Low-color scratch-resistant articles with a multilayer optical film

1. An article comprising:

a substrate having a surface; and

an optical film disposed on the substrate surface forming a coated surface;

wherein the article comprises a maximum hardness of 12 GPa or greater, as measured by a Berkovich Indenter Hardness Test along indentation depths of about 100 nm or greater, an average transmittance of 85% or greater over a visible spectrum, and a color shift of 2 or less, when viewed at an incident illumination angle in the range from about 2 degrees to about 60 degrees from normal incidence under an illuminant comprising CIE A illuminants, CIE B illuminants CIE C illuminants, CIE D illuminants or CIE F illuminants,

wherein color shift is determined by the equation √((a* 2 −a* 1 ) 2 +(b* 2 −b* 1 ) 2 ), where a* 1 and b* 1 are coordinates of the article when viewed at normal incidence and a* 2 , and b* 2 are coordinates of the article viewed at the incident illumination angle, and wherein the coordinates of the article when viewed at normal incidence and at the incident illumination angle are both in transmittance or reflectance.

2. The article of claim 1 , wherein the optical film further comprises an optical interference layer disposed between a scratch-resistant layer and the substrate.

3. The article of claim 2 , wherein the optical interference layer comprises a first low refractive index (RI) sub-layer and a second high RI sub-layer.

4. The article of claim 3 , wherein the difference between the refractive index of the first low RI sub-layer and the refractive index of the second high RI sub-layer is about 0.01 or greater.

5. The article of claim 2 , wherein the optical interference layer comprises a thickness of about 800 nm or less.

6. The article of claim 2 , wherein the optical interference layer comprises an average light reflection of about 0.5% or less over the optical wavelength regime.

7. The article of claim 2 , wherein the optical interference layer comprises a plurality of sub-layer sets, the plurality of sub-layer sets comprising a first low RI sub-layer and a second high RI sub-layer.

8. The article of claim 7 , wherein the optical interference layer further comprises a third sub-layer disposed between at least one of:

the plurality of sub-layer sets and the scratch-resistant layer; and

the substrate and the plurality of sub-layer sets, and

wherein the third sub-layer has a RI between the refractive index of the first low RI sub-layer and the refractive index of the second high RI sub-layer.

9. The article of claim 7 , wherein the optical interference film comprises up to about 10 sub-layer sets.

10. The article of claim 7 , wherein at least one of the first low RI sub-layer and the second high RI sub-layer comprises an optical thickness (n*d) in the range from about 2 nm to about 200 nm.

11. The article of claim 1 , wherein the article comprises an average transmittance or average reflectance having an average oscillation amplitude of about 5 percentage points or less over the optical wavelength regime.

12. The article of claim 1 , wherein the optical film comprises a sensor layer.

13. The article of claim 1 , wherein the substrate comprises an amorphous substrate or a crystalline substrate.

14. The article of claim 13 , wherein the amorphous substrate comprises a glass selected from the group consisting of soda lime glass, alkali aluminosilicate glass, alkali containing borosilicate glass and alkali aluminoborosilicate glass.

15. The article of claim 14 , wherein the glass is chemically strengthened and comprises a compressive stress (CS) layer with a surface CS of at least 250 MPa extending within the chemically strengthened glass from a surface of the chemically strengthened glass to a depth of layer (DOL) of at least about 10 μm .

16. An article comprising:

a substrate comprising a substrate surface; and

an optical film disposed on the substrate surface forming a coated surface, wherein the optical film comprises a scratch-resistant layer and an optical interference layer disposed between the scratch-resistant layer and the substrate, the optical interference layer comprising at least one set of sub-layers, the set of sub-layers comprising a first low RI sub-layer and a second high RI sub-layer,

wherein the article comprises a maximum hardness in the range from 12 GPa to about 50 GPa, as measured by a Berkovich Indenter Hardness Test along indentation depths of about 100 nm or greater, and

wherein the article comprises a color shift of less than 2, when viewed at an incident illumination angle in the range from about 2 degrees to about 60 degrees from normal incidence under an illuminant comprising CIE A illuminants, CIE B illuminants CIE C illuminants, CIE D illuminants or CIE F illuminants,

wherein color shift is determined by the equation √((a* 2 −a* 1 ) 2 +(b* 2 −b* 1 ) 2 ), where a* 1 and b* 1 are coordinates of the article when viewed at normal incidence and a* 2 , and b* 2 are coordinates of the article viewed at the incident illumination angle, and wherein the coordinates of the article when viewed at normal incidence and at the incident illumination angle are both in transmittance or reflectance.

17. The article of claim 16 , wherein the first low RI sub-layer comprises at least one of SiO 2 , Al 2 O 3 , GeO 2 , SiO, AlO x N y , SiO x N y , Si u Al v O x N y , MgO, MgF 2 , BaF 2 , CaF 2 , DyF 3 , YbF 3 , YF 3 , and CeF 3 , and wherein the second high RI sub-layer comprises at least one of Si u Al v O x N y , Ta 2 O 5 , Nb 2 O 5 , AlN, Si 3 N 4 , AlO X N y , SiO x N y , HfO 2 , TiO 2 , ZrO 2 , Y 2 O 3 , Al 2 O 3 , and MoO 3 .

18. The article of claim 16 , wherein the scratch-resistant layer comprises at least one of AlN, Si 3 N 4 , AlO x N y , SiO x N y , Al 2 O 3 , SixCy, Si x O y C z , ZrO 2 , TiO x N y , diamond, diamond-like carbon, and Si u Al v O x N y .

19. The article of claim 16 , wherein the article further comprises a crack mitigating layer.