Corrosion Behavior Of Metal Matrix Composites Research Articles

Investigation of Mechanical and Tribological Behaviors of MMC Fabricated through FSP

Researchers and various industries place a high value on metal matrix composites (MMCs) made using friction stir processing (FSP), which has superior and finer particle dispersion and also successfully displays equalized grains through dynamic recrystallization. In the present research work magnesium alloy AZ31 reinforced with MoS2 was successfully made using FSP. The FSP samples are fabricated at 1000, 1200 and 1400 RPM while the traverse speed of 70mm/min is kept constants for all the FSP samples. AZ31 has light weight and excellent weight to strength ratio for this reason it can be used in various application like Aerospace Industry, Ship building and automotive applications but it has limitation in wear resistance and AZ31 Alloy is reactive and can corrode easily in corrosive medium. The present work aim is to investigate the mechanical and tribological behavior of AZ31/MoS2 Metal Matrix Composite (MMC) and then compared the properties with the base alloy. Here the specimen AZ31 is reinforced with MoS2 and processed by FSP to improve the tribological behavior the pin on disk wear test is conducted to study the wear performance. To investigate the hardness of the specimen, the hardness test is performed on the Brinell hardness apparatus. The corrosion behavior of MMC is also investigated by the immersion test conducted with 3.5% weight NaCl solution for 24 hours. All these properties are then compared with base Alloy. The SEM analysis is also investigated to study the surface behavior.

Additive manufacturing SiC-reinforced maraging steel: Parameter optimisation, microstructure and properties

The unique deposition manner of additive manufacturing (AM) allows the near-net-shaping of components with multiple materials configurations and complex geometries, which sheds light on the process of high-performance metal matrix composites (MMCs). This work explores laser powder bed fusion (LPBF) AM of SiC-reinforced maraging steel MMCs to consolidate the merits of both ceramics and metal matrix for improving overall properties. The laser processing parameters were systematically optimised based on the density, roughness and hardness of the deposited samples. The effects of SiC content on the microstructures, mechanical properties, tribological performance, and wear resistance are elucidated. SiC particles are refined with uniform distribution in the metal matrix after laser processing. The highest tensile strength reaches 1611 ​MPa together with an elongation of about 10.1% with 3 ​vol% SiC addition. The tribological performance of MMCs is investigated by studying the coefficient of friction (COF), wear rate, and worn morphology. The COF has been slightly reduced with the SiC addition, and the wear rate of MS reduced from 3.25 ​× ​10 −5 to 1.72 ​× ​10 −5 mm 3 /Nm with the 12 ​vol% SiC addition. The underlying wear mechanisms are also investigated. Besides, the corrosion behaviour of MMCs is also investigated; the addition of SiC (≥6 ​vol%) has improved the corrosion properties of the matrix.

Microstructure, wear, and corrosion characterization of high TiC content Inconel 625 matrix composites

Titanium carbide/Inconel 625 (nickel alloy) metal matrix composites (MMCs) are developed for the combination of the super mechanical and corrosion properties of nickel alloy matrix and the high hardness of reinforcing titanium carbide particles (TiCp). The microstructure, hardness, wear, and corrosion behavior of MMCs with different volume contents of TiCp (25, 50 and 70vol.%) were investigated. The effect of increasing TiCp on the intermetallics and precipitates formed was examined using SEM/EDS and XRD analyses. The tribological behavior of the MMCs was investigated using wear testing with a pin-on-disk machine. The corrosion behavior was examined using potentiodynamic polarization experiments in 3% (w/v) NaCl solution. The results showed that the addition of TiCp into the Inconel 625 alloy resulted in formation of several intermetallics such as MoNi4, Cr2Ni3 and MoCr, in addition to molybdenum and chromium carbides in the matrix alloy. A great improvement in the hardness was resulted with addition of 25vol.% TiCp and consequently the wear resistance was also improved. Further increase of TiCp from 50 to 70vol.% did not result in more improvement of both hardness and wear resistance. The corrosion resistance of TiCp (25vol.%) composite was comparable to that of monolithic Inconel 625 matrix alloy, while clear reduction in the corrosion resistance was found in the 50 and 70vol.% composites.

Improvement in the corrosion resistance of aluminum 2009/SiCw composite by Nd :YAG laser surface treatment

The corrosion behavior of metal-matrix composites (MMCs) is closely associated with the presence of heterogeneities such as reinforcement phase(s), microcrevices, porosity, secondary phase precipitates, and interaction products [1, 2]. Among the various possible corrosion mechanisms, microgalvanic coupling between the matrix alloy and the reinforcement phase(s), which is commonly associated with intermetallic precipitates, is generally recognized to be responsible for causing pitting corrosion in some silicon carbide reinforced aluminum MMCs [3±5]. Paciej [6] demonstrated that solution heat treatment combined with a high extrusion ratio could affect the precipitation behavior and enhance the corrosion resistance of an Al7091=SiCp composite. Ahmad [7] also denoted that a natural age-hardening process after solution heat treatment (T4) could reduce the corrosion rate of an Al-6013=SiCp composite by re®ning and homogenizing its secondary phases. However, using bulk heat-treating processes to improve the corrosion properties of MMCs can sometimes reduce the mechanical properties of the material. To solve this problem, surface treatment techniques are recommended. It is well known that laser surface melting can produce a rapidly solidi®ed surface layer, in which both the microstructure and the distribution of alloying elements can be greatly modi®ed. Our previous studies [8±10] have demonstrated that excimer laser surface treatment was an ef®cient way to improve the corrosion resistance of both aluminumand magnesium-based composites. However, the relatively low energy output of excimer lasers and their high running costs have so far restricted them from being extensively used for surface treatment. Unlike excimer lasers, Nd:YAG lasers can now be operated in continuous mode and in kilowatts range. With these new facilities, highpower YAG lasers could be effectively used for surface modi®cation of metals and composites alike. Preliminary results reported in this paper formed part of a wider study of the laser surface treatment of MMCs. The material used in this study was a 15 vol % SiC whisker, reinforced aluminum AA2009(Al3.8Cu-1.3 Mg) composite, which was produced by using a powder metallurgy route, and was supplied in 2.5 mm-thick annealed sheets. The diameter of the SiC whisker was between 0.4 im±0.65 im. Prior to laser treatment, all the specimens were polished with a 1 im diamond suspension. A laser surface treatment was conducted using a 2 kW continuous wave (CW) YAG laser. In the experiment, the laser beam size was ®xed at 3 mm, and the laser power and the scanning velocity were ®xed at 500 W and 35 mm sy1, respectively. During laser treatment, argon gas was blown over the molten pool to minimize any oxidation problem. Anodic polarization tests were carried out in a 3.5 wt % NaCl solution, which was prepared by using analytical grade reagents. The initial pH value of the solution was 7.8. The specimen was driven from y0.250 V below the steady open circuit potential at a scanning rate of 0.333 mV sy1 to produce potentiodynamic polarization plots. All potentials were measured with reference to a standard calomel electrode (SCE). Fig. 1(a,b) shows the surface morphology of the untreated and the laser-treated specimens, respec-