Protective layer for optical coatings with enhanced corrosion and scratch resistance
An oxidizable metal silicide or metal aluminide is used as one of the outer layers of an optical coating to provide a corrosion and scratch resistant barrier. This layer is initially deposited in an unoxidized or partially oxidized state. In this chemical state it provides corrosion protection to the layers underneath. The metal compound or intermetallic layer has hardness properties greater than most metals and therefore provides significant scratch protection.
1 . A method for making an article with improved corrosion and scratch protection, comprising
depositing an optical coating comprising one or more layers on a substrate,
depositing a layer comprising an unoxidized or partially oxidized or nitrided metal compound or intermetallic on said optical coating to provide a corrosion and scratch protection layer, wherein said metal compound or intermetallic is selected from the group consisting of metal silicide and metal aluminide, and
oxidizing or partially oxidizing said metal compound or intermetallic layer.
2 . The method according to claim 1 ,further comprising heating said substrate in an atmosphere containing oxygen after depositing said metal compound or intermetallic layer on said optical coating.
3 . The method according to claim 1 , wherein said metal compound layer is deposited to a thickness of between 3 to 10 nm.
4 . The method according to claim 3 , wherein said metal compound layer is deposited to a thickness of between 4 to 6 nm.
5 . The method according to claim 1 , wherein the metal portion of said metal compound is selected from the group consisting of chromium, iron, titanium, zirconium, hafnium, niobium, tantalum, molybdenum, tungsten, iron, nickel, aluminum and silicon.
6 . The method according to claim 6 , wherein said metal portion is zirconium.
7 . The method according to claim 1 , wherein the metal compound is zirconium silicide.
8 . The method according to claim 1 wherein said substrate is a transparent article.
9 . The method according to claim 1 , wherein said substrate is glass.
10 . The method according to claim 9 , wherein said optical coating includes one or more layers of TiO 2 , NiCrO x , Ag, NiCr, and SiAlN x .
11 . The method according to claim 10 , wherein the metal compound is zirconium silicide.
12 . The method according to claim 1 , wherein said metal compound is deposited on said substrate by co-sputtering from at least two sources comprising metal and silicon.
13 . The method according to claim 1 , wherein said intermetallic is deposited by co-sputtering from at least two sources comprising a first metal and second metal which are capable of forming an intermetallic layer.
14 . The method according to claim 13 , wherein said intermetallic is an intermetallic compound.
15 . An article with improved corrosion and scratch protection, comprising
a substrate,
an optical coating comprising one or more layers on the substrate, and
an outermost layer comprising a protective metal compound or intermetallic coating, wherein said metal compound or intermetallic is selected from the group consisting of metal silicide and metal aluminide.
16 . The article according to claim 15 , wherein said metal compound is at least partially oxidized.
17 . The article according to claim 11 , wherein said metal compound layer is between 3 to 10 nm thick.
18 . The article according to claim 15 , wherein said metal compound layer is between 3 to 6 nm thick.
19 . The article according to claim 11 , wherein the metal portion of said metal compound is selected from the group consisting of chromium, iron, titanium, zirconium, hafnium, niobium, tantalum, molybdenum, tungsten, iron, nickel, aluminum and silicon.
20 . The article according to claim 18 , wherein said metal portion is zirconium.
21 . The article according to claim 15 , wherein the metal compound is zirconium silicide.
22 . The article according to claim 15 , wherein said substrate is a transparent substrate.
23 . The article according to claim 22 , wherein said transparent substrate is glass with optical coatings deposited on it.
24 . The article according to claim 23 , wherein said optical coatings comprise one or more layers of TiO 2 , NiCrO x , Ag, NiCr, and SiAlN x .
25 . The article according to claim 24 , wherein the metal compound is zirconium silicide.