Abstract: The emphasis of this study was in-situ synthesis of carbon nanotubes (CNTs) on Mg matrix at 480°C. The process involves homogeneous deposition of Co catalyst onto Mg by deposition-precipitation route with low Co content (1.0 wt.%) and in situ synthesis of CNTs by chemical vapor deposition. The morphologies and microstructure of the as-obtained CNTs/Mg composite powders was characterized by SEM, TEM, Raman spectrum, and XRD. The results indicated that CNTs were well graphitized and uniformly distributed on the surface of Mg powders, which would be beneficial to the mechanical property of CNTs/Mg composites.
Abstract: Technical analysis was used to analyze the roasting of molybdenum concentrate on the basis of thermal balance test of rotary furnaces used for Roasting, and the results indicate that, on the condition of commercial production, the Roasting of MoS2 can occur spontaneously because the heat of reaction is so much that proper cooling measures should be adopted in case overheating happens. According to above analysis, carbon-free roasting technology of molybdenum concentrate was proposed in this paper. The results, which come from thermal balance test and technical analysis of rotary furnaces used for carbon-free roasting of molybdenum concentrate, indicate that outer heat source used in traditional Roasting technology is not needed in carbon-free roasting technology, because enough heat is generated during Roasting to ensure spontaneous reaction. In fact, heating is not needed in operating process except at the beginning, to make molybdenum concentrate catching fire, and when reaction completing, to remove residual sulphur. The technology in this paper is obviously advantageous in aspects of energy saving, output, quality of production, heat loss, the concentration of SO2 in flue gas, etc. and will have remarkable environmental benefits, economic benefits and social benefits.
Abstract: The grade of molybdenum in one processed tailing from a molybdenum plant is 0.0063%.The assay of mineral composition shows that the molybdenum metal mainly exists in the form of molybdenite. Employing the flow-sheet with one rougher and one scavenger, in which kerosene is used as collector, we can obtain the rough concentrate, of which the yield is 0.65%, and its grade is 0.73% with a recovery of 77.04%. Then, the rough molybdenum concentrate was milled and floated again, and its yield of final flotation concentrate is 0.01534%, with the grade of 24.87% and a recovery of 61.39%.
Abstract: This paper introduces the structure of the resin bonded abrasive wire saw manufacture equipment. The equipment can complete the process of the wire saw production, including uncoiling wire, cleaning wire, binder coating, Pre-curving and coiling wire. Wire saw are manufactured successfully by this equipment in the manufacture experiment. The quality of the wire saw was examined by SEM. The average slicing ability of the wire saw is 205 mm2 per meter in the experiment of KDP crystal slicing.
Abstract: The machinability of Nickel-based superalloy GH4169 is poor, the traditional methods to machining is application of cutting fluids with the active additives which cause environmental pollution and health problems. In this paper, the water vapor was applied on milling instead of cutting fluids for the aim of green milling GH4169. The effects of water vapor, oil emulsion and dry cutting on milling force and the surface roughness have been examined with carbide tools YG6A. The results of experiments indicated that application of water vapor produced lower milling force, the values were reduced about 7 percent compared to dry cutting, and it is advantage in surface roughness. The research results show that clean production was achieved in metal cutting associated with water vapor cooling and lubricating.
Abstract: The thermal conductive composites prepared by twin-screw extrusion extrudes polypropylene and graphite.This paper studies the influence of molding process on the thermal conductivity.The experimental results show that thermal conductivity of composites changes with the screw rotate speed changing,obtaining the maximum when the screw rotate speed is 300r/min.Results indicate that the opposite trend with thermal conductivity and the melt index and injection speed,and the injection temperature has not a big influence on the thermal conductivity. The crystallization influences the electrical conductivity and density of some points of molding samples.In addition,the test condition has cast impact on thermal conductivity,in the lower temperature(lower than the Debye temperature),the thermal conductivity of composites increased with the of temperature and humidity increasing.
Abstract: Through study on the regulation of tensile strength and reduction of area after artificial aging and natural aging for SWRH82B wire rod, indicate that the tensile strength of wire rod unchanged through artificial aging or natural aging treatment while the reduction of area changes significantly the reduction of area is effected by aging temperature and aging time. Reduce the residual stress in the wire rod and lattice distortion is the main reason for reduction of area improving the composite brittle inclusions in the wire rod are not good for the rod plastic recovery.
Abstract: During sheet metal processing, the price of the mechanical punch is cheap, but its noise is too big, the price of CNC punch is too expensive, so it isn’t suitable for small and medium-sized manufacturers as well. A kind of hydraulic punch which has convenient operation and low price is developed. And design process of mechanical part, X axis and Y axis blocking material design, hydraulic system and electrical system are introduced in the paper.
Abstract: The rotary working table of C5250 vertical lathe requires high reliability. Based on the Fault Mode and Effect Analysis, the fault-tree of “guide surface lapping damage about rotary table” was established. To solve the problem of failure probability of bottom events obtaining insufficiently, fuzzy set theory was introduced into the fault tree analysis method. The failure probability distribution of bottom events was described as triangular fuzzy number. The occurrence probability distribution of the top event and the fuzzy importance of basic events were calculated according to fuzzy calculation rule. Through the analysis, the weak reliability links of the fault tree such as hydraulic pump, oil film thickness measuring installation and hydraulic valve were found out.
Abstract: As the resonance frequency of the ultrasonic vibration system drifts according to the different operating condition, Ultrasonic power supply based on MSP430 is designed in this thesis. Series inductance and parallel capacitance are used to match the vibration system and series resonance technology used in primary side of inverter transformer can reduce switch loss. ADC module in MSP430 is used to get frequency shift, and PWM module is made to adjust the operating frequency of TL494, which can realize closed loop control of frequency tracking. The results of experiments show that the method designed in this thesis has high detection accuracy, high speed dynamic response and high stability of frequency tracking.