Effect Of Content And Length Of Nylon Fiber On Properties Of Silica Sol Shell For Casting

The Investment casting is one of the major forming technologies of the complex aerospace precision castings.The traditional investment casting manufacturing cycle of shell was long,the coating slurry was slowly drying;the wet strength of shell was low,shell was easily damaged during transportation;the residual strength of shell was high,the husking property of shell was difference;the permeability of shell was poor,affecting the quality of precision castings,and there are the restrictive relation among strength and breathability of shell.The effects of content and length of the fiber on the properties of silica sol slurry and shell were studied by adding nylon fibers reinforced shell,to provide the theoretical guidance for casting manufacturing of shell.This paper adopts nylon fibers to reinforced shell,adding different content and length of nylon fibers in the silica sol slurry,the nylon fibers in silica sol slurry were dispersed by mechanical stirring,studying effect of content and length of nylon fibers on the coating performance of silica sol slurry and its influence on shell properties,analyzing the enhancement mechanism of nylon fibers of shell casting,optimizing the firing process of nylon fibers reinforced shell.The experimental results show that the mixing effect can be dispersed in the slurry to improve nylon fibers,when the stirring speed was 210n/min,the nylon fibers dispersed uniformly;when the content of the nylon fibers increases from 0% to 0.75%,the length of fiber increases from 2mm to 6mm,with the increase of the content of fiber and the increase of the length of fiber,the movement viscosity of slurry increases gradually,the quality of moistening slurry of shell and the coating thickness of shell in each direction increase;with the increase of the content of fiber and the increase of length of fiber,the green flexural strength of shell was all increases first and then decreases,the fired flexural strength of the shell all increases first and then decreases again increases,the air breathability of shell first increases and then decreases;when the content of fiber was 0.6%,the green flexural strength was the maximum value3.06 MPa,when the length of the fiber was 4mm,the green flexural strength was the maximum value 2.92MPa;when the content of fiber was 0.45%,the fired flexural strength was the minimum value 3.96 MPa,when the length was 5mm,the fired flexural strength was the minimum value 4.03MPa;when the content of nylon fiber was 0.60%,the air breathability was the maximum value3.25,when the length of fiber was 5mm,the air breathability was the maximum value3.42.The nylon fibers in the silica sol slurry were dispersed by the mechanical stirring,and the effect of length of nylon fibers and content of nylon fibers on the properties of the silica sol slurry and shell was studied,when the length of the fiber was in 4mm~5mm,the content of the fiber was in 0.45%~0.60%,flexural strength and air permeability of the shell was in best performance,to provide the theoretical and technical guidance for high quality complex casting production.