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Comparative study on the mechanical, tribological, morphological and structural properties of vortex casting processed, Al–SiC–Cr hybrid metal matrix composites for high strength wear-resistant applications: Fabrication and characterizations

Publication date: November–December 2020

Source: Journal of Materials Research and Technology, Volume 9, Issue 6

Author(s): Jatinder Kumar, Dilbag Singh, Nirmal S. Kalsi, Shubham Sharma, Catalin I. Pruncu, Danil Yu. Pimenov, Kalagadda Venkateswara Rao, Wojciech Kapłonek

Republished by Plato

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The cast aluminum–silicon alloys are used to make various automobile components like pistons, cylinder blocks, piston insert rings, connecting rod, brake disc, etc. but low strength, hardness, and wear resistance restricted their use in several applications. Silicon carbide reinforced aluminum matrix composites exhibit better properties than base metal alloys. As an alloying element, the chromium improves the hardness, strength, and elastic limit of the steel. In this study, the characterization of Al–Si alloy-based metal matrix composites that are reinforced with silicon carbide and chromium is performed with the help of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), microhardness test, tensile test, sliding wear test, scratch test, and porosity analysis. The aluminum matrix composites with a varying weight percent of chromium (0–3 wt.% in steps of 1.5) and a fixed percentage of silicon carbide (10%) were formulated through the vortex casting process. The SEM and EDS images illustrate the occurrence and somewhat uniform dispersion of the reinforcement particulates. In hybrid composites, the Cr3C2 compound formation is observed with the least intensity. The reinforcement content contributes significantly to improve the hardness, strength, abrasion resistance, and wear résistance along with a modest reduction in the ductility and gain in friction coefficient. The porosity level obtained in the composites revealed that composites are free from casting defects.

Source: https://www.sciencedirect.com/science/article/pii/S2238785420318603?dgcid=rss_sd_all

Material

Evaluation of microstructural effects on corrosion behavior of AZ31B magnesium alloy with a MAO coating and electroless Ni-P plating

Publication date: November–December 2020

Source: Journal of Materials Research and Technology, Volume 9, Issue 6

Author(s): Chi-An Chen, Shun-Yi Jian, Chia-Hsin Lu, Chia-Yu Lee, Salim Levent Aktuğ, Ming-Der Ger

Republished by Plato

Published

on

open access

Abstract

A bi-layer coating is deposited on the surface of the AZ31B Mg alloy for corrosion protection of the Mg alloy. The bi-layer coating is composed of a micro-arc oxidation coating (MAO), and an electroless plated Ni-P coating. The micro-arc oxidation (MAO) treatment in the electrolyte with or without the addition of phosphate ions is carried out under unipolar power mode. The microstructure and composition of the MAO coatings are analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The roughness of the MAO coatings is obtained by using 3D white light interferometry. The corrosion resistances are evaluated by potentiodynamic polarization test as well as electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution and salt spray test. The adhesion test results of the MAO/Ni-P composite coatings by drawing test machine. The results showed that the micro-pores size of the MAO coating treated in the phosphate-free bath is uniform and smaller than the phosphate-containing solution, which could decrease the roughness and enhance the corrosion resistance. The corrosion resistance of MAO coating with the phosphate-free solution for 2.8 times was better than that of phosphate-containing solution. Moreover, phosphate-free MAO/Ni-P composite coating showed the corrosion rate is more than 4 times lower than the phosphate-containing MAO/Ni-P composite coating. Furthermore, the MAO/Ni-P composite coatings prepared by the MAO coating treated in the phosphate-free bath could suppress the erosion of aggressive media during exposure after 120 h salt spray test (corrosion area is approximately 5%) and present excellent adhesion.

Keywords

AZ31B magnesium alloy

MAO

Electroless Ni-P plating

Adhesion

Corrosion resistance

© 2020 The Authors. Published by Elsevier B.V.

Source: https://www.sciencedirect.com/science/article/pii/S223878542031824X?dgcid=rss_sd_all

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Material

Influences of impact energy on the densification and mechanical properties of powder metallurgical Fe–C–Cu preforms during a powder-forged process

Publication date: November–December 2020

Source: Journal of Materials Research and Technology, Volume 9, Issue 6

Author(s): Biao Guo, Qiang Li, Hui Wu, Jinqing Ao, Qifeng Tang, Yu Zhang, Xiao Li, Yun Lu

Republished by Plato

Published

on

open access

Abstract

Accurate impact energy control is important for the success of the powder-forged (P/F) technique. This paper address how impact energy influences the densification and mechanical properties of powder metallurgical (P/M) preforms during a P/F process by combining finite element simulations and experiments. The simulated results coincide well with the experimental results. Results reveal that impact energy strongly influences the P/M preform densification by controlling their stress states and strain rate. The densification continuously proceeds throughout the P/F processing by the three steps of micro-pore compression, segmentation, and closure, while the densification uniformity gradually deteriorates in the earlier free upsetting step and then significantly improves in the later closed compressing step. The increased impact energy within the range below 56.3 J/cm3 induces a higher strain rate, and thus facilitates the P/M preform densification notably. Inversely, the excessive impact energy not only has less influence on the densification but also creates exceptionally high forging pressure. The notably increased density improves the mechanical properties of the P/F forgings significantly; meanwhile, the concomitant work hardening changes their tensile fracture modes and slows down their ductility rising. In this study, the P/F Fe–C–Cu forgings prepared at the optimized impact energy of 56.3 J/cm3 have a high and uniform density and good mechanical properties. This study can provide theoretical guidance for the rational process design of powder forging.

Keywords

Powder-forged

Impact energy

Finite element simulation

Densification

Mechanical properties

© 2020 The Authors. Published by Elsevier B.V.

Source: https://www.sciencedirect.com/science/article/pii/S2238785420318081?dgcid=rss_sd_all

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Material

Cattaneo-Christov double diffusions (CCDD) in entropy optimized magnetized second grade nanofluid with variable thermal conductivity and mass diffusivity

Publication date: November–December 2020

Source: Journal of Materials Research and Technology, Volume 9, Issue 6

Author(s): Yu-Ming Chu, Faisal Shah, M. Ijaz Khan, Seifedine Kadry, Zahra Abdelmalek, Waqar A. Khan

Republished by Plato

Published

on

open access

Abstract

In this research communication, mathematical model is developed to scrutinize the two-dimensional magnetohydrodynamic boundary layer flow of non-Newtonian nanofluid (second grade) toward a permeable and stretchable Riga plate surface. To examined the thermal and solutal relaxation characteristics the proposed model of Cattaneo-Christov double diffusions (CCDD) model is supposed. Furthermore, variable thermal conductivity and variable mass diffusivity are accounted. In addition, the convective condition of heat transfer is involved. The concept of entropy generation is also highlighted. Formulation also consists of thermal radiation, mixed convection and thermophoresis. The resulting problems are computed by modern approach known as optimal homotopy analysis method (OHAM). OHAM is a powerful method to used for the series solution of highly non-linear equations in comparison to other analytical and numerical methods. Total square residual error is computed. Velocity distribution enhances for second grade fluid parameter but reverse trend is seen for larger estimation of inverse Darcy number. Temperature profile increases for larger estimation of thermal relaxation parameter and characterize temperature (

ɛ1

). Nanoparticles concentration decays for boost values of solutal relaxation parameter and characterize concentration (

ɛ2

). Physical arguments for important parameters of interest are organized.

Keywords

Non-Newtonian (second grade) fluid model

Cattaneo-Christov double diffusions (CCDD)

Nanofluid

Stretched Riga plate

Temperature dependent thermal conductivity and mass diffusivity

Entropy generation rate

© 2020 The Author(s). Published by Elsevier B.V.

Source: https://www.sciencedirect.com/science/article/pii/S2238785420318263?dgcid=rss_sd_all

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