Standard No.:	GB/T 7962.21-2019
Chinese Name:	无色光学玻璃测试方法 第21部分：耐碱稳定性
English Name:	Test method of colourless optical glass—Part 21:Resistance to attack by aqueous alkaline solutions
Professional Classification:	L50 Optoelectronic device assembly
ICS Classification:	81.040.01 Glass in general
Issued by:
Issued on:	2019-08-30
Implemented on:	2020-03-01
Status:	VALID
Language:	English
File Format:	PDF
Word Count:	8000 words
Price(USD):	240 (USD)
Delivery:	via email in 1-3 business day

1 Scope

This part is applicable to colorless optical glass, and may apply for other types of glasses.
This part of GB/T 7962 specifies the principle, procedure, data processing and classification for testing the resistance of colorless optical glass to attack by aqueous alkaline solutions.

2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 903 Colorless optical glass
GB/T 1185-2006 Surface imperfections of optical elements
GB/T 1804-2000 General tolerances—Tolerances for linear and angular dimensions without individual tolerance indications (eqv ISO 2768-1:1989)
GB/T 6682-2008 Water for analytical laboratory use—Specification and test methods?(ISO 3696: 1987, MOD)

3 Principle

Attack on polished test sample by a test solution (0.01 mol/L sodium hydroxide solution) at 50℃ for specified times. Weighing to determine the loss in mass and calculation of depth of attack based on the density of the glass. Determination of the alkali resistance class according to the time, t0.1, required for an attack to a depth of 0.1 μm and the change in the attacked surface of the test sample.