Thermal spray is one of the most widely used coating techniques to improve wear, surface fatigue or corrosion properties. In the atmospheric plasma spray (APS) process, a powdered material is melted by hydrogen and argon combustion and is propelled at high speed onto the target substrate. The high impact energy of the particles produces a dense and resistant coating layer. Mechanical and surface properties of the obtained coating depend on various spraying parameters, such as gas flow, traverse speed and spraying distance, among others. In this research, the influence of these manufacturing parameters on the thickness, hardness and resistance of the coating obtained from a Ni-Al alloy sprayed onto an aluminum alloy substrate was studied. In order to analyze the effect of these parameters on the coating properties, an extensive experimental program was carried out. A metallographic analysis, hardness and strength measurements were carried out using the small punch test to locally study the mechanical properties of the coating surface. The design of experiments and the response surface methodology facilitate the assessment of the optimal set of spraying parameters.

The strain-rate sensitivity of the yield stress for Acrylonitrile-Butadiene-Styrene (ABS) tensile samples processed via material extrusion additive manufacturing (ME-AM) was investigated. Such specimens show molecular orientation and interstitial voids that affect the mechanical properties. Apparent densities were measured to compensate for the interstitial voids. Three different printing speeds were used to generate ME-AM tensile test samples with different molecular orientation. Printing velocities influenced molecular orientation and stretch, as determined from thermal shrinkage measurements. Likewise, infill velocity affected the strain-rate dependence of the yield stress. The ABS material manifests thermorheollogically simple behavior that can correctly be described by an Eyring flow rule. The changing activation volume, as a result of a varying print velocity, scales linearly with the molecular orientation, as captured in an estimated processing-induced pre-strain. Therefore, it is suggested that ME-AM processed ABS shows a deformation-dependent activation volume. This paper can be seen as initial work that can help to improve quantitative predictive numerical tools for ME-AM, taking into account the effects that the processing step has on the mechanical properties.