Performance characteristics of the metal foam wick prepared by magnetron sputtering method

The magnetron sputtering has been used to prepare metal foam wicks for heat pipes by coating the surface of copper foam with zinc oxide (ZnO) nanoparticles. The main properties, including microscopic appearance, contact angle, and capillary performance, as well as the boiling heat transfer performance of the metal foam wicks, are characterized and tested. The results indicate that, compared with the smooth copper, the low PPI (the number of pores per inch) copper foams, for example, 30 or 70 PPI, can directly enhance the boiling heat transfer performance, whereas the 110 PPI copper foam is not conducive. In addition, the effect of sputtering time was conducted. After 12 h ours of magnetron sputtering, the heat and mass transfer performance of the 30 PPI copper foam wick improves significantly. Its wick surface changes from hydrophobic to hydrophilic, the maximum wall superheat reduces by 11.11 K, and the critical heat flux and maximum heat transfer coefficient increase by 29.35% and 80.14%, respectively.