METHODS OF SURFACE ROUGHENING FOR SPHERICAL SOLID PARTICLES

Abstract

Five methods for surface roughening (Coarse emery papers, Pasting small glass spheres, Pasting sand, Chemical corrosion and CNC machining) were studied experimentally to choose the best method to produce three different grades of surface roughness for solid (Carbon steel) spherical particles of five diameters (10, 14, 18, 22 and 25) mm accelerated with rotation in Newtonian and non-Newtonian liquids. The results showed that coarse emery papers method gives irregular surface roughness and to measure the surface roughness it must be made of a plane sample so the devices of surface roughness measurement can predict the value of surface roughness and this is impossible to be produced with coarse emery papers (for the sphere and the plane sample with the same grade of surface roughness). Both pasting small glass spheres and sand gives regular and measurable surface roughness but they are irrelevant for the rotation of solid spherical particles because of the broking of roughened surface after a small period of time because of the liquid's resistance to the accelerated spheres motion. The chemical method gave one grade of surface roughness only and it is relevant and the surface roughness is measurable. The CNC machining method was the best method, it gave three different grades of surface roughness which were (74, 176 and 243) μm.