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Particle reinforced light alloy matrix composites have low density, high specific strength, high stiffness, wear resistance, low thermal expansion and dimensional stability, etc., in the application prospects of the aerospace, defense and industrial and automotive, electronic industries extensive. Vacuum pressure impregnation method due to seepage, pressure control is easy, uniform penetration, good compactness, etc., become the main method of preparation of metal matrix composites. Preparation of high performance particle preform the focus of the study and one of the difficulties of the method is a novel, selective laser sintering technology to prepare ceramic particles preform, fast and effective method of preparation, but people know it is very limited. Selective Laser Sintering of SiC particulate ceramic preform forming process and mechanism of particle reinforced metal matrix composites provide a theoretical basis and process experimental basis, has important theoretical significance and value of the works. This paper SiC particles coupled modified experimental, organic, inorganic binder combination of dual binder, focusing on different binder ceramic preform molding of the preform laser \analysis, and after firing the preform for a vacuum pressure aluminized experiment. Its main findings are as follows: Application KH-570 silane coupling agent modified SiC particles, significantly improved formability Laser Sintering of SiC particles. SiC particles forming the powder of dual binder, laser sintering experiment showed that: in the laser sintering process of the organic binder is an epoxy resin (EP) or nylon 6 (PA6), play a major role in adhesion, an inorganic binder ammonium dihydrogen phosphate (MAP) from the bonding effect of the auxiliary. Laser sintering mechanism of the inquiry, wherein SEM: EP and MAP dual laser sintering of the binder member, between the particles mainly through EP bonded integrally, but based on the characteristics between the workpiece layers and EP thermosetting lap not compact, laser sintering EP easily into blocks; PA6 and MAP pairs of laser sintering of the binder member, PA6 as a thermoplastic binder, in the scanning process of laser transient melt and penetrate between the connection layer between the particles within the layer, that the interlayer connections are tight lap firm, tightly packed particles, uniform distribution of SiC particles with the binder interface. In the selection of EP and MAP dual binder (its contents were 6wt%, 8wt%), selective laser sintering by orthogonal experiment, to obtain its optimum sintering process parameters: 42.5W, the scanning speed of the laser power 1400mm / s, scanning spacing 0.1mm, Shop powder thickness 0.2mm. And the tensile strength of the sintered samples was 1.11 MPa, the bending strength of 0.74MPa, forming member shrinkage less than 3.6%. Choice the PA6 and MAP pairs binder (the content thereof was 20 wt%, 8wt%), by orthogonal optimization experiments, to obtain its optimum sintering process parameters: laser power of 15W, the scanning speed of 1200mm / s, the scan pitch 0.1mm Shop powder thickness 0.1mm, preheat temperature of 175 ° C. And the tensile strength of sintered samples was 2.44 MPa. Here, the bending strength of 2.22MPa, the shrinkage rate of the forming member is less than 2.2%. The secondary roasting preform by XRD analysis showed the organic binder completely burning calcined through MAP decomposition generate phosphates new phase, from bonding effect. Wherein the the EP and MAP pairs binder sintered preform generated SiP2O7, there is a certain decrease in the strength of the sample after calcination, a tensile strength of 0.17 MPa, the bending strength of 0.5 MPa; PA6 and MAP pairs binder sintered preform produce two phosphate: SiP2O7 2Si O2 · P2O7, the tensile strength of the sample after calcination was 1.24MPa, the bending strength of 1.05MPa. Vacuum pressure impregnation experiment SiC particles calcined ceramic preform pressure 0.4-0.5MPa penetration, a clear outline, size preform SiC particles distributed uniformly aluminum matrix composites.
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