Abstract: The main factors that influence the deposition efficiency and forming quality are the state
of in-flight particles, which are directly effected by process parameter during plasma spray forming.
In this study, plasma spraying of ZrO2 powder was employed according to the method of orthogonal
experiments, and the relationship between spray parameters and characteristics of in-flight particles,
which were monitored by an optical monitoring system of CCD camera, were investigated. Radial
basis function (RBF) neural network model had been designed to forecast the temperature and
velocity of in-flight particles, and optimized spray parameter. The comparison of the simulations
with the experimental results shows the validity of the model.
Abstract: A thermodynamic analysis of the Ti-Zr-H ternary system has been performed by combining
first-principles calculations with the CALPHAD approach. To enable the thermodynamic description
of the binary systems, the results from our previous evaluation were adopted for the Ti-H, Zr-H, and
Ti-Zr systems. The ternary compound, Ti2ZrH4, with an Fd3m-type crystal structure, exists over a
wide composition range, and the (Ti)2(Zr)1(H,Va)4-type three-sublattice model was applied to
describe its thermodynamic properties. Because of the lack of experimental information available, the
enthalpy of formation of the Ti2ZrH4 phase was evaluated using the Full Potential Linearized
Augmented Plane Wave method, and the estimated values were introduced into a CALPHAD-type
thermodynamic analysis with some other experimental information. The calculated phase diagrams
and the hydrogen isotherms were in good accordance with previous experimental results. Our
calculations revealed that the ternary compound decomposes into a bcc and gas phase in the vicinity
of 1270 K.
Abstract: The Conical Ring with Inner Steps (CRIS) is a typical profile ring, which is hard to be
formed by ring rolling. Less-profile-filling and shrinking-drawing are the two main defects formed in
the rolling process. Through the study of the rolling formability of CRIS with different ratio of height
to diameter with the combination of FEM simulation method and experimental method, the main
factors that affect the CRIS rolling formability are determined. The CRIS forging is designed. And
the FEM simulation and experimental results show that the design method is reasonable.
Abstract: Friction stir welding (FSW) process of aluminum alloys was investigated using a
two-dimensional Eulerian formulation coupling viscoplastic flow and heat transfer and strain
hardening. The thermal equation for the temperature was modified to stabilize temperature
distribution using a Petrov-Galerkin method. The evolution equation for strength was calculated
using a streamline integration method. Predicted strength was compared with experiments. Based on
crystal plasticity, texture evolution was predicted during FSW of AA6061.
Abstract: Grain boundary characteristics are defined by five parameter, grain boundary plane normal
and misorientation angle/axis between two adjacent grains. The influence of the grain boundary
character distribution on lattice evolution during deformation was investigated using
three-dimensional crystal plasticity finite element method (CPFEM). Various combinations of grain
boundaries were modeled systematically. In analyzing the numerical microstructural characterization
obtained by the simulation, orientation average scheme and correlation parameters between
misorientation and its special distribution are used. Inter- and intra-grain structures were investigated
using the spatial distribution of lattice orientation. Main emphasis was placed on misorientation
distributions around grain boundaries, where grain interaction mainly occurred.
Abstract: Recently the application of lever cam ass’y made of the high-functional polymer is
increasing internationally to improve the productivity and weight reduction. But the application of
injection molding of lever cam ass’y in our country is not reported yet because of the lack of the
optimal selection technique of proper material and the optimal design of injection parameter. In
order to solve the problem, the injection molding simulation is used. The modification of gate
position and rib thickness was done and the parameters like injection time, injection temperature,
packing pressure and cooling time were changed. As a result, the comparison between models was
done and the optimal shape of lever cam ass’y was developed.
Abstract: Many engineers want to prevent crack defects because the defect is fatal to casting products
and the desire has induced many studies of the crack generation. However, this study is intricate
because the casting involves a complicated process; Casting products experience large thermal
variations from pouring temperature to room temperature, phase transformation and mechanical
contact with mold during the process. Especially, a crack phenomenon like hot tearing involves an
interaction between stress and metallurgical properties. In this paper, we studied the relationship
between hot tearing and thermal stress considering metallurgical properties. We performed thermal
stress analysis as computational method and proposed a hot tearing predictor including thermal and
mechanical stress phenomena and metallurgical characteristics. The proposed hot tearing predictor is
verified by the results of applying this predictor to different casting conditions.
Abstract: The quality of coatings is directly influenced by the flattening and solidification of many
individual molten droplets in plasma spray forming, so many properties such as thermal, electrical,
mechanical etc are strongly linked to the real contact between the “piled-up” splats. The research on
the transient temperature of impacting droplets and the heat transfer between droplets and substrate
plays an important role in improving the quality of coatings. Because of complexity and high cost of
temperature measurement systems for molten droplet during flattening in plasma spray forming at
present, this paper presents a new kind of simulation measurement system for transient temperature of
spray droplets when impacting on substrate based on LabVIEW, which could display the real-time
changes of the temperature by waveform graph. Finally, the experiments were carried out on Pb-Sn
alloy molten droplets to reveal the close connection between the impacting droplets temperature
changes and the coatings quality, and the heat transfer between droplets and substrate was discussed.
Abstract: The recycling of magnesium chloride brines via a multi-step chemical reaction and
precipitation process has been studied in waste bittern from a salt purification plant. In this study,
the rates of particle (magnesium hydroxide) growth, the effects of initial concentration of reactants
and optimum condition of reaction to make high purity magnesium hydroxide were investigated.
Produced magnesium hydroxide was separated and washed using carboxy methyl cellulose as
sedimentation agent, and used sodium stearate to prevent particle from aggregating. The mean
particle size of obtained high quality magnesium hydroxide are 5 μm and concentration is 99.5%.
Abstract: The flow stress-strain curves and other information during hot compression testing of
AZ61B magnesium alloy was investigated by simulated test on Gleeble-1500D thermal-mechanical
simulator. The relations between Z and other characteristic value, including peak stress, peak strain
and grain size, was calculated by regression analysis. The mathematical model of flow stress was
introduced to predict the flow stress. The predicting values is close to the experimental values with
not more than 10% error.