The surface roughness of additively manufactured (AM) components can have deleterious effects on the properties of the final part, such as corrosion resistance and fatigue life. Modification of the surface finish or parts produced by AM processes, such as cold spray, through methods such as mass finishing, can help to mitigate some of these issues. In this work, the surface evolution of as-produced copper cold sprayed material consolidations was studied through mass finishing. Three different copper powders attained by different production methods and of different sizes were used as feedstock. The surface topography of the cold spray deposits was measured as a function of the mass finishing time for the three copper cold spray samples and analyzed in terms of relative area and complexity, revealing an inverse correlation relating material removal rate and hardness/strength of the cold sprayed deposits. The material removal rate was also affected by the quality of the cold spray deposition, as defined by deposition efficiency (DE). Large initial drops in relative area and complexity are also likely due to the removal of loosely bonded powders at the start of mass finishing. Based on this study, the cold spray parameters that affect the rate of mass finishing have been explored.

In this work, the influence of thermal pre-processing upon the microstructure and hardness of Al 6061 feedstock powder is considered through the lens of cold spray processing and additive manufacturing. Since solid-state cold spray processes refine and retain microstructural constituents following impact-driven and high-strain rate severe plastic deformation and bonding, thermal pre-processing enables application-driven tuning of the resultant consolidation achieved via microstructural and, therefore, mechanical manipulation of the feedstock prior to use. Microstructural analysis was achieved via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, energy dispersive spectroscopy, and differential thermal calorimetry. On the other hand, nanoindentation testing and analysis were relied upon to quantify pre-processing effects and microstructural evolution influences on the resultant hardness as a function of time at 540 °C. In the case of the as-atomized powder, β-Mg₂Si-, Al-Fe-, and Mg-Si-type phases were observed along polycrystalline grain boundaries. Furthermore, after a 60 min hold time at 540 °C, Al-Fe-Si-Cr-Mn- and Mg-Si-type intermetallic phases were also observed along grain boundaries. Furthermore, the as-atomized hardness at 250 nm of indentation depth was 1.26 GPa and continuously decreased as a function of hold time until reaching 0.88 GPa after 240 min at 540 °C. Finally, contextualization of the observations with tuning cold spray additive manufacturing part performance via powder pre-processing is presented for through-process and application-minded design.

Internal combustion engines remain a predominant source of global energy consumption, contributing substantially to both operational costs and greenhouse gas emissions. This work evaluates a nanomaterial-based engine oil additive that reduces friction and wear and increases torque, horsepower, and fuel efficiency. This novel nano oil additive contains functionalized carbon nanotubes and hexagonal boron nitride nanosheets that are dispersed in base oil using a proprietary ultrasonication process. Block-on-ring tests performed by multiple testing facilities demonstrated up to a 17% decrease in coefficient of friction and up to a 78% decrease in wear compared to the base oil after treating with the nano oil additive. Thermal properties enhancement by the nano oil additive was evaluated and increases up to 17 °C in thermal stability were obtained. Additionally, the nano oil additive increased torque and horsepower by an average of 7% in motorcycles and 2.4% in pickup trucks. Most importantly, the nano oil additive demonstrated improvements in fuel economy in both gasoline and diesel engines, with laboratory tests reporting 3–5% increases and practical field tests on a commercial truck fleet reporting an average of a 6% increase. The improved engine efficiency leads to reduced turbo temperature in heavy diesel engines and prolonged engine life expectancy and will significantly improve global environmental sustainability.