Advanced Materials Research Vol. 699

Abstract: This study discussed the possibility and factors of employing the Yellow River Silt (YRS) as the starting materials to produce lightweight ceramisite (LWC) by a non-sintering process. Cement and sodium silicate were used as additives. The performance was evaluated though hospital wastewater degradation in a biological aerated reactor (BAF). Results presented that: (1) YRS could be used to prepare the LWC under the propitious condition (the ratio of YRS to cement was 75:25, the percentage of sodium silicate was 7% and the curing time was 5 d); (2) LWC could be used as a packing medium in the BAF. The BAF has large removal efficiencies on COD¬cr and NH3-N when the hydraulic retention time (HRT) and the ratio of air to liquid (A/L) were 6 h and 5:1 respectively.

Abstract: To raise the extraction efficiency of the organic components of coal, samples were selected from tectonic coal and original bituminous coal in symbiotic seam of coal in Pingdingshan 8th coal mine and 5th coal mine. For comparing the extraction time required under the same extraction rate, two different extraction methods, ultrasonic-microwave coordination extraction and traditional soxhlet extraction, was adopted. The experimental results showed that the extraction proportion of ultrasonic-microwave coordination extraction was 10.7911% when adopted tectonic coal of 8th coal mine as sample, selected 80mL pyridine as solvent, set 95W as microwave power and 3min as extraction time. Under the condition of same extraction proportion, soxhlet extraction time is 39.43h.So the extraction efficiency of the ultrasonic-microwave coordination extraction was as 788.6 times as soxhlet extraction. The ultrasonic-microwave coordination extraction was a simplify method with fast extraction speed, large volume sample, energy saving and environmental friendly.

Abstract: Flotation behavior of apatite was investigated by micro-flotation with five kinds of fatty acid as collectors; the mechanism was studied by thermodynamic calculation. In the thermodynamic discussion, the Gibbs energy (∆G) of reactions, which is between the collectors and Ca2+ ions dissolved by apatite in pulp, were computed with pH as a function. A comparison of the calculated results with the flotation behavior of apatite shows that the thermodynamic results agree well with the experimental data. This finding indicates an identical characteristic between the two reactions with a variation in pH, in which one is between the collectors and Ca2+ ions dissolved by apatite in the pulp, and the other is between collectors and Ca2+ ions on apatite. Therefore, from the thermodynamic results, the mechanism for the flotation behavior of apatite could be deduced. The decrease in recovery is due to the decrease in effective constituent of collector (A–) with the falling pH. Once the concentration of A– ions is lower than a certain value, the reactions of the collectors with mineral are terminated and thus result in the depression of apatite in an acidic environment.

Abstract: In this paper, two heat treatment routes have been carried out on a set of hot compressed 7075 aluminum alloy samples under different deforming conditions. By considering the hot deformation history the law of 7075 aluminum alloy’s microstructure evolution during these two heat treatments was studied and the microhardness was discussed. The results show that: (1) Static recrystallization in 7075 aluminum alloy was discovered during these two heat treatments (solid solution (465°C/40min) +T6 aging (120°C/24h) and solid solution (465°C/40min) + T73 aging (107°C/7h+177°C/7h)), its driving force was from stored energy which was not released in the previous thermal deformation process. Formation of recrystallized grain was due to subgrain merger mechanism. The static recrystallization became more remarkable as the hot deforming temperature decreasing. (2) The effects of strain rate on the statically recrystallized grain size of 7075 aluminum alloy were opposite under different deformation temperatures. Deformed at 450°C, during these two heat treatments the recrystallized grain size became smaller as the strain rate increasing. While deformed at 350°C, during solid solution+T73 aging treatment the recrystallized grain size increased as the strain rate increasing. (3) Under the same deformation conditions a difference existed in the microstructure of 7075 aluminum alloy after solid solution +T6 aging and solid solution + T73 aging, which was mainly due to different precipitated phases in the aging process. (4) Both two heat treatments can raise the microhardness of 7075 aluminum alloy remarkably. The hardness of 7075 aluminum alloy after solid solution+T73 aging was lower than that after solid solution+T6 aging, the main reason was the precipitated small  phase in the first stage of the T73 aging coarsen in the second stage of high-temperature aging process.

Abstract: Recently, the different types of biliary stent are widely used to provide a longer patency and are more cost-effective for patients surviving. In this study, the design of biliary stent can be fabricated by femtosecond laser ablation in wavelength of 1035 nm. Here the pulsewidth of this laser is smaller than heat diffusion time to reduce heat-affected zone (HAZ). And then, the smart material of nitinol (Ni-Ti) alloy is used to fabricate the stent for medicine application of cholangiocarcinoma. The experimental results show the good quality edge of stent can be obtained via the nonlinear ablation process; however, the kerf surface of stent still can generate some nano-scale structures after this process.

Abstract: This study explores and demonstrates the effectiveness of employing Electro Discharge Machining (EDM) for processing ceramics particularly Metal Matrix Composite (MMC) materials. Conductive ceramics can be easily machined and non conductive ceramics can be made machinable by doping them with conductive metal particulates. In a related experimental study the effects of the concentration and size of these particulates are analyzed on the machining rate of MMC components.

Abstract: Iron and steel scrap have been reused to produce new steel and cast iron in the steelmaking and foundry industry for more than 150 years, but the accumulation of tramp elements contained in steel scrap such as copper, tin, antimony, and arsenic is a major concern. This is primarily because these tramp elements are difficult to remove in conventional steelmaking processes. In particular, the presence of copper during the recycling of steel scrap can cause severe surface cracking during hot rolling (hot shortness), inhibit recrystallization during hot forming, and reduce ductility in deep drawing. For these reasons, considerable efforts have been made in recent decades to develop a technology that can remove copper from ferrous scraps[1-3].

Abstract: 316L stainless steel is widely used in various industries due to low cost, ease of availability and exceptional combination of mechanical properties along with corrosion resistance as compared to the other available metal alloys. In powder injection molding, debinding is very critical step and improper debinding can change the final properties dramatically. In the present study, affects of debinding on mechanical properties of powder injection molded 316L stainless steel were studied. The prepared feedstocks were molded according to MPIF 50 standard using vertical injection molding machine (KSA100). The plastic binder was removed at 450°C from the molded test samples using two different furnaces i.e. commercial and laboratory furnace followed by the sintering in vacuum, hydrogen, mixture of H2 and N2 (9:1) and nitrogen at 1325°C for 2hr with post sintering cooling rate 3°C/min . Test samples debound in commercially available furnace showed 97% densification and higher mechanical properties. The corrosion resistance was reduced due to presence of residual carbon during thermal debinding. The presence of carbon and formation of carbides and nitrides were confirmed by XRD and microstructural analysis. The results showed that the test samples debound in commercial furnace showed brittle behavior due to the presence of carbides and nitrides. Test samples sintered in N2 showed 96.3% density and tensile strength 751MPa. This value of strength is twice as compared to the sample debound in laboratory furnace followed by the sintering in vacuum. The achieved mechanical properties in vacuum sintered samples were comparable to the wrought 316L stainless steel (according to ASTM standard).

Abstract: P-Least Squares (P-LS) method is Least Squares (LS) method promotion, based on the criteria of error -squares minimal to select parameter , namely satisfies following constitute the curve-fitting method. Due to the arbitrariness of the number , P-LS method has a wide field of application, when , P-LS approximation translated Chebyshev optimal approximation. This paper discusses the general principles of P-LS method; provides a way to realize the general solution of P-LS approximation. P-Least Squares method not only has significantly reduces the maximum error, also has solved the problems of Chebyshev approximation non-solution in some complex non-linear approximations，and also has the computation conveniently, can carry on the large-scale multi-data processing ability. This method is introduced by some examples unified in the materials science, the chemical engineering and the life body change.

Abstract: This research work includes a combination of Fisher’s Linear Discriminant (FLD) analysis by combining Radial Basis Function Network (RBF) and Back Propagation Algorithm (BPA) for monitoring the combustion conditions of a coal fired boiler so as to control the air/fuel ratio. For this two dimensional flame images are required which was captured with CCD camera whose features of the images, average intensity, area, brightness and orientation etc., of the flame are extracted after pre-processing the images. The FLD is applied to reduce the n-dimensional feature size to 2 dimensional feature size for faster learning of the RBF. Also three classes of images corresponding to different burning conditions of the flames have been extracted from a continuous video processing. In this the corresponding temperatures, the Carbon monoxide (CO) emissions and other flue gases have been obtained through measurement. Further the training and testing of Parallel architecture of Radial Basis Function and Back Propagation Algorithm (PRBFBPA) with the data collected have been done and the performance of the algorithms is presented.