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Use skills and special attention of vacuum sintering furnace

Views: 0     Author: Site Editor     Publish Time: 2022-12-23      Origin: Site


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Vacuum sintering furnace is mainly used for the sintering process of semiconductor components and power rectifier devices. 

It can be used for vacuum sintering, gas sintering and conventional sintering.

It is a novel process equipment in the series of special semiconductor equipment. 

It has novel design concept, convenient operation, compact structure, and can complete multiple process flow in one equipment.

 Can also be used in other fields of vacuum heat treatment, vacuum brazing and other processes. What are the precautions for using vacuum sintering furnace? 

What contingency plans are in place for daily use? Let's take a look!

First, the use of vacuum sintering furnace necessary skills

Vacuum sintering furnace is in the vacuum after hydrogen filling protection state, using the principle of medium frequency induction heating,

 so that the tungsten crucible in the coil to produce high temperature, through the heat radiation conduction to the work, 

suitable for scientific research, military units to refractory alloy such as tungsten, molybdenum and alloy powder forming sintering. 

The place where the electric furnace is installed should meet the requirements of vacuum sanitation, the surrounding air should be clean and dry, 

and there should be good ventilation conditions, and the working place is not easy to raise dust. Vacuum furnace

Daily use skills of vacuum sintering furnace:

1. Check whether all parts and accessories in the control cabinet are complete and intact.

2. The control cabinet is installed on the corresponding foundation and fixed.

3, according to the wiring diagram, and refer to the electrical schematic diagram, connect the external main circuit and control circuit, and reliable grounding, to ensure the connection is correct.

4, check the electrical movable part should be free of movement, no card phenomenon.

5, insulation resistance should not be less than 2 megohm.

6. The valves of the vacuum electric furnace must be in the closed position.

7. The control power switch is placed in the off position.

8, manual pressure control knob counterclockwise rotation head.

9, alarm button on the open position.

10. Complete the connection of circulating cooling water of the equipment according to the plan. It is suggested that the user connect a spare water (available tap water) to the total inlet and outlet pipe of the equipment to prevent the sealing ring from burning out due to the failure of circulating water or power failure.

It is especially reminded that the following points should be paid special attention when using vacuum sintering furnace:

1. Because the mold is generally prepared by the user, the mold material is basically high purity graphite, and its pressure tolerance limit is 40MPa. It is recommended that the user use it below 30MPa, which is safer.

System allows pressure (tons) = upper or lower punch area ×30MPa

2, thermocouple for tungsten rhenium type, used will be brittle, can not contact. If damaged, replace it in time. The model number is W2.

3, winter should pay attention to the circulation of water to keep warm, otherwise easy to occur pipe burst.

4. The furnace body should be kept vacuum after use, because the thermal insulation layer in the furnace is susceptible to moisture, so that the next vacuum pumping will be faster.

5, because the equipment is more complex, it is recommended that special personnel use, special personnel are responsible for the strict implementation of pre-use training for the novice, post-use inspection, operation and use of records and other equipment use regulations.

6, the hot press furnace can also be used as a vacuum sintering furnace, for vacuum sintering furnace, pay attention to the crucible placed in the furnace, after covering the thermal insulation screen cover do not forget to cover the small cover in the middle. Otherwise it is easy to burn the furnace.

7. Before operation, we should clean and observe the window glass, clean the inner wall of the furnace, observe the water pressure, observe whether the graphite in the furnace is damaged, observe whether the instrument is normal after power-up, and test whether the hydraulic system can work normally.

8. After one year of use, the instrument should be sent to the metering department for proofreading.

2. Emergency method of vacuum sintering furnace

Cooling water anomaly

1. Confirm that the heating power supply has stopped.

2. If water leakage occurs outside the furnace and the cooling water is abnormal, emergency measures should be taken as soon as possible. If the water can be guaranteed, please continue to keep the vacuum.

3. When the cooling water is abnormal, the equipment is in the stopped state, and the emergency cooling water is connected immediately.

4, in the high temperature (more than 200℃ is regarded as high temperature), if the cooling water stops, if the emergency water supply, water cooling electrode, heat exchanger, vacuum chamber shell and the pump may be damaged.

Cessation of compressed air

1. When the compressed air is abnormal and the equipment is in the stopped state, go to the spare compressor room as soon as possible and let it resume work.

2. If the compressed air in the vacuum is abnormal and the recovery takes a long time, the vacuum should be terminated and the equipment should stop.

Sudden power failure

1. In case of power failure, if the water is cut off, the standby cooling water should be connected immediately and the water source should be connected.

2, if in the non-heating, heating and cooling, can be recovered as soon as possible, restart the equipment, continue to operate if it takes a long time, then the equipment will remain in the original state.

3, if is heating and cooling, can be restored as soon as possible, restart the equipment, if it takes a long time, keep the original state, let the equipment cool down naturally.

The heating power supply is disconnected

1, low water pressure, when the water pressure is lower than 0.15MPa, pressure gauge alarm.

2. Ground fault.

3, vacuum discharge, water cooled electrode joint and heater connection must be firmly connected, and reflection screen insulation.

4, if the pressure in the furnace is 13.3-66.5Pa (this vacuum is prone to discharge). The cause of power failure can be considered as discharge caused by dielectric breakdown.

5 Stop aerating gas (argon or nitrogen)

1. Before vacuuming starts, if the gas filling time is long or cannot be filled, please confirm whether the gas pipeline is blocked.

2. If there is no problem with the gas pipeline, check the action of the solenoid valve and the gas filling valve. For the sake of safety, all the equipment associated with it should be stopped and then checked.

3. When charging into the vacuum chamber cannot be stopped, all gas systems including the gas supply valve and piping should be closed when the pressure relief valve is operating.

4. Confirm whether there is any air leakage in the gas filling piping. If there is, it will affect the quality of the product.

Vacuum chamber pressure deteriorates

1. When the vacuum exhaust time is longer than usual, the equipment should be stopped for inspection. According to the influence of gas discharge in different states of the vacuum chamber structure, there is also the situation of pressure rise.

2. Confirm the effect of gas leakage and venting through pressure rise test or helium leak detection.

The above content is to introduce the use of vacuum sintering furnace necessary skills and daily emergency methods, in a vacuum and protective atmosphere, the metal, ceramics and some refractory metal intermediate compound powder heating sintering, to obtain a certain density and a certain mechanical properties of the material, generally using two processes; Namely pressure sintering and non-pressure sintering. Pressure sintering has the characteristics of high temperature, high vacuum degree and high heat pressure

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