| As vehicle speeds and safety requirements increase,brake discs,the core component that ensures the safety of automobile braking,are required to have high strength,high wear resistance,and high heat dissipation performance while being lightweight in design.Traditional cast iron and aluminum alloy brake discs do not meet the above requirements.Therefore,in this paper,AlSi10Mg composite material and cast iron were used to compose Functionally Graded Materials（FGM）brake disc,and the thermal coupling analysis of the brake disc under emergency braking conditions was carried out to study the structural characteristics of FGM.ZrO2 and Ni particles have great potential to enhance the performance of metallic matrix.Aiming at the defect of insufficient strength of traditional AlSi10Mg alloy,the properties of AlSi10Mg alloy reinforced by ZrO2 and Ni particles and its influencing factors were studied by Selective Laser Melting（SLM）technology.The main works of this paper include:（1）Optimal formation mass parameters for AlSi10Mg alloy were investigated.Based on the parameters of the AlSi10Mg formation process package,several sets of experiments with different laser powers and scanning speeds were designed to explore the density and hardness of the formed samples with different parameters.The results show that the formation quality of AlSi10Mg alloy is best for laser power and scanning speed of 350 W and 1850 mm/s.（2）The effects of scanning speed（1650,1850 and 2050 mm/s）on forming quality,microstructure and properties of 0.5wt%ZrO2/AlSi10Mg composites were investigated.The mechanism of enhancement of AlSi10Mg by ZrO2 particles was revealed by observing and comparing the density,eutectic Si network,grain size,mechanical and tribological properties of the formed samples.At a scanning speed of 1850 mm/s,the ZrO2/AlSi10Mg composites exhibit excellent mechanical properties with hardness,strength,yield and elongation up to 135.54 HV,418.61 MPa,345.77 MPa and 6.21%respectively.（3）The effects of Ni content（0wt%,1wt%,3wt%and 5wt%）on forming quality,microstructure,crystal texture and properties of Ni/AlSi10 composites were investigated.By observing and comparing the density,eutectic Si network,grain size,mechanical and tribological properties of the formed samples,the strengthening mechanism of Ni particles on AlSi10Mg is revealed.The results show that the Ni/AlSi10Mg compound with 3wt%Ni particles has the best integrated performance.（4）The shock resistance of the FGM brake disc was investigated.By comparing and analyzing the surface temperature field and thermal stress field distribution of FGM,pure cast iron and pure Ni/AlSi10Mg composite brake disc,the thermal shock resistance performance of FGM structure was systematically studied,and the comprehensive performance of FGM structure such as heat dissipation was optimized through the gradation index.The results show that the temperature and thermal stress of FGM and cast iron are basically the same,but the temperature and thermal stress of these two materials are lower than that of pure Ni/AlSi100Mg composite,the difference is about 20～26°C and 24～37 MPa,respectively.In addition,when the classification index is 1.5,the weight of the FGM brake disc component reaches 17.4%. |
