Silicon carbide ultrasonication

Alloy surfaces for FT-IR and SIMS were initiall ground to a no. 600 grit finish on silicon carbide strips, followed by 10 urn and 5 urn grinding on Struer rotating SiC discs. The. surfaces were polished with 3 1 um diamond pastes on nap cloths. Samples were immer ultrasonically in deteregent. deionized water rinsed, degreased by immersions in acetone followed by CC1-. ... 

Removal of materials using an axially oscillating tool at ultrasonic frequency (about 20,000 Hz) with a fine abrasive of silicon carbide, aluminum oxide, or boron carbide carried by a liquid between tool and workpiece. 

An example of mechanical aids to cavitation can be found in the field of ultrasonic cell disintegration. These activators are often glass beads or ceramic disks, but sand or plastic chunks can also be employed. Other examples of solids added to improve cavitation effects are silicon carbide, any hard ceramic material or AI2O3 for micronizing species or for surface abrasion, Si02 which favors mechanochemical events, talc for the activation and probably alteration of the chemical properties of surfaces. 

Steel disks (AISI 52100) were polished to a nal surface roughness Ra) below lOnm using silicon carbide paper and diamond paste. The samples were ultrasonically cleaned in ethanol and analyzed for surface contamination by XPS immediately prior to tribotesting. Commercial 4 mm ball-bearings (AISI 52100) were used as a counter-face. 

For indoor exposures, the metals used are usually copper, silver, or steel. Typical expxrsure panels are 10 by 50 mm by 0.5 mm thick. These panels are usually abraded with a fine silicon carbide abrasive praprer 1200 grit for copper and silver and 500 for steel. After pxrUshing, the specimens should be cleaned in ethanol in an ultrasonic bath before exprosure. Occasiorrally, rrickel or zinc specimens may be used in special circurrrstances where these metals are to be used. 

The action of ultrasonic-activated abrasive particle suspension determines the materials removal rate, which is affected by the particles itself, their size and concentration in the suspension. The ideal abrasive particles have high hardness and high compressive strength, a lot of sharp edges and usual fracture behaviour [281,282]. The use of diamond particles allows high ablation rates because of their enormous hardness. However, they are expensive. Boron carbide is an alternative material, which allows an ablation rate of 90% as compared to diamond grains at a significant lower cost. Silicon carbide can also be used however its ablation rate is even lower than those for boron carbide. 

---