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In the various processes of fabricating and applying of optical components, the ability of the polished surface in resisting various erosion is called chemical stability of optical glass.


3.1 Humidity resistance (RC (S), surface method)

The humidity resistance of optical glass is divided into three class according to the time required for a polished surface to form a hydrolyzing spot at 50℃, 85% humidity.

Table 4

Class

1

2

3

Time (hours)

>20

5~20

<5



3.2 Acid resistance (RA (S), surface method)

The acid resistance of optical glass is divided into three class according to the time required for a polished surface to be etched to a depth of 135nm in 0.1N acid solution at 50℃.

Table 5

Class

1

2

3

Time (hours)

>5

1~5

<1




3.3 Water Resistance (Dw, powder method)

Calculations are made by the following formula according to the test method described in GB/T17129.

 

Where

DW—the percentage of mass loss of glass, %;

B—mass of leach and specimen, g;

C—mass of leach and specimen after losing, g;

A—mass of leach, g.

According to the percentage of mass loss measured, Dw is classified into 6 class as shown in Table 6.

Table 6

Class

1

2

3

4

5

6

Mass Loss(%)(DW)

<0.04

0.04~0.10

>0.10~0.25

>0.25~0.60

>0.60~1.10

>1.10



3.4 Acid resistance DA (powder method)

Calculations are made by the following formula according to the method described in GB/T17129.

Where

DA—the percentage of mass loss of glass, %;

B—mass of leach and specimen, g;

C—mass of leach and specimen after losing, g;

A—mass of leach, g.

According to the percentage of mass loss measured, DA is classified into 6 class, as shown in Table7.

Table 7

Class

1

2

3

4

5

6

Mass Loss(%)(DA)

<0.20

0.20~0.35

>0.35~0.65

>0.65~1.20

>1.20~2.20

>2.20





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