Advanced Materials Research Vols. 199-200

Abstract: A lower-temperature and cost-efficient way is developed to produce Fe-TiC powders. Fe-TiC is produced by means of mechanical activation -reductive diffusion with ilmenite and graphite. The feasibility of this method and the kinetics of the carbothermic reduction are studied with both natural ilmenite and synthetic ilmenite, respectively. The result approved that Fe-TiC powder could be produced by this new technique; moreover, the particles were prominently diminished in size and activated after ball milling. No obvious reactions were detected when ball milling time was less than 8h by EPMA and XRD; however, the mixed powder of Fe and TiC was obtained after annealing for different time intervals. The kinetic study showed that the apparent activation energy of the reductive reaction decreased gradually with milling time due to mechanical activation, but this effect weakened after ball milling for 6h. As ascertained experimentally, the optimum ball milling time was between 4h and 6h.

Abstract: A home-made automatic analyzer to determine the dissolved organic carbon (DOC) in seawater was introduced in this paper. This analyzer was based on ultraviolet-potassium persulphate oxidation method. The analyzer has 7 parts, including sampling, purging of inorganic carbon, enter sample, oxidation, cooling, apart of gas/liquid and analysis of CO₂. The program was compiled by programming language of Visual Basic as the control system. All of the action of the analyzer is auto controlled. Different samples are separated by worked air and Milli-Q water and enter the system using six-way valve. With the catalysis of ultraviolet radiation, the organic matter in samples can be oxidated to CO₂ quantitatively by K₂SO₂O₈ and analyzed by non-dispersive infrared (NDIR) detector latter. The results showed that the oxidation efficiency, as well as the detect limit and the veracity are satisfying. The home-made analyzer was compared with the high temperature oxidation method, and the results showed that the two methods have little difference. The cost of the instrument is cheaper, and need not expensive catalyst, so the DOC in seawater can be analyzed with much lower prices.

Abstract: In order to improve the water-solubility of chitosan, chitosan biguanidine hydrochloride was synthesized by modified chitosan with dicyandiamide in the presence of hydrochloric acid. The guanidinylation chitosan was then applied to Antheraea pernyi (A. pernyi) silk fabric in the presence of 1,2,3,4-butane tetracarboxylic acid with sodium hypophosphite as catalyst. Studies on the effect of chitosan biguanidine hydrochloride treatment on morphology and textile properties of A. pernyi silk fiber and fabric have been conducted. The changes in the morphological structure have been monitored by scanning electron microscope. The changes in some of textile properties including wrinkle recovery angles and bacterial reduction owing to the treatment have also been investigated. It has been found that the surface of A. pernyi silk gets rough. The wrinkle-resistant performance improved, and the antibacterial activity of the treated A. pernyi silk fabric against E. coli was more than 99%.

Abstract: The wire electrical discharge machining (WEDM) technology is widely used in the field of mold industry, aerospace, automobile and so on. However, in the discharge machining, the electrode wire wear will affect the machining accuracy and machining efficiency. There are many factors that affect the electrode wire wear, and cutting many work-piece and precise surveying are needed in the wear experiment, so the whole experiment is complex. This article analyzed the wear mechanism and found the main reason of affect the electrode wire wear by using the ANSYS software to do the temperature field simulation. The simulation parameters and simulation results were verified through experiments. The experiment showed that appropriate ratio of peak current and pulse width and the slow current rise slope can reduce the electrode wire wear significantly.

Abstract: A piezoelectric hydrophone is design and made with Pb(Zr,Ti)O₃ ceramic. The technology is presented and its impedance characteristics and directivity are researched. Experimental result manifests its usability of the hydrophone.

Abstract: The technology of (Pb,La)(Zr,Ti)O₃ (PLZT) ferroelectric cathode is introduced. Stable emission current and high current density are obtained from it driven by positive high-voltage pulses with a repetition rate of 80 Hz. Proximity-imaging techniques are used to record the electron beam spot shape.

Abstract: Annealing treatment of cold compression deformation red copper was heated by microwave. The feasibility of microwave heating technology applied to heat treatment of metallic materials, and the effect of annealing process on microstructure were discussed. The results show that the phenomenon of arc discharge do not occur during the process of microwave heating red copper, which illustrates that microwave can be used as heat source for heat treatment of metallic materials. When annealing condition is 510°C for 30min, the grains of deformation red copper undergo a transition from fibrous grain to equiaxial grain, and it completes recrystallization. Compared with traditional annealing treatment, microwave annealing treatment can prevent oxidation phenomenon of specimen surface effectively, reduce annealing temperature, shorten heating and holding time, reduce the consumption of energy greatly, and the degree of hardness decline is smaller under the same annealing condition.

Abstract: Processes of rolling after wedge pressing and extruding for multi-layer spray deposited Al-Fe-V-Si/SiCP sheet formation were described in this paper, and the effects of the two different processes on the microstructure and mechanical properties of the composite were investigated. The microstructure of the composite prepared by different processes was observed by OM, SEM, and TEM. The experimental results show that the wedge pressing process can obviously eliminate the pores in the as-deposited preforms and improve the formability effectively. And more uniform microstructure and more excellent mechanical properties of the compositesheets were obtained by rolling after wedge pressing than that by extruding. The excellent mechanical properties can be attributed to avoiding of SiC particles lamination and aggregation which are familiar to the composite as-extruded. Stable microstructure, and good bonding between SiC particles and the matrix improve its mechanical properties further.

Abstract: The paper studied on the balling-up mechanism of hard-grinding by focusing on the defects in the process of the hard-grinding of steel ball. In order to achieve better precision and efficiency in the process of producing steel ball, we improves the grinding wheel’s structure by increasing the rotation velocity of the ball and thereby improving the producing efficiency.

Abstract: In modern manufacturing industry, there are a great deal of micro inclined holes, which is a difficult problem to machining. A novel micro inclined hole drilling method, step vibration drilling, is adopted. The experiments are carried that 45 degrees inclined hole is drilled into the 45 steel workpiece with Φ0.5mm carbide drill bit. The notable result was obtained with the method of step vibration drilling for drilling 45 degrees inclined holes on 45 steel, which break the restriction of drill jig. The new approach is put forward for micro inclined hole.