Additive manufacturing, also commonly referred to as 3D printing, stands to transform sand casting with binder jetting technology that can create sand molds with unmatched geometric complexity. With printed sand molds, castings can be optimized with regard to the strengthversus-weight trade-off and structures such as periodic lattices are now available within molds that are not possible with traditional casting technology. However, an increase in design complexity invites more challenges in terms of understanding and managing both the thermodynamics and physics of the casting process. Simulations of castings are more important than ever, and empirical in situ sensor data are required to validate high fidelity computer modeling (e.g., MAGMASOFT Ò ). One novel solution is to leverage the design freedom of CAD-based solid modeling to introduce unique mold features specifically for housing sensors (Internet of Things) within the mold to enable the collection of a diversity of data at manifold locations: temperature, pressure, moisture, gas chemistries, motion of the molds and internal cores (shifting or rotation), and magnetic field. This report describes a proof of concept in which unprecedented levels of process monitoring were integrated-both wirelessly and wired-at strategic locations throughout a printed mold and inside of internal cores. The collected data were used to validate the quality of a casting in situ as well as to provide feedback for optimizing the casting process, mold design, and simulations. A trade-off was explored between sensor survivability and disposability.

Publication costs assisted by the Petroleum Research Fund A new chemical actinometer especially designed for intensity measurements on high power lasers in the uv to green region is described. The actinometer consists of a closed 02-filled system containing methanolic tris(2,2'bipyridine)ruthenium(II) chloride ([Ru(bpy)3]Cl2) and tetramethylethylene (TME). The highly colored Ru(bpy)32+ absorbs the laser radiation to form a long-lived charge-transfer excited state which is efficiently quenched by dissolved O2 to form singlet oxygen (102). The 102 reacts efficiently with TME to give a nonvolatile hydroperoxide. The laser intensity is determined from the rate of 02 consumption monitored on a gas buret. The system is easy to use, has a quantum flat response over the 280-560-nm region, and is particularly suited for the ionized Ar laser lines. Detailed characterization and use of the system are presented,

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