Modernization of heater unit for the machine for growing sapphire single crystals by Kyropoulos method

Is actual for machines for growing crystals with mass more 60 kg
The main upgrade is to use a new type of heater.

Standard heater

Modernized heater

Advantages of the new heater:

• absence of heating elements in the lower part of the heater unit (under the crucible);
•  all tungsten rods are straight, there are no bent elements, which provides higher reliability of the heater (30 processes without a single breakdown), the total service life of the heater is doubled compared to the standard one;
•  lower price, by reducing the number of tungsten rods, by lack of WRe wire and simplifying the manufacture of the heater;
•  change in the temperature field, which is why there is a change in the axial and radial gradient in the melt. Reducing the axial gradient leads to an improved germination of the crystal cone. An increase in the radial gradient leads to a decrease in the sticking of the crystals.

After the modernization of the heater unit, we were able to control the shape of the crystallization front of the growing crystal. In certain periods of crystal growth, it was possible to change the heat dissipation from the rack.

Maximum heat dissipation

Middle heat dissipation

Mainimum heat dissipation

Due to the controlled crystallization front it is possible to obtain practically defect-free crystals. Using our updated software, in which all operations during crystal growth are maximally automated, we achieved stable high results.

Modernization of the heater unit allowed us to obtain the following results:

• reduction of power consumption of machine by 15-20%;
• increase in yield of 15-30%;
• reduction of operating costs due to increased reliability of the heater, its durability and cost reduction.