Advanced Materials Research Vols. 129-131

Abstract: The effectiveness of the usage of coolant in high speed machining of highly reactive material like titanium and its alloys is still far away uncertain. For this reason, it is wiser to study the effectiveness of MQL under transient cutting speed before we go to the high speed machining. This paper discusses the effect of MQL on the machinability of Ti-6Al-4V by using PVD coated cemented carbide tools. The machinability of Ti-6Al-4V was investigated based on the effect on cutting force and the tool life. The performance of PVD coated cemented carbide tool was investigated at various cutting condition. Completely dry machining and near dry (MQL) were applied in this experiment. For near dry machining, two levels of coolant flow rate were investigated, 50 and 100 mL/H. The effectiveness of mist coolant was tested at three different levels of cutting speed, 120, 135 and 150 m/min. Application of mist coolant is more significant at cutting speed of 135 m/min. At this speed longer tool life was obtained when more coolant was applied. No significant effect of the cutting speed and coolant flow rate on the surface roughness. Surface roughness is more sensitive to the feed rate and the depth of cut. No significant effect of application of MQL on cutting force at early stage of machining. MQL seems to be more affective when tools start worn out where greater contact area between tool and work piece occur to give better lubrication effect.

Abstract: The aim of this study is to determine the nanocrystalline size by using Williamson-Hall method of Fe80Cr20 powder which prepared by mechanical alloying process. X-rays diffraction line profile analysis was adopted to analyze the crystallite size and microstrains of Fe80Cr20 alloys powder. Transmission Electron Microscopy (TEM) was used to examine the microstructure morphology of the nanosized of Fe80Cr20 alloys. The crystallite size, microstrain, and lattice parameters were estimated by Williamson–Hall plot. The results showed that the mechanical alloying processes resulted the final product in nanocrystalline size range (below 12 nm) which confirmed by TEM observation and XRD line profile analysis.

Abstract: This paper reports the results of an experimental works, where Inconel 718, a highly corrosive resistant, nickel-based super alloy, was finish-turning under high speed conditions. The machining processes were carried out at three different cutting conditions (DRY, MQL 50 ml/h and MQL 100 ml/h), three levels of cutting speed (Vc=90, 120 and 150 m/min), two levels of feed rate (f=0.10 and 0.15 mm/rev) and two levels of cutting depth (d=0.30 and 0.50 mm). The tool wear and flank wear progression were monitored, measured and recorded progressively at various time intervals. The experiments indicated that MQL condition performs better than dry condition in term of tool life. Most of the tool failures during machining were due to gradual failure where abrasive and notching wear on the flank face was the dominant followed by, fracture on the flank edge and nose radius. Tool failure due to crater wear was not significant. Wear mechanism such as abrasive and adhesion were observed on the flank face and diffusion wear was observed on the rake face.

Abstract: During a post-earthquake restoration and reconstruction process, a building material project could be initiated to respond the short supply speedily for social welfare. At the same time, the project would be generally profitable but less sustainable. By a case study, a trade-off process pertinent to raw material and manufacturing alternative with a building brick project is explored, and then an environmentally sustainable manufacturing system for meeting building brick demands is revealed by an economic analysis.

Abstract: For the dynamic and shortest path problem, a novel algorithm SH(simulate human) is designed by simulating the process of our searching path in real life. The algorithm adopts the idea of heuristic search and integrates with the ant colony algorithm, in which the saved current path, the idea of “ask once every junction”, the bypassing barrier search and other some related definitions are proposed, as well as the ant colony algorithm is improved, so as to find the better solution and reduce the searching time. The experimental results show that the algorithm runs better than other existing methods. Moreover, it can find the shortest path or the approximate shortest one in a shorter time on road networks of any scales. Especially, SH algorithm is more effective for the large scale road network.

Abstract: A preparation method of Urea-formaldehyde performed polymer(UFP) with low molecular weight and high reactivity is presented. The UFP can impregnate into wood along trachea from the ends with pressurized impregnation method. In the following heating and pressing processes of the wood, the UFP polymerizes, and it enhances stability and strength of the wood. The impregnating-pressing-drying method avoiding the disadvantage of dealing with the large specimens using vaccum-pressing method is suitable for industrial production. Results from test showed the degree of crystallinity tested by XRD were 30%, 32% in different dosage of the modifier. Utilizing a combination of low molecular weight resin impregnation and pressing resulted in a density increase of UFP treated wood from 0.214 to 0.268g/cm3. At the same time, the Young’s modulus and bending strength increased from 1.407GPa to 1.759GPa and 64MPa to 74.5MPa, respectively. But the formaldehyde emission is great reduced from 0.5% to 0.008%. It can be concluded that the effective utilization of UFP impregnated in wood is a promising technique for the production of high-strength in the drying and pressing processing.

Abstract: Thermo mechanical processing and controlled rolling of microalloyed steel sheets are affected by several factors. In this investigation, finishing temperature of rolling which is considered as the most effective parameters on the final mechanical properties of hot rolled products has been studied. For this purpose, three different finishing temperatures of 950, 900 and 850 °C below the non-recrystallization temperature and one temperature of 800 °C in the intercritical range were chosen. It is observed that decreasing the finishing temperature causes increase of strength and decrease of total elongation. This is accompanied by more grain refinement of microstructure and the morphology was changed from polygonal ferrite to acicular one. Findings of this research provide suitable connection among finishing temperature, microstructural features, and mechanical properties of hot rolled Nb-microalloyed steel sheets.

Abstract: Nanosized β-tricalcium phosphate (TCP) material was produced in this study using a wet precipitation method and characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Human ovarian sarcoma SKOV-3 cells were cultured and the influence of nanoscale β-TCP particles on SKOV-3 cell behavior was studied in vitro. As a result, β-TCP nanoparticles with average size of 100 nm were obtained. Cell growth of SKOV-3 cells was noticeably declined in the presence of β-TCP nanoparticles (200ng/ml). The distribution of cell cycle for SKOV-3 cells cultured with and without β-TCP nanomaterials was quite different. In G1 phase of cell cycle, the percentage of SKOV-3 cells cultured in the absence of β-TCP nanoparticles was significantly lower than that cultured in the presence of β-TCP nanoparticles (p<0.01). In S phase of cell cycle, on the other hand, the percentage of SKOV-3 cells cultured without β-TCP nanoparticles was noticeably increased compared with that cultured with β-TCP nanoparticles (p<0.01). Moreover, the expression of proliferating cell nuclear antigen (PCNA) in SKOV-3 cells cultured in medium containing 200ng/ml β-TCP nanopaticles was significantly lower than that in the cells cultured without β-TCP nanoparticles (p<0.01). In conclusion, the nanoscale β-TCP material synthesized in this study can exert anti-tumor effects on SKOV-3 cells through mechanisms of cell growth inhibition, downregulation of PCNA expression and cell cycle arrest at G1 phase.

Abstract: The γ-alumina powder is a potential material for washcoat application. This paper shows the preparation of γ-alumina using ultrasonic technique in order to obtain nanocrystalline of γ-alumina powder. The 50 gr of the γ-alumina powders was treated in the 250 gr ethanol solution using ultrasonic technique within 10, 20, 30, and 60 minutes, respectively. The process of sonication was set at the fixed frequency (18.520 kHz) and current of 2 A. Crystallite size was evaluated by using X-ray diffraction (XRD) data based with Scherrer analysis and Williamson-Hall method. The microstructural characterization of the γ-alumina powders was observed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) analysis. The result shows that the optimum of nanocrystalline size of γ-alumina at ultrasonic process for 30 minutes are approximately 4.80 nm and 29.50 nm with Scherrer and Williamson-Hall calculation, respectively.

Abstract: Reinforced concrete construction is very common recently and extensively used both in industrial and commercial buildings. With the gradual rise in occurrences of fire accidents in recent years, a more thorough and quantitative understanding of the damage phenomenon in concrete structures is required. However, the mechanical behavior of concrete could actually be more complex under high temperature conditions than at room temperature. Restoration and reinforcement of the structures exposed to fire may have to be based on residual strength analysis and therefore require a correlation between temperature and mechanical properties. Thus, in order to meet the modern challenges of rapid engineering advances and societal development, further research on the concrete material and its structural behavior at high temperatures becomes extremely important. The present paper deals with investigations on the effect of high temperature exposure on the compressive strength of natural aggregate concrete. Experiments were conducted to study the compressive strength variations with increasing temperatures, up to 700 °C, and the subsequent cooling modes such as natural and spray cooling. Results show that the compressive strength gradually decreases with increasing temperatures. And micro-structural observations of the concrete specimens by means of scanning electron microscopy (SEM) were obtained. These test methods and results can be used for analyzing and investigating the behavior of recycled aggregate concrete with increasing temperatures.