选择性激光烧结尼龙12／碳酸钙复合材料的成型工艺

摘要

Pure nylon (PA) 12,PA12/calcium carbonate (CaCO3) and PA12/CaCO3 modified by silane coupling agent KH–550 (PA12/CaCO3/KH–550) composite sintered parts were prepared by selective laser sintering technology. The molding quality (Z direction size precision,bending strength and tensile strength) of the three sintered parts were studied under the same process param-eters. Under the layer thickness of 0.15 mm and scanning interval of 0.28 mm,the effects of laser powder,scanning speed,preheat-ing temperature on the molding quality of PA12/CaCO3/KH–550 sintered parts were studied. The results show that compared with untreated CaCO3,the CaCO3 treated with KH–550 can improve the molding quality of PA12 sintering parts to some extent. In the range of experimental value,the bending strength and tensile strength increase with the increase of laser power and preheating tem-perature and decrease with the increase of scanning speed,and the relative error of Z direction size shows gradually from negative to positive development along with the increase of laser power and preheating temperature,shows gradually from positive to negative development along with the increase of scanning speed. Laser power is one of the biggest influence factors on the molding quality of the parts,the second is scanning speed,the third is preheating temperature. Laser powder of 25 W, scanning speed of 2 000 mm and preheating temperature of 85℃are the best process parameters, at this time the relative error of Z direction size is-0.02%,the bend-ing strength of the parts is 30.3 MPa and the tensile strength is 26.4 MPa.%采用选择性激光烧结技术制备了纯尼龙(PA)12，PA12／碳酸钙(CaCO3)和PA12／硅烷偶联剂KH–550改性碳酸钙(CaCO3)(PA12／CaCO3／KH–550)复合烧结件。在相同工艺参数下研究了这3种烧结件的成型质量（Z向尺寸精度、弯曲强度和拉伸强度）。在单层厚度0.15 mm、扫描间距0.28 mm下研究了激光功率、扫描速度和预热温度对PA12／CaCO3／KH–550烧结件成型质量的影响。结果表明，相比未改性的CaCO3，经KH–550改性的CaCO3在一定程度上提高了PA12烧结件的成型质量；在实验取值范围内，PA12／CaCO3／KH–550烧结件的弯曲强度和拉伸强度随激光功率和预热温度的增大而增大，随扫描速度的增大而降低，而Z向尺寸相对误差随激光功率和预热温度的增大表现出由负值逐渐向正值发展，随扫描速度的增大表现出由正值向负值发展；激光功率对烧结件成型质量影响最大，扫描速度影响次之，预热温度影响最小；确定了激光功率25 W、扫描速度2000 mm／s、预热温度85℃为最佳工艺参数，此时烧结件Z向尺寸相对误差为-0.02%、弯曲和拉伸强度分别为30.3，26.4 MPa。