Preparation of Microcoiled Si3 N 4 Fibers by Impurity Metal Activated Chemical Vapor Deposition and Their Mechanical Properties

Microcoiled fibers have been prepared by the metal impurity activated chemical vapor deposition process using gas mixtures. Growth conditions, microstructures, and mechanical properties of the coils were examined. Among the metal impurities used, Fe and Co were the most effective for growing coiled fibers. The coiled fibers were in amorphous state. The driving force of coiling or what affects the amorphous state during coiling is still unknown. The coils showed a maximum shear stress of about 12 GPa and the shear modulus of 110 GPa.