Coatings for Metals, Ceramics, and Composites

SRI's Chemical and Ceramic Product Development Laboratory is using silicon-based polymers to make versatile coatings for protecting metals, ceramics, and composites. The coatings can be made from polymers alone or from polymers filled with metal or ceramic powders. By selecting chemistries, constituents, and heat treatments, we can formulate the coatings to cover the gamut from low to high temperature applications. The coatings are superior to conventional paints at low temperatures. The high temperature coatings prevent the corrosion and oxidation problems that limit use of the substrates. The coatings can be applied by painting, dipping, or spraying. Partial funding for the development of coatings has come from the Department of Energy.

Advantages of Low Temperature Coatings
Equipment or structures can fail when metals corrode in salt, extreme temperatures, and harsh chemical environments. Most protective paints are based on organic resins and suffer from deterioration, especially under those conditions. SRI's new coatings are proving to be much less costly and have better performance than the silicon-based coatings currently in development.

SRI's coatings are adherent, protective, and offer higher levels of thermal, hydrolytic, and UV stability, providing added corrosion protection to structural metals. Our coatings can be tailored to specific applications by modifying the base polymer, selecting the constituents, and fabricating multiple-layer coatings with various compositions.

Opportunities for Low Temperature Coatings
The technology presents a superb licensing opportunity. The coating can be formulated for general-purpose use or for more specialized applications like industrial maintenance paints, baked coatings, marine and aircraft paints, and hot zones.

Advantages of High Temperature Coatings
Structural failure can occur when structural ceramics, composites, and metals oxidize at high temperatures. Even nonoxide ceramic composites can oxidize rapidly at elevated temperatures. SRI's adherent, protective coatings are designed to be dense enough to withstand thermal cycling and attack by the atmosphere.

SRI's high temperature coatings are designed to be versatile and inexpensive. The properties and composition of a coating can be tailored to each application by varying the constituents as well as by fabricating multiple-layer coatings with different compositions. The technique offers improved cost and application flexibility advantages over CVD approaches. Because SRI's coatings allow for the incorporation of active metals, which help compensate for shrinkage, they offer advantages over sol-gel options.

Opportunities for High Temperature Coatings
SRI's high temperature coating technology is ideally suited for use in turbine and aerospace components, including engines. Strong interest has been expressed by turbine manufacturers and leading aerospace companies, especially for C-C and C/SiC composites. Licensing opportunities are available.

Technical Contact:
Yigal Blum
(650) 859-4367
e-mail: yigal.blum@sri.com