Research On SiC_3D / Al Composites With Organizational Performance And Interface

In this paper, prepared by vacuum pressure impregnation of SiC_3D / Al was investigated using surface modification, mold improvement, solution heat treatment, electron backscatter diffraction and finite element simulation method, it focuses on the production of a composite dip Effect of infiltration process parameters, oxidation reforming process, alloying elements, mold, heat treatment and other organizations on the interface, and the establishment of quantitative characterization of the stress applied to the interface method SiC_3D / Al EBSD detected and the corresponding sample preparation process. The main results are as follows:（1） To establish a vacuum pressure impregnation Preparation SiC_3D / Al infiltration critical pressure calculation model to analyze the three-dimensional connectivity SiC ceramic matrix preform pore size, porosity and pore tortuosity factors such as the influence of pressure on the critical infiltration, a clear infiltration of the porous preform during the pore size effect on infiltration greatest pressure. Forecast prepared by vacuum pressure impregnation dense required SiC_3D / Al composites critical infiltration pressure, SiC_3D prepared / Al composites density above 99%.（2） SiC porous skeleton 1200 ℃ oxidation reforming technology to solve Al4C3 because SiC_3D / Al interface reaction results in performance degradation of the mechanical problem, and with the oxidation time, the compressive strength of the composite material exhibits asymptotic linear rise, And after flexural strength increased and then decreased. On the basis of established critical porosity porous SiC oxidation model, since the SiC surface oxygen partial skeleton decision SiO2 layer growth rate, so that there is a critical oxidized porous SiC matrix pore size, smaller than the critical size of the pores is difficult to get enough oxygen to fully oxidized, In the infiltration process can not effectively organize interface Al4C3 production, resulting in decreased strength of the area of the interface, in the composite load carrying bending when stress concentration region, as extended oxidation time, the stress concentration factor increase, which led to a curved composite After the intensity increased and then decreased root causes.（3） ZL201 A, ZL205 A, 2A12, three aluminum prepared dense SiC_3D / aluminum composite material, wherein the compression strength ZL201 A and ZL205 A prepared composites prepared than pure aluminum increased by 30%, but the bending strength decreased, analysts believe that prolonged exposure to molten aluminum and steel molds cause Fe elements dissolved, and the resulting alloy elements in SiC / Al interface segregation is the main reason for reduced bending strength due to composite materials can not be reflected by plastic deformation of 2A12 strengthening effect, it does not apply for the preparation SiC_3D / Al composites.（4） In order to avoid the introduction of Fe element mold, mold-based guarantee tightness, the principle of mold and molten aluminum to reduce exposure time, the design of the new anti-pressure mold, which can meet SiC_3D / Al pressure during preparation of the load demand, while in contact with liquid aluminum die by the four hours long reduced to 10 minutes, reducing the diffusion of Fe to the alloy elements, thus improving the interface segregation composites.（5） SiC_3D / ZL201 A composites were heat treated at 545 ℃ × 2h composites after heat treatment from 673 MPa compressive strength raised to 888 MPa, flexural strength from 169 MPa raised to 185 MPa, during the heat treatment, the interface position CuAl2 decomposition aluminum center section with respect to diffusion and homogenization, the aluminum phase hardness may be raised, thus further develop the aluminum support frame relative to SiC and binding effect, heat the composite material interface transforming from SiO2 / Al2O3 to SiO2 / Al-O-Si / Al2O3, the performance of the composite material is most prone to failure strength of the region continue to rise, work together to enhance the mechanical properties of the aluminum phase itself and the improved interface organization is to enhance the performance of the composite material reasons. But the holding time is too long, it will form Al-O-Si / Al2O3 interface tissue, leading to decreased interfacial strength.（6） To establish a new method for characterizing EBSD Si C_3D / Al composites residual stress, the method by analyzing the material lattice grain under stress produce deflection, the establishment of a difference between the parameters and the relationship between the in-situ stress orientation, access to the SiC_3D / Al composites of aluminum relative expression of residual stress.（7） To establish a "vibratory finishing- Ion Polishing- vibratory finishing" a new method for preparing samples obtained SiC_3D / Al composites EBSD test sample, the method based on the stress distribution of the sample retained on to meet the EBSD credible degree（CI value） requires parameters. EBSD test results showed that the maximum residual stress of the interfacial region 22.96 MPa, and FEM distribution range in the same amount, the distribution is characterized by a rapid decline from the interface to the aluminum center section with residual stress, consistent with FEM analysis.