fashion jewelry wholesale in mumbai Talk about the application of gemstone crystal growth method and the decline method in gemstone crystal growth

polki diamond jewelry wholesale Liao Yongjian Tang Yuanfen
This About: Liao Yongjian, the third member of the China Treasure Association Artificial Gem Professional Committee, and the manager of Shanghai Xinman Sensing Technology Research and Development Co., Ltd.
The Tang Yuanfen, the second and third sessions of the China Treasure Association Artificial Gem Professional Committee, senior engineer of Qinghua Company, Shanghai Institute of Silicon Academy, Shanghai Academy of Sciences.
If artificial gemstone crystals, with its unique crystal clear, colorful, glorious attributes, and their good physical chemistry and optical properties, have important appreciation and collection value, and have many important industrial uses, in jewelry, The fields of jewelry and functional crystals are widely used. According to incomplete statistics, there are more than 30 synthetic gems that have been successfully studied and put into mass production in the world today, of which more than 10 are particularly important. Our common synthetic gemstones include artificially synthetic sapphire, ruby, cubic oxidation, emerald, crystals, spinels, golden redstone, golden green cat eyes, diamonds, etc. Colorless sapphire is widely used in high -temperature -resistant and high -pressure devices, wear -resistant devices, special windows, infrared guidance, missile rectification hoods and other national defense, military, and scientific research high -tech fields. (LD) The first choice of the industry is the key material for manufacturing the blue light -emitting diode of the semiconductor. It is widely used in the energy -saving emitting body of mobile power supply. At present, the entire international market demand is large. Most of these gem crystals are very high. For example, the melting points of gems, spinels and cubic oxidation are 2050 ° C, 2100 ° C, and 2700 ° C. In order to facilitate the specific explanation, this article takes the growth of the corrian gemstone as an example.
It the growth of crystals with a melting point temperature of up to 2000 ° C, and there are great difficulties in heating methods and ingredients.
1) The heating method can reach the following 3 types of heating above 2000 ° C:
· hydrogen oxygen flames: relatively simple heating methods, but the temperature gradient control is difficult; Heating: It is necessary to conduct electricity for ingredients or crystal raw materials, otherwise it will not be heated;
. Use graphite/molybdenum as the resistance of the heating material to heat.
2) 材 Materials: Mainly with graphite, molybdenum, and crickets. These ingredients must be used in vacuum or protective atmosphere. This greatly improves the requirements of the equipment, and the cost of using these crickets is not expensive. In order to solve the problem of the above -mentioned 料 materials, people have developed the technology of non -坩埚 and using raw materials itself.
The selection of different heating methods and 坩埚 is classified below to obtain the roughly different growth methods of gemstone crystals as shown in Table 1.
Table 1 Different heating methods and 坩埚 combinations form different crystal growth methods
The main method of growing gemstone crystals from the melt, basically the growth of gemstones can be used in the gemstone series. Among them, the flame melting method is relatively easy to heat the use of hydroxide flames. The growth equipment of the entire crystal is relatively simple, at the same time, the growth efficiency is relatively high, the cost is relatively low, it is very suitable for industrial production. It is the most commonly used method for gemstone crystals. However, this method has large temperature gradients, leading to large temperature of transistor stress requires high temperature annealing and strict requirements for powder; poor crystal quality is limited to applications other than decorative uses.
This method is mainly used to grow cubic oxidation. It first heats the metal induction buried in ZRO2 raw materials and heats the ZRO2 around the metal tadpoles to above 1200 ° C. The melting, by controlling the cooling device around the raw material to make the surface layer of the raw material not melt, forming a layer of unbound solid shell to play a pupa. The molten ZRO2 melt is crystal to obtain cubic oxidation crystals during the decline of the base.
The process of melting method in the area is to sinter or suppress the crystal material into a rod, and then put the fixed material rod in the insulation pipe, rotate and drop (or move the heater) to melt it. The melting area is in a floating state With the support of the surface tension alone, it can obtain a crystal of purification or heavy crystal.
The commonality of these methods is not to be used or used by yourself. The growth equipment is greatly simplified, but at the same time, the quality of the crystal is limited. It is not good for developing functional uses. Application.
In order to obtain a substrate or window -level rigid jade crystal, other methods must be adopted, such as Tiram, Division method, descending method, or bubble method. Because these technologies are more advanced, the craftsmanship is difficult, and the world is currently in the world. At present, the world is in the world. The scale and capabilities of industrialized production cannot meet market demand. It is understood that only Russia, Japan, the United States and other countries currently have achieved the quality and size of the substrate greater than 2 inch
1 inch = 25.4mm. Industrial production of crystals required. These methods are heated by inductive or resistor (graphite) and molybdenum. It can better control the temperature field required for crystal growth. The disadvantage is that graphite and molybdenum must work under the protection of vacuum or inert gas. Therefore It is relatively high and the production cost is relatively large, but this cost is acceptable for the substrate -level Jade.
The research on the use of these methods in China to grow substrates/window -level jade crystals in China is mainly:
The "guided warm ladder method" in Shanghai Optical Machinery grows 2 to 4 inches high -quality sapphire crystals, breaking through internationally recognized The technical difficulties of sapphire crystal growth have laid a good foundation for the industrialization of large -sized sapphire crystals.
The high -quality colorless sapphire with a diameter of 120mm and 3kg of 3kg in 1993 in Shanghai Optics Machinery Institute.
The independent innovation research and development of Lanjing Technology Co., Ltd., Yuxi City, Yunnan Province, successfully developed independent intellectual property rights and mixing induction heating 坩埚 decreased.
Themid -grade colorless sapphire with a diameter of 80mm and 90mm thick in 2000 in the Beijing Artificial Crystal Institute in 2000.
In from the above, although most of the growth methods of Jade gemstone crystals are generally introduced, most of the 坩埚 decline method is not introduced, but in actual situation, it should be a useful gem growth method. The so-called tadpole method, also known as the gradient furnace method or the Bridgeman-method, is a common method for growing crystals from the melt. It is usually slowly decreased by the loaded melting 坩埚 in the crystal furnace. When the temperature gradient is large, the melt is crystals from bottom to top crystals. The typical crystal furnace structure schematic diagram is shown in Figure 1. This process can also be risen with a crystalline furnace along the pyrophology, or the 坩埚 and crystal furnaces are not moving, but it is completed by slowly cooling the crystal furnace. It can be seen that the essence method is essentially the decline method.
FIG. 1 降 Swatching of the crystal furnace structure
坩埚 The decreased method has the following advantages compared to the flame melting method, Tira method, etc.:
1) The warm field is easy to adjust. It can easily obtain the required temperature field by setting up multi -level heating, changing the temperature and adjusting thermal inspection method, which is very important for improving the quality of the crystal.
2) Very convenient for growing large -sized crystals. The diameter and height of this method can reach hundreds of millimeters.
3) It can grow multiple crystals at the same time, and it is easy to master the process conditions.
But it also has the shortcomings that are difficult to observe directly, requires vacuum or inert gas to protect the equipment.
The use of 降 decline to grow Gangyu crystals, which can be used as a cricket, and uses high -frequency induction heating or graphite resistance. Put the alumina raw material in a seed with seed crystals, and then install a furnace to prepare for growth. Smash the furnace body or fill the protective gas, and then heated melting. After a few hours of constant temperature, the drop -down speed of 0.5 to 5mm/h slowly slowly passes the crystal area with a temperature gradient of 20-40 ° C/cm. Need jade crystals.
In order to make the 降 reduction method better adapt to the growth of gemstone crystals, it is necessary to develop new technologies on the basis of the ordinary felling method. The possible development direction is:
1) Multi -坩埚 Technology: 坩埚 Decrease The law can grow more in one furnace, which is very meaningful for increasing production and finished product rates, reducing production costs, and has an absolute advantage compared to the ritual. Due to the obviously destroying the uniform symmetry of the warm field, it greatly increases the difficulty of growth, and it is necessary to make a reasonable design of the multi -坩埚 reduction furnace. It can be said that the reasonable use of multi -坩埚 technology makes the production cost lower than the possibility of the flame melting method.
2) Following agent 坩埚 Decrease method: The fuse method is particularly suitable for oxide crystals with high growth temperature and high difficulty. The gemstone crystal is exactly this type of crystal. However, there are great limitations of the fuse method, such as small temperature gradients, and the crystal size is not large; If these two methods can be combined, it is good for gemstone crystals. For example, PBF2-PBO is used as a fuse, and it can obtain a colorless sapphire crystal with lower density density at 1350 ° C, but its size, high cost, and difficult to produce in large quantities. If it can be combined with the decrease method, it may be improved.
3) Introduction of forced convection: By introducing forced convection, the material transmission and heat transmission in the melt can be significantly accelerated, thereby improving the quality of the crystal, especially for gemstone crystals, because its melting point temperature is high, the viscosity is large, and the effect is particularly obvious. The way to introduce forced convection has accelerated rotation technology or mixing technology. For example, Yuxi City Lanjing Technology Co., Ltd., Yunnan Province, has developed a single crystal growth technology with independent intellectual property rights and mixing induction heating. The high -quality sapphire crystal rods of 4 inches and crystal defects such as 4 inches and no crystal boundaries have realized the production capacity of 150,000 tablets of 150,000 tablets of 2.4 -inch sapphire single crystal models an annual production diameter. Compared with the traditional decline method of the traditional decline, the growth process is stable, the production cost is low, the finished product rate (up to 90%), and the technology has reached the advanced domestic level.
In all, as a commonly used crystal method, the 坩埚 drop method should be able to make a lot of actions in the growth of gemstone crystals through further experimental research.
The reference
He Xuemei, Shen Caiqing. 2005. Herbal artificial synthesis technology. Beijing: Chemical Industry Press.
Wu Xing, Wu Kang. : Cn1 683608a.
Xu Jiayue, Fan Shi. 2002. The decline of oxide crystals. With application. Beijing: Chemical Industry Press.
Zhang Kecheng, Zhang Leyi's. 1981. Crystal growth. Beijing: Science Press.
Zou Meng, Fan Zhida, Li Nan. 2000. Study of defects. Journal of artificial crystals, 29 (1).