Effects of Calcining Temperature and Holding Time on the Synthesis of Aluminum Titanate

We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holding time on crystalline, microstructure and content of aluminum titanate materials to determine the preferred calcining temperature and holding time. XRD and SEM methods were utilized to characterize the crystalline and microstructure of each specimen, Rietveld Quantification software was used for the determination of different crystalline contents of specimens, and Philips plus software was applied to determine the cell parameters of aluminium titanate in different specimens. According to the experimental results, preferred calcining temperature is determined as 1400℃ and preferred holding time is 2 h, at which the grains of aluminum titanate grow completely and the purity of aluminum titanate is 97.2wt%.

Effect of Holding Time on the Microstructure and Mechanical Properties of Dual-Phase Steel during Intercritical Annealing

Continuous annealing simulation tests were conducted by using a continuous annealing thermomechanical simulator. Holding times of 5, 60, 180, and 480 seconds for an intercritical annealing temperature of 820℃ were adopted to investigate the evolution of the mierostructure and mechanical properties of ferrite-bainite dual-phase steel. The ferrite-bainite dual-phase steel was characterized by high strength and low yield ratio due to the presence of the constituents （polygonal ferrite, bainite, martensite and retained austenite） of the steel microstructure. Specimen 3 exhibits the highest value of A50 （7.67%） and a product of Rm × A50 （10453MPa%） after a 180s holding. This is likely attributed to the presence of a C-enriched retained anstenite in the microstructure. And the effect of martensite islands and carbide precipitate is thought to be able to contribute in strengthening the present steel. It is expected that equilibrium of anstenite fraction would be reached for reasonable intercritical holding period, regardless of the heating temperature. The results suggest that long increasing holding times may not be needed because the major phase of the microstructure does not change very significantly. It is favorable for industrial production of DP steels to shorten holding times. Key words： ferrite-bainite dual-phase steel; holding time; martensite islands; mechanical properties

Microstructure Characterization and Mechanical Properties of TRIP-aided Steel under Rapid Heating for Different Holding Time

In order to develop a comprehensive understanding about the effect of different holding time under rapid heating on the microstructural evolution and mechanical properties of transformation-induced plasticity （TRIP） steel, continuous annealing process simulations were performed using a thermal system with resistance heating method. The morphology and distribution of all phases present in the microstructure and the mechanical properties of TRIP steel were revealed. It appeared that the final tensile strength of the TRIP steel increased and retained austenite car bon content decreased with increasing holding time. An overlap between ferrite recrystallization and austenitization was observed during intercritical holding. In addition, the work hardening of the samples was evaluated by calculat ing the instantaneous ~l value as a function of the true strain. The difference in work hardening behavior corresponds to the rate of the retained austenite transformation during straining, which can be attributed to the carbon content and the morphology of the retained austenite.

Development of inclusions in 3104 alloy melt during heating and holding treatments

Developments in the contents of different typical inclusions in 3104 alloy melt were described during heating and holding processing. The settling process of inclusion particles was investigated by measuring the contents of inclusions in the surface, center, and bottom layers of the molten metal. In the results, main inclusions observed and determined by Prefil and PoD FA methods are MgO, Al2O3, spinel（MgAl2O4）, and TiB2 particles or thin films. It is found that some small particles of Al2O3 and MgO are transformed into spinel particles, and the formation rate increases as the temperature and the holding period of melt increase. The content of inclusions increases from 3.37 mm^2×kg^-1 to 7.54 mm^2×kg^-1 and then decreases to 3.08 mm^2×kg^-1 after holding for 90 min. This is attributed to a settling phenomenon and a significant increase in settling velocity after holding for 60 min. The content of inclusion particles decreases by means of settlement and flotation in liquid aluminum with an increase in holding time. The theoretical analysis and experiment results are in essential agreement with those from industrial production.

Effect of pyrolysis temperature and hold time on the characteristic parameters of adsorbent derived from sewage sludge

According to the Doehlert's matrix method, the adsorbent derived from sewage sludge was prepared through chemical activation under controlling the pyrolysis temperature and hold time. The characteristic parameters including the total yield, adsorption of methylene blue, adsorption of iodine, BET surface area, micro-pore volume are 35%—49%, 16.5—38 mg/g, 285—362 mg/g, 185—359 m2/g, and 0.112—0.224 m3/g, respectively. According to the experimental data, the multi-linear regression method was adopted to fit the relations between the characteristic parameters and influential factors. At final, through optimization method, the optimal adsorbent is obtained when using 62 min as hold time and 1105K as pyrolysis temperature. Under the conditions, the adsorbent was produced and compared the characteristic parameters with model forecast value, the coherence is satisfied.

Factors impacting nanoindentation testing results of the cuticle of dung beetle Copris ochus Motschulsky

The cuticle of dung beetle is a layered composite material in micro- or nano-scale. Dung beetle can fly, walk and dig. It can shovel and compact dung of mammals into balls. It use foreleg to walk, midleg and hindleg to hold and impel dung ball. Its two foreleges as digging legs are developed. The factors impacting the nanoindentation testing results of the femur cuticle of forelegs of dung beetle Copris ochus Motschulsky were examined. The nanomechanical test instrument used for the tests was Hysitron nanomechanical system. The results shown that the holding time and loading time are important factors im- pacting the accuracy of such indentation properties as reduced modulus (Er) and the harness ( H ) of the femur cuticle of the forelegs of dung beetle Copris ochus Motschulsky in nanoscale. There exists a threshold holding time of 20 s for the reduced modulus of the femur cuticle. The tests of nanoindentation creep property and the regression analysis of relationship between the depth increment at the maximum load and the time further confirmed the correction of the above threshold holding time. There exist visco-elastic-plastic behaviour and creep phenomenon in the femur cuticle during indenting. Its creep property during the holding procedure at maximum load can be regressed by a general logarithmic equation. The equation fitted by the testing data is ? h = 54.83452 ln(0.00723t +1.00486), where, ? h is the depth increment at the maximum load and t is the time.

Research of High Temperature Crystalline Structure and Property Evolution of Magnesium Aluminate Spinel

Magnesium aluminate spinel （MgAl2O4） with high purity has been prepared by using anodized waste slag from aluminum factory and （MgCO3）4Mg（OH）2.5H2O as the main raw materials to discuss the change laws and characteristics of crystalline structure, microstructures and properties. X-ray diffraction （XRD） and scanning electron microscopy （SEM）, together with relevant analysis software, were used to characterize the crystal phases and microstructures so as to get MgAl2O4. Results show that when increasing the holding time the amount of MgAl2O4 increases fwstly and then keeps stable, but bulk density and bending strength increase firstly and then decrease. The best holding time is determined to be 3 h because at this time the corresponding MgAl2O4 content is up to 93%, bulk density 3.23 g·cm^3, apparent porosity 4.6% and bending strength 122.4 MPa.

The effect of high-pressure and high-temperature drying treatments on the deresination ratio of Pinus massoniana

This study investigated the possibility of using high-temperature and high-pressure schedules to treat Pinus massoniana wood in order to reduce its oil content. We discuss the effect of drying temperature, absolute pressure and the holding time on the deresination ratio in R massoniana wood and establish a model for the deresination ratio as a function of drying temperature, absolute pressure and holding time. The results show that the deresination ratio in- creased from 7.14% to 87.04% when the temperature increased from 150 to 200℃, the absolute pressure from 0.1 to 0.6 MPa and the holding time from 1 to 3 h. The optimal model for the deresination ratio （Y） with drying temperature （t）, absolute pressure （p） and holding time （r） is： Y = 0.284t ＋ 113.424p ＋ 3.518r - 42.486, with a coefficient of determina- tion （R2） of 0.930. Compared with drying temperature and holding time, absolute pressure plays the more significant role in the deresination process. This study could provide a theoretical basis to the practical production of R massoniana wood.

Influence of Temperature Conditions on Dynamic Young’s Modulus Testing

The Young’s modulus was measured at high temperatures by impulse excitation of vibration method,and the effects of heating rate,holding time and temperature cycle on the test results were analyzed.The results show that the heating rate has obvious effect on the high temperature Young’s modulus of the green body,but has no obvious effect on that of the sintered products;the holding time of the heating process has no regular effect on the Young’s modulus,and the effect varies with the different products at a certain temperature;the method can also be used to test the Young’s modulus during cooling process.

Influence Factors Analysis of Fe-C Alloy Blocking Layer in the Electromagnetic Induction-Controlled Automated Steel Teeming Technology

In the electromagnetic induction-controlled automated steel teeming(EICAST)technology of ladle,the height and location of the blocking layer are critical factors to determine the structure size and installation location of induction coil.And,they are also the key parameters affecting the successful implementation of this new technology.In this paper,the influence of the liquid steel temperature,the holding time and the alloy composition on the height and location of the blocking layer were studied by numerical simulation.The simulation results were verified by 40 t ladle industrial experiments.Moreover,the regulation approach of the blocking layer was determined,and the determination process of coil size and its installation location were also analyzed.The results show that the location of the blocking layer moves down with the increase in the liquid steel temperature and the holding time.The height of the blocking layer decreases with the increase in the liquid steel temperature;however,it increases with the increase in the holding time.The height and location of the blocking layer can be largely adjusted by changing the alloy composition of filling particles in the upper nozzle.When the liquid steel temperature is 1550℃,the holding time is 180 min and the alloy composition is confirmed,the melting layer height is 120 mm,and the blocking layer height is 129 mm,which are beneficial to design and installation of induction coil.These results are very important for the industrial implementation of the EICAST technology.

An EPQ model with variable production,probabilistic deterioration and partial backlogging under inflation

This paper develops an economic production quantity(EPQ)model under the effect of inflation and time value of money.The rate of replenishment is considered to be a variable and the generalized unit production cost function is formulated by incorporating several factors,such as raw material,labour,replenishment rate,advertisements and other factors of the manufacturing system.The selling price of a unit is determined by a mark-up over the production cost.We have considered three types of continuous probabilistic deterioration function,and also considered that the holding cost of the item per unit time is assumed to be an increasing linear function of time spent in storage.In addition,shortages are allowed and partially backlogged.This model aids in minimizing the total inventory cost by finding the optimal cycle length and the optimal production quantity.The optimal solution of the model is illustrated with the help of numerical examples.