Study On Selective Laser Sintering Mechanism And Process Of Prosopis Chilensis/polyethersulfone Composite

Selective Laser Sintering(SLS)technology offers many advantages over other 3D technologies: no need supports during processing,unsintered material can be reused and recycled,and parts made via SLS are more dimensionally accurate.Environmentally friendly SLS materials with low cost,low energy consumption and small deformation have become an important direction for the development of SLS technology.At present,SLS materials at home and abroad are mainly focused on metals,ceramics and polymers,but there are few biomass composite materials with good environmental sustainability and low energy consumption.Based on the current direction of ecological engineering,forestry and agricultural wastes have started to be used in SLS technology,such as wood waste,bamboo waste,straw,rice husk,walnut husk,sisal fiber,peanut husk,etc.Sudan is rich in Prosopis Chilensis(mesquite)resources.In this paper,an energy-saving and environmentally friendly Prosopis Chilensis powder(PCP)/polyethersulfone(PES)mixture(PCPC)is proposed as a new biomass raw material for SLS,which can expand the range of materials available in the SLS process.Besides that help to reduce the pollution associated with the disposal of Prosopis Chilensis waste and achieve high-value utilization of natural biomass materials.This paper aims to study the design and preparation process of PCPC materials for SLS,establish a quantitative evaluation method for sintered parts,optimize the SLS process parameters of PCPC materials,and combine theoretical analysis,numerical simulation test and experimental test,and carry out the following main researches content.First,the thermophysical properties of PCPC,namely thermal conductivity,specific heat capacity and density were determined in this paper.Through the single-layer sintering test,the feasibility of PCP as an additive raw material for SLS was verified.A design and performance study of PCPC was performed,and the desired properties of SLS feedstock ascertained according to the theoretical knowledge and the limitations of the processing capacity of the SLS equipment.In addition,the formability,microstructure and particle distribution of various PCPC parts and various PCPC SLS parts before and after mechanical testing(break)were investigated by multilayer experiments and SEM tests,respectively.At the same time,the mechanical strength,surface roughness value and dimensional accuracy(DA)of parts produced by PCPC with different PCP ratios and different PCP particle sizes were measured.Through the comprehensive results,the optimal mass ratio of PCP and PES powders and the appropriate PCP particle size were determined.To prevent warpage and deformation of PCPC sintered parts during SLS manufacturing,the PCPC material was preheated within a specific temperature range according to the differential scanning calorimetry(DSC)test results.Before DSC testing,it is necessary to determine the thermal decomposition temperature of PCPC components;therefore,thermogravimetric analysis(TGA)of PCP and PES powders is required.According to DSC and TGA test results,they were selected the various SLS process parameters of PCPC material.Secondly,based on the analysis of the thermal action process of the laser beam on the PCPC powder,this paper establishes the heat transfer model of the SLS PCPC powder material and establishes the heat source model of the laser beam.To verification the PCPC experimental tests results,the mechanical analysis in ANSYS simulation was used to determine the tensile force(N)of both experimental and simulation tests results that were performed under same tensile strength(stress field)(MPa)and same SLS parameters,as in experimental section;and then was comparing between these two values.Multi-field coupling simulation research is carried out on the equivalent(Von mises)stress field of PCPC material in the SLS process.Through the simulation results,the effects of different SLS process parameters on the equivalent stress,strain and deformation of the formed parts are determined.Thirdly,the five factors and four levels orthogonal test method is used to optimize the SLS process parameters of PCPC parts.The X,Y,and Z-directions dimensional accuracy,tensile strength and bending strength were taken as indicators to obtain the best SLS process parameters.This study is among the first to elucidate the influence of the various SLS processing parameters on mechanical properties,which demonstrated experimentally the effects of various process parameters on SLS sintered parts,namely laser power,scanning speed,preheating temperature,scanning spacing and layer thickness,as well as the effects of mixing ratio and different PCP particle sizes on the mechanical properties of PCPC SLS parts,were studied through single and multi factor experiments.Finally,in order to further improve the mechanical strength,density and surface roughness of PCPC material SLS parts,the posttreatment technology of wax infiltration was introduced.The influence of different parameters on the mechanical properties of the wax-penetrating parts was studied,and the mean value,standard deviation,and 95% confidence interval of the mean value were used for statistical analysis to prove the reliability of the results.The potential application of the produced PCPC parts is manufacture of roof materials and wooden floors,and furniture manufacturing.