Corrosion Resistance of the Ceramic Coating Formed by Micro-Plasma Arc Oxidation on AZ91D Alloy

2007 ◽  
Vol 336-338 ◽  
pp. 2451-2453
Author(s):  
Shu Hua Li ◽  
Fu Chi Wang
Keyword(s):  
Magnesium Alloy ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Az91d Alloy ◽  
Plasma Arc ◽  
X Ray Diffraction ◽  
Compact Layer ◽  
Az91d Magnesium Alloy ◽  
Loose Layer ◽  
Salt Fog

The ceramic coating was formed by micro-plasma arc oxidation (MPAO) on AZ91D magnesium alloy. The surface and section morphology of coatings were observed using scanning electron microscopy. The phase composition of coatings was analyzed by X-ray diffraction. The method of salt fog experimental was carried out to proof-test performances of anti-corrosion of material. The results showed that the ceramic coating was composed by loose layer and compact layer. The coating surface has a large number of grains with various sizes. In addition, there is also a lot of pore in the loose layer, but the compact layer is tighter than the loose layer. Compact layer has a good combination with substrate magnesium alloy. The MPAO coating is mainly composed of silica oxide (MgAl2Si3O12 and β-Mg2SiO4 and (Mg4Al14) (Al4Si2)O20) and composite oxide of Mg and Al (δ-MgAl28O4). The performance of resistant corrosion of AZ91D coved by ceramic coating is higher than AZ91D magnesium alloy. The corrosion ratio of AZ91D alloy coved by ceramic coatings to AZ91D alloy is 1:8.61.

Microstructure and Mechanical Properties of Ceramic Coating on AM50 Magnesium Alloy by Microarc Oxidation

2005 ◽  
Vol 488-489 ◽  
pp. 693-696 ◽  
Author(s):  
Hui Zhao ◽  
Ji Chen ◽  
Zhen Liu
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Magnesium Alloy ◽  
Ceramic Coating ◽  
Microarc Oxidation ◽  
Oxide Coating ◽  
Compact Layer ◽  
Alloy Substrate ◽  
Maximum Value ◽  
Loose Layer

The coating formed on AM50 magnesium alloy by microarc oxidation (MAO), using DC pulse power in Na2SiO3 solution. The oxide coating contains a loose layer and a compact layer, the loose layer consisting of MgO, Mg2SiO4 and MgSiO3 phases and the compact layer mainly of the MgO phase. The curves of hardness (H) and elastic modulus (E) across the coating are similar, from the surface to the interior of the coating, H and E increase, and both of them exhibit a maximum value at the same depth of the coating. After MAO treatment, the mechanical properties, such as hardness and elastic modulus, can be improved, and the microstructure of the alloy substrate has not been changed.

Antiwear Behavior of Micro-Arc Oxidated Coating Rubbing on Abrasive Paper

2011 ◽  
Vol 704-705 ◽  
pp. 1210-1215 ◽  
Author(s):  
Yan Tang ◽  
Jin Yong Xu ◽  
Fang Yong Ye ◽  
Cheng Gao ◽  
Jing Chun Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Aluminium Alloy ◽  
Dry Friction ◽  
Ceramic Coating ◽  
Friction Pair ◽  
Ceramic Coatings ◽  
Compact Layer ◽  
Wear Rates ◽  
Loose Layer

To research the tribological properties of micro-arc oxidized ceramic coating in extreme friction condition, ceramic coatings were tested with 1000# waterproof sand paper friction pair for the first time. The phase composition of ceramic coating was analyzed by X-ray diffraction (XRD).Micro structures of ceramic coating surface were observed by scanning electron microscopy (SEM). Friction coefficient of ceramic coating was measured by ball-on-disc wear tester with a 3 mm steel ball. Wear weight loss and wear rate of ceramic coating were measured and calculated by photoelectron balance. The results show that ceramic coatings in various roughnesses have different former wear rates and close wear rates at stable stage. Under water-lubricated condition, wear rate is as low as 0.2 mg/min to 0.3 mg/min. The antiwear behavior of ceramic coating is about 5.3 times compared to aluminium alloy at dry friction. While under water-lubricated condition, the antiwear behavior of ceramic coating improves about 94 times compared to aluminium alloy. The friction coefficient of loose layer is higher than compact layer at dry friction. And there are positive correlation between wear rate and surface roughness of ceramic coating. So it can be verified that compact layer has well antiwear behavior better than loose layer.

scholarly journals The technology of preparing green coating by conducting micro-arc oxidation on AZ91D magnesium alloy

2016 ◽  
Vol 18 (4) ◽  
pp. 36-40 ◽  
Author(s):  
Sheng Wang ◽  
Pengcheng Liu
Keyword(s):  
Electron Microscopy ◽  
Magnesium Alloy ◽  
X Ray Diffraction ◽  
Compact Layer ◽  
Silicate System ◽  
X Ray ◽  
Az91d Magnesium Alloy ◽  
The Matrix ◽  
Micro Arc Oxidation ◽  
Scanning Electron

Abstract Micro-arc oxidation was applied to AZ91D magnesium alloy by taking K2Cr2O7 as the colouring salt in the silicate system. It was shown that the green coating obtained through performing micro-arc oxidation on magnesium alloy consisted of Mg, Mg2SiO4, MgO, and MgCr2O4 based on analysis of X-ray diffraction (XRD), and scanning electron microscopy (SEM). Among which, MgCr2O4 was the colouring salt; there were something in the lamellar, pit, and convex forms found on the surface of the coating. The coating consisted of a porous, and a compact, layer from the outside to the inside. As demonstrated, the colour of the coating depended on the K2Cr2O7 concentration: it became gradually deeper with the addition of K2Cr2O7 and the increasing micro-arc oxidation time. The corrosion resistance and hardness of the green coating were greater than that of the matrix.

Room Temperature Screw Form Rolling of AZ91D Magnesium Alloy through Processing by Extrusion-Torsion Simultaneous Working

2014 ◽  
Vol 783-786 ◽  
pp. 375-379
Author(s):  
Mitsuaki Furui ◽  
Shouyou Sakashita ◽  
Kazuya Shimojima ◽  
Tetsuo Aida ◽  
Kiyoshi Terayama ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Room Temperature ◽  
Hardness Measurement ◽  
Rolling Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Az91d Magnesium Alloy ◽  
Microstructure Observation ◽  
Fine Grain ◽  
Simultaneous Processing

Extrusion-torsion simultaneous processing is a very attractive technique for fabricating a rod-shape material with fine grain and random texture. We have proposed a new screw form rolling process combined with preliminary extrusion-torsion simultaneous working. Microstructure evolution and mechanical property change of AZ91D magnesium alloy during extrusion-torsion simultaneous processing was examined through microstructure observation, X-ray diffraction analysis and micro-Vickers hardness measurement. By the addition of torsion, the crystal orientation of AZ91D magnesium alloy workpiece was drastically changed from basal crystalline orientation to the random orientation. Crystal grain occurred through the dynamic recrystallization and tended to coarsen with an increase of extrusion-torsion temperature. Grain refinement under 2 um was achieved at the lowest extrusion-torsion temperature of 523 K. M8 gauge AZ91D magnesium alloy screw was successfully formed at room temperature using the extrusion-twisted workpiece preliminary solution treating at 678 K for 345.6 ks. It was found that the extrusion-torsion temperature of 678 K must be selected to fabricate the good screw without any defects.

Tribological behavior of AZ91D magnesium alloy composite: effect of hybrid WC – SiO2 nanoparticles

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammed Fahad ◽  
Bavanish B.
Keyword(s):  
Magnesium Alloy ◽  
Wear Rate ◽  
Az91d Alloy ◽  
Hybrid Particles ◽  
Wear Properties ◽  
Sliding Speed ◽  
Composite Effect ◽  
Content Type ◽  
Climate Conditions ◽  
Az91d Magnesium Alloy

Purpose Aviation field requires a material with greater tribological characteristics to withstand the critical climate conditions. Hence, it is of paramount importance to enhance the wear resistance of material. AZ91D magnesium alloy is a light weight material used in the aviation field for the construction work. The purpose of this study is to augment the wear properties of AZ91D alloy by reinforcing with hard particles such as tungsten carbide (WC) and silicon dioxide (SiO2). Design/methodology/approach In this work, three types of composites were fabricated, namely, AZ91D – WC, AZ91D – SiO2 and AZ91D – (WC + SiO2) by ball milling method, and the tribological properties were analyzed using pin-on-disc apparatus. Findings Results showed that the hardness of AZ91D alloy was greatly improved due to the reinforcing effects of WC and SiO2 particles. Wear study showed that wear rate of AZ91D alloy and its composites increased with the increase of applied load due to ploughing effect and decreased with the increase of sliding speed owing to the formation of lubricating tribolayer. Further, the AZ91D – (WC + SiO2) composite exhibited the lower wear rate of 0.0017 mm3/m and minimum coefficient of friction of 0.33 at a load of 10 N and a sliding speed of 150 mm/s due to the inclusion of hybrid WC and SiO2 particles. Hence, the proposed AZ91D – (WC + SiO2) composite could be a suitable candidate to be used in the aviation applications. Originality/value This work is original which deals with the effect of hybrid particles, i.e. WC and SiO2 on the wear performance of the AZ91D magnesium alloy composites. The literature review showed that none of the studies focused on the reinforcement of AZ91D alloy by the combination of carbide and metal oxide particles as used in this investigation.

Anti-Wear Coating Grown by Micro-Plasma Oxidation on Aluminum Alloys in the Solution of Aluminate-Titania

2011 ◽  
Vol 239-242 ◽  
pp. 667-670 ◽  
Author(s):  
Li Gong Zhang ◽  
Gui Mei Zhao ◽  
Xiao Ming Lai
Keyword(s):  
Aluminum Alloys ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Wear Property ◽  
Plasma Oxidation ◽  
X Ray Diffraction ◽  
Electrolytic Solution ◽  
X Ray ◽  
Hardness Tester ◽  
Wear Coating

In this paper, Aluminum trioxide ceramic coatings were grown on surfaces of 2024 Aluminum alloys by micro-plasma oxidation in an aluminate electrolytic solution. In order to decrease the density of the pores and increase the anti-wear property of the ceramic coatings, Titania were added into the aluminate electrolytic solution. The struture and anti-wear property of the produced ceramic coatings were measured by X-ray diffraction, scanning electron microscope , hardness tester and frictionometer. The results show that the thickness of the ceramic coating is about 24±1 μm, surfaces of the ceramic coatings are very uniform. The hardness of the doped coating is up to 930 HV, and the wear property of the coating is the more excellent than that of undoped coating.

Grain Refinement of AZ91D Magnesium Alloy by In Situ Al4C3 Particles

2011 ◽  
Vol 306-307 ◽  
pp. 429-432
Author(s):  
Hui Han ◽  
Hua Ming Miao ◽  
Sheng Fa Liu ◽  
Yang Chen
Keyword(s):  
Magnesium Alloy ◽  
Grain Refinement ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Az91d Magnesium Alloy ◽  
Average Grain Size ◽  
Central Regions ◽  
Heterogeneous Nucleus

Experiments were conducted to fabricate the Al4C3 particles by powder in-situ synthesis process under argon atmosphere and examine the grain refinement of AZ91D magnesium alloy with the addition of 0.6%Al4C3(hereafter in mass fraction,%). By means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS), the results show the successful fabrication of Al4C3 particles. After adding 0.6%Al4C3, the average grain size of AZ91D magnesium alloy decreased from 360μm to 243μm. Based on the differential thermal analysis (DTA) results and calculations of the planar disregistry between Al4C3 and α-Mg, Al4C3 particles located in the central regions of magnesium grains can act as the heterogeneous nucleus of primary α-Mg phase.

Laser Cladding of Zr55Al10Ni5Cu30/SiC Amorphous Composite Coatings on AZ91D Magnesium Alloy for Improvement of Corrosion Resistance

2011 ◽  
Vol 179-180 ◽  
pp. 757-761 ◽  
Author(s):  
Kai Jin Huang ◽  
Hou Guang Liu ◽  
Chang Rong Zhou
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Laser Cladding ◽  
Composite Coatings ◽  
Corrosion Property ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Good Corrosion Resistance ◽  
Az91d Magnesium Alloy

To improve the corrosion property of magnesium alloys, Zr-based amorphous composite coatings have been fabricated on AZ91D magnesium alloy by laser cladding using mixed powders Zr55Al10Ni5Cu30/SiC. The microstructure of the coating was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The corrosion resistance of the coatings was tested in 3.5wt.% NaCl solution. The results show that the coatings mainly consist of amorphous and different crystalline phases. The coatings compared with AZ91D magnesium alloy exhibit good corrosion resistance because of the presence of the amorphous phase in the coatings.

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