JPS5945998A - Preparation of corundum - Google Patents

Abstract

PURPOSE:To prepare red orange-colored jewels inexpensively, by molding and sintering a corumdum raw material blended with chromium oxide and nickel oxide as a color producing reagent into a cylindrical shape to give a raw material, heating it in infrafed rays using corumdum seed crystal. CONSTITUTION:Aluminum oxide as a main bomponent, 0.2-0.5wt% chromium oxide and 0.2-0.5wt% nickel oxide as a color producing reagent based on the total amount, respectively, are powdered, blended, packed into a rubber tube, and molded into a cylindrical rod by rubber pressing method. It is sintered in an electric furnace at 1,200-1,700 deg.C to give a raw material, and corumdum crystal or sintered corumdum is used as a seed crystal. The material rod 3 and the seed crystal 4 are molted by the artificial source lamp 2 set at one foucs of the ellipsoidal mirror 1 by a production unit for single crystal under concentrated heating by infrared rays shown by the figure, and the top and bottom shaft 5 and 6 are dropped while being rotated, to synthesize the crystal. Red orange- colored Paparachia sapphire can be prepared inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing corundum using an infrared concentrated heating single crystal MJ production apparatus.

The color of corundum becomes ruby if chromium oxide is used as a coloring agent, and blue sapphire if titanium oxide or ferric oxide is used as a coloring agent. In the present invention, Padparadscha sapphire using chromium oxide or nickel oxide as a coloring agent will be described.

The main component is aluminum oxide, and chromium oxide and nickel oxide are added as coloring agents to the total Ll, each at 02W% to 0.5%.
w%, 0.2 w% to 0.5 w% is added to the milk drum,
Mix thoroughly. At this time, if the amount of nickel oxide is less than 0.2 w%, it is unsuitable because the nickel oxide will evaporate during the synthesis, and if it is more than 0.5 w%, the yellow color will become too strong, which is unsuitable. Further, if the chromium oxide content is less than cO,2W% for all sets, the red color will be weak and unsuitable, and if it is more than 0.5W% for the whole set, the red color will be too strong and unsuitable. Next, the mixed powder is packed into a rubber tube, and the air inside the tube is removed. This is formed into a cylindrical rod using the wrapper press method. This rod is sintered at 1200°C to 1600°C in an electric furnace. At this time, temperatures below 1200° C. are not suitable because sintering is insufficient and many air bubbles are incorporated into the crystal during synthesis. Also 1700℃
Above this, the degree of sintering does not change.

Using this sintered body as a raw material and a corundum single crystal or a corundum sintered body as a seed crystal, a single crystal is synthesized using an infrared concentrated heating single crystal manufacturing apparatus as shown in FIG. The synthesized crystals are reddish-orange.

Among the corundum crystals, the reddish-orange crystal is called Pavaratia sapphire, and it is a very rare gemstone that only produces Srilan power, and is very expensive. The present invention has made it possible to provide this precious gemstone to the general public at a low cost.

Examples will be described below to make the effects of the present invention more clear.

<Example 1> (1) Raw material rod production method Aluminum oxide 2988? Chromium oxide 0061i′ nickel oxide
0061 The above three kinds of raw material powders are thoroughly mixed in an alumina pestle. This is packed into a rubber tube, the air inside the tube is removed with a vacuum pump, and the 3000
"F'/C/J pressure 10 words (φ) x 120vn
(1) Shape into a rod. This bar is sintered in a Keramax electric furnace at 1600°C.

(2) Synthesis method Crystals are synthesized under the following conditions using the equipment sound shown in Figure 1.

Seed crystal Corundum single crystal Growth direction (100) Growth rate 2 wn / H Upper shaft rotation speed 3 Orpm (Top, classic rotation)
Lower shaft rotation speed: 30 rp+n Growth atmosphere: Air Synthesis time: 50 hours (3) Result: A reddish-orange oval rod-shaped single crystal was synthesized.

<Example 2> (1) Raw material rod production method Aluminum oxide 29.70 f Chromium oxide
0.159 disokel oxide
015v The following operations follow <Example 1>.

(2) Synthesis method According to <Example 1>.

(3) Results Crystals with a deeper reddish-orange color than in Example 1 were synthesized. In addition, the crystals were oval and rod-shaped.

[Brief explanation of drawings]

As shown in Fig. 1, an artificial generator lamp (2) is placed at one focal point of the spheroidal mirror (1), and the light is focused at the other focal point, and the raw material rod (3) and seed crystals ( 4) is melted to form a zone. And upper and lower shaft 7
(5) and (a) are lowered while rotating to synthesize crystals. Furthermore, it is possible to change the growth atmosphere by flowing an appropriate gas into the quartz tube (7). Applicant Suwa Seikosha Co., Ltd. Patent Attorney Tsutomu Mogami

Claims (1)

[Claims] (1) A corundum raw material containing aluminum oxide as a main component and chromium oxide and nickel oxide as coloring agents is packed into a rubber tube and formed into a cylindrical rod by a rubber press method. This is sintered at 1200°C to 1700°C in an electric furnace. A method for producing corundum, which comprises using this rod as a raw material, using a corundum crystal or a sintered body of corundum as a seed crystal, and using an infrared concentrated heating single crystal production apparatus as shown in FIG. (2. In claim 1, each of chromium oxide and nickel oxide as coloring agents is 0.2% of the total amount.
The method according to the same item, which comprises setting the content to w% to 0.5 w% and 0.2 w% to 0.5 W%.