Читать книгу Materials for Biomedical Engineering - Mohamed N. Rahaman - Страница 180

Characterization of surface topography commonly starts with examining the surface of one or more representative specimens of the material in a scanning electron microscope (SEM) (Figure 5.18). Qualitative information about topographical features such as surface roughness at a microscale or nanoscale, the waviness and spacing of the surface roughness, and the presence of surface flaws can be obtained using this technique. Thereafter, other techniques, classified into two broad categories, depending on whether a component of the measuring instrument makes contact with the specimen surface (contact type) or not (noncontact type), can be used to obtain topographical data such as surface roughness parameters. As a contact‐type technique has the potential for damaging a soft surface, applied loads on the contacting component (for example, a stylus) should not exceed the hardness of the surface. The major techniques used for biomaterials are profilometry and atomic force microscopy (AFM), both of which can be used in a contact or noncontact mode.