Abstract: in this lecture
(2) on the classification of glass and metal sealing, pointed out that in addition to the two direct sealing, there is a kind of indirect sealing, in which low-melting glass powder solder has been widely used in indirect sealing.Due to the direct sealing between the lead glass used in the core column of the electric vacuum device and the sodium calcium glass used in the glass shell, the high temperature of 950 ~ 1050℃ is required, which will damage the performance of the cathode and the aspirating material.It is ideal if it can be sealed at 500 ~ 600℃.
Crystal handicraft has man-made crystal and natural crystal 2 kinds, introduce its identify method below:
(2) tongue lick: even in the hot summer dog days, with the tongue lick natural crystal surface, there is a cold and cool feeling.False crystal, there is no cool feeling.
(3) light: natural crystal vertical under the sun, no matter from which Angle to see it, can release beautiful luster.Not with fake crystals.