When it comes to evaluating the corrosion resistance of materials and surface coatings, two widely used standardized test methods come into play: salt spray testing (SST) and cyclic corrosion testing (CCT) which are both offered through the Qualitest product range. These tests aim to assess how well materials withstand corrosion under accelerated conditions, offering valuable insights for manufacturers seeking to enhance the durability of their products.
Salt spray testing, conducted in accordance with the ASTM B117 procedure, involves placing metallic samples with surface coatings in a controlled environment. The samples endure exposure to a dense fog created by atomizing a 5% sodium chloride solution at a temperature of 35⁰C. This test allows for the comparison of the relative corrosion resistance of coatings within an accelerated timeframe, typically ranging from 72 to 1,000 hours.
While SST provides an efficient means of checking corrosion, it's crucial to note that it doesn't perfectly replicate real-world corrosion scenarios. The test doesn't mimic natural environments where corrosion may occur, and it may not be suitable for assessing the corrosion resistance of coatings on non-precoated metals with no galvanized precoating.
Furthermore, the continuous spray during the salt spray test accelerates the wrong corrosion mechanism for galvanized steel. Zinc, known for its corrosion resistance, forms a protective zinc carbonate barrier on its surface. However, the constant spray in SST prevents exposure to the atmosphere needed for this barrier formation. As a result, the salt spray interacts directly with the zinc, leading to rapid corrosion.
In contrast, cyclic corrosion testing (CCT) offers a more comprehensive approach. Unlike SST, there isn't a universally accepted international CCT standard, but it has gained prominence in the automotive industry. Recognizing that SST doesn't perfectly correlate with real-world corrosion, automotive companies developed their own CCT methods to simulate natural corrosion failures in a controlled laboratory setting.
CCT exposes samples to a series of different environments in a repetitive cycle, providing a more accurate representation of real-world conditions. The test typically includes phases such as salt spray, drying, condensing humidity, and controlled temperature humidity. Each cycle lasts 24 hours, and the overall duration of CCT may range from 40 to 100 cycles, depending on the product and manufacturer.
By incorporating various environmental conditions, CCT methods allow manufacturers and suppliers to predict the service life expectancy of their products more accurately. These methods have evolved according to specific industry requirements and are tailored to the diverse needs of different sectors within the automotive realm.
In conclusion, while salt spray testing remains a valuable tool for assessing corrosion resistance, cyclic corrosion testing stands out as a focussed approach, providing a closer simulation of real-world conditions and offering enhanced predictive capabilities for product durability.
Qualitest’s SST range includes 4 capacities of 108L, 270L, 480L and 800L, while the CCT range includes 450L, 960L and 1280L capacities.
Refrigeration manufacturing company relies on Qualitest Salt Spray Chamber to perform corrosion testing on their painted and treated panels.
The Qualitest Salt Sprayers are designed to perform accelerated corrosion testing in accordance with a number of test methods including the popular ASTM B117, CASS and NSSACSS.
This practice provides a controlled corrosive environment which has been utilized to produce relative corrosion resistance information for specimens of metals and coated metals exposed in a given test. This powerful product data is fundamental for QA purposes in predicting product longevity in the field over extended periods.
A salt spray test is an inexpensive method to measure how materials and industrial coatings can be broken down over time, improving our understanding of the impact of rust and other types of corrosion. Salt spray testers produce a standardized corrosive environment in order to evaluate the protective properties of products in many industry sectors.
Qualitest's Salt Spray Tester is used to create a salt spray fog in a controlled test environment. The anti-corrosion quality of materials protected by rust-proof paint, coating, electroplating, and anodizing can be tested in a chamber with capacities ranging up to 1440 litres.
Meeting rigorous international standards including ASTM-B117, JIS-D0201, JIS-H8502, JIS-H8610, and JIS-Z2371, Qualitest's Salt Spray Tester provides a reliable testing space for manufacturers across the world. We recently delivered one of our Salt Spray Testers to a leading producer of high-performance wire and cables in Mexico, which will help them to create products that remain durable in even the harshest environments.
