What should be paid attention use of corundum tube in vacuum tube furnace?

What should be paid attention to when using corundum tube of vacuum tube furnace in vacuum heat treatment furnace?

First, when setting out and sampling, it should not be higher than 140 degrees. High temperature sample sending and sampling may cause fracture of corundum tube. Do not touch the furnace tube in high temperature with low temperature object. In the use of corundum pipe, heat insulation plug should be placed in the pipe. If it is necessary to ventilate the atmosphere, the air flow shall not be excessive, so as to avoid the fracture of furnace tube caused by large temperature difference. When using high temperature corundum furnace tube, bracket shall be added on both sides of the tube to avoid deformation and fracture caused by gravity of the tube.

Second, when using the corundum furnace tube to burn the sample to about 1300 ℃, the water content is required to be less. For the samples with more water content produced in the crystallization water and heating process, it is recommended to first pre burn the sample to drain the water, and then put it into the corundum furnace tube for sintering. The newly purchased furnace tube should be heated to 1300 ℃ once at a heating rate of 5-8 ℃ / min, and then be used for work to eliminate water Stress and contamination removal. The heating speed shall not be too fast, and the cooling curve shall be set for cooling. The heating rate shall not be higher than 10 ℃ / min, and the cooling rate shall be lower than 10 ℃ / min. Be sure to set the cooling rate, and do not directly suspend the program at high temperature.

Thirdly, the corundum furnace tube has the high-quality characteristics of high-purity and high temperature, but the corundum material has poor thermal shock resistance and is not resistant to rapid cooling and heating. It needs careful operation in the use process, otherwise it will cause furnace tube cracking, work interruption and unnecessary loss. The cracking of furnace tube is mainly caused by too large temperature difference, and the temperature rise and fall rate of high temperature furnace tube is better at 5 ℃ per minute. Quench and heat is the important reason for the broken tube of corundum furnace. At last, keep the tube clean, clean the inner wall of furnace tube, and do not leave any sample in the tube.