The mechanical properties, dimensional tolerance and microstructural characterization of micro-molded ceramic and metal components

Abstract

Metal and ceramic micro-components with ∼10 μm features were fabricated by molding nano-powder-binder mixtures in micro-molds produced from LiGA-formed masters and then sintering to achieve the desired density and properties. The mechanical properties of the metals nickel and 316L stainless steel were measured in tension using miniature dog bone shaped, micro-molded test specimens. The sintering temperature controlled yield stress (YS), the ultimate tensile strength (UTS) and the ductility of the nickel with the YS and the UTS decreasing and the ductility increasing with increasing sintering temperature. For the stainless steel, the YS was nearly 400 MPa, UTS was 650 MPa and the ductility was 3%. The mechanical properties of aluminum oxide ceramics were determined using 4-point bending on miniature micro-molded bend bars. The average modulus of rupture (MOR) was 260 MPa. Careful measurements were made of the dimensional tolerance of the micro-molded parts both before and after sintering using automated optical metrology. The variability in the dimensions of a sintered SS gear after sintering was <3 μm. Finally microscopic examination of the micromolded components indicated that the final grain size was generally less than 1 μm with minimal residual porosity.