The salt spray testing machine is used to simulate a salt spray environment and test the corrosion resistance of products. However, various factors may lead to errors in the test results, affecting the accurate evaluation of product quality. Hubei Gaotian Experimental Equipment Co., Ltd. will analyze the reasons in detail and provide corresponding solutions.

1、 Experimental environmental factors

1. Temperature impact

Reason: The salt spray test has strict temperature requirements, and temperature fluctuations can change the salt spray settling rate and chemical reaction rate. If the temperature inside the test chamber is unstable, salt spray corrosion will intensify when it is too high, and slow down when it is too low, causing the test results to deviate from the true situation. For example, the standard temperature for neutral salt spray testing is 35 ℃, and for every 2 ℃ temperature fluctuation, the corrosion rate may change by 10% -20%.

Solution: Install high-precision temperature sensors to monitor temperature in real time, paired with an intelligent temperature control system to automatically adjust the heating or cooling device according to the set temperature. Regularly calibrate temperature sensors to ensure accurate measurements, while checking the working status of heating and cooling systems, and promptly repairing or replacing aging components.

2. Influence of humidity

Reason: Environmental humidity affects the formation and distribution of salt spray. When the humidity is high, the salt spray has a high water content and increased corrosiveness; Low humidity is the opposite. The humidity outside the test chamber varies greatly. If the sealing is poor, external humidity interference can cause unstable humidity inside the chamber, resulting in test errors.

Solution: Strengthen the sealing of the test chamber, check and replace the aging sealing strips to prevent external humidity from entering. Install humidity control devices, such as humidifiers and dehumidifiers, to accurately regulate the humidity inside the box according to the test requirements. At the same time, monitor the environmental humidity during the experiment and take measures to stabilize the external humidity if necessary.

2、 Experimental solution factors

1. Deviation in solution concentration

Reason: The concentration of the salt spray test solution is a key parameter, and inaccurate concentration directly affects the corrosion effect. Insufficient accuracy of measuring tools, incorrect measurement of solutes or solvents during solution preparation can lead to concentration deviations. A standard 5% sodium chloride solution with a concentration deviation of ± 1% may cause a 15% -30% change in corrosion rate.

Solution: Use high-precision measuring tools, such as electronic scales with an accuracy of 0.01g, and volumetric flasks with accuracy that meets standard requirements. Strictly follow the operating procedures to prepare the solution, and take the average of multiple measurements to reduce errors. Regularly check the accuracy of measuring tools, calibrate or replace them in a timely manner.

2. Impurities in the solution affect

Reason: Impurities in the solution can alter its chemical properties and affect corrosion reactions. Minerals in water, residual impurities in containers, etc. entering the solution may catalyze or inhibit the corrosion process, leading to errors.

Solution: Use distilled water or deionized water to prepare the solution, avoiding interference from impurities in the water. Clean the container before configuration to prevent residual impurities from entering. Regularly replace the solution to avoid accumulation of impurities caused by prolonged use.

3、 Equipment intrinsic factors

1. spray system failure

Cause: The spray system is the core component of the salt spray tester. Blocked nozzles, uneven spray or unstable spray volume will cause uneven distribution of salt spray in the test chamber, resulting in local corrosion differences and errors. If the nozzle is partially blocked, the salt spray deposition in the corresponding area will decrease, and corrosion will slow down.

Solution: Regularly clean the nozzle and use an ultrasonic cleaner to remove blockages. Check the pressure of the spray system to ensure that it is stable, and adjust the position and angle of the nozzle to ensure that the spray is even. Install spray quantity monitoring device to monitor and adjust spray quantity in real time.

2. Equipment aging

Reason: After long-term use, equipment components age, such as reduced heating efficiency of heating tubes, decreased sensor accuracy, aging and leakage of sealing components, which affect equipment performance and lead to test errors.

Solution: Establish equipment maintenance records and conduct regular comprehensive inspections and maintenance of the equipment. Replace aging components according to regulations, such as replacing temperature sensors every 1-2 years and checking and replacing sealing strips every 3-6 months. Conduct performance testing on key components to promptly identify and resolve potential issues.

4、 Factors related to operational standards

1. Improper placement of samples

Reason: The angle, position, and spacing of the sample placement affect the salt spray settling and corrosion effect. The placement angle does not meet the standard, and the salt spray is unevenly distributed on the surface of the sample; The sample spacing is too small, which obstructs each other and affects salt spray deposition, resulting in inconsistent corrosion levels and errors.

Solution: Place the samples strictly according to the testing standards and use specialized fixtures to ensure accurate placement angles. Control the sample spacing, generally not less than 20mm, to ensure that the salt spray can evenly settle on the surface of each sample.

2. Inaccurate control of test time

Reason: The test time is an important basis for evaluating the corrosion resistance performance of products. Inaccurate time control, early or delayed completion of the test, can cause the test results to be inconsistent with the actual situation.

Solution: Use a high-precision timer and set a reminder function to ensure accurate testing time. The operators shall strictly abide by the test time regulations and shall not make arbitrary changes. Special circumstances shall be recorded in detail and analyzed for their impact on the results.

Understanding the causes of errors in salt spray testing machines and adopting corresponding solutions can effectively improve the accuracy of testing and provide reliable basis for evaluating the corrosion resistance of products. Hubei Gaotian Experimental Equipment reminds you that operators should strictly follow the operating procedures, regularly maintain the equipment, and ensure the reliability of the test results.