Master Bond MasterSil 151S is an addition-curing, two-part silicone system that can be used as an adhesive, sealant, coating, or form-in-place gasketing material. Despite its silicone chemistry, it passes NASA low-outgassing specifications. In addition, it purportedly retains superior electrical conductivity with a volume resistivity of 0.004 ohm-cm at 75°F.

“This silicone is ideal for applications where low stress is required, since it is highly flexible across a wide service temperature range. It is capable of resisting aggressive thermal cycles and shocks,” said Rohit Ramnath, senior product engineer.

The mix ratio of MasterSil 151S is 100:5 by weight, and it cures with the addition of heat. Upon mixing, it reportedly retains its smooth, paste consistency and has a long working life of 6-12 hrs for a 50-g mass. Master Bond reports that this silicone product has an elongation between 100-150%, tensile strength of 400-700 psi, and can cure beyond ¼-inch thick. It features a thermal conductivity of 1.30-1.59 W/(m•K), a coefficient of thermal expansion of 150-200 x 10-6 in/in/°C, and hardness of 80-90 Shore A. It is serviceable over the temperature range of -80°F to +400°F.

This compound bonds well to a variety of substrates including metals, ceramics, composites, and many plastics and rubbers. It is available for use in 20-, 50-, and 100-g glass jars. The color of Part A is silver, and Part B is clear. MasterSil 151S has a low linear shrinkage upon curing and is RoHS compliant.

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