Fabrication of Alumina Composite Microengine Parts using Softlithography

In this work, a detailed process for manufacturing 3D alumina composite microengine pistons is presented. A novel moulding process is developed for shaping alumina composites into accurate micrometer-sized parts with a combination of softlithography micromoulding techniques and colloidal ceramic powder process. Ultrathick SU-8 UV-lithography is used for making master moulds followed by mirror duplication of PDMS softmoulds. A preceramic coating resin (PCR) was used as the binder instead of the traditionally organic binders and the PCR turns into an additive to the composite after the sintering process. The sedimentation of Al2O3/acetone suspensions has been characterized with varying poly vinyl pyrrolidone (PVP) as a dispersant. Optimized PCR and curing conditions have been investigated in the soft moulding process, and prove successful in achieving dense and uniform microcomponents. The optimal parameters of alumina composite suspension for mould filling have been achieved at a concentration of PVP in acetone = 0.1 g/ml; minimum amount of PCR = 8%; solid loading = 60 wt%.