Title:
Glossing corundum and spinel
United States Patent 2448511


Abstract:
ness of 1780 after glossing by heating, which is comparable to the hardness of mechanically polished corundum, namely 1600 to 2100. Crystalline precious and semiprecious stones treated by the process of the invention have glossy, clear, and scratch-free surfaces which render them useful for...



Inventors:
Barnes, Malcolm H.
Mccandless, Edward L.
Application Number:
US50454443A
Publication Date:
09/07/1948
Filing Date:
10/01/1943
Assignee:
LINDE AIR PROD CO
Primary Class:
Other Classes:
63/32, 427/248.1, 427/376.2, 428/446
International Classes:
C04B41/50; C04B41/86; C30B29/26
View Patent Images:
US Patent References:



Foreign References:
GB243251A1925-11-26
GB502978A1939-03-29
Description:

ness of 1780 after glossing by heating, which is comparable to the hardness of mechanically polished corundum, namely 1600 to 2100.

Crystalline precious and semiprecious stones treated by the process of the invention have glossy, clear, and scratch-free surfaces which render them useful for many purposes. For example. fully heat glossed stones, such as unicrystalline synthetic corundum and spinel, are useful- as jewel bearings. Heat glossed synthetic spinel 1r and corundum rods also may be used as thread guides and tension posts in textile mills. Partially glossed synthetic corundum and spinel rods, having a wavy surface, are particularly useful as thread guides and tension posts because the 1 slightly wavy surfaces provide a series of grooves within which the thread may run.

The process of the invention has been described specifically by way of illustration only.

It is apparent, however, that variations in procedure may be made within the spirit and scope of the invention, as defined in the claims.

What is claimed is: 1. A process for glossing a unicrystalline body of material selected from the group consisting of corundum and spinel comprising applying to a rough surface of such a body in thin film of at least one substance selected from the group consisting of metal oxides and substances forming metal oxides fulfilling at least one of the following requirements: having a melting point lower than such material forming a eutectic with such material, forming a low melting peritectic with such material, and forming a solid solution with such material; and subsequently heat bonding such film to said surface.

2. A process for glossing a unicrystalline body of material selected from the group consisting of corundum and spinel comprisin csg applying to a rough surface of such a body a thin film of a slurry including at least one substance selected from the group consisting of metal oxides and substances forming metal oxides fulfilling at least one of the following requirements: having a melting point lower than such material, forming a eutectic with such material, forming a solid solution with such material, and forming a low melting peritectic with such material; and fusing such film to said surface.

3. A process for glossing crystalline precious and semiprecious stones selected from the group consisting of unicrystalline corundum and spinel comprising vaporizing at least one metal oxide fulfilling at least one of the following requirements: having a melting point lower than such a stone, forming a eutectic with such a stone, forming a low melting peritectic with such a stone, and forming a solid solution with such a stone; condensing a thin film of the oxide vapor on a rough surface of such a stone; and fusing such film to said surface.

4. A unicrystalline corundum body having a glossy scratch-free surface, said body having small surface pits and crevices, said body having bonded thereto over a substantial surface area a film of fused oxide selected from those of calcium, silicon, magnesium, and sodium, said pits and crevices being filled with such fused oxide, said surface having a Knoop hardness of at least 1600, 5. A unicrystalline spinel body having a glossy scratch-free surface, said body having small surface pits and crevices, said body having bonded thereto over a substantial surface area a film ol fused oxide selected from those of calcium, silicon, magnesium, and sodium, said pits and crevices being filled with such fused oxide.

6. A unicrystalline body of material selected from the group consisting of corundum and spinel having bonded thereto over a substantial surface area a film of metal oxide fulfilling at least one of the following requirements: having a melting point lower than such material, forming a eutectic 0 with such material, forming a solid solution with such material, and forming a low melting peritectic with such material, said body having a glossy scratch-free surface.

7. A body as claimed in claim 6, wherein such oxide comprises calcium oxide.

8. A body as claimed in claim 6, wherein such oxide comprises silicon dioxide.

9. A unicrystalline body of material selected from the group consisting of corundum and spinel having bonded thereto over a substantial surface area a film of metal oxide fulfilling at least one of the following requirements; having a melting point lower than such material, forming a eutectic with such material, forming a solid solution with Ssuch material, and forming a low melting peritectic with such material.

10. A unicrystalline corundum body having small surface pits and crevices, said body having bonded thereto over a substantial surface area 30 thereof a film of fused oxide selected from those of calcium, silicon, magnesium, and sodium, said pits and crevices being filled with such fused oxide, said oxide-filmed surface area having a Knoop hardness of at least 1600.

11. A process in accordance with claim 1 wherein said metal is calcium.

12. A process in accordance with claim 1 wherein said metal is silicon.

13. A process in accordance with claim 1 where40 in said metal is magnesium.

14. A body as claimed in claim 6, wherein such oxide comprises magnesia.

MALCOLM H. BARNES.

EDWARD L. McCANDLESS.

45 REFERENCES CITED The following references are of record in the file of this patent: Number 270,018 1,178,256 1,422,216 1,653,918 1,680,681 1,775,868 1,806,589 1,814,219 1,852,840 1,949,884 2,018,056 2,043,867 2,085,757 2,145,732 2,152,754 2,332,424 2,371,486 Number 243,251 502,978 Name Date Chevassus ---------- Jan. 2, 1883 Miller --------------- Apr. 4, 1916 McDougal ---------- July 11, 1922 Martin ------------ Dec. 27, 1927 Herzog ------------ Aug. 14, 1928 Sandmeier --------- Sept. 16, 1930 Espig -------------- May 26, 1931 Jaeger ------------ July 14, 1931 uwa -------------- Apr. 5, 1932 Slayter ------------ Mar. 6, 1934 Delpech ----------- Oct. 22, 1935 Rava --------------- June 9, 1936 KazanJian ---------- July 6, 1937 Nickle -------------- Jan. 31, 1939 Wagner ------------ Apr. 4, 1939 Zwermann ------- Oct. 19, 1943 Walker ------------ Mar. 13, 1945 FOREIGN PATENTS Country Date Great Britain ------ Nov. 26, 1925 Great Britain ------- Mar. 29, 1939