The aim of this study is to determine how feedstock shape affects deposition efficiency and coating formation in cold spraying. Spherical and irregular-shaped Cu powders were sprayed on Al substrates at gas temperatures ranging from 100 to 650 °C. Rebound particles were collected and examined and various coating qualities were assessed, including deposition efficiency, hardness, stack morphology, and adhesion strength. In order to explain certain discrepancies between predicted and measured data, as-sprayed and heat-treated coatings were compared and powder hardness was analyzed in detail. Contrary to simple theoretical hydrodynamic simulations, the critical threshold velocity for irregular particles was higher than that of the spherical ones. The results and practical implications of the study are discussed in the paper.

A standby current failure of the 80nm design-ruled Dynamic Random Access Memory (DRAM) during burn-in stress was investigated. In our case, hot electron induced punch-through (HEIP) of a PMOS transistor was a leakage current source. The bake test is a useful method to identify the mechanism of a standby current failure due to hot carrier degradation.