Method for preparing vitreous body by diffusion of ions through a coating layer

Claim 2

A process as defined in claim 1 comprising creating an electric field across the interfaces between the surface layer of the body and the medium for promoting diffusion.

Claim 3

A process as defined in claim 1 wherein the medium is a molten salt.

Claim 4

A process as defined in claim 4 wherein the molten salt comprises a crystallization-promoting agent.

Claim 5

A process as defined in claim 5 wherein the crystallization-promoting agent provides lithium ions.

Claim 6

A process as defined in claim 1 which comprises exposing said coating layer to a crystallization-promoting agent.

Claim 7

A process as defined in claim 1 wherein the coating layer contains aluminum, and further comprising promoting crystallization of the coating layer by a substance which is in the medium and which provides ions selected from the group consisting of those of Ti, Mn, Mg, Co, Cu, Ni, Zn, and Cr.

Claim 8

A process as defined in claim 1 wherein the coating layer contains zirconium and crystallization of the coating layer is promoted by a substance selected from the group consisting of Fe, Ca, Mg, Ti, and rare earths.

Claim 9

A process as defined in claim 1 wherein the coating layer contains silicon and crystallization of the coating layer is promoted by a halogen.

Claim 10

A process as defined in claim 1 wherein the coating layer contains titanium and crystallization of the coating layer is promoted by a substance selected from the group consisting of Zn, Cd, Bi, Ni, Al, Cr, a halogen, and water vapor.

Claim 11

A process as defined in claim 1 wherein the coating layer subsequent to diffusion comprises at least one crystalline phase formed by a member selected from the group consisting of Al2O3, SiC, SiO2, ZrB2, TiN, TaC, ZrC, TiC, AlB, B4C, TiO2, ZrO2, ZrSiO4, Al2Be3Si6O18, (Al2SiO3) (F,OH)2, Ta2O5, Y2O3 and CeO2.

Claim 12

A process as defined in claim 1 wherein said body is soda-lime glass.

Claim 13

A process as defined in claim 1 wherein said medium includes a substance which provides alkali metal ions and the ion exchange is an exchange of alkali metal ions.

Claim 14

A process as defined in claim 1 wherein the body is soda-lime glass, the coating layer is Al2O3, the medium is potassium nitrate, and diffusion is caused by heating the glass.

Claim 15

A process according to claim 15 wherein the medium contains a crystallization-promoting agent selected from the group consisting of chromium, titanium, manganese, magnesium, cobalt, copper, nickel and zinc, and the agent is contained therein in an amount of at most 10 percent by weight.

Claim 16

A process as defined in claim 1 wherein the body is vitrocrystalline, the coating layer is amorphous titanium and iron oxides, and the medium is potassium nitrate.

Claim 17

A process as defined in claim 1 wherein the body is soda-lime glass, the coating layer is Al2O3 and boron, and the medium is potassium nitrate.

Claim 18

A process according to claim 1 for strengthening a vitreous, vitrocrystalline or ceramic body containing exchangeable ions comprising coating the body with an adherent layer of material different from that of the body prior to exchanging larger ions in the medium for smaller ions in said body through the coating layer and at least partially crystallizing the coating layer.

Claim 19

A process according to claim 1 wherein the body is a vitreous body.

Claim 20

A process according to claim 1 wherein the body is a vitrocrystalline boDy.

Claim 21

A process according to claim 1 wherein the body is a ceramic body.

Claim 22

A process according to claim 1 which consists essentially of: coating onto at least a portion of the body a coating layer which is capable of being in an at least partly crystalline form; contacting the coating layer with a contacting medium containing ions capable of penetrating through the coating layer and into at least a surface layer of the body in exchange for exchangeable ions in said body; effecting ion exchange through said coating layer and between ions initially in the contacting medium and the exchangeable ions; and providing said coating layer with a surface hardness greater than that of the coated surface of the body, said coating layer with greater surface hardness being at least partially crystalline.

Claim 23

A process according to claim 1 which comprises partially crystallizing the coating layer concurrently with the diffusion.

Claim 24

A process according to claim 1 which comprises at least partly crystallizing the coating layer after completion of the diffusion.

Claim 25

A process according to claim 1 which comprises separately applying constituents to the body and reacting the constituents together in situ to form the coating layer.

Claim 26

A process according to claim 1 which comprises modifying the coating layer by reacting at least one constituent in said coating layer with another substance during diffusion.

Claim 27

A process as defined in claim 27 wherein the resulting reaction is accompanied by crystallization in the coating layer.

Claim 28

A process according to claim 1 which comprises modifying the coating layer prior to effecting the diffusion.

Claim 29

A process according to claim 29 wherein the body is a borosilicate glass, the coating layer through which the diffusion is effected is of silicon dioxide, the medium is cesium nitrate, and said diffusion is effected by heating the glass.

Claim 30

A process according to claim 1 wherein the body is a soda-lime glass, the medium is potassium nitrate and the diffusion is effected through a ZrB2 coating layer.

Claim 31

A process according to claim 1 wherein the body is a soda-lime glass, the medium is potassium nitrate and the diffusion is effected through a titanium oxide coating layer.

Claim 32

A process according to claim 1 which comprises imparting to the coating a hardness greater than that of the surface layer, the resulting coating being at least partially crystalline.

Claim 33

A vitreous, vitrocrystalline, or ceramic body strengthened according to the process defined in claim 1.