Abstract
The temperature dependence of the solid particle erosion of polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE) and high carbon steel using aluminum oxide particles was investigated. The most efficient machining of PDMS occurred at approximately -178°C, at angles of attack between 30° and 60°. Although it was demonstrated that PDMS could be machined at temperatures above its glass transition, the erosion rate increased by a factor of more than 10 when the machining temperature was below this point. The maximum erosion in PTFE occurred at the coldest temperature of -177°C between the angles of 30 and 90°. This scenario improved the erosion rate by more than a factor of five. The erosion rate in high carbon steel was increased approximately twofold when lowering the temperature from 17°C to -177°C. The surface evolution results presented can be used to predict feature shapes both polymers while minimizing cooling costs, minimizing mask wear or maximizing substrate erosion.
Highlights
1.1 MotivationAbrasive jet micromachining (AJM) is a relatively new micro-fabrication technology in which a jet of pressurized air is used to accelerate small particles towards a target surface which is machined by solid particle erosion mechanisms
The G(α) curve for -178°C shows a maximum erosion rate in the range of 3060°, indicating a more brittle erosion mechanism below the glass transition temperature which is in the vicinity of -120°C
Glass reference channels machined at other impact angles during each PDMS erosion rate measurement, provided an accurate way of obtaining the G(α) curves that was independent of fluctuations in the mass flow rate
Summary
1.1 MotivationAbrasive jet micromachining (AJM) is a relatively new micro-fabrication technology in which a jet of pressurized air is used to accelerate small particles towards a target surface which is machined by solid particle erosion mechanisms. AJM can be used to machine glass, ceramics, ferrous materials and a variety of polymers Plastics such as polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA) are widely used in, e.g., microfluidics since the fabrication of polymeric chips does not require expensive equipment (i.e. soft lithography and hot embossing) [3, 4]. The elastomer Polydimethylsiloxane is of particular interest in microfluidics because it is chemically resistant, biocompatible, and relatively easy to mold and seal [5]. Polymeric materials such as PDMS and PMMA have problems of adsorption, absorption and incompatibility with organic solvents. PTFE is known to retain ductility in tensile tests even at low temperatures (-196°C)[8] For these reasons, PTFE shows great potential in the microfluidic sector
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