With reinforced material of carbon fiber modified by different modifier

SLS coated sand specimens were prepared.The effects of carbon fiber modification and content on tensile strength and bending strength of the samples were analyzed by mechanical test and scanning electron microscopy（SEM）.The results indicate that the modified carbon fibers treated by nitric acid and silane coupling agent（KH550）present the desirable reinforcement effect on SLS coated sand mold

and the strength of SLS coated sand mold is increased firstly and then decreased with the increase of carbon fiber content.When the carbon fiber content is 3%

the curing tensile strength and bending strength of the SLS coated sand mold reach maximum value of 6.385 MPa and 8.011 MPa

increased by 46.18%and 33.92%respectively

compared with those of one added unmodified carbon fibers

and increased by 23.18% and 31.46%

respectively

compared with those of ones with absence of carbon fibers.