What are the applications of silicone elastomers in the aviation industry?

Organic silicone elastomers are widely and critically used in the aviation industry, mainly in sealing, damping, electromagnetic protection, fire-resistant insulation, high-temperature resistant coatings, and lightweight structures, as follows:


1、 Sealing application
Universal silicone sealant: The working temperature range in air medium is -60~250 ℃, and it is widely used for sealing the surfaces of aircraft structural components and electronic equipment, as well as repairing finished products with sealing performance. For example, HM321 high-strength two-component condensed silicone sealant has a tensile strength of over 6.0MPa and a tensile elongation at break of over 450%, exhibiting excellent adhesion performance to metals and organic glasses, and is widely used for the sealing of aircraft cabin windshields.
High temperature resistant silicone sealant: High temperature resistant silicone sealant is required for aircraft engines, rear fuselage and other high-temperature working areas to ensure that they can maintain good flight conditions even under high temperature conditions. The commonly used ones currently include HM301 high-temperature resistant silicone sealant, HM325 high-strength and high hardness silicone sealant, HM306 two-component silicone sealant, and XY-602S adhesive. The latter two sealants can withstand temperatures up to 350 ℃ and have excellent heat resistance. Moreover, these sealants have good resistance to sealing degradation and do not require the application of adhesive primer on metal surfaces to achieve and complete bonding tasks.
Fluorosilicone sealant: China's HM804 two-component fluorosilicone sealant is currently the most widely used, widely used, and mature fluorosilicone sealant in the aviation industry. It has a wide temperature range and can achieve good performance at -55~230 ℃. Its excellent high temperature resistance, sealed degradation, and electrical insulation performance make it effective for sealing, bonding, and sealing electrical components in aircraft fuel systems, and therefore it has been widely used.
Foam silicone sealant: it is a kind of sealing material with light weight, new functions different from general materials, and good application effect. The specific advantages are mainly shown in excellent workability, high temperature resistance, airtight degradation resistance, caulking performance, mechanical performance, high and low temperature resistance, radar wave absorption performance, thermal conductivity, etc. Different foam silicone sealants show different excellent performance.
2、 Damping and vibration reduction
Damping and vibration reducing rubber is a material that mainly utilizes the damping characteristics of rubber to improve the anti vibration effect. It can effectively avoid and reduce the probability of electronic equipment and instrument failures, improve the service life of mechanical components, and thus enhance the accuracy and reliability of aircraft equipment.
The temperature change of silicone rubber is not significant, and even at room temperature or nearby environments, its performance changes are not very obvious. Moreover, the main chain silicon oxygen silicon structure can ensure that its mechanical properties remain stable in a wide temperature range (-50~200 ℃). Therefore, silicone rubber is often used as the first choice for damping materials in the aviation field, especially in situations where high stress and strain generate high heat.
3、 Electromagnetic protection and sealing
The main application range of conductive organosilicon is in the electronic equipment compartment, work compartment and other parts of the aircraft where there are gaps. Using it to bond all the areas that need to be sealed together can achieve electromagnetic protection and sealing functions, ensuring that electronic equipment inside the aircraft is protected from electromagnetic interference and ensuring communication confidentiality.
At present, the most widely used conductive silicone rubber materials in China are the EC series and EF series. Among them, the EC series is conductive phenyl silicone rubber, and the EF series is conductive fluorosilicone rubber.
4、 Fire resistance and insulation
In order to isolate potential flammable areas such as aircraft engines, auxiliary power units (APU), and missile launch pads, fire-resistant and heat-insulating silicone sealants must be used. At present, HM317 flame-retardant silicone sealant and HM320 low-density fire-resistant silicone sealant are the most widely used.
The working temperature of HM317 fireproof and flame-retardant silicone sealant is -55~204 ℃, and the flame retardant performance reaches FV-0 level. The 3.2mm sealant burns with a flame at 1050-1150 ℃ for 15 minutes, and the flame will not penetrate.
The working temperature of HM320 low-density fireproof and heat-insulating silicone sealant is -60~204 ℃, with a density of 0.8g/cm ³. The 3.2mm thick sealant will not penetrate after 15 minutes of flame combustion at 1050-1150 ℃, and has good thermal insulation performance.
5、 High temperature resistant coating
Silicone resin is a thermosetting polysiloxane system with a highly cross-linked structure, and is mainly used as a high-temperature resistant coating in the aviation industry. For example, in areas such as aircraft engines that are prone to operating temperatures, after prolonged operation, the temperature rises to 500 ℃. At this time, HM310 silicone resin sealant is selected, and all components can operate continuously for 36 hours at a high temperature of 500 ℃ without peeling, bubbling, or cracking. At the same time, the adhesion can be maintained at level 1, and there is no leakage under a pressure test of 1.0MPa, proving its good high-temperature sealing performance.
6、 Lightweight and Structural Enhancement
Silicone elastomer can be used to manufacture lightweight structural materials, such as silicone foam sealant. It is not only light in weight, but also has good cushioning, heat insulation, sound insulation and compressibility. It is an ideal lightweight packaging material.
In addition, silicone elastomers can also be compounded with other materials to form composite materials with excellent properties, which are used for structural reinforcement and functional enhancement of aircraft.