Improving the corrosion resistance of cured polysilazane products in high humidity environments can be approached from the following aspects:
1. Modification of Polysilazane Raw Materials
Introducing corrosion-resistant functional groups:
In the synthesis stage of polysilazane, functional groups with corrosion resistance can be introduced through chemical modification. For example, by introducing fluorine atoms or fluorine-containing groups, fluorine elements have extremely low surface energy and strong chemical stability, which can effectively block the contact between external corrosive substances and cured products of polysilazane, and improve its ability to resist corrosion such as water, acid, and alkali. By copolymerizing fluorinated organic silicon monomers with polysilazane raw materials, the molecular structure of the final cured product contains fluorocarbon segments, enhancing its resistance to corrosive media in high humidity environments.
Enhanced cross-linking structure:
Optimize the molecular structure design of polysilazane to form a denser and more stable cross-linked network structure after curing. It can be achieved by adding specific crosslinking agents or using special polymerization processes. For example, adding multi-functional silane crosslinkers can promote the formation of more chemical bonds between polysilazane molecules during the curing process, constructing a more compact three-dimensional network and reducing the channels for corrosive substances to penetrate. Even in high humidity environments, it can better block the invasion of moisture and other chemical corrosive substances, thereby improving corrosion resistance.
2. Optimization of curing process
Use catalyst regulation:
Select appropriate catalysts to control the curing reaction rate and crosslinking degree of polysilazane. For example, by using organic metal catalysts (such as organotin compounds), the speed of the curing reaction can be precisely adjusted to avoid poor performance of the cured product due to too fast or too slow reaction in high humidity environments. Suitable catalysts can guide the curing reaction towards the formation of a more regular and corrosion-resistant cross-linked structure, enabling the cured product to maintain good corrosion resistance under high humidity conditions.
Step by step solidification strategy:
Implement a step-by-step curing method, first perform preliminary curing in an environment with low relative humidity (which can be created through dehumidification equipment, such as humidity control at around 30% -40%), to form a certain cross-linking structure foundation for the polysilazane, and then transfer to a high humidity environment to continue curing the entire process. This can to some extent reduce the interference of high humidity environment on key reactions during the initial curing stage, making the structure of the cured product more stable and improving its corrosion resistance.
3. Coating Composite and Modification
Add corrosion inhibitor:
Adding corrosion inhibitors to the polysilazane system can adsorb on the interface between the solidified products of polysilazane and corrosive media, and suppress the occurrence of corrosion reactions by changing the electrochemical properties of the interface. For example, by adding organic corrosion inhibitors containing nitrogen and phosphorus, they can preferentially interact with the surface of the metal substrate in high humidity environments when there is moisture and corrosive substances present, forming a protective film that delays the spread of corrosion to the interior of the cured product of the polysilazane, thereby improving the overall corrosion resistance.
Composite corrosion-resistant coating:
Using a composite coating method, a layer of other materials with high corrosion resistance is applied on top of the cured polysilazane coating. For example, first apply a polysilazane coating, wait for it to cure, and then apply a corrosion-resistant coating such as epoxy resin coating or fluorocarbon coating on top. By utilizing the complementary advantages of different coatings, a multi-layer protective system is constructed. The outer coating can better resist moisture, oxygen, and other chemical corrosive substances in high humidity environments, protect the polysilazane coating and substrate, and enhance the overall corrosion resistance.
4. Post processing technology
High temperature heat treatment:
Suitable high-temperature heat treatment can be carried out on the cured product of polysilazane, and the temperature range can be selected between 200 ℃ and 500 ℃ according to the specific type of polysilazane. Through high-temperature treatment, on the one hand, the cross-linking structure of the cured product can be further improved, making it denser and reducing defects such as pores; On the other hand, it can promote the transformation or decomposition of some unstable functional groups, improve the overall chemical stability of the product, and enhance its resistance to corrosion in high humidity environments.
Surface passivation treatment:
Using surface passivation technology to treat the surface of cured polysilazane products, such as soaking or spraying with chemical passivation solutions (such as those containing chromate, phosphate, etc.) to form a passivation film on the surface. This passivation film can isolate the contact between external corrosive substances and solidified products of polysilazane, especially in high humidity environments, effectively preventing moisture adsorption and corrosion from corrosive media, and improving corrosion resistance.
5. Substrate pretreatment
Cleaning and activation:
Before coating with polysilazane, the substrate should be thoroughly cleaned to remove impurities such as oil stains, dust, and oxide layers on the surface. At the same time, appropriate methods (such as chemical etching, plasma treatment, etc.) should be used to activate the surface of the substrate and increase its active sites. This can better bond the polysilazane with the substrate, reduce the problem of adhesion decrease caused by high humidity environment, and indirectly improve the corrosion resistance of the cured product of polysilazane, because good adhesion is the basis for the coating to exert corrosion resistance.
Apply primer:
First, apply a layer of specialized primer on the substrate. The primer can be made of materials with good water and alkali resistance, such as epoxy primer. Primer can fill the tiny pores on the surface of the substrate, playing a sealing role, and can have a better connection with the polysilazane coating, enhancing the density of the entire coating system. In high humidity environments, it can better block the invasion of corrosive substances and improve the overall corrosion resistance.

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