To fabricate 316L stainless steel part with a pore gradient structure, the method using selective laser melting (SLM) technique is exploited. Scan tracks feature, densification, and tensile property of SLMproduced samples prepared via different scan speeds were investigated. The results show that the porosity is strongly influenced by scan speed. On this basis, a gradient changed scan speed was applied in every SLM layer for the purpose of producing a gradient porosity metal. The results indicate that the structure exhibits a gradually increased porosity and a reduced molten pool size along the gradient direction of scan speed variation. The forming mechanisms for the gradient porosity were also addressed.

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A new method, namely Metal Powder Extrusion & Stacking Modeling is proposed in this paper based on RP and Metal Injection Molding (MIM) principle. Stainless steel powder and thermoplastic paraffin wax-based binder are used in our experiment. Firstly, feedstock is generated by mixing power and binder in a rotor internal mixer. Then the granular feedstock is put into screw-extruder devices to extruded filament, and accumulating green part at atmospheric status. Finally, green part is thermal defatted and sintered in hydrogen atmosphere to product the sintered parts. The testing results are as follows. The density of our RP product is 73.75%. The average shrinkage rate is 7.51%, 18.00%, and 29.31%, for diameter, thickness and volume respectively. Brinell hardness is HB77.52, while bending strength is 457MPa and tensile strength is 163Mpa. The experimental results verify that our proposed method is promising.

Aiming to investigate the effects of custom-made and thread dental implant systems on the stress distribution in alveolar bone using linear analysis of the finite element method (FEM). Two types of systems: the custom-made implant and the thread dental implant system, were studied using a three-dimensional finite element analysis (3D FEA). Comparing the parts of all systems for loading in different directions, the stress and deformation distribution in custom-made implant and alveolar bone are better than that in thread dental implant system. The analysis data definitely demonstrated the difference in stress and deformation distribution of components in different dental implant systems. Results show the custom-made implants are provided with more advantages and can be used in future experiment and clinical test.

In order to improve the output force characteristics of permanent magnet linear motor (PMLM), studied from permanent magnets (PMs) structure that is the key component of PMLM, different magnetization methods of single PM and different array structures of multiple PMs are compared, and a novel PMLM magnetized alone the external field force lines using 8 pieces tegular Halbach magnet array with air gaps is proposed as well. The analysis on magnetic field of PMLM shows that the force between the coil and the single PM increases by more than 40%, and the average magnetic induction in coil centre generated by the 8 pieces Halbach magnet array arrives at the maximum value, 10% higher than that of 1 piece structure.