Moisture-Proof and Anti-Corrosion Properties of Conformal Coating Materials: Realization and Measurement

 

In numerous fields such as electronic devices, aerospace, and the automotive industry, moisture-proofing and anti-corrosion are key factors to ensure the long-term stable operation and extend the service life of equipment. As a material that can form a thin and uniform protective film on the surface of objects, conformal coating is widely applied due to its excellent moisture-proof and anti-corrosion properties. Understanding the realization mechanisms and accurate measurement methods of the moisture-proof and anti-corrosion properties of conformal coatings is of great significance for optimizing the coating formulation, improving the coating quality, and rationally selecting and applying conformal coatings.

Basic Composition and Working Principles of Conformal Coatings

(1) Basic Composition

Conformal coatings usually consist of components such as resins, solvents, and additives. Resin is the main film-forming substance of the coating, and common resins include acrylic resin, epoxy resin, silicone resin, etc. Solvents are used to dissolve the resin, enabling it to be evenly coated on the surface of the object, and they will volatilize during the drying process. Additives include curing agents, leveling agents, defoaming agents, etc., which are used to improve the performance of the coating and the construction process.

(2) Working Principles

Conformal coatings form a continuous and dense protective film by being coated on the surface of the object. This film can block the contact between harmful substances such as moisture, oxygen, corrosive gases, and liquids and the surface of the object, thus playing the roles of moisture-proofing and anti-corrosion. At the same time, conformal coatings also have a certain degree of flexibility and adhesion, which can adapt to the shape changes of the object surface and environmental stress, ensuring the integrity of the protective film.

 

Realization of the Moisture-Proof Performance of Conformal Coatings

(1) Blocking Moisture Penetration

The molecular structure of conformal coatings is compact, which can effectively prevent the penetration of water molecules. For example, silicone resin has a low surface energy and hydrophobicity, which can form a water-repellent layer on the surface of the object, reducing the adsorption and penetration of moisture. The polymer network structures formed after the curing of epoxy resin and acrylic resin also have good barrier properties, which can block the intrusion of moisture.

(2) Preventing the Formation of Condensate Water

Under some environmental conditions, condensate water may appear on the surface of the object, which increases the difficulty of moisture-proofing. Conformal coatings can reduce the formation of condensate water by adjusting the surface temperature and humidity. For example, some conformal coatings with special thermal properties can absorb or release heat when the temperature changes, thus reducing the temperature gradient on the surface and reducing the generation of condensate water.

 

Realization of the Anti-Corrosion Performance of Conformal Coatings

(1) Physical Isolation

Similar to the principle of moisture-proofing, conformal coatings isolate the object from corrosive media by forming a protective film on the surface of the object. This protective film can prevent the contact between oxygen, corrosive gases (such as sulfur dioxide, hydrogen chloride, etc.) and liquids (such as acid, alkali, and salt solutions) and the surface of the object, thus preventing the occurrence of corrosion.

(2) Chemical Inhibition

Some conformal coatings contain components with chemical inhibition effects, which can react chemically with corrosive media, thus inhibiting the progress of corrosion. For example, the corrosion inhibitors added in some coatings can form a passive film on the metal surface, preventing further oxidation and corrosion of the metal.

 

Measurement Methods of the Moisture-Proof and Anti-Corrosion Properties of Conformal Coatings

(1) Standard Test Methods

1. Humidity Test: Common humidity test methods include constant humidity test and alternating humidity test. In the constant humidity test, the sample coated with the conformal coating is placed in a constant humidity environment, and the changes of the sample are observed. The alternating humidity test simulates the humidity changes in the actual environment, and the moisture-proof performance of the conformal coating is evaluated through multiple cycle tests.
2. Salt Spray Test: The salt spray test is a commonly used method for evaluating the anti-corrosion performance. The sample is exposed to a salt spray environment containing a sodium chloride solution, and the corrosion situation on the surface of the sample is observed. According to the degree of corrosion and time, the anti-corrosion performance of the conformal coating can be evaluated.
3. Warm and Humid Test: The warm and humid test combines the factors of humidity and temperature. The sample is placed in a high-temperature and high-humidity environment to test the moisture-proof and anti-corrosion performance of the conformal coating under harsh conditions.

(2) Monitoring Means in Practical Applications

1. Electrochemical Impedance Spectroscopy (EIS): EIS is an electrochemical technique used to study the corrosion process of materials. By measuring the impedance of the sample at different frequencies, the protective performance of the conformal coating and the kinetic parameters of the corrosion process can be understood.
2. Scanning Electron Microscope (SEM): SEM can be used to observe the microstructure and surface morphology of the conformal coating. By analyzing the microstructure of the coating, the internal mechanisms of its moisture-proof and anti-corrosion performance can be evaluated.
3. Fourier Transform Infrared Spectroscopy (FTIR): FTIR can be used to analyze the chemical composition and structural changes of the conformal coating. By monitoring the chemical changes of the coating during the moisture-proof and anti-corrosion processes, the stability of its performance can be evaluated.

 

Factors Affecting the Moisture-Proof and Anti-Corrosion Performance of Conformal Coatings

(1) Coating Formulation

The formulation of the coating plays a crucial role in its moisture-proof and anti-corrosion performance. Different combinations of resins, additives, and solvents will affect the film-forming performance, barrier performance, and chemical stability of the coating. For example, the mixed use of epoxy resin and silicone resin can improve the comprehensive performance of the coating.

(2) Construction Process

The construction process also has an important impact on the performance of the conformal coating. The coating thickness, uniformity, and curing conditions of the coating will all affect its moisture-proof and anti-corrosion performance. The correct construction process can ensure that the coating forms a complete and dense protective film.

(3) Environmental Factors

Environmental factors such as temperature, humidity, and the concentration and type of corrosive media will all affect the performance of the conformal coating. Under different environmental conditions, the moisture-proof and anti-corrosion performance of the conformal coating may vary.

Conclusion

The moisture-proof and anti-corrosion performance of conformal coatings is realized through their special composition and working principles. Through various means such as blocking moisture penetration, preventing the formation of condensate water, physical isolation, and chemical inhibition, conformal coatings can effectively protect objects from the infringement of moisture and corrosion. At the same time, accurately measuring the moisture-proof and anti-corrosion performance of conformal coatings is crucial for their research, development, production, and application. Standard test methods and monitoring means in practical applications provide a reliable basis for evaluating the performance of conformal coatings. However, the performance of conformal coatings is also affected by many factors such as the coating formulation, construction process, and environmental factors. Therefore, in practical applications, these factors need to be comprehensively considered, the appropriate conformal coating should be selected, and the correct construction process should be adopted to ensure the maximization of its moisture-proof and anti-corrosion performance. In the future, with the continuous progress of science and technology, the performance of conformal coatings will be continuously improved, and the application fields will also be continuously expanded.

For more about a complete guide to moisture-proof and anti-corrosion properties of conformal coating materials: realization and measurement, you can pay a visit to Deepmaterial at https://www.adhesivesmanufacturer.com/ for more info.