Silica coatings on bismaleimide (BMI) polymeric substrates

For many years, ceramics have been added to polymeric materials as reinforcements or extenders. Recently, thin ceramic coatings have been applied to polymers for biomedical applications, and in this paper ceramic coatings are applied to an aerospace polymer, bismaleimide (BMI). Unreinforced BMI specimens were coated with a thin, protective layer of a dense silicate ceramic material. Vickers indentation testing on the coated and uncoated BMI specimens indicated that the coatings adhere surprisingly well to the substrate, with cracking of the coating taking place only within a diamond-shaped region with diagonal dimensions equivalent to the Vickers indentation impression.