Brands
Vishay Measurements Group
Interactive Guide
Technical Articles
Surface Preparation
|
|
|
|
Surface Abrasion
Matrix-rich surfaces can usually be abraded with 320-grit silicon carbide paper ( M-LINE SCP-2 ) to produce a satisfactory matte finish. However, unless their surfaces have been machined flat, test specimens of matrix-poor composites or those with textured surfaces require alternate techniques. For these, the grit on the silicon carbide paper will not reach into the "valleys" to produce the desired finish. For small areas (a square inch or so), try a fiberglass brush as shown here. 
For larger areas or a large number of smaller areas, an air-abrasive unit may be used to advantage. 
Care must be taken, however, to ensure that neither the air nor the abrasive contaminate the surface. Accordingly, either bottled dry air or shop air highly filtered at the unit inlet is recommended. Clean alumina in the 27-50 micron size is the ideal abrasive. Prior to abrasion, mask the gage area with drafting tape ( M-LINE PDT-1 ). Handling the air nozzle as if spray painting, start and finish each pass on the drafting tape to avoid excess abrasion. Dust off loose particles (with a brush if necessary) and wipe the area with surface cleaning solvent and gauze sponges ( M-LINE GSP-1 ). Repeat as necessary until the surface has a satisfactory matte finish. Dry the surface with a hair dryer for a few seconds prior to gage installation to ensure complete solvent removal. 
Page 3 of 4 |