Nov_Dec_AMP_Digital

iTSSe TSS A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 1 7 4 1 iTSSe TSS JTST HIGHLIGHTS 11 weight in excess of 50 lb. is undertaken, involving thermal-me- chanical characterization of the material in as-deposited condition, characterization of the interface adhesion on cy- lindrical substrate in as-deposited condition, and developing a means to assess target integrity under thermal-mechanical loads during the physical vapor deposition (PVD) sputtering process. Mechanical characterization of cold spray deposited CIG alloy is accomplished through the use of indentation test- ing and adaptation of Brazilian disk test. A custom lever test was developed to characterize adhesion along the cylindrical interface between the CIG deposit and cylindrical substrate, overcoming limitations of current standards. A cohesive zone model for crack initiation andpropagation at the deposit inter- face is developed and validated using the lever test and later used to simulate the potential catastrophic target failure in the PVD process. It is shown that this approach enables reli- ability assessment of sputter targets and improves robustness (Fig. 2). MACHINABILITY OF AL 6061 DEPOSITED WITH COLD SPRAY ADDITIVE MANUFACTURING Barry Aldwell, Elaine Kelly, Ronan Wall, Andrea Amaldi, Garret E. O’Donnell, and Rocco Lupoi Additive manufacturing techniques such as cold spray are translating from research laboratories into more mainstream high-end production systems. Similar to many additive processes, finishing still depends on removal process- es. This research presents the results from investigations into aspects of the machinability of aluminum 6061 tubes manu- facturedwith cold spray. Through the analysis of cutting forces and observations on chip formation and surface morphology, the effect of cutting speed, feed rate, and heat treatment was quantified, for both cold sprayed and bulk aluminum 6061. High-speed video of chip formation shows changes in chip form for varying material and heat treatment, which is sup- ported by the force data and quantitative imaging of the ma- chined surface. Results shown in this paper demonstrate that parameters involved in cold spray directly impact machinabil- ity and therefore have implications for machining parameters and strategy (Fig. 3). Fig. 3 — Sample prepared for machining test. MECHANICAL PERFORMANCE OF COLD- SPRAYED A357 ALUMINUM ALLOY COATINGS FOR REPAIR AND ADDITIVE MANUFACTURING K. Petráčková, J. Kondás, and M. Guagliano Cold spray coatings made of A357 aluminum alloy, a casting alloy widely used in aerospace, underwent a set of standard tests as well as a newly developed fatigue test to gain information about the potential of cold spray for repair and additive manufacturing (AM) of loaded parts. With opti- mal spray parameters, coating deposition on substrates with a smooth surface resulted in relatively good bonding, which can be further improved by application of grit blasting on the substrate’s surface. However, no enhancement of adhesion was obtained for shot-peened surfaces. Process temperature, which was set either to 450° or 550°C, was shown to have an effect on adhesion and cohesion strength, but it does not influence residual stress in the coating. To assess cold spray perspectives for AM, flat tensile specimens were machined fromthe coating and tested in the as-sprayed andheat-treated (solution treatment and aging) condition. Tensile properties of the coating after treatment correspond to properties of cast A357-T61 aluminum alloy. Finally, the fatigue specimen was proposed to test overall performance of the coating and the coating’s fatigue limit, and is compared to results obtained on cast A357-T61 aluminum alloy (Fig. 4). Fig. 4 — BSE image of powder feedstock. OVERVIEW ON RECENT DEVELOPMENTS OF BONDCOATS FOR PLASMA SPRAYED THERMAL BARRIER COATINGS D. Naumenko, R. Pillai, A. Chyrkin, and W.J. Quadakkers The performance of MCrAlY (M=Ni,Co) bondcoats for atmospheric plasma sprayed thermal barrier coatings (APS- TBCs) is substantially affected by the contents of Co, Ni, Cr, and Al as well as minor additions of Y, Hf, Zr, etc., but also by manufacturing related properties such as coating thickness, porosity, surface roughness, and oxygen content. The latter properties depend in turn on the exact technology and set of