High Temperature Silicone
Silicone rubber is a common material used in many different applications. Its ability to withstand high temperatures, unlike most other rubbers, makes it an ideal choice for a wide variety of jobs.
The key factor in silicone’s ability to withstand high temperatures is the length of time it is exposed to them. This will determine its lifespan and performance within the application.
Automotive
As the demand for fuel efficiency and performance continues to grow, the need for high-performance materials that are capable of handling harsh environment conditions has never been greater. Silicone elastomers offer excellent temperature performance, low moisture permeability and dielectric properties. This makes them a great fit for automotive applications like sealants, adhesives and potting gels.
Under-the-hood environments are highly demanding, with extreme environmental factors like weathering, UV radiation and salt as well as component-generated heat that must be effectively dissipated to maintain reliable performance and a long product life span. Silicone rubber offers a range of solutions to meet these needs from traditional pre-cut gaskets to fast curing lid seal adhesives and low viscosity conformal coatings for PCB protection.
The use of silicone in automotive applications has also grown with advancements in Electric & Hybrid Vehicle design, where space constraints and high power outputs can create unique challenges for assembly. Silicone RTV technology can address these issues with a range of solutions including adhesives, sealants, gap fillers and encapsulants as well as thermally conductive adhesives.
Ensure that surfaces to be bonded are clean and dry. Cut the nozzle of the silicone sealant tube to about a 45-degree angle, then apply an even bead of the product to one surface. Use a sealing tool, damp cloth or gloved finger to smooth the bead. Allow to cure for 24 hours before using.
Industrial
Silicone’s unique chemical structure allows it to handle high temperatures. The long siloxane backbone creates a barrier that prevents the silicone from degrading in contact with heat, enabling it to stand up to a wide range of temperatures without changing shape or losing its adhesiveness.
High-temperature silicone sealants are used in a variety of industrial applications to create waterproof and airtight bonds to various materials under high temperatures. This includes sealing and bonding of equipment, assembling machinery and creating a protective layer for surfaces.
These types of silicone sealants are available in a variety of hardnesses, ranging high temperature silicone from very soft to medium. They can be cured at room temperature using a single-component product or mixed from two components (a base and curative). You can choose a low modulus, neutral cure or acetoxy cure silicone, depending on how much force you’ll need to apply to stretch the material.
Silicone sealants are often used to assemble components in fire-rated buildings and to act as smoke barriers in walls and floors of tall structures. These silicones are typically tested to ensure that they maintain their integrity when exposed to high temperatures and smoke. They are also often used to seal linear joints and penetration seals in fire-rated structures.
Crafts
When you need to bond a surface that is going to be exposed to high temperatures, silicone can be an excellent choice. This type of adhesive can resist the ravages of heat up to 400 degrees Fahrenheit, and it also offers flexibility that can accommodate substrates that expand and contract. It is a better option than regular sealants, which may harden or crack with extreme heat.
Moldmakers rely on tough-but-flexible silicones to create accurate replicas of masters made from glass, tile, metal and even wood. The RTV silicones used for this work are resistant to a wide range of chemicals and can withstand service temperatures up to 600 degrees Fahrenheit.
Some applications, such as sealing the valve covers of an automobile engine, require a special silicone that can handle intermittent exposure to hot temperatures. This silicone is often referred to as form-in-place auto engine high temperature silicone gasket compound because it allows you to replace the original gaskets with less expensive standard components. It is non-corrosive and resistant to oil, water and the ethylene glycol commonly used in automotive coolants.
Many crafters use silicone to add a unique look to their home decor or handmade products. For example, some people use it to add dots or squiggles to children’s onesies and footed pajamas. You can purchase silicone in a wide array of colors to match your design scheme.
Home
At home, you can use high temperature silicone as an adhesive or sealant. The silicone will not melt in the heat and will provide a strong bond. You can seal and bond items such as a fireplace or a chimney cap to withstand wind, rain and hot smoke. You can also use it as a weatherseal around windows and doors.
Choose the type of silicone that best meets your needs. You can select a neutral cure, acetoxy cure or low modulus silicone that is appropriate for your project. A neutral-cure silicone is safe for most materials and surfaces, including glass, aluminium and plastic. The acetoxy-cure and low-modulus options require less force to stretch and are more elastic than neutral silicones.
One example is Thurmalox 2655, a high-temperature RTV silicone that is ideal for industrial applications. It has a service temperature of -40 to 500oF on a continuous basis and can withstand temperatures up to 600oF for short periods of time. The silicone dries quickly and is odorless after curing. The elastomeric compound is non-slumping and resists UV and weathering. It adheres to most clean metals, most paints, wood, glass and ceramics. It is safe to use near electrical equipment and systems.