光学玻璃晶体的化学抛光是利用氢氟酸破坏玻璃表面，使原有的表层矽氧膜破坏，生产新的表面矽氧膜，使得玻璃得到很高的透过率且表面很光洁。目前，平板玻璃的抛光大多用化学抛光和机械抛光相结合的方法，也即化学机械抛光。
采用化学侵蚀抛光玻璃时，除使用氢氟酸外，还要加入能使侵蚀生成物（矽氟化物）溶解的添加物。一般采用硫酸，硫酸具有酸性强，沸点高、不易挥发、室温下比较稳定等特点，故通常将硫酸加入氢氟酸中配成抛光液。另外，因氢氟酸易挥发。侵蚀性强，故需要在密闭条件下进行抛光，同时要对抛光过程中产生的废气、废水进行严格的处理。
影响化学抛光的因素如下：
1、玻璃的成分 一般情况下钠钙矽玻璃抛光比较困难，效果较差，含铅玻璃化学抛光效果较好；
2、抛光液的成分 特别是抛光液中氢氟酸和硫酸的比例构成，要根据玻璃的成分进行调整。一般的铅晶质玻璃配方中：7%~10.5%的氢氟酸和58%~65%的硫酸。对钠钙矽玻璃来说，水、氢氟酸、硫酸的体积比比例为1：（1.62~2）：（2.76~3）。
3、抛光温度 温度过低则反应慢，温度过高反应剧烈，一般以40~50℃为宜。
4、处理时间 处理时间短，抛光作用不完全，处理时间长则玻璃表面会有盐类沉积物，因此具体的抛光时间，应依据抛光液的培比、处理温度等来决定。一般情况下采用短时间多次抛光的方法来处理，每次处理时间在6~15s左右，处理次数不超过10次，若处理次数过多易在表面形成波纹等缺陷，每次酸处理完后都应将玻璃表面用水冲洗以去掉沉淀的盐类。
Chemical Polishing of Optical Glass Crystals
Chemical polishing of optical glass crystals involves using
hydrofluoric acid (HF) to erode the glass surface. This process breaks down the
original silicon-oxygen layer on the surface and generates a new silicon-oxygen
layer, resulting in a glass surface with high transmittance and excellent
smoothness.
Currently, the polishing of flat glass often employs a
combination of chemical polishing and mechanical polishing, commonly referred
to as chemical-mechanical polishing (CMP).
Process of
Chemical Polishing
When using chemical etching to polish glass, hydrofluoric
acid is the primary agent. Additives are also required to dissolve the etching
byproducts (such as silicon fluorides). Sulfuric acid is commonly used due to
its strong acidity, high boiling point, low volatility, and relative stability
at room temperature. Therefore, a polishing solution is typically prepared by
mixing sulfuric acid with hydrofluoric acid.
Due to hydrofluoric acid's volatility and strong
corrosiveness, the polishing process must be conducted under sealed conditions.
Additionally, strict treatment is required for waste gases and wastewater
generated during the polishing process.
Factors
Affecting Chemical Polishing
Glass Composition
• Sodium-Calcium-Silicate Glass: Polishing is more challenging, with less effective results.
• Lead-Containing Glass: Shows better results in chemical polishing due to its composition.
• Polishing Solution Composition
• The ratio of hydrofluoric acid (HF) to sulfuric acid (H₂SO₄) in the polishing solution must be adjusted based on the glass composition.
• For lead crystal glass: The solution typically contains 7%–10.5% HF and 58%–65% H₂SO₄.
• For sodium-calcium-silicate glass: A volume ratio of water: HF: H₂SO₄ = 1 : (1.62–2) : (2.76–3) is recommended.
• Polishing Temperature
• Low Temperature: Leads to slower reactions.
• High Temperature: Results in overly aggressive reactions.
• The optimal temperature is usually 40–50°C.
• Polishing Time
• Short Time: Results in incomplete polishing.
• Long Time: May cause salt deposits on the glass surface.
• The specific polishing time should depend on the composition of the polishing solution and the processing temperature.
• Generally, short multiple polishing sessions are recommended:
Each session lasts about 6–15 seconds.
Total sessions should not exceed 10, as excessive processing may create surface defects like ripples.
After each acid treatment, the glass surface must be rinsed with water to remove deposited salts.
