under the action of atmosphere, observe the changes on the sample surface, and pay attention to the temperature data; when the ignition point test sample ignites and emits a dazzling white light (which is manifested in the temperature recording curve, that is, the curve has a temperature rise inflection point and the temperature rises rapidly), quickly turn off the power.

[0053] In the above specific implementation steps, commercial AZ80 magnesium alloy was cut, the heating rate was set to 5°C / min, the atmosphere supplied by the gas cylinder was air, and the gas flow rate was 5L / min. Figure 6 The ignition point inflection point is shown, and the ignition point in air environment is 561.3℃.

[0054] In the above specific implementation steps, commercial AZ80 magnesium alloy was cut, the heating rate was set to 5°C / min, the atmosphere supplied by the gas cylinder was oxygen, and the gas flow rate was 5L / min. Figure 7 The ignition point in oxygen environment is 544.1℃.

[0055] The above description is only a preferred specific implementation manner of the invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the invention, which should be covered by the protection scope of the present invention.

Claims

1. A magnesium alloy ignition point test device under different atmosphere environments, comprising a bracket (4), a sample hanging basket (61) and an air guide tube (2), characterized in that: A heating furnace (41) is installed on the upper part of the support (4), a resistance belt (43) is installed on the inner wall of the heating furnace (41), the sample hanging basket (61) is installed at the center of the heating furnace (41), the bottom of the sample hanging basket (61) is used to place the ignition point test sample (7), a thermocouple group (62) for monitoring the temperature change of the ignition point test sample (7) is installed on the upper part of the sample hanging basket (61), a first thermocouple (51) for monitoring the temperature change inside the heating furnace (41) is also installed inside the heating furnace (41), the first thermocouple (51) is connected to the temperature control module (5), the thermocouple group (62) is connected to the data recording module (6), one end of the air guide pipe (2) is connected to the heating furnace (41), the other end of the air guide pipe (2) is connected to the gas cylinder (3), and a flow meter (1) for controlling the atmosphere flow is installed on the air guide pipe (2); A central hole (71) is provided in the middle of the ignition point test sample (7); the thermocouple group (62) comprises a second thermocouple (621) and a third thermocouple (622); the second thermocouple (621) is used to monitor the temperature change of the outer surface of the ignition point test sample (7); the third thermocouple (622) is used to be inserted into the central hole and is used to monitor the temperature change of the interior of the ignition point test sample (7); and a heat-conducting roller belt (63) is also installed on the second thermocouple; The heat-conducting roller belt (63) includes a hanging plate (631), the hanging plate (631) is installed at the monitoring end of the second thermocouple (621), a rotating roller (632) symmetrically distributed up and down is installed on the hanging plate (631), a rotating roller (633) symmetrically distributed up and down is arranged on the outer side of the rotating roller (632) in the vertical direction, and a heat-conducting belt sheet (634) for conducting temperature with the ignition point test sample (7) is sleeved on the outer side of the two groups of rotating rollers (633), and the inner belt of the heat-conducting belt sheet (634) is tightly attached to the ignition point test sample (7). On the outer surface of the sample (7), two sets of rollers (632) are pressed against the outer belt of the thermal conductive sheet (634), so that the inner belt of the thermal conductive sheet (634) and the outer belt of the thermal conductive sheet (634) are in contact with each other, and the belt surface of the outer belt of the thermal conductive sheet (634) is in contact with the monitoring end of the second thermocouple (621), and the second thermocouple (621) is installed on the carrier plate (65), and a lifting rod (64) for controlling the lifting and moving of the carrier plate (65) is installed on the outside of the heating furnace (41).

2. The magnesium alloy ignition point testing device under different atmospheres according to claim 1, characterized in that: The heating furnace (41) is internally provided with a radiation tube (44) located outside the sample hanging basket (61), an outer ring cavity is formed between the radiation tube (44) and the heating furnace (41), the upper end of the outer ring cavity is connected to the upper end of the tube cavity of the radiation tube (44), the air guide tube (2) includes a branch bronchus (21) connected to the lower end of the outer ring cavity, and the bottom of the heating furnace (41) is provided with a through hole (47) connected to the tube cavity of the radiation tube (44).

3. The magnesium alloy ignition point testing device under different atmospheres according to claim 2, characterized in that: The annular cavity between the upper end outer wall of the radiation tube (44) and the upper end of the outer annular cavity is provided with rotatable stirring blades (45).

4. The magnesium alloy ignition point testing device under different atmospheres according to claim 3, characterized in that: The inner wall of the upper end of the radiation tube (44) is provided with vertical flow dividing baffles (46) distributed in a circumferential manner.

5. The magnesium alloy ignition point testing device under different atmospheres according to claim 4, characterized in that: The first thermocouple (51) is arranged inside the cylinder cavity of the radiation cylinder (44).

6. The magnesium alloy ignition point testing device under different atmospheres according to claim 2, characterized in that: A collecting box (42) is provided below the through hole (47).

7. The magnesium alloy ignition point testing device under different atmospheres according to claim 1, characterized in that: The depth of the central hole (71) is half the height of the ignition point test specimen (7).

8. The method for testing a magnesium alloy ignition point testing device under different atmospheres according to any one of claims 1 to 7, characterized in that: It includes the following steps: S1: Prepare the fire point test specimen required for the fire point test; S2: The surface of the ignition point test sample is polished with sandpaper, then cleaned with acetone and blown dry; S3: placing the ignition point test sample into a sample hanging basket; S4: Set the heating rate of the ignition point test; S5: The atmosphere required for the ignition point test is supplied by a gas cylinder; S6: Turn on the power of the equipment, start the ignition point test under the action of atmosphere, observe the changes on the surface of the sample, and pay attention to the temperature data.

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