SJ 3232.4-1989 Determination of crystallization time of low melting welding glass powder SJ3232.4-1989 Standard download decompression password: www.bzxz.net

Standard of the Ministry of Machinery and Electronics Industry of the People's Republic of China Method for determining the crystallization time of low-melting welding glass powder 1 Subject content and scope of application 1.1 Subject content This standard specifies the determination of the crystallization time of low-melting welding glass powder. 1.2 Scope of application This standard applies to low-melting welding glass powder used in color picture tubes and other electronic devices 2 Key points of the method SJ3232.4-89 Since low-melting welding glass powder releases heat during crystallization, the differential thermal analyzer can be used to measure the differential thermal curve between it and the standard sample, and the graphical method can be used to obtain the crystallization time of the low-melting welding glass powder. 3 Instruments and Materials
3.1 Differential thermal analyzer: DT30;
3.2 Recorder: RT-22;
3.3 Analytical balance: sensitivity 0.1mg;
3.4 ​​Sample box: aluminum stamping, external dimensions Φ×h, mm: 6×5; 3.5α-AlO powder.
3.6 Pure zinc flakes, purity 99.999%, dimensions I×b×h, mm: 1×1×0.24 Determination steps
4.1 Wrap the pure zinc flakes in an aluminum box and place them at the bottom of the sample box. Weigh about 50mgα-AlO powder in the sample box and weigh 120±5mg glass powder in another sample box. Put the two sample boxes into the designated sample rack in the furnace at the same time. Cover the furnace cover. Add the furnace cover.
4.2 According to the instrument manual, set the detector knob on DT-30 to PL and DTA, and set the selector switch and rate knob to UP-HOLD. Increase the temperature at 10C·min. The limit temperature is set to 440℃, and the starting temperature needs to be 3℃ lower than the room temperature. Set the thermocouple, range, and selector knob on DA-30 to PL, 100, and DTA respectively. Turn on the power switch on DA-30. 4.3 Turn on the power switch on DT30.
4.4 Turn on the recorder and adjust the pen for recording temperature to "0\" on the recording paper, so that the pen for recording differential thermal curve is in the middle of the recording paper. Then adjust the range of recording temperature to 25mV, the range of recording differential heat to 20mV, and the paper feed speed to 2.5mm·min-l
Approved by the Ministry of Machinery and Electronics Industry of the People's Republic of China on 1989-03-20 and implemented on 1989-03-25
SJ3232.4-89
4.5 Press the ready and start buttons on DT-30. When the second exothermic peak appears on the differential thermal curve, turn off the power and stop the measurement.
SCalculation of test results
Draw tangents on both sides of the second peak on the recorded differential thermal curve to find the distance from the start of insulation to the highest point of the second exothermic peak. The time represented by this distance is the crystallization time, as shown in the figure below. (Use 1: 400 scale directly read)
1 Melting point of zinc;
Crystallization time
Crystallization time diagram bZxz.net
2 Heating curve;
3 Differential thermal curve.
6 Notes
SJ3232.4—89
6.1 Because the starting positions of the temperature recording pen and the differential thermal curve pen are not on the same straight line, the distance ahead of the temperature recording pen should be subtracted when drawing the graph,
6.2 Pure zinc sheet is used as the correction temperature, and its melting point is 420°C. The constant temperature of 440°C needs to be corrected by the measured zinc temperature. The temperature affects the crystallization time. Correction is made according to the following table. Correction table
Time min
Additional instructions:
This standard is under the jurisdiction of the Electronic Standardization Research Institute of the Ministry of Machinery and Electronics Industry, and this standard is drafted by Factory 4400.
The main drafters of this standard are Shi Jifen and Li Guanghui439
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