GLASS SHEET WITH HIGH NEAR-IR TRANSMISSION AND VERY LOW VISIBLE TRANSMISSION

Abstract

A silicate-type glass sheet that includes 0.002-1.1% total iron (expressed as Fe.sub.2O.sub.3), greater than or equal to 0.005% manganese (expressed as MnO), and optionally 0-1.3% chromium (expressed as Cr.sub.2O.sub.3). The sum of the contents of total iron, manganese, and chromium, expressed as weight percentages are greater than or equal to 1% of the total weight of the glass. The ratios R1, defined as Fe.sub.2O.sub.3*/(49+0.43(Cr.sub.2O.sub.3* —MnO*)), and R2, defined as Fe.sub.2O.sub.3*/(34+0.3(Cr.sub.2O.sub.3*—MnO*)), both being less than 1. Fe.sub.2O.sub.3*, MnO* and Cr.sub.2O.sub.3* represent the relative percentages with respect to the sum of (Fe.sub.2O.sub.3+MnO+Cr.sub.2O.sub.3). Such a glass sheet shows a very low visible transmission together with high IR transmission in the region 1000-2000 nm, especially at wavelengths of interest between 1050 and 1550 nm, thereby valuable within the context of autonomous cars, in particular those fully integrating LiDAR systems.

Claims

1. A silicate-type glass sheet having a composition comprising, in a content expressed as weight percentages, by total weight of glass: TABLE-US-00011 total iron (expressed as Fe.sub.2O.sub.3) 0.002-1.1%; Manganese (expressed as MnO) and optionally, .sup. ≥0.005%; Chromium (expressed as Cr.sub.2O.sub.3)    0-1.3%, and wherein a sum (Fe2O3+MnO+Cr2O3) of the contents of total iron, manganese and chromium, expressed as weight percentages, ≥1% a ratio R1 defined as Fe.sub.2O.sub.3*/(49+0.43(Cr2O3*-MnO*))<1; and a ratio R2 defined as Fe.sub.2O.sub.3*/(34+0.3(Cr2O3*-MnO*))<1; Fe.sub.2O.sub.3*, MnO* and Cr2O3*being relative percentages with respect to the sum (Fe.sub.2O.sub.3+MnO+Cr.sub.2O.sub.3).

2. The silicate-type glass sheet according to claim 1, wherein the composition comprises: manganese (expressed as MnO)≤4%.

3. The silicate-type glass sheet according to claim 1, wherein the composition comprises: manganese (expressed as MnO)≤3%.

4. The silicate-type glass sheet according to claim 1, wherein Fe.sub.2O.sub.3+MnO+Cr.sub.2O.sub.3)≥1.1%.

5. The silicate-type glass sheet according to claim 1, wherein TABLE-US-00012 Manganese (expressed as MnO) >1%; and Chromium (expressed as Cr.sub.2O.sub.3) 0-0.15%.

6. The silicate-type glass sheet according to claim 5, wherein the composition comprises: total iron (expressed as Fe.sub.2O.sub.3) 0.002-0.1%.

7. The silicate-type glass sheet according to claim 5, wherein the composition comprises chromium (expressed as Cr.sub.2O.sub.3) 0-0.1%.

8. The silicate-type glass sheet according to claim claim 5, wherein the composition is free of Cr.sub.2O.sub.3.

9. The silicate-type glass sheet according to claim 1, wherein the composition comprises: TABLE-US-00013 Manganese (expressed as MnO) 0.005-1%; and Chromium (expressed as Cr.sub.2O.sub.3) 0.2-1.3%.

10. The silicate-type glass sheet according to claim 9, wherein the composition comprises: Manganese (expressed as MnO) 0.03-1%.

11. The silicate-type glass sheet according to claim 1, wherein a ratio R3, defined as MnO/(MnO+Cr.sub.2O.sub.3)>0.7.

12. The silicate-type glass sheet according to claim 11, wherein R3>0.9.

13. The silicate-type glass sheet according to claim 1, wherein the glass sheet has a TLD4 lower than 5%.

14. The silicate-type glass sheet according to claim 1, wherein the glass sheet has a T.sub.1050 higher than 82%.

15. The silicate-type glass sheet according to claim 1, wherein the glass sheet has a T.sub.1550 higher than 85%.

16. The silicate-type glass sheet according to claim 2, comprising manganese (expressed as MnO)<3%.

17. The silicate-type glass sheet according to claim 6, wherein the composition comprises chromium (expressed as Cr.sub.2O.sub.3) 0-0.1%.

18. The silicate-type glass sheet according to claim 4, wherein the composition comprises: TABLE-US-00014 Manganese (expressed as MnO) 0.005-1%; and Chromium (expressed as Cr.sub.2O.sub.3) 0.2-1.3%.

19. The silicate-type glass sheet according to claim 18, wherein the composition comprises: Manganese (expressed as MnO) 0.03-1%.

Description

EXAMPLES

[0096] Different glass sheets/samples according to the invention and not according to the invention (comparative) were prepared, with variable amounts of total iron, manganese and chromium, as 3 sets of examples.

[0097] For the preparation of the glass samples from sets #1-2, the starting materials were mixed in the powder form and placed in a crucible for the melting, according to an identical base composition specified in the table below, and to which were added starting materials comprising total iron, manganese and chromium in variable amounts as a function of the contents targeted in the final composition (it should be noted that the iron being already, at least in part, present in the starting materials of the base composition as impurity).

TABLE-US-00007 Base composition Content for Sets #1-2 [% by weight] CaO 8.86 K.sub.2O 0.01 Na.sub.2O 12.96 SO.sub.3 0.41 Al.sub.2O.sub.3 0.03 MgO 4.07 SiO.sub.2 to 100%

[0098] For the preparation of the glass samples from set #3, the starting materials were mixed in the powder form and placed in a crucible for the melting, according to a varying base compositions, and to which were added starting materials comprising total iron, manganese and chromium in fixed amounts.

[0099] The optical properties of each sample, moulded and processed in the form of a sheet, were determined on a Perkin Elmer Lambda 950 spectrophotometer equipped with an integrating sphere with a diameter of 150 mm, and in particular: [0100] the near-infrared transmission was determined according to the ISO9050 standard for a thickness of 4 mm at a solid angle of observation of 2° and for specific wavelengths, namely 1050 nm (T.sub.1050) and 1550 nm (T.sub.1550); [0101] the light transmission TL was also determined according to the ISO9050 standard for a thickness of 4 mm at a solid observation angle of 2° (with illuminant D65) and for a wavelength range between 380 and 780 nm.

[0102] Set #1

[0103] Examples 9 to 13 correspond to glass sheets according to the invention. Example 1 (comparative) corresponds to a low-iron glass with chromium and cobalt according to WO2015/091106. Examples 2-7 (comparative) correspond to glass sheets with manganese and chromium, not in accordance with the invention. Example 8 (comparative) corresponds to a glass sheet with manganese, not in accordance with the invention.

[0104] Each Example 9-13 according to the invention was optimized so as: [0105] to maximize its transmission of near infrared radiation, especially at 1050 and 1550 nm, to reach in particular values above 80% and better above 85-90%; [0106] while minimizing its visible transmission TL, in particular to reach values<20% and more preferably values below 10%, 5% (reaching then a good opacity).

[0107] Table 1 presents the optical properties for Examples 1 to 13, their respective amounts of iron, manganese and chromium (and cobalt), their sum (Fe.sub.2O.sub.3+MnO+Cr.sub.2O.sub.3, mentioned as “Sum”) and their determined ratios R1 and R2.

TABLE-US-00008 TABLE 1 EX1 EX2 EX3 EX4 EX5 EX6 EX7 EX8 EX9 EX10 EX11 EX12 EX13 Fe.sub.2O.sub.3 (wt %) 0.01 1.2 0.6 0.85 0.6 0.4 0.3 0.11 0.015 0.013 0.015 0.015 0.187 MnO (wt %) / 0.2 0.3 0.4 0.8 0.3 0.5 1.4 2.36 1.4 1.4 0.8 0.73 Cr.sub.2O.sub.3 (wt %) 0.07 0.32 0.16 0.11 0.1 0.3 0.2 0 0 0 0.14 0.6 0.27 Co (wt %) 0.21 / / / / / / / / / / / / Sum 0.08 1.72 1.06 1.36 1.50 1.00 1.00 1.51 2.38 1.41 1.56 1.42 1.19 Fe.sub.2O.sub.3* (%) / 70 57 63 40 40 30 7 1 1 1 1 16 Cr.sub.2O.sub.3* (%) / 19 15 8 7 30 20 0 0 0 9 42 23 MnO* (%) / 12 28 29 53 30 50 93 99 99 90 57 61 R1 / 1.34 1.31 1.57 1.38 0.82 0.83 0.80 0.10 0.14 0.07 0.02 0.49 R2 / 1.93 1.88 2.26 2.00 1.18 1.20 1.18 0.15 0.22 0.10 0.04 0.70 TL (%) 0.4 39.3 59.3 61.6 66.0 35.9 40.5 32.0 4.5 11.9 1.3 0 0.8 T.sub.1050 (%) 54.8 28.7 46.9 33.4 50.1 87.6 89.8 90.8 88.9 90.0 87.6 83.0 86.9 T.sub.1550 (%) 0.1 51.9 65.8 55.6 68.1 90.2 91.3 91.8 91.7 91.8 91.6 90.9 91.5

[0108] Table 1 shows that the presence of total iron, manganese and optionally chromium in contents according to the invention while respecting the conditions put on the “sum”, R1 and R2 makes it possible to obtain a glass sheet with a visible transmission that is very low (11.9 to 0%) and with high transmission at 1050 nm (83-90%) and 1550 nm (90.9-91.8%). Not realizing one of the conditions of the invention leads to deteriorate greatly at least one of TL or T.sub.1050, 1550.

[0109] First, concerning example 1, the results show that, even if this glass is “opaque” due to its TL very close to 0, its transmissions at the wavelengths of interest (1050 and 1550 nm) are not satisfying: poor performances at 1050 nm (T.sub.1050=54.8%) and almost complete absorption of the radiation at 1550 nm (T.sub.1550=0.1%). This glass sheet was designed to be performant in transmitting lower IR wavelengths, near 850-950 nm (T.sub.850 of EX1=87.5%).

[0110] FIG. 1 represents the curves in transmission between the wavelengths 300 and 2000 nm (gathering the visible and near infrared regions) for Examples 3, 6 and 12.

[0111] Set #2

[0112] Examples 14-23 correspond to glass sheets according to the invention.

[0113] Table 2 presents the optical properties for Examples 14 to 23, their respective amounts of iron, manganese and chromium, their sum (Fe.sub.2O.sub.3+MnO+Cr.sub.2O.sub.3, mentioned as “Sum”) and also their determined ratios R1, R2 and R3.

TABLE-US-00009 TABLE 2 EX14 EX15 EX16 EX17 EX18 EX19 EX20 EX21 EX22 EX23 Fe.sub.2O.sub.3 (wt %) 0.58 0.015 0.58 0.06 0.581 0.015 0.297 0.015 0.015 0.015 MnO (wt %) 0.07 1.39 0.12 1.38 0.17 3.5 0.26 2.5 0.75 2.5 Cr.sub.2O.sub.3 (wt %) 0.74 0.05 0.73 0.09 0.73 0 0.56 0.05 0.3 0.1 Fe.sub.2O.sub.3* (%) 41.7 1.0 40.6 3.9 39.2 0.4 26.6 0.6 1.4 0.6 Cr.sub.2O.sub.3* (%) 53.2 3.4 51.0 5.9 49.3 0.0 50.1 1.9 28.2 3.8 MnO* (%) 5.0 95.5 8.4 90.2 11.5 99.6 23.3 97.5 70.4 95.6 Sum 1.39 1.46 1.43 1.53 1.48 3.52 1.12 2.57 1.07 2.62 R1 0.60 0.11 0.60 0.31 0.60 0.07 0.44 0.07 0.05 0.06 R2 0.86 0.16 0.87 0.45 0.87 0.10 0.63 0.11 0.07 0.09 R3 0.09 0.97 0.14 0.94 0.19 1.00 0.32 0.98 0.71 0.96 TL (%) 8 6.7 4.5 4.3 2.7 2.1 1.47 1.71 0.3 0.63 T.sub.1050 (%) 87.5 89.3 87 88.8 86.6 87.9 87.8 88.1 86 86.6 T.sub.1550 (%) 90.6 91.7 90.6 91.7 90.6 91.5 91 91.6 91.4 91.5

[0114] Results from this set of examples (Table 2) show that, for glass sheets with a similar level of TL, better transmission performances at 1050 and/or 1550 nm can be reached with a ratio R3 that increases (R3 being defined as MnO/(MnO+Cr.sub.2O.sub.3), each content being expressed as wt %).

[0115] It is to be noted that an increase of T.sub.1050 or T.sub.1550 of 0.5% is already significant and of value in most of the described applications (i.e. LIDAR systems).

[0116] Set #3

[0117] Examples 24-26 correspond to glass sheets according to the invention, with different base compositions (glass matrix) and fixed amounts of total iron, manganese and chromium. Example 24 corresponds to a soda-lime-silicate-type glass, example 25 corresponds to an alumino-silicate-type glass and example 26 corresponds to a borosilicate-type glass.

[0118] Table 3 presents the optical properties for Examples 24 to 26, their respective base composition and amounts of iron, manganese and chromium, and also their determined ratios R1 and R2.

TABLE-US-00010 EX24 EX25 EX26 SiO.sub.2 (wt %) 71.4 65.4 65.7 Al.sub.2O.sub.3 (wt %) 0 7.93 0 B.sub.2O.sub.3 (wt %) 0 0 6 CaO (wt %) 9.03 8.35 9.21 MgO (wt %) 4.22 3.86 4.18 Na.sub.2O (wt %) 13.49 12.78 13.02 K.sub.2O (wt %) 0.013 0.014 0.013 TiO.sub.2 (wt %) 0.016 0.015 0.016 Fe.sub.2O.sub.3 (wt %) 0.194 0.192 0.2 MnO (wt %) 0.75 0.75 0.75 Cr.sub.2O.sub.3 (wt %) 0.55 0.55 0.55 SO.sub.3 (wt %) 0.29 0.20 0.34 Fe.sub.2O.sub.3* (%) 13 13 13 Cr.sub.2O.sub.3* (%) 37 37 37 MnO* (%) 50 50 50 R1 0.30 0.30 0.31 R2 0.43 0.43 0.44 TL (%) 0 0.1 0 T.sub.1050 (%) 84.3 82.2 80.4 T.sub.1550 (%) 91.2 89.8 90.7