Advanced Materials Research Vol. 845

Abstract: Results of beta forging of titanium alloy Ti-10V-2Fe-3Al and subsequent thermal treatment are presented, with analysis of the effect of the processing route on the final mechanical properties, correlated with microstructure of thermomechanically processed material. Investigation of response to high strain-rate hot-forging of microstructure and mechanical properties is focused on the effect of the strengthening mechanisms in the material after two common manners of deformation typical of that alloy. The effect of deformation conditions on final microstructure and mechanical properties was analyzed in three crucial stages of thermomechanical processing, e.i. after deformation, quenching and aging. In result, conclusions were formulated as for processing conditions promoting high strength and/or ductility.

Abstract: The phenomenon of direct-contact condensation gains attention because of various industrial applications; nuclear reactor emergency core cooling systems,steam driven jet injectors, direct-contact heat exchangers etc..The phenomenon was investigated computationally by injecting an inclined steam jet using a supersonic nozzle submerged in subcooled water. The condensation mechanism is based on two resistance model, which involves consideration of the heat transfer process on both sides of the interface along with use of a variable steam bubble diameter. For computations, ANSYS Fluent based Euler-Euler multiphase model is used. The angle of inclination varies from 5^o to 45^o at constant inlet pressure of 7 bars with water temperature of 30°C. The maximum penetration length is achieved using a right angled vertical injection.

Abstract: Ti-50.7at.%Ni as one of Ni-rich TiNi shape memory alloy is very responsive to precipitation ageing treatment due to the formation of Ti₃Ni₄ precipitates. This study indicates that this alloy exhibits different transformation sequences under different ageing temperatures. Precipitation of Ti₃Ni₄ has introduced the formation of intermediate R-phase prior to martensitic transformation. The lack of 2-step R-phase transformation, B2→R1 and B2→R2 transformation in this alloy, suggested that Ti₃Ni₄ precipitation occurs homogeneously.

Abstract: Wavelet analysis is a very useful tool for machinery faults diagnosis. However, actual application of wavelet analysis for machinery fault diagnosis in the field is still relatively rare. This is partly due to the fact that visual interpretation of wavelet results is often difficult and very challenging. This paper investigates an effective method to present wavelet analysis results in order to simplify the interpretation of wavelet analysis result for machinery faults diagnosis. Analysis of residual wavelet scalogram was proposed in this study as a mean to display and extract key faults signatures from raw sensor signals. Simulated signals were generated to test the feasibility of the proposed method. Test results showed that the proposed wavelet method provides a simple and more effective way to diagnose machinery faults.

Abstract: The properties of Al-Si-Cu cast alloys are strongly affected by eutectic Al-Si and Al-Cu phases. The characteristic parameters of these two phases with additions cerium 1wt % (Ce) and lanthanum1 wt % (La) were investigated in Al-11Si-2Cu near eutectic alloy using computer-aided cooling curve thermal analysis. As a result, the La additive showed the highest (T_N^Al-Si) while the Ce additive showed very little effect. In addition, the growth temperature (T_G^Al-Si) is decreased by adding Ce compared to the base alloy and La addition. Additives showed an increase of recalescence magnitude (T_R^Al-Si). Addition La and Ce increased the nucleation and growth temperature of Al-Cu phase. The microstructure analysis on the silicon morphology showed that 1 wt % La and 1 wt % Ce additions play refiner role in Al-Si-Cu near eutectic alloys. Findings are also confirmed by aspect ratio of eutectic silicon phase.

Abstract: Blade faults are ranked among the most frequent causes for gas turbine failures. This paper provides a review on the types of blade faults as well as its pertinent detection methods. In this paper, blade faults are categorized into five major groups according to their nature and characteristics namely, blade rubbing, blade fatigue failures, blade deformation, blade fouling, and blade root related problems such as cracked root and loose blade. This paper aims to provide an overview on the characteristics of each type of blade fault as well as its best detection methods available to date.

Abstract: This study investigated the influence of ⁶⁰Co-γ-irradiation on the structure and properties of Cu-Al-Ni shape memory alloys. The phase transformation temperatures were evaluated by differential scanning calorimeter (DSC). It was found that the γ-irradiation had a complex influence on the phase transformation parameters of Cu-Al-Ni SMAs. However, the transformation temperatures were shifted and a new curve was obtained after exposure to different irradiation doses. The thermodynamic parameters such as enthalpy and entropy tended to increase/decrease depending on the amount of the exposure. The structural properties of the exposed samples were studied by using optical microscopy and hardness measurements at room temperature. It was also found that the structural-properties of the Cu-Al-Ni SMAs were completely affected by the amount of the applied γ-irradiation dose.

Abstract: Blade fault is one of the most common faults in turbomachinery. In this article, a rotor system consists of multiple rows of blade was developed. The effectiveness of conventional FFT spectrum and wavelet analysis in the diagnosis of multi stage blade rubbing faults is examined at different stages, variety of blade fault conditions, and different blades rubbing severity. Blade fault caused impacts and the use of wavelets as analysis tool to detect the blade faults was studied. Results showed that, vibration spectrum can clearly depict the location and the stage of blade rubbing, while it is difficult to be identified in wavelet analysis. The limitations of wavelet analysis for multi stage blade fault diagnosis were identified. Some probable solutions to improve wavelet time-frequency representation in blade fault diagnosis were also presented.

Abstract: Abstract. The commercialization of biodiesel/diesel blends on the market can cause environmental damages due to spills. This study aims to investigate the effectiveness of Pseudomonas putida as oil-biodegradable agent in soil contaminated with biodiesel/diesel blend (B20). The effectiveness on bioremediation have been conducted by examined several physico-chemical tests on biodiesel/diesel-contaminated soil before and after seeding of P. putida. The spillage stimulation of B20 was conducted at laboratory scale for 24 days of incubation time. The results show that the bioremediation treatment able to remove up to 82%, 77%, 16%, and 10% of nitrogen, phosphate, sulfate and total organic carbon, respectively. The pH of soil sample was changed from pH 7.45 (Day 0) to 7.25 (Day 24) after the treatment. Meanwhile, the moisture content in the sample has increased from 44.11% (Day 0) to 50.35% (Day 24). All of these results show the good indication of quality improvement of polluted soil after treated with P. putida. It is apparent from the acquired results that the application of P. putida is suitable as effective microorganism and potentially exploits as useful oil-soil biodegradable agent in polluted soil.

Abstract: Abstract. Soils are increasingly threatened by spillage of petroleum products such as petrol, diesel fuel, gasoline at oil refineries, underground storage tanks and pump stations pipelines. This study aims to investigate the effectiveness of Pseudomonas putida as oil-biodegradable agent in soil contaminated with diesel (D100). The effectiveness on bioremediation have been conducted by examined several physico-chemical tests on diesel-contaminated soil before and after seeding with P. putida. The spillage stimulation of D100 was conducted at laboratory scale for 24 days of incubation time. The results show that the bioremediation treatment able to remove up to 82%, 55%, 48%, and 34% of nitrogen, total organic carbon, phosphate, sulfate and, respectively. The pH of soil sample was changed from pH 7.8 (Day 0) to 6.78 (Day 24) after the treatment. Meanwhile, the moisture content in the sample has increased from 39% (Day 0) to 59% (Day 24). All of these results show the good indication of quality improvement of polluted soil after treated with P. putida. It is apparent from the acquired results that the application of P. putida is suitable as effective microorganism and potentially exploits as useful diesel-soil biodegradable agent in polluted soil.