Bacterial contamination on touch surfaces results in increased risk of infection. In the last few decades, work has been done on the antimicrobial properties of copper and its alloys against a range of micro-organisms threatening public health in food processing, healthcare and air conditioning applications; however, an optimum copper method of surface deposition and mass structure has not been identified.

Bacterial and viral contamination of contact surfaces increases the risk of infection. A great deal of work has been done on the capabilities of copper and its alloys to protect against a variety of microorganisms endangering public health, particularly in healthcare and food processing applications. This work has conclusively shown the effectiveness of copper for touch surface disinfection; however, the optimum microstructural characteristics of the copper surface have not been established. The sterilization effectiveness of three kinetically sprayed copper surfaces and two copper feedstocks were examined. The surfaces were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and influenza A virus. After a two-hour exposure to the surfaces, the surviving microorganisms were assayed, and the results contrasted. These tests showed substantial antimicrobial differences between the coatings generated by the spray techniques and those obtained by different feedstock powders. The significance of the copper spray application was demonstrated, and the application-dependent mechanism for antimicrobial effectiveness was explained.

The ability to join aluminum to magnesium is important for many industries but is a challenge due to the formation of brittle intermetallic compounds (IMCs). This article presents a practical method to join and provide structural repair of cast ZE41A-T5 cast magnesium (Mg) by the cold spray (CS) process using 6061 Aluminum (Al). In this study, the CS process was used to deposit 6061 Al onto ZE41A-T5 Mg substrates, which were subjected to materials testing and characterization. Shear, hardness, and tensile testing were conducted to determine bond integrity at the dissimilar metal joint. Electron and optical microscopy were performed to analyze the interface and microstructure. A review of dissimilar metal joining techniques is provided for comparative purposes, and the unique bonding mechanisms of cold spray are discussed because of its relevance to the results obtained. Results showed that the cold spray process limited the formation of Mg₂Al₃ and Mg₁₇Al₁₂ intermetallic compounds and the bond strength of the dissimilar metal joints created by the cold spray process, had an ultimate tensile strength, hardness, and shear strength comparable to the weakest material being joined (Mg). This study serves to demonstrate the potential of the cold spray process to create high strength dissimilar joints and provide structural repair between Mg and Al.

Multicomponent oxides, such as many minerals and high entropy oxides, show promise as materials for protection in extreme environments. Similar to other phononically dominated materials, the spectrum of vibrational carriers and phonon scattering heavily influences thermal transport in multi-cation oxides. In this work, we experimentally and computationally investigate the nature of phonon scattering and thermal transport in a series of single and multi-cation rare earth sesquioxides and zirconates. A reduction in thermal conductivity was observed from the single to multi-cation oxides, which is directly correlated to measured optical mode lifetimes. Via spectroscopic ellipsometry, we observe red shifting of the optical modes from local bonding distortion. Density functional theory calculation was used to evaluate how bonding distortions influence the phononic scattering rate observed through modal broadening and reduced thermal conductivity. Compared to single-cation oxides, the multi-cation oxides, especially those with larger cation size variance, exhibited lower effective coordination number and greater bond distortion.