Advanced Materials Research Vols. 482-484

Abstract: A novel spiral stacked thin film transformer was designed based on Si IC technology in this paper. And also, the stacked air core and ferrite core thin film transformers with different turns ratio were prepareed. Then, the S-parameter performance of these two kinds of transformers were measured. The measurement results show that the magnetic core thin film transformer has a better electronic transmission performance. It obtains maximum transmission efficiency 93.7% at the frequency range from 10MHz to 20GHz, and the air core transformer obtains maximum 89% at the same frequency range. Many testings show that ferrite core thin film transformer with turns ratio 1:1 can obtain the transmission efficiency over 60% at the frequency range from 2GHz to 16GHz.

Abstract: By using dynamic simulation method, the launching technique of high firing rate for automatic rifle was studied. The influence of structure parameters of airway device, the stiffness of buffer spring and return spring on firing rate was studied. The simulation results provide the reference for the designing of high firing rate automatic rifle.

Abstract: The mechanical properties of B4C-CeB6 composite prepared by hot pressed sintering method were tested. The study shows: the hardness of B4C-CeB6 composite increases with the content of cerium boride. When the content of the cerium boride is 4wt%, the hardness reaches its supreme value of 31.98Gpa，its hardness is improved nearly 21.09% compared to monolithic boron carbide. The content of the cerium boride does not affect greatly on flexibility strength. However，it gives much effect on fracture toughness. When the content of the cerium boride is 4wt%, the fracture toughness reaches its supreme value of 5.06MPa.m1/2, which is improved nearly 37.5% compared to monolithic boron carbide materials. The main fracture way of B4C-CeB6 composite is intercrystalline rupture, while the transcrystalline rupture is minor. It appears that this change of fracture mode gives rise to the improvement of the fracture toughness.

Abstract: A comprehensive analysis of the physical processes that occur in Electroslag Remelting (ESR) process under steady state conditions and axisymmetric was performed using the simulation software MeltFlow. The detailed plots of current distribution, volumetric heating, flow, temperature and turbulent mixing provide insight into the various physical phenomena that occur in ESR process. The effect of current frequency on various physical fields was analyzed. It is shown that, the current in the slag tends to become more uniform due to the low electrical conductivity of the slag; after the current enters the ingot, the skin effect increases with the increase of the current frequency; the Joule heating and the Lorentz force are highest near the tip of the electrode in the slag, and increase with the increase of the current frequency; the velocities in the slag are slightly higher than those in the molten metal pool; with the increase of the current frequency, the liquidus temperature moves down, and the molten metal pool is deepened. Simulation results agree well with experimental results. Therefore, the generation and extent of defects could be predicted in different process.

Abstract: The performance of non-clinker slag cement concretes depends on the alkalinity of water quench blast furnace slag, the chemical composition, the rate of vitrification and the type and quantity of excitant. Non-clinker slag cement concretes was prepared with phosphorus gypsum as the excitant. by using the method compare with ordinary cement concrete（OPC）,We test strength and the bond strength of reinforced. The result showing, the Workability of NSC is better than OPC, the early strength lies in the ettringite and Approaching OPC. The long-term intensity lies in the C-S-H and Far more than OPC.

Abstract: There has been a substantional increase of atributes for building constructions in area of thermal protection in last decade. This was shown as increasing of requirements for materials and components intended for building of cover constructions as well. In case of shaped bricks used for perimeter walls advanced production technologies were applied. These technologies consist of decreasing thermal conductivity coefficient for brick clinker, of decreasing inner ribs thickness and in last years this concerns the technology of filling inner cavities of shaped bricks with thermal insulating materials as well. This paper describes possibilities of using alternative raw material sources (natural fibres originated in agriculture, separate textile waste, ....) as integrated insulating layers in contemporary ceramic shaped bricks with high usable qualities.

Abstract: The electrodeposition can endow many properties for the devices, which plays an important part in the field of electronic manufacturing. The thin film transformer, fabricated with the usage of electrodeposition, expands the performance of traditional transformer, leading to many new characteristics and functions. The paper chiefly analyses the processing conditions of electrodeposition, including the solution composition, current density, PH value, temperature, stirring, power waveform, heat time, additives, etc. These factors bring significant influences on the behaviors of thin film transformer, for example magnetization, coercivity, compactability, density, ductility, wear resistance, corrosion resistance, porosity, brightness, molecular structure, crystal properties. It also presents some possible reasons about the different performances among the thin films. All these work provides beneficial exploration for the fabrication and optimization on the magnetic core of thin film transformer.

Abstract: As an important lightweight and high-strength structural material, aluminum alloy is the optimum material for airplane and aircraft. Amorphous Al-based alloys are attractive materials for structural applications because of their high strength of about 1000MPa. Crystallization behavior of amorphous Al-based alloys is critical to the synthesis of high-strength nanocrystalline aluminum alloys in bulk form. The crystallization behavior of an Al₈₅Y₈Ni₅Co₂ metallic glass produced by rapid solidification of the melt was studied in this paper. Microstructure transformation during crystallization was identified by X-ray diffraction. It is found that the initial crystallization of the amorphous alloy occurs through the precipitation of α-Al particles, followed by precipitation of hcp-Al₃Y and an unidentified phase.

Abstract: In this paper, we report a new phenomenon observed in the gamma-ray radiation-induced hydrophobic effects on an Invar surface: When the Invar alloy is subjected to different doses of gamma-ray irradiation, the contact angle increases with the radiation dose. Invar samples with exposed to a higher dose appear more hydrophobic, but this tendency disappears following post-irradiation etching. The contact angles of the irradiated and etched Invar samples can be restored back to a stable value with small deviation after 30 min of annealing at 150°C. X-ray diffraction (XRD) analysis found no crystalline structural changes. High resolution field emission scanning microscope (FE-SEM) analyses showed that irradiation might induce crack-like surfaces which could be removed at higher radiation dose in the following acid etchings. It is believed that the chemical bonds of Invar oxide on the surface were broken by the gamma-ray irradiation, thus raising the likelihood of binding with free ions in the air and resulting in the exclusion of the hydrophilic OH bonds, leaving a hydrophobic post-irradiation Invar surface.

Abstract: Erosion phenomenon is quite common in petroleum industry, as one of the main mechanisms of material degradation, occurs frequently on high-pressure pipelines in hydraulic fracturing operation. With the increasing of operation times, the erosion and corrosion defects on the inner surface of the pipeline, would lead to serious material loss and equipment failure. In this paper a new type of test machine was developed to simulate the erosive wear behavior of metal materials caused by the multiphase fluid such as fracturing fluid, and study the erosion failure mechanism by various metal erosion influencing factors including the velocity of multiphase flow, solid particles of fracturing proppant and impact angles, etc. The erosion-wear experiments on 20CrNiMo steels used in high-pressure pipelines is described in detail. Finally, the microcosmic surface testing was also used to analyze the erosion failure mechanism of metal materials for high pressure pipelines.