In the field of shipbuilding, the protection of ship outer panels is crucial, as they directly face the erosion of seawater, the scouring of waves, and the complex and ever-changing marine environment. Polysilazane coating plays a key role in the protection of ship exterior panels due to its excellent performance. The following provides a detailed introduction to its usage and related precautions.
Usage
Surface pretreatment:
The outer panels of ships are mostly steel structures, and strict rust removal work must be carried out first. Sandblasting rust removal is a commonly used and efficient method, which uses powerful high-pressure airflow to spray abrasives at high speed onto the surface of the outer plate, removing stubborn rust, oxide scale, and previous residual old coatings. It is necessary to meet the rust removal standard of Sa2.5 or above, so that the steel surface presents a uniform and bright metallic texture. This process is like a deep "cleaning" of the outer panel, laying a solid foundation for the subsequent coating adhesion.
After rust removal is completed, the oil and grease removal process cannot be ignored. Seawater contains impurities such as salt, which can easily adsorb onto oily surfaces and accelerate corrosion. So, it is necessary to use professional organic solvents such as acetone to carefully wipe the surface of the outer panel, or use cleaning equipment and degreaser for comprehensive cleaning, thoroughly removing oil and grease that may affect the adhesion of the coating, to ensure a clean and flawless surface.
At the same time, in order to further optimize the bonding effect between the coating and the outer panel, it is necessary to adjust the surface roughness. By reasonably controlling the type, particle size, and spray pressure of the abrasive during sandblasting, the surface roughness of the outer plate can be maintained within the ideal range of 30-70 μ m. This can greatly increase the "grip" between the coating and the steel, just like creating solid "attachment points" for the coating.
Coating preparation:
For the special use environment of long-term immersion in seawater and exposure to wave impact on ship exterior panels, it is necessary to carefully select polysilazane coating materials with excellent resistance to seawater corrosion and erosion. There are various products with different formulas and performance focuses available in the market, and accurate selection must be based on actual engineering needs.
During the blending process, it is necessary to strictly control the addition of specialized diluents according to the precise ratio specified in the product manual. Use professional mixing equipment to stabilize the mixing speed at 300-500 revolutions per minute, and continue stirring for no less than 15 minutes to ensure that the coating material and diluent are fully and evenly mixed together. The viscosity of the mixed coating should be precisely controlled at around 20-30 seconds (coating -4 cups), only in this way can the coating smoothly cover the surface of the outer panel during subsequent coating, without being too thin and causing poor protective effect, nor too thick and difficult to apply.
Coating construction:
For large areas such as ship exterior panels, high-pressure airless spraying is the preferred construction method. Carefully load the prepared polysilazane coating into the storage tank of the high-pressure airless spraying equipment, as if filling the spray gun with ammunition. Then, based on factors such as the material, shape, and construction environment of the outer panel, the spraying pressure is carefully adjusted, usually set between 10-15 MPa. This pressure range can evenly atomize and spray the coating onto the outer panel.
In actual spraying, the spray gun should always be kept perpendicular to the surface of the outer panel, with a stable distance of about 20-30 centimeters. The operator holds the spray gun and moves it at a uniform and smooth speed, with a speed of about 40-60cm/s. It is like carefully drawing a protective "coat" for the outer panel, ensuring that the coating can evenly and smoothly cover every inch of the outer panel, avoiding problems such as sagging and missed spraying that affect the protective effect and aesthetics. The thickness of the coating formed by each spraying should be strictly controlled at around 20-30 μ m. Depending on the required protective strength and service life of the ship's outer panel, 3-5 layers of spraying operations are generally required. Moreover, after each layer of spraying is completed, allow 10-15 minutes for the coating to naturally level, making its surface smoother and improving the overall protection quality.
Curing treatment:
In order to fully utilize the excellent performance of the polysilazane coating on the outer panel, curing treatment is an essential step. When the natural environmental conditions are relatively suitable, that is, when the temperature is between 15-30 ℃ and the relative humidity is between 40% -70%, it is possible to choose to let the coated layer dry and cure naturally. This process requires patience and can take anywhere from several hours to several days, depending on the thickness of the coating and the characteristics of the product itself. During this period, it is essential to ensure good ventilation conditions at the construction site, such as creating a "healthy breathing" environment for the outer panels, to prevent dust and other impurities from adhering to the coating surface, affecting the curing effect and final protection quality.
However, for some key protection areas of the ship's outer hull, such as the bow, due to the greater impact force and seawater corrosion pressure it bears, relying solely on natural solidification may not meet performance requirements. At this point, it is necessary to use heating curing method. Place the coated outer panel in a constant temperature oven or use professional heating equipment such as a hot air blower for heating treatment. According to the strict heating curve, the heating operation is carried out, and the heating rate is controlled at 5-10 ℃/min. The temperature is gradually raised to 150-200 ℃ and maintained at this temperature for 1-2 hours, allowing the molecules inside the polysilazane coating to fully crosslink and solidify, like putting a strong "armor" on the outer panel, greatly enhancing its key properties such as hardness, wear resistance, and corrosion resistance, ensuring long-term and reliable protection for ship outer panels in harsh marine environments.  

Room termperature curing polysilazane, pls check IOTA 9150, IOTA 9150K.       
High termperature curing polysilazane, pls check IOTA 9108, IOTA 9118.