Cold gas-dynamic spray is a solid-state materials consolidation technology that has experienced successful adoption within the coatings, remanufacturing and repair sectors of the advanced manufacturing community. As of late, cold spray has also emerged as a high deposition rate metal additive manufacturing method for structural and nonstructural applications. As cold spray enjoys wider recognition and adoption, the demand for versatile, high-throughput and significant methods of particulate feedstock as well consolidated materials characterization has also become more notable. In order to address the interest for such an instrument, nanoindentation is presented herein as a viable means of achieving the desired mechanical characterization abilities. In this work, conventionally static nanoindentation testing using both Berkovich and spherical indenter tips, as well as nanoindentation using the continuous stiffness measurement mode of testing, will be applied to a range of powder-based feedstocks and cold sprayed materials.

The study of bone tools, a specific class of artifacts often essential to perishable craft production, provides insight into industries otherwise largely invisible archaeologically. Building on recent breakthroughs in the analysis of microwear, this research applies confocal laser scanning microscopy and texture analysis techniques drawn from the field of surface metrology to identify use-wear patterns on experimental and archaeological bone artifacts. Our approach utilizes both conventional parameters and multi-scale geometric characterizations of the areas of worn surfaces to identify statistical similarities as a function of scale. The introduction of this quantitative approach to the study of microtopography holds significant potential for advancement in use-wear studies by reducing inter-observer variability and identifying new parameters useful in the detection of differential wear-patterns.

The role of high strain rate and severe plastic deformation, microstructure, electrochemical behavior, surface chemistry and surface roughness were characterized for two copper cold spray material consolidations, which were produced from conventionally gas-atomized copper powder as well as spray-dried copper feedstock, during the course of this work. The motivation underpinning this work centers upon the development of a more robust understanding of the microstructural features and properties of the conventional copper and nanostructured copper coatings as they relate to antipathogenic contact killing and inactivation applications. Prior work has demonstrated greater antipathogenic efficacy with respect to the nanostructured coating versus the conventional coating. Thus, microstructural analysis was performed in order to establish differences between the two coatings that their respective pathogen kill rates could be attributed to. Results from advanced laser-induced projectile impact testing, X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, scanning transmission microscopy, nanoindentation, energy-dispersive X-ray spectroscopy, nanoindentation, confocal microscopy, atomic force microscopy, linear polarization, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy and copper ion release assaying were performed during the course of this research.

A relatively new GelSight Max measurement instrument was applied to the microtopographies of experimental hardened clay surfaces, both with and without fingerprint (dermatoglyph) impressions, and the surface of an archaeological pottery handle fragment with a preserved fingerprint (paleodermatoglyph). The experimental clay surfaces were documented in order to determine the instrument’s ability to capture these surfaces in three-dimensions by imprinting them onto an elastomeric tactile membrane. Fingerprints on the experimental hardened clay and the archaeological pottery fragment were mathematically documented to test this instrument’s ability to capture these impressions. The surface texture measurements of the hardened clay and the pottery fragment were mathematically compared using conventional topographic characterization parameters (height and hybrid), fractal dimensions (Das) with associated coefficients of determination (R²), and multiscalar geometric characterization parameters, particularly relative area (Srel), area-scale complexity (Asfc), relative length (RL), and length-scale complexity (Lsfc). The surfaces of the experimental hardened clay with and without fingerprints and the archaeological pottery handle fragment with a fingerprint can be discriminated using some conventional height parameters, as well as some multiscale geometric topographic characterization parameters. Specifically, relative area (Srel), area-scale complexity (Asfc), relative length (RL), and length-scale complexity (Lsfc) could all discriminate between the hardened clay block with and without fingerprints and the fingerprint on the archaeological pottery handle fragment at different scales of measurement. Mean square ratios (MSRs) above 90% and 95% confidence levels indicated that the discrimination of these multiscale geometric characterizations was significant. In sum, the GelSight Max has the potential to be a valuable instrument for archaeologists studying pottery and fingerprints.

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.