Tungsten and molybdenum parts used in the thermal field of sapphire

    The introduction of thermal field of sapphire

    In recent years, with the wide application of LED, the demand for sapphire substrate of LED has been increased greatly since 2010. The temperature for sapphire crystal growth is more than 2200℃ and the requirement of temperature stability and environment of thermal field in process of crystal growth is very high. The tungsten and molybdenum material that has the properties of a high melting point and chemical stability and low contamination under a high temperature has been widely used in the sapphire crystal growth furnace. The crystal growth crucibles, heaters, heat insulation barrels, heat shields, thermal field cover plate, seed crystal contact and binding wires used in a crystal growth furnace are all made of tungsten and molybdenum material or tungsten and molybdenum alloy material.

                                                     

   Figure 2. Sapphire production workshop

                                               

      Figure 1. Sapphire                                                                                 Figure 3. Sapphire thermal field

                                                                                                                    diagram of kyropoulos method

    Artificial sapphire production has more than 100 years of history and at present the main sapphire growth techniques are flame fusion method, Czochralski method, EFG method, vertical gradient freeze method, heat exchanger method, temperature gradient method and kyropoulos method, etc. (see Table 1). The sapphire crystal grown with kyropoulos method takes up about 70% of the current market share.

                                  Table 1 Comparison of growth technology

The main growth        technology	Advantages	Disadvantages	Application
Czochralski method	High quality (optical grade), low defect density, large size, high production capacity and relatively low cost	The operation is complicated, the consistency is not high and the rate of finished products is low. It is difficult to grow C axle crystal	More than 70% of the sapphire substrates of LED in the whole world。The United States（Rubicon）、Russia（Monocrystal）、South Korea（Astek）
Czochralski method	The growth status easy to be observed, the size easy to be controlled and crystal shape relatively regular	Great density of defects; the use of iraurita crucible required, high cost; and size is limited	Honeywell in Canada (it was acquired in 2008 by China Silian Group), Saint-Gobain in France   and Sapphire enterprise in Japan.
EFG method	The quality is good.	Crystal direction of large size difficult to be adjusted	Namiki in Japan                  Japan's Kyocera
The temperature gradient method	Simple equipment, convenient operation, no mechanical disturbance, stable interface, high rate of finished products, C axle crystal can be grown	No crystal rotation, thermal field difficult to be even; the crystal to be annealed successively, long cycle and high cost; remarkable forced crucible effect	Photoelectric Materials Division of CAS Shanghai Institute of Optics and Fine Mechanics, and Epistone in Shenzhen, China
Vertical gradient freeze method	Simple equipment, high rate of finished products	High crystal defect density	Yunnan sapphire crystal has been put into mass production, but the price is about half of that of the crystal chip grown by kyropulos method
Vertical horizontal gradient freezing	The crystal size (diameter and  height) and shape relatively unrestricted	Patent is in the hands of STC South Korea	South Korea (STC)
Heat exchanger method	The crystal diameter is big and quality is high	The crystal is short, the equipment and the process requirements are complex, high cost, high technological requirements and the main problem is that the crystal is easy to crack	The United States Crystal System (acquired by GT-Solar of America in July 2010) and China has started to step into this area.
Sapphire growth technique with micro-pulling and shoulder-expanding at cooled center	Crystal integrity is good; original annealing can be achieved, short cycle and low cost	Vulnerable to the impact of temperature fluctuation and difficult in growth of C axle crystal;	HIT Druid Electronic Technology Co Ltd

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Recommended products: 1. tungsten crucible                2.tungsten heater        3.tungsten insulation barrel

                                       4. molybdenum heat shield,     5. top cover plate,       6. bottom cover plate, 

                                       7. molybdenum rack               8. tungsten seed crystal contact 

                                       9. tungsten and rhenium binding wire   

                                      10. copper flange ring, 11. molybdenum cover crucible (spinning pressure crucible)

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Call us if you have any requirement:

BEIJING TOPONE TUNGSTEN& MOLYBDENUM TECHNOLOGY CO., LTD

Contact: Li Shuqing

Mobile:13501237966130

Telephone: 010-61705387

Fax: 010-61705847

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