Jinsong Yang

An organically modified montmorillonite/nylon‐12 composite powder for selective laser sintering

Purpose – The purpose of this paper is to reinforce the selective laser sintering (SLS) parts of nylon‐12 using organically modified montmorillonite (OMMT).Design/methodology/approach – A dissolution‐precipitation process is developed to prepare an OMMT/nylon‐12 composite powder (3 wt% OMMT). X‐ray diffraction (XRD) was used to characterize nanostructure features. The dispersion of OMMT in the nylon‐12 matrix was observed by scanning electron microscope (SEM). The effect of OMMT on the thermal properties of nylon‐12 was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The mechanical properties of the SLS parts made from the composite powder and neat nylon‐12 powder were measured and compared.Findings – The X‐ray diffraction and SEM results indicate that the OMMT is intercalated by nylon‐12 molecular chains and uniformly dispersed in the nylon‐12 matrix during the dissolution‐precipitation process, and thus the OMMT/nylon‐12 intercalated nanocomposites are formed. Th...

Preparation and selective laser sintering of nylon‐coated metal powders for the indirect SLS process

Purpose – The purpose of this paper is to report a new method, the dissolution‐precipitation process, to prepare nylon‐coated metal powders for the indirect selective laser sintering (SLS) process.Design/methodology/approach – The nylon‐12 coated carbon steel powders were prepared by the dissolution‐precipitation process. The powder characteristics are examined by scanning electron microscope (SEM) and laser diffraction particle size analysis. The effect of the applied laser energy density on the three‐point bend strength and dimensional accuracy of the SLS specimens are studied. The influence of nylon‐12 content on the bend strength are also investigated.Findings – The SEM and laser diffraction particle size analysis results indicate that the steel particles are well coated by nylon‐12 resin. The bend strength of the SLS specimens increases with increasing the applied energy density until it reaches a maximum value, and then further increasing energy density will cause the decrease in the bend strength. ...