In the process of conventional bending, the inner-arc side of pipe is always subjected to compress and the outer-arc side is subjected to tension during bending, as a result, non-uniform thickness of the pipe is often produced. The expanding-bending technology is an efficient way to solve this issue. However, this technology has a complex process and the forming quality might be affected by many factors. High quality titanium elbow requires high strength and uniform wall thickness. On the basis of theoretical analysis, the hot expanding-bending technology test of high strength titanium alloy was carried out. The flow law of metal in the forming process was studied. The proportional relationship between the bending deformation amount and the expansion diameter was given. Finally, the uniform thickness of 1300MPa grade elbow were obtained through the hot expanding-bending technology by means of inducing heating, and the relative wall thickness tolerance of the wall thickness was about 6%. This study is of certain guiding value for the bending process of titanium alloy.

    Thermal barrier coatings (TBCs) is the key technology for the hypersonic aircraft and the aero-engine. At present, yttria stalized zirconia (YSZ) is widely used as the thermal barrier coatings ceramic top-coatings. However, it cannot use for the next generation of engine in the future, owing to the volume difference caused by T–M phase transformation of ZrO2. Obviously, it is imperative to find a kind of more advanced TBCs. The experiments have shown that the rare earth tantalate prepared by the solid-state reaction has more excellent thermophysical and mechanical properties, such as lower thermal conductivity (1.1–1.3W/(m·K), 1000℃ ), higher temperature gradient (300–500℃ ) and better fracture toughness. Besides, the rare earth tantalate is transmitted at a much lower rate than YSZ through O2– anions, which can effectively prevent the growth of thermal growth oxides (TGO). Considering the above advantages, the rare earth tantalate would be the great potential TBCs in the next generation of gas turbine.

    The thermal barrier coatings (TBCs) is an important technology for aero-engine hot components. Moreover, the strength analysis and lifetime prediction of TBCs are hot issues of basic research. During the service of hot components, the failure of TBCs will accelerate the degradation of substrate and threaten the safety of flight. The proper life model of TBCs can release the probability of failure and improve the reliability of engines. The damage mechanism of TBCs and the development of lifetime prediction were introduced. Furthermore, the development trend of thermal barrier coating life analysis technology for aero-engines was discussed.

    NiAl coating obtained by pack aluminization is the firstly used as Al₂O₃-forming high-temperature coating. Since the middle of the last century, NiAl coatings were employed in hot sections of aero-engines for protection against high temperature oxidation. Investigations of the oxidation mechanisms of the coating, and exploration of the coating techniques continue up to now. On a basis of understanding to the oxidation mechanism of alloys and thermal growth of Al2O3, a concept of improving the oxidation resistance of nickel aluminide coating by means of grain refinement and typical metal oxide dispersions has been proposed. Meanwhile a method to refine the grains of the nickel aluminide coating and disperse it with metal oxide nanoparticles has been presented, and key factors (including growth rate of the Al₂O₃ scale, Al₂O₃ phase transformation from metastable phases to the stable phase, the Al₂O₃ adhesion to the coating as well as the interdiffusion between the coating and the metal substrate) intrinsically correlated with the oxidation resistance of the coating which can be significantly affected by its modification in microstructure and chemical composition have been reviewed. The new result is expected to be helpful to further offer theoretical and experimental bases for tapping the potential and prolonging the service life of the aluminized coatings in application.

    As a novel technique, plasma spray–physical vapor deposition (PS–PVD) process combines advantages of high deposition rates and cost-efficiency of plasma spraying and columnar structure of electron beam-physical vapor deposition (EB–PVD), so that PS–PVD has received considerable attention to manufacture thermal barrier coatings (TBCs) for some advanced turbines. In this paper, yttria stabilized zirconia (YSZ) coatings were fabricated by PS–PVD. Field emission scanning electron microscopy (FE–SEM) and electron backscatter diffraction (EBSD) were used to observe and analyze the microstructure and crystallographic feature of the coating. The result shows that the microstructure of as-sprayed YSZ coating is columnar structure crystals. During the process of deposition, at a certain spraying distance, the transition zone from the center to the edge of the spraying spot, the end surface of columns is transformed from a quadrangular pyramid structure to a cauliflower-like structure, and the mono-column exhibits a certain preferred orientation, but other columns have different orientations, and the ceramic does not exhibit a distinct preferred orientation on the whole.

    The TiCN coating were successfully fabricated by reactive plasma spraying. The microstructure of coating was characterized by scanning electron micrograph (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The mechanical and tribological properties of coatings were evaluated by Vickers microhardness tests, nanoindentation tester and block-on-ring tribometer. Results showed that the main phases are TiC_0.7 N_0.3 and TiN with some amount of amorphous graphite and CN_x phase. There are some Ti₂O due to the plasm spraying carried out in atmosphere. The coating exhibits typical thermal spray spreading out morphology and a good bonding status between the coating and substrate was obtained. The microhardness value of coating still exceeds 1000HV_0.2, which is higher than that of substrate and bond coat. Due to the H³/E² of coating is greater than 0.1, it indicated that TiCN coating possessed a high resistance of plastic deformation and excellent wear resistance.

    The ZT1 amorphous alloy film with a thickness of 70μm was ablated and cut in ultrafast laser (250fs). The study of ultrafastlaser removing morphologies and removing thresholds indicated thattwo distinctive ablation regimes including unmelted ablation and melted ablation existed in ZT1 amorphous alloy, depending on the incident laser fluence. The removing thresholds for these two ablation regimes were determined to be F_th1=0.17J/cm², F_th2=2.15J/cm², respectively. In cutting, the processing quality was closely related to the laser energy density. Andin the larger parameter range (2.2J/cm²<F₀<12.8J/cm²), the cutting edge withoutcollateral damage could be obtained, which was closely related to the characteristics of laser Gaussian energy distribution and the threshold for material removal.

    A promising technique to solve the microstructure degradation problem caused by conventional diffusion bonding process of copper (500–800℃) is low-temperature (400℃) diffusion bonding method. Shot peening treatment was applied to copper surfaces before bonding to active the diffusion of atoms under low bonding temperature. Four samples with shot peening time of 10s, 40s, 70s, 100s, respectively, were observed under optical microscope before bonding. Severe plastic deformation occurred, and fine-grained layer formed near the surface after shot peening. The thickness of the finegrained layer increased with the increase of the shot peening time. After low-temperature diffusion bonding, recrystallization was proved to take place. The tensile strength of the joint increased with the increase of the shot peening time. The highest strength was 314.5MPa with shot peening time of 100s, reaching 86.1% of the base metal.

    In order to improve the frequency and the magnetic field uniformity of electron beam high frequency deflection scanning, based on the working principle of the Helmholtz coil, a high frequency deflection scanning coil was designed using a hollow structure. According to the structure of the electron gun and the technical requirements of electron beam deflection scanning, the required magnetic field strength and the number of ampere turns are calculated. The threedimensional software Pro/e was used to establish the geometric model and the finite element analysis model, and Maxwell was used to simulate the electromagnetic field. The uniformity of the electromagnetic field distribution of the designed high-frequency deflection scanning coil was analyzed, and the actual measurement was made. The measurement results were basically consistent with the simulation results. The magnetic field intensity and magnetic field uniformity generated by the designed deflection scanning coil meet the technical requirements of the high-frequency deflection scanning of the electron beam. The experimental results show that the deflection scanning coil can achieve a scanning range of 350mm×350 mm and high frequency scanning can reach 7000mm/s.

    In order to establish a comprehensive model for simulating the machining deformation, it was studied a series of key techniques including constitutive model, residual stress, material removal, finite element control etc. Subsequently, a milling test was conducted to verify the model. The result shows that the simulation accords with the experiment, which means the model meets the requirement of engineering. Thus the model was used for optimizing the processing of the large integral aero-component.

    The excitation device is the core device of the trapezoidal thread vibration-assisted cold extrusion machine, which is a new type of mechanical torsional vibration device based on the torque balance state. On the basis of introducing its structural principle, the dual effect of auxiliary vibration on the trapezoidal thread cold extrusion process is analyzed. On the one hand, the change of the taper angle amplitude in the whole process is explored, as well as the influence of the spindle speed and the excitation frequency on the tap angle. It is concluded that the vibration of the excitation device is effectively transmitted to the working part of the tap. On the other hand, through the frequency domain analysis of machine signals under different operating conditions, the excitation device does cause the forced vibration of machine parts. Finally, by comparing the processing quality and the processing surface quality of the trapezoidal thread obtained by the traditional cold extrusion method and the vibration-assisted cold extrusion method, it is concluded that the auxiliary vibration of the exciting device is dominated by the beneficial effect.

    This paper introduces the optimization of the machining process of ball support parts in detail, through the optimization of the technological process and the numerical control program of these parts, and rationally designs the tools, selects the new type of convertible tools, and then optimizes the machining cutting parameters through orthogonal experiments. Finally, the machining verification is carried out. It improves the production efficiency of this kind of part, saves the part material, improves the surface quality of the part, and has a certain reference for the processing of this type of part in the future.