SONOCHEMICAL FORMATION OF INTERMETALLIC COATINGS

An energy-dispersive X-ray (EDX) study of the agglomerates produced du ring the sonication of a series of mixed-metal powders in decane indic ates that metal particles are both fused by the action of ultrasound a nd develop coatings which are intermetallic in nature. The principal m echanism of these effects is believed to be interparticle collision ca used by the rapid movement of particles of less than 50 mum diameter w hich are propelled by shockwaves generated at cavitation sites. By exa mination of mixed-metal systems including Ni/Co, Al/Ni, Al/Co, Ni/Mg, and Cu/Mo with substantially different tribological characteristics, i t has been determined that the coatings are generated by both adhesive wear and direct impact. The fusion of Cu and Mo is particularly intri guing, as these two metals are immiscible below 1000-degrees-C. This i ndicates the enormous impact temperatures produced in sonically induce d collisions. The mechanisms of intermetallic coatings produced via ul trasound are discussed.