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Optimization of the Morphological Parameters of a Metal Foam for the Highest Sound Absorption Coefficient Using Local Search Algorithm

Jafari Mohammad Javad, Khavanin Ali, Ebadzadeh Touraj, Fazlali Mahmood, Sharak Mohsen Niknam, Madvari Rohollah Fallah

Archives of Acoustics

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2020

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Vol. 45, No. 3

487--497

EN

Due to its unique features, the metal foam is considered as one of the newest acoustic absorbents. It is a navel approach determining the structural properties of sound absorbent to predict its acoustical behavior. Unfortunately, direct measurements of these parameters are often difficult. Currently, there have been acoustic models showing the relationship between absorbent morphology and sound absorption coefficient (SAC). By optimizing the effective parameters on the SAC, the maximum SAC at each frequency can be obtained. In this study, using the Benchmarking method, the model presented by Lu was validated in MATLAB coding software. Then, the local search algorithm (LSA) method was used to optimize the metal foam morphology parameters. The optimized parameters had three factors, including porosity, pore size, and metal foam pore opening size. The optimization was applied to a broad band of frequency ranging from 500 to 8000 Hz. The predicted values were in accordance with benchmark data resulted from Lu model. The optimal range of the parameters including porosity of 50 to 95%, pore size of 0.09 to 4.55 mm, and pore opening size of 0.06 to 0.4 mm were applied to obtain the highest SAC for the frequency range of 500 to 800 Hz. The optimal amount of pore opening size was 0.1 mm in most frequencies to have the highest SAC. It was concluded that the proposed method of the LSA could optimize the parameters affecting the SAC according to the Lu model. The presented method can be a reliable guide for optimizing microstructure parameters of metal foam to increase the SAC at any frequency and can be used to make optimized metal foam.

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The corrosion resistance of laser surface alloyed stainless steels

Brytan Z.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 91, nr 2

49--59

EN

Purpose: of this paper was to examine the corrosion resistance of laser surface alloyed (LSA) stainless steels using electrochemical methods in 1M NaCl solution and 1M H2SO4 solution. The LSA conditions and alloying powder placement strategies on the material's corrosion resistance were evaluated. Design/methodology/approach: In the present work the sintered stainless steels of different microstructures (austenitic, ferritic and duplex) where laser surface alloyed (LSA) with elemental alloying powders (Cr, FeCr, Ni, FeNi) and hard powders (SiC, Si3N4) to obtain a complex steel microstructure of improved properties. Findings: The corrosion resistance of LSA stainless steels is related to process parameters, powder placing strategy, that determines dilution rate of alloying powders and resulting steel microstructure. The duplex stainless steel microstructure formed on the surface layer of austenitic stainless steel during LSA with Cr and FeCr reveal high corrosion resistance in 1M NaCl solution. The beneficial effect on corrosion resistance was also revealed for LSA with Si3N4 for studied steels in both NaCl and H2SO4 solutions. Ferritic stainless steel alloyed with Ni, FeNi result in a complex microstructure, composed of austenite, ferrite, martensite depending on the powder dilution rate, also can improve the corrosion resistance of the LSA layer. Research limitations/implications: The LSA process can be applied for single phase stainless steels as an easy method to improve surface properties, elimination of porosity and densification and corrosion resistance enhancement regarding as sintered material. Practical implications: The LSA of single phase austenitic stainless steel in order to form a duplex microstructure on the surface layers result in reasonably improved corrosion performance. Originality/value: The original LSA process of stainless steels (austenitic, ferritic and duplex) was studied regarding corrosion resistance of the alloyed layer in chloride and sulphate solutions.

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Modelling of Cr3C2-25% NiCr Laser Alloyed Cast Iron in High Temperature Sliding Wear Condition Using Response Surface Methodology

Jeyaprakash N., Duraiselvam M., Raju R.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1303--1315

EN

The wear behaviour of Cr3C2-25% NiCrlaser alloyed nodular cast iron sample were analyzed using a pin-on-disc tribometer. The influence of sliding velocity, temperature and load on laser alloyed sample was focused and the microscopic images were used for metallurgical examination of the worn-out sites. Box-Behnken method was utilised to generate the mathematical model for the condition parameters. The Response Surface Methodology (RSM) based models are varied to analyse the process parameters interaction effects. Analysis of variance was used to analyse the developed model and the results showed that the laser alloyed sample leads to a minimum wear rate (0.6079 ×10–3 to 1.8570 ×10–3 mm3/m) and coefficient of friction (CoF) (0.43 to 0.53). From the test results, it was observed that the experimental results correlated well with the predicted results of the developed mathematical model.

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Diode laser surface modification of Ti6Al4V alloy to improve erosion wear resistance

Lisiecki A., Klimpel A.

Archives of Materials Science and Engineering

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2008

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Vol. 32, nr 1

5-12

EN

Purpose: Purpose of this paper : The purpose of the study was to develop new laser alloying technology providing high erosion wear resistance of the working surfaces of blades made of titanium alloy Ti6Al4V. Design/methodology/approach: High power diode laser HPDL with a rectangular laser beam spot of multimode and uniform intensity of laser radiation was applied in the process of laser surface modification of the titanium alloy Ti6Al4V. During the laser surface remelting and alloying of the titanium alloy in argon and nitrogen atmospheres, surface layers of high hardness and significantly higher erosion wear resistant, compared with the base material of titanium alloy Ti6Al4V, were produced. Findings: The surface layers are composites of titanium nitrides participations in the titanium alloy matrix. Hardness of the surface layers and erosion wear resistance depends strongly on parameters of laser processing and on the partial pressure of nitrogen in the gas mixture of nitrogen-argon atmosphere. Research limitations/implications: The most critical parameter of the functional quality of titanium alloy blades of turbofan engine and steam turbines is the fatigue strength, therefore further investigations are required to determine the fatigue strength and also internal stresses in the nitrided surface layers. Practical implications: The novel technology of high power diode laser surface modification of the titanium alloy Ti6Al4V can be applied to produce erosion wear resistant and long lifetime surface layers of turbofan engine blades and steam turbine blades. Originality/value: The laser surface modification of titanium alloy by the high power diode laser with the rectangular laser beam spot of multimode and uniform intensity of laser radiation is very profitable in a case of laser surface remelting and alloying because the treated surface is heated uniformly, so uniform penetration depth and uniform thickness of the surface layer can be achieved, as opposed from circular laser beams of solid states YAG and gas lasers.

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Diode laser gas nitriding of Ti6Al4V alloy

Lisiecki A., Klimpel A.

Archives of Materials Science and Engineering

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2008

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Vol. 31, nr 1

53-56

EN

Purpose: To produce erosion wear resistant and high hardness surface layers of turbofan engine blades and steam turbine blades made of titanium alloy Ti6Al4V laser gas nitrating (LGN) technology of laser alloying was selected to produce titanium nitrides participations in the titanium alloy matrix surface layers. Design/methodology/approach: Studies on influence of the parameters of laser gas nitriding of titanium alloy and partial pressure of nitrogen and argon in the gas mixture on the surface layers shape, penetration depth, microhardness, erosion wear resistance at different angles of erodent particles stream were conducted. The high power diode laser HPDL with a rectangular laser beam of even multimode intensity on the beam spot was applied in the laser gas nitriding process. Tests of erosion wear resistance were conducted according to the ASTM 76 standard at velocity of the erodent particles stream 70 [m/s], at angles 90 [°] and also 30 [°]. Findings: High quality surface layers of high hardness and erosion wear resistant were produced on the substrate of titanium alloy Ti6Al4V during Laser Gas Nitriding - LGN. Results of the study show that the erosion resistance of laser nitrided surface layers is significantly higher compared with the base material of titanium alloy Ti6Al4V, and depends strongly on the inclination angle of the erodent particles stream. Research limitations/implications: Further investigations of internal stresses in the nitrided surface layers and the fatigue strength of extremely hard surface layers are required, because the fatigue strength is decisive for the functional quality of the surface layers. Practical implications: The investigated technology of laser gas nitriding can be applied for increasing erosion wear resistance of surface layers of turbofan engine blades and steam turbine blades made of titanium alloy. Originality/value: Application of the rectangular diode laser beam spot of multimode and uniform intensity of laser radiation is very profitable in a case of laser surface remelting and alloying because it guarantees uniform heating of the treated surface, consequently uniform thermal cycle across the area of the beam interaction and also uniform penetration depth of the single bead of the surface layer.