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High-temperature protective coatings are designed not only to resist aggressive chemicals and corrosive environmental conditions, but also to withstand physical and chemical stresses from processes that operate under either rapid temperature cycling or sustained elevated temperatures of 400 to 1500 F (204 to 816 C). The coatings are also known as high-heat or heat-resistant coatings.
The technology for high-heat coatings is complex, and there is a range of heat-resistance capabilities for some generic coating types. This article is not intended to address such complexities but is a review of the technology for persons new to the industry or those seeking a refresher on basic technology for high-heat coatings. Specifically, this article reviews a sampling of high-heat coating technology available in the marketplace. The review is based on manufacturers' published technical documentation about their products. This review illustrates the very broad technology currently used in the chemistry of the high-heat binder systems, the wide range in continuous service temperature of high-heat coatings available, and the unique coating properties available in the different technologies presently currently used in highheat coatings. The reader should note that no attempt wasmade to test or otherwise verify performance claims.
Background
How do protective coatings defined as resistant to elevated temperatures (high-heat coatings) differ from conventional protective coatings that may include specific temperature resistance limitations among their other coating properties?
Suppliers of conventional coatings often (but not always) state temperature limitations in some fashion, and the limitations may be expressed in one or more of these three ways:
* continuous service,
* intermittent service, and
* resistance to dry or wet elevated temperature service conditions.
(The same language is used to describe high-heat coatings but the limits are generally higher.)
A review of technical data sheets for conventional protective coatings from several key coating suppliers indicates dry temperature resistance in the range of 180 to 250 F (82 to 121 C) for continuous service and 250 to 350 F (121 to 177 C) for intermittent service. The exception to this generalization is for two-part epoxy coatings. For epoxies not promoted for elevated temperature service, the limit of service temperature is usually not higher than 250 F. However, the epoxy coatings considered in this article (in Table 1, to be discussed later) are...