Advanced Materials Research Vols. 148-149

Abstract: Cu-14Al-X alloys was made into powder and then the powder was coated onto the surface of AISI 1045 steel respectively via plasma spraying and laser cladding technologies. Microstructure and phases of the coating were investigated by EPMA, XRD, SEM et al. Friction and wear properties of the two coatings were tested by RFT- friction and wear testing machine. The results indicates that the two coatings all consists of β′, α, K and γ2 phases and the structure of laser cladding is more evenly distributed. Under the condition of boundary lubrication, abrasion mechanism of laser coating remains abrasive grain abrasion. There is also adhesion abrasion under the condition of high load. While abrasion mechanism of plasma coating is slight abrasive grain abrasion and adhesion abrasion under low load. With the load increasing, adhesion abrasion intensifies. In a word, microstructure of laser coating is more even and compact.

Abstract: In this paper, a new analytical method of laser clad geometric simulation was developed. The effects of laser process parameters such as laser power, scanning speed, and powder feed rate on estimating clad geometry were investigated in this approach. A series of cladding was prepared by 1 kW diode pumping solid-state laser, to characterize the cross-section image of the clad by optical microscope. The clad profile was fitted by pitch arc and line in AutoCAD, with results displaying the arc-like upper profile of the clad. The theoretical results are discussed and compared with experimental data. The simulation based on the mass conservation is capable of predicting the clad width and depth with reasonable accuracy at medium powder feed rate.

Abstract: In order to research the adhesion of sputtering protective coating of Gd.Gd substrates were differently coated with Cu and Al by means of DC magnetron sputtering technology. The characteristics of the films were investigated by scanning electron microscopy (SEM), EDS, and the adhesions of films were tested by tension test. The results show that the films of Al are smooth and perfect, the interferences between Al and Gd join together strongly, and the largest strength of adhesion is 27.6MPa in these tests on the optimize parameters through orthogonal experimental design. While the films of Cu are rough and bad, the interferences between Cu and Gd join together loosely, and the largest strength of adhesion is only 3.02MPa in these tests on the optimize parameters through orthogonal experimental design.

Abstract: The Al-4.5Zn-1.5Mg-0.5Mn aluminum alloy was welded by MIG welding in test, and the microstructure and mechanical property of joint were investigated. The results of experimentation show that the microstructure of welding metal is as-cast microstructure, and the microstructure of base metal is isometric crystal. There is a narrow fusion zone near the edge of weld seam, which consists of fine columnar grains. In the base metal and heat affected zone, the precipitation was diffuse in the intragranular, while strengthening phase η mainly focused on grain boundaries. The precipitation phases in the heat-affected zone distributed unevenly with large size, intermittent and segregation. In the welding metal, there is no precipitation phase. The microhardness on center of welding metal is lowest in joint. The tensile strength of welding joint is 272MPa, and the percentage elongation after fracture is 6.6%. The zone of fracture is located in the welding metal.

Abstract: The effects of AC frequency, magnetic field strength, ribbon length and test temperature on the Fe72Co8Si15B5 amorphous ribbon’s magnetic impedance were studied. The results showed that the resistance, reactance and impedance of amorphous ribbons increased with the increase of AC frequency, but decreased as magnetic field strength decreased; the rangeability of resistance, reactance and impedance increased as AC frequency and magnetic field strength increased; the resistance and reactance increased as ribbon length increased; the ribbon had a good temperature stability in resistance.

Abstract: A 5-axis turning-milling complex center (TMC) is regarded as the combination of a turning center (TC) and a machining center (MC). However, in structural kinematic chains and kinematic properties, TMCs are pretty different from TCs and MCs, which causes that TMC error generations has inherent properties. This paper researched kinematic chain, controllable axis, simultaneous moving axis, processable part face and error component, from the view of machine structures. A simple calculation formula of error component numbers on CNC machine tools is pointed out according to controllable axis numbers. Through setting up space kinematic equation on TMC, translational and rotational axis error influences are considered. Some views are put out on the error measurement, identification, modeling and compensation for the future research.

Abstract: In order to find a proper resolution scheme for the formation process of tandem Explosively Formed Projectile (EFP) from shaped charge with double liners (SCDLL). 2D hydrocode was used to study the formation and penetration of SCDLL impelled by detonation products. The simulation is conducted to compare the effect of the following three resolution techniques on the prediction of velocity and shaped of EFP: Lagrangian, Eulerian-Lagrangian Coupling and Eulerian. In the simulation, shaped charge with one high explosive and two liners, ignited at the center point is studied. The results obtained from simulations are compared to experimental X-ray pictures. The simulation results including the Lagrangian resolution applied on liners agree well with experimental results when the friction coefficient between two liners is set to 0.28. The study results can provide important reference for engineers to analyze and design the tandem EFP.

Abstract: Commercially pure Titanium (CP-Ti) TIG weld joint was treated by means of high energy shot peening (HESP) using a shot peening equipment commonly used in industry. The nanostructured surface layer was characterized by XRD, TEM, SEM and Microhardometer. The results showed that surface nanocrystallization of CP-Ti TIG weld joint were realized by high energy shot peening treatment. The finest grain size in the top surface layer is about 40nm. The hardness of the surface layer is enhanced significantly after shot peening compared with that of the as-welded joint, which resulted in a remarkable surface hardening effect. Surface welded defects such as air pores are eliminated successfully so that relative uniform surface layer was obtained.

Abstract: The effect of melt-casting temperature on the microstructure and properties of transition interlayer for CuNiMnFe/30CrMnSi material was investigated in vacuum condition. The results show that the thickness of the transition layer and its bond strength increase, and then decrease with increasing temperature. At 1130 , the intermediate transition layer has the largest width, which is 132μm, and the tensile strength can reach up to 1322Mpa. In the intermediate transition layer, mutual diffusion occurs among these alloying elements. These elements, such as Cu, Ni and Mn, diffuse into 30CrMnSi and results in the formation of Fe base solid solution, and no harmful brittle phases are produced in the proximity of bonding interface, thus it has a good metallurgical bonding for the two materials.

Abstract: Prepared a electrode with high concentration and strong active oxidizing property which used titanium as anode’s substrate material, used gradient method the anode surface was coated with a definite ratio RuO2、TiO2、IrO2、SnO2、Ga and Ce in order to extend the operational life span. Use scanning electron microscope to present the surface property, the result shows that the surface coat of self-made titanium positive plate is densification and well-distributed which has good catalytic activity and reaction stability, meanwhile the surface coated with metallic oxides has less and short cracks which can extend the useful life. Through the electrochemistry property detection by electrochemistry workstation, Tafel curve shows that the chlorine precipitation potential is 1.41V which is just a little higher than the standard potential 1.36v of Cl- reacting to form Cl2, meanwhile lower than the oxygen precipitation potential, these shows that the plate has good electro-catalysis property and selectivity. The self-made experimental setup includes four parts as direct supply, reactive tank, electrode, collecting bottle. Prepared solution with deionized water and analytical pure agents with NH4Cl and NaCl, with draining water method collecting the electro-catalysis gas and gas chromatographic analysis shows the main component includes N2 62.73%, O2 21.47%，H2 13.95%，Cl2 1.85%, meanwhile analysis the trends of nitrogen forms concentration, chloridion concentration and pH by electrolysis time, concluding that the indirect oxidation is dominant process during electrochemistry, active substrate OCl- is the principal oxidation. The electrolyte pH keeps range between 7.5 and 9.5 which is favorable to free ammonia forming that can be directly electrochemical oxidized, meanwhile is disadvantage of free chlorine forming that can keep cyclic utilization in solution.