Why should graphite paper be placed between the heater and the graphite electrode?
Heater design, the common heater has three shapes, cylinder, cup, spiral, the vast majority of the current heater is cylindrical, as shown in figure. The spiral heater has complicated processing technology and has been eliminated. Cup shaped heater for hemispherical crucible, the bottom melt temperature is more uniform, because the processing technology is difficult, already no use. Nowadays, most of them use cylinder heaters. The cylindrical heater is not only easy to process, but also is related to the large number of flat crucible used in the direct drawing single crystal furnace.
Determine the thickness of the graphite bowl, the thickness of the graphite bowl is generally 3 mm -6 mm, three, determine the diameter of the heater, according to the diameter of the crucible and the thickness of the graphite bowl, calculate the inner diameter of the heater. The gap in the quartz crucible diameter phi = +2 times is +2 times the wall thickness of stone bowl bowl and graphite heater if the graphite bowl wall thickness is a, graphite bowl gap and heater for B (b=5 mm), phi = Phi Phi +2a+2b= within the outer crucible outer crucible +2 (a+b) four, to determine the effective heater the height after practice, the effective length of the quartz crucible heater is high 1.6 to 1.8 times.
. Different single crystal furnace heaters may be of the same size or may be different. The heater is determined according to the size of the Czochralski single crystal furnace and the parameters of the drawn single crystal, and is generally designed in the form of a parallel circuit, and the following parameters. A heater, the heater, the shape of two inner diameters of three, four, the effective length of the heater heater, the heater piece is five thickness and gives the heater diameter. These parameters are determined according to Czochralski single-crystal furnace parameters and its crystal diameter. The power transformer parameters are mainly based on the single crystal furnace heating power: maximum output power, maximum output voltage and maximum output current, diameter and height of the crucible. The design of the heater has the following steps: 1. Selecting and determining the shape of the heater; the heater is made of high purity graphite; the resistivity of the high purity graphite; the heater is usually made into a cylinder at present.
