鹽霧測試與實際天數換算

ASTM B-117

美國材料標準協會制定，測試標準參數為：

5％的鹽水溶液的pH值範圍在6.5～7.2，霧化成霧，加熱櫃保持在95華氏度（35℃）

測試時間範圍從24到數千小時，通常以24小時為增量單位

換算時間（數據僅供分享參考，表面處理、鍍層型態、基底金屬都會影響腐蝕曲線，天數並非一成不變）

一小時鹽霧測試（NSS）約等於5天海岸天數，15天自然暴露環境天數

24小時鹽霧測試（NSS）約等於120天海岸天數，一年自然暴露環境天數

一小時醋酸鹽霧測試（ASS）約等於15天海岸天數，45天自然暴露環境天數

24小時醋酸鹽霧測試（ASS）約等於一年海岸天數，三年自然暴露環境天數

一小時銅鹽加速醋酸鹽霧測試（CASS）約等於40天海岸天數，120天自然暴露環境天數

24小時醋酸鹽霧測試（CASS）約等於960天海岸天數，八年自然暴露環境天數

備註

除了中性鹽霧測試（NSS）之外，還有

醋酸鹽霧測試（ASS），其為5%氯化鈉鹽水溶液中加入一些冰醋酸，使溶液的pH值降為3左右，溶液變成酸性，最後形成的鹽霧也由中性鹽霧變成酸性，提供比NSS更快的腐蝕速度。

ASTM B368：銅鹽加速醋酸鹽霧試驗（CASS），是新近發展起來的一種快速鹽霧腐蝕試驗，試驗溫度為50℃，鹽溶液中加入少量銅鹽（如氯化銅），強烈誘發金屬（鍍層）腐蝕，提供比ASS更快的腐蝕速度。

Salt spray test hours correlation with real-world duration

ASTM B-117

Parameter testing by American Society for Testing and Materials (ASTM):

Salt spray testing typically involves using a 5% sodium chloride (NaCl) solution (with a pH of 6.5~7.2 ) and is atomized to create a saltwater mist. Heating container holding temperature at 95°F (35°C).

The testing is usually carried out between 24 and 1000 hours, and 24hr as an incremental unit.

Time conversion (The data is for reference only, may differ according to its corrosion curve, which is affected by surface treatment, coating type and base metal.)

Neutral salt spray test (NSS) 1h ⇌ Marine environment 5 days ⇌ Natural environment 15 days

Neutral salt spray test (NSS) 24h ⇌ Marine environment 120 days ⇌ Natural environment 1 year

Acetic acid salt spray test (ASS) 1h ⇌ Marine environment 15 days ⇌ Natural environment 45 days

Acetic acid salt spray test (ASS) 24h ⇌ Marine environment 1 year ⇌ Natural environment 3 years

Copper salt accelerated acetate spray test (CASS) 1h ⇌Marine environment 40 days ⇌ Natural environment 120 days

Copper salt accelerated acetate spray test (CASS) 24h ⇌ Marine environment 960 days ⇌ Natural environment 8 years

Notes

Apart from neutral salt spray test (NSS), there is also acetic acid salt spray test (ASS). It is to add some glacial acetic acid in 5% sodium chloride solution, so that the pH value of the solution drops to about 3, the solution becomes acidic, and finally the formation of salt fog from neutral salt fog to acid. Its corrosion rate is faster than the NSS test.

The copper salt accelerated acetate spray test (CASS test) is a rapid salt spray corrosion test recently developed. The test temperature is 50℃. A small amount of copper salt-copper chloride is added to the salt solution to strongly induce corrosion. Its corrosion rate is faster than the ASS test.

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