Ultrasound Assisted Production of Metal Foam From Polyurethane Precursor

Abstract

Metal foam is a novel class of metals that is inspired by naturally occurring, functionally graded, cellular structures like wood and bones. The properties of metal foam are so diverse that they can be tailored to suit the particular need, hence the study of metal foams has become attractive to researchers and efforts are being made to optimize the methodology to develop the metal foam. Most of the production methods cannot be widely utilized because of difficult process control and high production costs. One of the most economical ways to produce metal foam is adopting conventional electro deposition technique. The electro deposition technique starts from first metalizing the non-conducting polymeric foam and then electrically depositing metal onto this metallized precursor foam with open cells and later the precursor is removed by the sintering process. The main hindrance in this process is that foam being multi layered, a uniform deposition of the metal in the inner layers of the foam was not achieved. After sintering it was found that the foam sample turned out hollow at the center, due to lack or very less deposition of the metal. Experiments aiming to overcome this problem of non-uniform deposition of the metal in the inner layers of the precursor were conducted. It was found that mechanical agitation in the form of low frequency ultrasound promoted the uniform electro deposition throughout the metalized multilayered precursor. Finally, desired strength foam was produced.