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Vacuum hot pressing furnace operating procedures and precautions

Vacuum hot pressing furnace operating procedures and precautions
First, prepare
Turn on the chiller switch, otherwise the device will alarm due to low water pressure.
Second, turn on the power switch
Before powering up, you need to check the status of each switch:
1. The heating mode should be placed in the “manual” position, and the power adjustment should be rotated counterclockwise to the end;
2. Pressurize the “Lift-Stop-Lower” toggle switch to stop position, and pressurize the potentiometer to a small position; after the above checks are correct, first turn on the main power switch, then turn on the secondary power switch.
Third, open the furnace into the sample
When the furnace is not in use, it is generally in a vacuum state. Before use, observe the vacuum state of the furnace. If it is under vacuum, firstly inflate the furnace body to atmospheric pressure through the intake valve, then open the furnace cover with a thousand toys and take out the two covers. , the sample to be burned is placed in the furnace body. If you do not pressurize the sintering, do not forget that both the inner and outer insulation caps must be covered, otherwise the temperature may not rise; if it is to be heated and sintered, the small cover in the middle of the outer thermal insulation cover and the inner thermal insulation cover must be removed. Conduct experiment.
Note: Be careful not to trigger the hot body when placing the sample to avoid a short circuit between the heating element and the furnace shell.
Fourth, set the heating program
1. Temperature rises: generally set by the program, the heating rate is 100 C/min. If the temperature is to be raised rapidly in the early stage of the experiment, the temperature rise mode can be placed in the “manual” file, and the power is slowly adjusted clockwise to make the current rise slowly to warm up; Below 200 ° C, you can manually heat up, otherwise the temperature control is not allowed. 1000-2000 C, infrared temperatures can be used to automatically control the furnace temperature.
Note: The temperature rise must be carried out under vacuum; observe that the current meter indicate that the secondary rated current of 700A is prohibited.
2, cooling: can be set by the program, or directly turn off the heating to let it cool itself.
Note: Water is not allowed to stop during the cooling process, otherwise the furnace seal will be burned out.
Five, set the pressure program
1. Preload: The preload should be carried out before the temperature rise, usually the pressure setting range is between 1.0 and 1.5 MPa; the preload can be achieved by manual pressure.
2. Pressurization: After the temperature rises to the predetermined temperature, the sample is pressurized. Usually, the program is set to automatically pressurize the sample. The pressure value that the equipment can achieve is 16 MPa, which is equivalent to 10 t (16 MPa = 10 t).
A: Manual pressurization: Rotate the pressure potentiometer while observing the displacement indication. The displacement change is very small, indicating that the upper and lower punches have been in contact with the sample. At the end of the pressurization, the "Lift-stop-down" switch is turned to the stop position, and the pressure potential device is turned to a small position.
B: Automatic pressurization: first set the required pressure on the meter. When the required pressure and the measured pressure are basically the same, turn the “Lift-stop-down” switch to rise, observe the displacement and pressure change, and wait for the pressure to rise. Automatic pressure and voltage regulation are realized. At the end of the pressurization, simply turn the "Liter-stop-down" switch down. After the bottom is lowered, the "Lift-Stop-Lower" switch is turned to stop. Turn of the hydraulic pump.
Note: When no pressure or pressure is applied, the pressure should be set to a negative value and the hydraulic pump should be stopped. When the cylinder is not in use, it is set to the stop position, otherwise it will be mishandled.
Sixth, electric furnace vacuuming steps:
Open the vacuum gauge switch
1. Pumping low vacuum: Close all vacuum valves and start the mechanical pump. After it is running normally (about 1-2 min), open the low vacuum valve to the furnace body, that is, the upper disc valve, and pre-empt the furnace body. Vacuum;
2. Pumping high vacuum: open the lower disc valve and pump the diffusion pump. When the vacuum reaches 15 Pa or less, turn on the diffusion pumps to preheat. Generally, after about 45 minutes, the diffusion pump starts its action, and the disc can be closed. Valve, while opening the main blocking valve to a vacuum of 1.33 10-1Pa or more, you can turn on the heating button to heat the sample.
A: The vacuum gauge has two range meters, the low vacuum range is 1.0×105-1.0×10-1; the high vacuum range is 1.0×10-1-1.0×10-5, and the conversion range is generally started at 2Pa. Note that the vacuum gauge switch should be turned off before the atmosphere is filled in to prevent the gauge from aging.
Note: The upper disc valve and the main blocking valve cannot be opened at the same time.
Seven, the protection atmosphere
Sintering protection can be carried out with high purity argon or nitrogen. The inflation pressure range is usually 7000Pa.
Eight, after the end of the experiment
1. When not in use, the furnace should be kept in a vacuum state (open the mechanical pump - the upper disc valve will vacuum the furnace for about 1 hour, the pressure gauge behind the furnace body will be less than -0.1), otherwise next time Use will result in reduced vacuum efficiency;
2. Turn off the chiller switch;
3. Remove the observation glass of the vacuum furnace (especially the observation window for the infrared instrument) for cleaning;
4. Clean the surface of the electric furnace to keep it clean and tidy;
5. Make relevant records on the experimental book.
6. Before leaving, please check if the water heater air conditioner window is closed. After confirming the error, lock the door and then leave.

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