Electrostatic containerless processing system

Abstract

We introduce a materials science tool for investigating refractory solids and melts: the electrostatic containerless processing system (ESCAPES). ESCAPES maintains refractory specimens of materials in a pristine state by levitating and heating them in a vacuum chamber, thereby avoiding the contaminating influences of container walls and ambient gases. ESCAPES is designed for the investigation of thermophysical properties, phase equilibria, metastable phase formation, undercooling and nucleation, time–temperature–transformation diagrams, and other aspects of materials processing. ESCAPES incorporates several design improvements over prior electrostatic levitation technology. It has an informative and responsive computer control system. It has separate light sources for heating and charging, which prevents runaway discharging. Both the heating and charging light sources are narrow band, which allows the use of optical pyrometry and other diagnostics at all times throughout processing. Heat is provided to the levitated specimens by a 50 W Nd:YAG laser operating at 1.064 μm. A deuterium arc lamp charges the specimen through photoelectric emission. ESCAPES can heat metals, ceramics, and semiconductors to temperatures exceeding 2300 K; specimens range in size from 1 to 3 mm diam. This article describes the design, capabilities, and applications of ESCAPES, focusing on improvements over prior electrostatic levitation technology.