scholarly journals Cold-Sprayed Aluminum-Silica Composite Coatings Enhance Antiwear/Anticorrosion Performances of AZ31 Magnesium Alloy

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Lijia Fang ◽  
Yuting Xu ◽  
Li Gao ◽  
Xinkun Suo ◽  
Jianguo Gong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Magnesium Alloys ◽  
Cold Spray ◽  
Protective Coatings ◽  
Composite Coatings ◽  
Silica Content ◽  
Protective Layers ◽  
Structural Applications ◽  
Enhanced Surface

Extensive efforts devoted in recent years to booming structural applications of lightweight magnesium alloys are usually undermined by their insufficient surface properties. Surface modification is therefore necessarily required in most cases for enhanced surface integrity of the alloys. Here, we report construction of aluminum-silica protective layers by cold spray on AZ31 magnesium alloys, and the effect of the silica additives on microstructure and mechanical properties of the coatings was examined. The ceramic particles were dispersed evenly in the coatings, and increased silica content gives rise to enhanced adhesion, antiwear performances, and microhardness of the coatings. The even distribution of silica in the coatings altered the wear regimes from adhesive to abrasive wear. The cold spray fabrication of the aluminum-silica protective coatings would facilitate structural applications of the magnesium alloys.

Modification in Texture of Magnesium by the Addition of Rare Earth Elements and its Influence on Mechanical Properties

2012 ◽  
Vol 736 ◽  
pp. 307-315 ◽  
Author(s):  
Murugavel Suresh ◽  
Satyam Suwas
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Magnesium Alloys ◽  
Aluminium Alloys ◽  
Room Temperature ◽  
Main Obstacle ◽  
Rare Earth Addition ◽  
Structural Applications ◽  
Re Elements ◽  
The Relationship

Mg alloys show limited room temperature formability compared to its lightweight counterpart aluminium alloys, which is a main obstacle in using this metal for most of the structural applications. However, it is known that grain refinement and texture control are the two possibilities for the improvement of formability of magnesium alloys. Amongst the approaches attempted for the texture weakening, additions through of rare-earth (RE) elements have been found most effective. The relationship between the texture and ductility is well established. In this paper, the effect of rare earth addition on texture weakening has been summarized for various magnesium alloys under the two most common modes of deformation methods.

scholarly journals Novel grain refinement of AZ91E magnesium alloy and the effect on hot tearing during solidfication

2021 ◽  
Author(s):  
Abdallah Elsayed
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Hot Tearing ◽  
Grain Refining ◽  
Grain Refiner ◽  
Structural Applications ◽  
Hot Tearing Susceptibility

For the A1-5Ti-1B grain refiner, the addition of 0.1 wt.% provided a 68 % reduction in grain size as compared to the unrefined AZ91E alloy at a holding time of five minutes. Grain growth restriction by TiB₂ particles was the source of grain refinement. With the addition of A1-5Ti-1B, only a small reduction in hot tearing susceptibility ws observed because large TiA1₃ particles bonded poorly with the eutectic and blocked feeding channels.The addition of 1.0 wt.% A1-1Ti-3B provided a grain size reduction of 63% as compared to the unrefined AZ91E alloy at a holding time of five minutes. The grain refinement with A1-1Ti-3B addition was attributed to a combination of TiB₂ grain growth restriction and A1B₂ nucleating sites. A significant reduction in hot tearing susceptibility was observed with A1-1Ti-3B addition as a result of a higher cooling rate and shorter local soldification time as compared to the AZ91E alloy. The reduction in hot tearing susceptibility was attributed to the good interface between eutectic and TiB₂ particles. Both grain refiners demonstrated a good resistance to fading during the holding times investigated. In addition, the AZ91E + A1-5Ti-1B and AZ91E + A1-1Ti-3B castings showed much fewer dislocation networks as compared to the untreated AZ91E casting.The development of efficient A1-Ti-B refiners can also improve castability of magnesium alloys. In addition, the fade resistant A1-Ti-B grain refiners can reduce operating costs and maintain productivity on the foundry floor. Thus, magnesium alloy with A1-Ti-B treatment have the potential for more demanding structural applications in the automobile and aerospace industries. Vehicle weight in the aerospace and automotive industries directly impacts carbon emissions and fuel efficiency. An increase in the use of lightweight materials for structural applications will result in lighter vehicles. Low density materials, such as magnesium (1.74 g/cm³) are a potential alternative to aluminium (2.70 g/cm³), to reduce component weight in structural applications.However, current magnesium alloys still do not have adequate mechanical properties and castability to meet the performance specifications of the automotive and aerospace industries. Grain refinement can significantly improve mechanical properties and reduce hot tearing during permanent mould casting. Recently, Al-Ti-B based grain refiners have shown potential in grain refining magnesium-aluminum alloys such as AZ91E. This study investigates the grain refining efficiency and fading of A1-5Ti-1B and A1-1Ti-3B in AZ91E magnesium alloy and their subsequent effect on hot tearing.The grain refiners were added at 0.1, 0.2, 0.5 and 1.0 wt.% levels. For the grain refinement and fading experiments, the castings were prepared using graphite moulds with holding times of 5, 10 and 20 minutes. For the hot tearing experiments, castings were produced representing the optimal addition level of each grain refiner. The castings were prepared using a permanent mould with pouring and mould temperatures of 720 and 180 ºC, respectively. The castings were characterized using SEM, TEM, optical microscopy and thermal analysis.

Mechanical Properties and Microstructure of AZ Magnesium Alloys Anodized by Phosphate Electrolyte

2010 ◽  
Vol 654-656 ◽  
pp. 771-774
Author(s):  
Teruto Kanadani ◽  
Shuji Hikino ◽  
Atsushi Saijo ◽  
Makoto Hino ◽  
Koji Murakami ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloys ◽  
Fatigue Cracks ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Phosphate Solution ◽  
Hardness Tests ◽  
Die Cast ◽  
Structural Applications ◽  
Good Creep Resistance

Magnesium alloys possess many advantageous functional properties. Use of magnesium alloys, mainly for vehicle parts as well as electronic appliances, has been booming in recent years because of their lightweight compared to aluminum alloys and good creep resistance relative to plastics. Most the use of magnesium for structural applications has been die-cast components and most of this in one alloy, AZ91D. Since magnesium has the lowest electrochemical potential out of all the common commercial metals and is extremely prone to corrosion, it is necessary that it undergoes surface treatment. It is well known that fatigue cracks start near the free surface. Surface microstructure, therefore, should have a significant effect on the fatigue strength. This study was carried out using a mainly phosphate solution without heavy metal onto various AZ magnesium alloys. The effect of anodizing on mechanical properties and microstructure was examined by repeated tension fatigue tests, tensile tests, hardness tests and electron microscopy.

Modifications of the Extrusion Process of Magnesium Alloys for Improved Mechanical Properties

2008 ◽  
Vol 367 ◽  
pp. 9-16 ◽  
Author(s):  
Sören Müller ◽  
Klaus Mueller ◽  
Walter Reimers
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloys ◽  
Differential Effect ◽  
Cold Deformation ◽  
Compressive Loading ◽  
Extrusion Process ◽  
Detailed Knowledge ◽  
Strength Differential Effect ◽  
Strength Differential ◽  
Structural Applications

In the course of the increasing discussions about a reduction of the CO2 emissions magnesium has gained importance since it is the lightest metal for structural applications. Currently magnesium alloys are almost exclusively used as cast parts in the automotive industry because due to their microstructure extruded magnesium profiles exhibit a strong asymmetry in the mechanical properties under tensile and compressive loading (strength differential effect). In order to improve the mechanical properties a detailed knowledge about the influence of the different extrusion parameters on the microstructure of the extrudates is necessary. Therefore, the parameters extrusion method, billet temperature, product speed, extrusion ratio and cooling condition were varied for the extrusion of the magnesium alloys AZ31, AZ61 and AZ80. Subsequently the microstructure was analyzed and the mechanical properties determined. With an additional analysis of the deformation modes of the extruded and cold deformed products it could be discovered that an improvement of the mechanical properties can be achieved by a modification of the extrusion process. Since the strength differential effect in caused by twinning which due to the texture of the extrudates is only active under a compressive loading along the extrusion direction the modification of the extrusion process aims at a suppression of this twinning. Because on the one hand compared to that for dislocation glide the Hall-Petch-Constant for twinning is bigger a grain refinement of the extruded products could be achieved by a predeformation using ECAE similar processes. On the other hand a process has been developed where the profiles are extruded into a hydrostatic counter pressure in order to alter the texture during the extrusion. Thereby the twinning is already activated during the extrusion. Both modifications of the extrusion process result in an increase of the critical resolved shear stress for twinning during the subsequent cold deformation and thus in improved mechanical properties.

Electrophoretic Composite Coatings on Magnesium Alloys

2015 ◽  
Vol 245 ◽  
pp. 97-102
Author(s):  
Dmitry V. Mashtalyar ◽  
Sergey V. Gnedenkov ◽  
Sergey L. Sinebryukhov ◽  
Igor M. Imshinetsky
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Electrophoretic Deposition ◽  
Plasma Electrolytic Oxidation ◽  
Corrosion Current Density ◽  
Composite Coatings ◽  
Corrosion Current ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic

Investigation results of the composite coatings obtained on MA8 magnesium alloy by plasma electrolytic oxidation (PEO) and post-treated by electrophoretic deposition of superdispersed polytetrafluoroethylene (SPTFE) are presented. Comprehensive research of electrochemical and mechanical properties of the obtained polymer-containing coatings on the magnesium alloy has been performed. It has been established that composite coatings to decrease the corrosion current density by three orders of magnitude (down to Ic = 2.0×10-10 A/cm2) and the wear by two orders of magnitude (down to 1.2×10-6 mm3/(N·m)), as compared to the basic PEO-coating.

scholarly journals Electro-plasticity’s Effect By Deformation And Impulse Impact Of A High Energy Electromagnetic Field

2021 ◽  
Vol 2131 (4) ◽  
pp. 042059
Author(s):  
Andrey Kochetov ◽  
Elena Fisunova ◽  
Tatiana Lavrenova ◽  
Lyubov Filonenko
Keyword(s):  
Mechanical Properties ◽  
Electromagnetic Field ◽  
Service Life ◽  
Protective Coatings ◽  
Composite Coatings ◽  
Amorphous Material ◽  
Physical And Mechanical Properties ◽  
High Energy ◽  
Ultrasonic Field ◽  
Subsequent Formation

Abstract The problem of obtaining predicted physical and mechanical properties and a given service life of multifunctional composite protective coatings in the form of barrier layers that increase the service life of mechanical engineering products and formative tools are inherently interconnected. Among all the variety of innovative highly efficient technological processes, a special place should be given to the method of electro-acoustic spraying (ELAN). This method is innovative in the field of synthesis of multifunctional composite coatings, which allows the formation of protective films of an amorphous material on any conductive substrates [1]. This technology is based on the use of the complex energy of an electric spark and a complex ultrasonic field. The aim of this work is to optimize the process of obtaining multifunctional composite protective coatings based on the complex mass transfer of the electrode material and the subsequent formation of amorphous structures with predictable physical and mechanical properties by the method of electro-acoustic spraying based on the effect of electro-plasticity during deformation and pulsed action of a high-energy electromagnetic field.

Formation of Composite Coatings Using Fluoropolymer Materials

2015 ◽  
Vol 245 ◽  
pp. 103-108 ◽  
Author(s):  
Konstantine Nadaraia ◽  
Dmitry Mashtalyar ◽  
Sergey Gnedenkov ◽  
Sergey Sinebryukhov
Keyword(s):  
Mechanical Properties ◽  
Surface Modification ◽  
Magnesium Alloy ◽  
Plasma Electrolytic Oxidation ◽  
Composite Coatings ◽  
Corrosion Current ◽  
Subsequent Treatment ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Peo Coatings

Surface modification of magnesium alloys by plasma electrolytic oxidation (PEO) and subsequent treatment with suspension of superdispersed polytetrafluoroethylene and tetrafluoroethylene telomeric solution are presented. Electrochemical, mechanical properties and wettability of obtained composite coatings were investigated. The polymer-containing coatings decrease the corrosion current and wear by orders of magnitude as compared to unprotected magnesium alloy and base PEO-coatings.

Improvement of the Corrosion Resistance of Biomedical Magnesium Alloys in the Ringer’s Solution Using Protective Coatings

2015 ◽  
Vol 227 ◽  
pp. 459-462
Author(s):  
Iwona Kot ◽  
Halina Krawiec
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Electrochemical Impedance ◽  
Protective Coatings ◽  
Corrosion Behaviour ◽  
Composite Coatings ◽  
Electrochemical Behaviour ◽  
Dip Coating ◽  
Biodegradable Implant ◽  
Ringer’S Solution

The corrosion resistance of magnesium alloys depends on their microstructure, especially the presence of different intermetallic phases and precipitates. In this paper, the electrochemical behaviour of Mg1Ca and Mg1Ca1Si magnesium alloys has been investigated in the Ringer’s solution at 37 °C. In order to improve the corrosion resistance of these magnesium alloys composite coatings were fabricated by modification of a chitosan layer. The coatings were prepared by dip-coating in a chitosan solution and then modified by electrochemical deposition of a layer from a solution containing fluorine ions and water glass. The electrochemical performance of chitosan and chitosan modified coated alloys was evaluated by linear sweep voltamperometry and electrochemical impedance spectroscopy. The coated magnesium alloys possess suitable corrosion behaviour for the application as biodegradable implant material.

scholarly journals Lightweight Structural Concrete

2021 ◽  
Author(s):  
Omnia Saad ◽  
◽  
Khaled S. Ragab ◽  
Omar Elnawawy ◽  
Yousef R. Alharbi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lower Cost ◽  
Lightweight Concrete ◽  
Silica Content ◽  
Nano Silica ◽  
Structural Concrete ◽  
Optimum Dosage ◽  
Structural Applications ◽  
Main Disadvantage ◽  
Clay Aggregates

Using of Lightweight concrete (LWC) amounts to a lower cost and a better thermal performance due to its unique properties and light density. The main disadvantage in using lightweight concrete is that its mechanical properties are relatively poor. An effective method to improve the mechanical properties of lightweight concrete is using a dosage of nano-silica in the concrete mix. The gained enhancement of mechanical properties promotes a more serious discussion of structural applications of lightweight concrete. There exists an optimum dosage of nano-silica by which the mechanical properties enhancement is maximized. Increasing the nano-silica content beyond the optimum dosage degrades the mechanical properties. However, a fixed optimum dosage is not agreed upon in literature. This paper investigates the optimum dosage of NS to enhance the mechanical properties and microstructure of a lightweight concrete made with lightweight expanded clay aggregates (LECA). The results concluded that a dosage of 0.75% of nano-silica is optimum for the studied lightweight concrete mixes.

Sign in / Sign up

Export Citation Format

Share Document