| With the rapid development of aviation,transportation,electronic information,military and other cutting-edge fields,there are higher standards and requirements for the comprehensive performance of materials.As the connecting parts of structural objects such as engines,lightweight rivets play a key role in"reducing the load"of aircraft,so the preparation technology of forming high-quality rivets has become a research hotspot.In this paper,the SiC_p/ZL106 composite rivet casting was obtained by using vacuum suction casting technology and SiC particles as reinforcement.First selected SiC particles way of surface treatment,vacuum casting equipment in use process of suction diameter and the size of the arc current control,the mass fraction of SiC particles size and scale as three kinds of different process parameters,experiment many times the casting forming rivet,the case for deeper study,finally,the optimum process parameters was determined by contrast experiment.Secondly,a new rivet mold was designed to simulate the process of forming the rivet casting.The suction diameter and arc current were selected as parameters to simulate the defect location,and the results were compared with those obtained in the actual experiment.The important conclusions are as follows:(1)The surface of SiC particles is copper-plated and pre-oxidized,both of which can improve the wettability of the interface with the matrix,effectively prevent harmful interface reactions to produce impurities,and improve the interface quality.The hardness,tensile strength and elongation at break of SiC_p/ZL106 composites(94.7HV,297.6MPa,58.9%)were the highest when pre-oxidized SiC particles were used as reinforcing parts,which increased by 51.5%,38.2%and 61.3%respectively compared with the matrix.(2)When the suction diameter increases to 3mm and the arc current increases to 350A,?(Al)grain refinement is obvious,the number of eutectic Si increases,and the solid solution effect is prominent.At the same time,the number of strengthening phase is also large,the distribution of SiC particles is discrete and uniform,without the state of accumulation,the defect situation has been significantly improved,the number of sharp decline,a fine hole shape.The SiC_p/ZL106 composite has the best comprehensive performance under this parameter.(3)When the mass fraction of nano-sic particles was 2%,they showed orderly dispersion without obvious agglomeration,and the maximum values(94.7HV,297.6MPa and 58.9%)of hardness,tensile strength and elongation at break of SiC_p/ZL106 composites were measured,which increased by 51.5%,38.2%and 61.3%compared with the matrix.(4)The SiC_p/ZL106 composites obtained from nano/microns SiC particles as stiffeners have finer grains,and their hardness,tensile strength and elongation are 109.5Hv,301.2Mpa and60.1%respectively,which increase by 75.2%,39.9%and 64.6%respectively compared with the matrix.(5)The mold structure of the new rivet casting was designed,and the filling shape and solidification process of the vacuum suction casting rivet were simulated by Pro CAST software.In the filling process of the rivet casting,the alloy fluid first flows straight down and rapidly fills the head of the rivet,and then,because of the rapid inflow and the non-returnability of the material,the alloy fluid flows into the middle of the head of the rivet and then springs back to the edge of the rivet on both sides.The rivet length is filled along the main path as the alloy fluid continues to fill.The solidification process of the rivet casting,with the passage of time,gradually ends along the path from the rivet head to the port,where the path from the bottom to the top conforms to the solidification law.(6)When the pouring temperature is set at 700?,rivet defects are greatly reduced.When the diameter of the suction orifice is set to 2.5mm,the shrinkage defects of formed rivets are less.The results obtained from the actual experiment were compared with those from the simulated rivet,and their state was completely consistent,and the data were verified. |
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