Fiber Diameter Measurement By Optical Microscope And Its Application In SiC Fiber Production

Diameter is a key technical parameter of ceramic fibers,which is widely used iN the evaluation of fiber properties and production quality control.At present,measuring fiber diameter by optical microscope is a conventional technology.Because of the shallow field depth of optical microscopy,it is not easy to obtain clear boundary when focused,which can easily lead to measurement errors.Therefore,it is important to define and optimize optical microscopy measurement technology for practical application.Four kinds of fiber samples,SiC fiber,Hi-Nicalon fiber,Si3N4 fiber and carbon fiber from Xiamen University,are measured and analyzed.The results are compared with the measurements under electronic microscope.Statistical results show that the diameter of the fibers measured under the electron microscope is stable at 5000 magnification,and the ultra-depth-of-field optical microscope can replace the electron microscope at 5000 magnification.The mechanical properties of SiC single fiber were tested by the diameter measurement method determined in this study.The relationship between fiber diameter and fiber strength and modulus was studied.The relationship between molecular weight,softening point and strength of precursor of SiC fibers was studied by mechanical properties experiments of SiC bundles produced from different batches of raw materials,which laid a foundation for performance evaluation and quality control of SiC fibers.