Maintaining the performance of metal products in corrosive environments is a critical challenge in materials science and industrial production. Salt spray testing, a key method for simulating marine or salt-laden conditions, plays a vital role in assessing product quality and reliability. This article explores the ISO 9227-2017 standard and the essential procedures for conducting effective salt spray tests.
The ISO 9227-2017 standard serves as the international benchmark for evaluating the corrosion resistance of metallic materials and their coatings. It specifies methods for accelerated corrosion testing in artificially created salt spray environments, providing insights into how materials will perform in real-world conditions.
Conducting salt spray tests requires strict adherence to ISO 9227-2017 specifications. The standard outlines three primary test variants:
- NSS (Neutral Salt Spray Test): Utilizes a mixture of deionized water and pure salt
- AASS (Acetic Acid Salt Spray Test): Incorporates glacial acetic acid into the NSS solution
- CASS (Copper-Accelerated Acetic Acid Salt Spray Test): Adds copper(II) chloride dihydrate to the NSS solution and operates at 50°C ± 2°C
All measurement equipment must undergo proper calibration before testing. Key components requiring calibration include:
- Chamber air temperature sensors
- Air saturator temperature controls
- Chamber pressure gauges (for atomizer pressure)
Additional calibration requirements cover pH meters, salinity refractometers, and conductivity meters. Temperature monitoring should be continuous, with daily manual recordings sufficient for salt spray tests.
Proper preparation of salt solutions is critical for test validity. Key parameters include:
- Water quality: Conductivity must be below 20 µS/cm at 25°C ± 2°C
- Concentration control: Precisely measured using calibrated refractometers
- pH adjustment: Carefully monitored and adjusted as needed
Test samples require thorough cleaning before testing, avoiding abrasives or solvents. Handling should always be done with latex gloves, and pre-test photographs should document sample conditions.
The testing process involves careful setup and monitoring:
- Proper sample placement to prevent interference
- Correct positioning of collection containers
- Continuous verification of environmental parameters
- Regular checks of solution collection rates and pH levels
Daily monitoring ensures all parameters remain within specified tolerances, with all deviations and adjustments meticulously recorded.