Effect and Strengthen Mechanism of Infiltrating Silica Sol into Green Part of Selected Laser Sintering Precoated Sand
LU Gang;ZHANG Xiao-song;YAN Qing-song;JI Chao-zhong;PAN Fei;National Defence Key Discipline Laboratory of Light Alloy Processing Science and Technology Institute,Nanchang Aeronautical University;
The effect and strengthen mechanism of infiltrating process on strength of selected laser sintering(SLS) coated sand were investigated by infiltrating silica sol into green part of SLS coated sand. The research results show that, when infiltrating temperature rises and infiltrating time increases, the strength of SLS coated sand increases obviously, and the strength reaches a maximum value when infiltrating temperature and infiltrating time is 30 ℃ and 15 h respectively; when infiltrating temperature and time continues to increase,silica sol viscosity increases, infiltration effect becomes poor, the strength of SLS coated sand decreases; when the curing temperature and time of SLS coated sand infiltrating silica sol is 180 ℃ and 0.5 h, the strength of SLS coated sand is the best; when curing temperature and time continues to increase, resin bond will decompose and carbide, resin bond ability decreases, the strength of SLS coated sand becomes smaller. The test results of fracture surface morphology and composition show that, the sintering neck size increases because of coating on sintering neck after infiltrating silica sol, and new connection necks form in part of area without sintering neck,the strength of SLS coated sand are improved finally.