In this study, Ni electroplating is applied to the surface of the lightweight Mg alloy specimen to form a sandwich structure, and strengths improvement is quantitatively compared with the bare Mg alloy. Specifically, the mechanical properties of three specimens were compared one with another using mechanical tensile testing. Accordingly, two Ni electroplated specimens (Ni electroplated only and Ni electroplated with hydroxypropyl cellulose additive) were prepared and compared with the bare Mg alloy. As a result, both Ni electroplated specimens exhibit drastic improvement of the mechanical strength, which is attributed to the interaction between the sandwich structure covered with stiffer Ni material and grain refinement. Consequently, the rule of mixture was used to calculate the intrinsic elastic modulus of the Ni layer from the effective modulus. Finally, the calculated moduli were implemented using FEA (finite element analysis) and compared with the experimental results to examine their accuracy and validity.

Cyclone separators are active filtering devices suitable for a variety of industrial applications from conventional cutting oil pumps to recycling liquids. Since the vortex flow inside cyclones is highly complicated, the performance and flow patterns of these filters should be thoroughly researched. Liquid–solid cyclones mostly use water. Numerical studies on cyclones using higher-viscosity oils are limited. In this study, a liquid–solid cyclone injected with medium-viscosity cutting oil containing various sized-particles was comprehensively investigated. The reliability of computational fluid dynamics (CFD) methods was verified through a comparison with the experimental results. Three models with different geometries were considered for the analysis. One model was used for CFD verification. The other two models involved adding sockets for hopper length extension and changing the shape of the bottom of the hopper. The models that changed the shape of the hopper, thus directly affecting the cyclone performance, were investigated, and each model was qualitatively compared using a validated method. In addition, particle separation efficiency was evaluated by focusing on the velocity distribution to quantitatively confirm the influence of changing the shape of the hopper. The tangential velocity was determined to be similar across all three models, while the axial velocity was different and the change in the velocity of transport of the particles affected the filter function.