Papers by Keyword: Al

Abstract: This paper applies Flow Drill Screws (FDS) technology to the joining of composite materials and metal materials. It investigates the connection strength and mechanism between thermosetting carbon fiber reinforced composites and metal materials, as well as between thermoplastic carbon fiber reinforced composites and metal materials. The study includes shear tests and metallographic tests to analyze the two types of connections. The experimental results demonstrate the feasibility of using the FDS process for composite materials and metal materials. It is found that the FDS process is more suitable for connecting thermoplastic composites and metal materials compared to thermosetting composites and metal. This type of connection exhibits a smaller damage range at the interface and allows the thermoplastic matrix to effectively fill the threaded connection area after heating. Additionally, the micro-mechanical interlocks generated at the laminate interface can effectively increase the connection strength.

Abstract: This study offers a comprehensive examination of the behavior of 3C-SiC crystals grown on 4° off-axis (100) Si substrates with different off-axis angles along <110> and <100> for N and Al doping, respectively. The investigation takes advantage of molten KOH etching to conduct an in-depth investigation of the average density and size of the SFs inside the crystal for both n- and p-type doped 3C-SiC epitaxial layers. Moreover, 3C-SiC grown on a <100> off-cut substrate was revealed to have a greater concentration of SFs due to the absence of self-annihilation along the plane (-1-10). Considering two different doping ranges suitable for IGBTs and MOSFETs development, the impact of doping and off-angle on the crystal quality, concentration, and length distribution of SFs was then investigated in order to quantify the influence of N and Al incorporation on the structural and optical characteristics of the semiconductor. It turned out that under heavy nitrogen doping (~10¹⁹ cm^-3), when the dopant concentration grew, the average length of the stacking faults (SFs) expanded while their density dropped.

Abstract: The effects of welding conditions such as the electrode type and welding current were investigated on the microstructure and joint strength of the resistance weld of A5052 and GA590. The reaction layer formed at the joint interface was inferred to consist of Fe-Al based intermetallic compounds (IMCs) which are FeAl, FeAl₂, Fe₂Al₅ and FeAl₃ by quantitative analysis. Although the thickness of the IMCs layer decreased from the center of the nugget towards the edge of it. When the DR type electrode was used, the cross tensile force became higher than those of the joints formed with the R type one. This is because the thickness of the reaction layer formed at the nugget end of A5052 was thin in the case of the DR type electrode. Also, it was found that cross tensile force increases when the thickness of the reaction layer is thin by multiple regression analysis.

Abstract: In this paper, the effect on the properties of alumina/aluminum cermet by changing the sintering temperature, and comparing the advantages and disadvantages of different characterization methods and their application range, it provides a reference for selecting the characterization technology suitable for alumina/aluminum composites.Through mixing, molding, sintering, sample preparation, scanning electron microscopic observation, energy spectrometer observation and analysis, the following conclusions can be drawn: the higher the vacuum sintering temperature, the more aluminum material is melted out of the body to form aluminum balls on the surface, and the green body The more severe the cracking. When the sample is sintered at a temperature of 600 °C, the density is the highest and the appearance is the best. When the molding pressure is 40 MPa and the sintering temperature is 700 °C, the microstructure of the sintered alumina/aluminum cermet is better. It can be seen from SEM and EDS analysis that the particles are continuously distributed and the larger one is metal Al, and the particles are discontinuously distributed and finer is Al₂O₃.

Abstract: In this paper, the effect of raw materaisl on the properties of coated Al₂O₃/Al cermet materials were investigated, the raw materials were prepared via different methods, which provide a reference for obtaining higher performance cermet materials. Through mixing, molding, sintering, sample preparation, scanning electron microscopic observation, energy spectrometer observation and analysis, the following conclusions can be drawn, the density of the cermet material prepared by the mechanical ball milling method (83.5%) is higher than that of the cermet material prepared by the chemical precipitation method (92.8%). It is nearly 10% lower. The alumina particles prepared by the ball milling method are agglomerated, and a large amount of agglomeration occurs in the aluminum, and the composition is very uneven. For materials prepared by the precipitation method, the aluminum oxide is uniformly distributed in the aluminum. The ball-milling powder is used to prepare materials, most of the alumina is in the form of particles, and in the precipitation method. In the powder preparation sample, the thin layer of alumina which forms the same eggshell envelops the aluminum, and the aluminum has a certain liquid phase change. the surface hardness (824HV) of the cermet material prepared by the mechanical ball milling method is lower than the surface hardness (1005HV) of the cermet material prepared by the chemical precipitation method.

Abstract: This work takes into account low Al implanted concentrations of 3 x 10¹⁸ cm^-3 and 1 x 10¹⁹ cm^-3 to compare the results of 1600°C and 1950°C post-implantation annealing treatments, done with two different annealing times per given implanted Al concentration and post implantation annealing temperature. Current-voltage and Hall effect measurements were performed to have the drift hole density and the drift hole mobility curves in the temperature range 100 - 650 K. The fitting of these curves in the frame of a carrier transport into the extended states of the valence band were performed to estimate the Al acceptor density, the donor compensator density, and the Al acceptor ionization energy. Peculiar feature of hole density and hole mobility curves is a contemporaneous increase of both carrier density and mobility values with increasing annealing time, which is congruent with the output parameters of the fitting procedure. The latter shows an almost stable Al electrical activation and a decrease of compensation with increasing annealing time for constant annealing temperature and given implanted Al concentration.

Abstract: In this paper, the effect of raw materaisl on the properties of coated Al₂O₃/Al cermet materials were investigated, the raw materials were prepared via different methods, which provide a reference for obtaining higher performance cermet materials. Through mixing, molding, sintering, sample preparation, scanning electron microscopic observation, energy spectrometer observation and analysis, the following conclusions can be drawn, the density of the composite material increases first and then decreases with the increase of the molding pressure. When the molding pressure is 30 MPa, the density of the composite material reaches the maximum value, that is 93.5%. The greater the applied pressure, the more compact the aluminum powder and alumina powder, and the longer the tissue composition, the more uniform. there is no crack in the c-picture, and there are cracks in the a and b pictures. The microstructure of metal matrix composites prepared at different molding pressures is also different. Sintering of the green body formed at 30 MPa resulted in relatively few cracks and voids in the material. The surface hardness of the composite material increases first and then decreases with the increase of the molding pressure, and the surface hardness of the composite material reaches a maximum value (875 HV) at a molding pressure of 30 MPa.

Abstract: The results of the first experiments for achieving the thermal equilibrium during 1300 °C annealing of 1×10²⁰ cm^-3 ion implanted Al⁺ in 3C-SiC are shown. X-ray diffraction, through reciprocal space maps and 2Θ scans, characterizes the 3C-SiC lattice recovery. The achievement of a ohmic behavior of Ni/Al/Ti alloy indicates the onset of a measurable electrical activation of the Al implanted layer. The Al electrical activation is qualified through the implanted layer sheet resistance.

Abstract: Ranges for Al implantations into 4H-SiC (0001) were compared between channeled-ion implantation (without using a MeV implanter) and non-channeled ion implantation using an ion energy E₀ in the Bethe–Bloch region (IIBB). Since the latter (i.e., projected range of 7.5 μm at E₀ = 26 MeV) was larger than the former (i.e., maximum channeled range of 3.4 μm at E₀ = 900 keV), IIBB was concluded to be suitable to minimize the repeat count of epitaxial growth/ion implantation steps used in the fabrication of 4H-SiC superjunction power devices.

Abstract: In atmospheric environments, Al₂O₃ ceramics have good oxidation resistance in water, acid, and other solutions and suitable corrosion medium resistance. Al₂O₃ ceramics is one of the most widely used engineering ceramics. In this paper, Al₂O₃/Al cermet matrix composites were prepared by mixing a series of powders with aluminum and alumina powders as raw materials. The interface of Al₂O₃/Al cermet was observed by scanning electron microscopy. The densification process of Al₂O₃/Al cermet was then explored from the aspects of formulation, molding pressure, holding time, and sintering process. After mixing and dry pressing, 50 wt% Al and 50 wt% Al₂O₃ were appropriate for sintering. Following sintering and measuring density, density was improved under 20 MPa with a 20-minute holding time. Through a comparison of the sintering process, the interface structure was observed via scanning electron microscopy, which found that secondary sintering is conducive to improving the density of Al₂O₃/Al cermet.