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.

Zn Coatings on AZ91D Magnesium Alloy Prepared by Electroplating from the Electrolyte Containing SnO2 sol

2007 ◽  
Vol 546-549 ◽  
pp. 593-596 ◽  
Author(s):  
Wei Ping Li ◽  
Li Qun Zhu ◽  
Meng Li
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Magnesium Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Az91d Magnesium Alloy ◽  
Phase Structures ◽  
Energy Dispersion Spectrometry ◽  
Solution Changes ◽  
Scanning Electron

A new method has been devised to obtain a Zn coating on the AZ91D magnesium alloy from the base electrolyte of ZnSO4 and K4P2O7 by electroplating. To improve the properties of the coating, a SnO2 sol was prepared and added in the electrolyte. The effects of the SnO2 sol addition on the morphologies, compositions and phase structures of the plated coatings were investigated by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS) and X-ray diffraction (XRD). The results reveal that the addition of SnO2 in the solution changes the polarization behavior of the electrolyte and the compositions of the plated coating. The plated coating formed in the electrolyte with an addition of SnO2 sol are more uniform and provide a better protection for the AZ91D substrate.

Characteristics of Ni–Cr–Fe laser clad layers on EA4T steel

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744031
Author(s):  
Wenjing Chen ◽  
Hui Chen ◽  
Yongjing Wang ◽  
Congchen Li ◽  
Xiaoli Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cladding Layer ◽  
Metallurgical Bonding ◽  
The Matrix ◽  
Feeding Speed ◽  
Upper Bainite ◽  
Scanning Electron

The Ni–Cr–Fe metal powder was deposited on EA4T steel by laser cladding technology. The microstructure and chemical composition of the cladding layer were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bonding ability between the cladding layer and the matrix was measured. The results showed that the bonding between the cladding layer and the EA4T steel was metallurgical bonding. The microstructure of cladding layer was composed of planar crystals, columnar crystals and dendrite, which consisted of Cr2Ni3, [Formula: see text] phase, M[Formula: see text]C6 and Ni3B phases. When the powder feeding speed reached 4 g/min, the upper bainite occurred in the heat affected zone (HAZ). Moreover, the tensile strength of the joint increased, while the yield strength and the ductility decreased.

A Porous TiO2 Coating with Vermiform Morphology Formed on Ti through Micro-Arc Oxidation

2013 ◽  
Vol 652-654 ◽  
pp. 1818-1821
Author(s):  
Zhen Fei Liu ◽  
Wei Qiang Wang ◽  
Min Qi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Temperature ◽  
Rutile Phase ◽  
Sodium Tetraborate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Porous Titania ◽  
Micro Arc Oxidation ◽  
Scanning Electron

A porous titania (TiO2) coating with vermiform slots was prepared on the Ti substrate through micro-arc oxidation (MAO) treatment using sodium tetraborate as electrolyte. Morphologies and phase structure were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Results show that the rutile phase increases and anatase decreases gradually with increasing MAO time. The electrolyte of sodium tetraborate has significant influence on the formation of vermiform coatings, which determine the corrosive patterning in the first stage during MAO processing. The evolution of vermiform morphology is proposed as followed: some corrosive pores appear on the surface before arcing; afterward, the adjacent micropores in the dense regions link each other due to the high temperature result from continuous arc action; then, the micropores grow up to big pits and combine with each other with increasing MAO treating time; finally, the vermiform morphology forms on the surface of Ti metal.

Fabrication of TiAl/Ti2AlC Composite by Reaction Hot Pressing

2011 ◽  
Vol 52-54 ◽  
pp. 842-845 ◽  
Author(s):  
Jian Feng Zhu ◽  
Wen Wen Yang ◽  
Yi Ping Gong
Keyword(s):  
Electron Microscopy ◽  
Reaction Process ◽  
Hot Press ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Composite ◽  
The Matrix ◽  
Morphology Characteristics ◽  
Scanning Electron

TiAl/Ti2AlC in situ composite was successfully fabricated by hot-press-assisted reaction process from the mixture of Ti, Al and carbon black. The phase formation and transformation were investigated in detail by X-ray diffraction (XRD) and the morphology characteristics were also studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that when the mixed powders were hot pressed at 1300 °C for 1 h, full dense and highly pure TiAl/Ti2AlC composite was synthesized. The TiAl was the matrix phase and the in situ synthesized Ti2AlC was reinforcing phase. The reaction process was also discussed.

Detection of Intermetallic Compounds in a Mg-5Al-3Ca-0.7Sr-0.2Mn Magnesium Alloy

2013 ◽  
Vol 197 ◽  
pp. 137-142 ◽  
Author(s):  
Tomasz Rzychoń ◽  
Janusz Szala ◽  
Tomasz Kukiełka
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Magnesium Alloy ◽  
Light Microscopy ◽  
Diffraction Analysis ◽  
Intermetallic Compounds ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

In this paper the results of microstructural investigations and methodology of detection of intermetallic compounds were reported. The microstructural investigations included the light microscopy, scanning electron microscopy, chemical microanalysis and X-ray diffraction analysis. It was found that the microstructure of Mg-5Al-3Ca-0.7Sr-0.2Mn alloy consists of α-Mg, (Mg,Al)2Ca, Al3Mg13(Sr,Ca), Mg2Ca and Al2Ca intermetallic phases. The correct detection of these phases requires the high magnifications and a large number of measurements fields.

scholarly journals Enhancing the Oxidation Resistance of Al2O3-SiC-C Castables via Introducing Micronized Andalusite

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4775 ◽  
Author(s):  
Xiaoyu Wang ◽  
Saixin Wang ◽  
Yuandong Mu ◽  
Ruijie Zhao ◽  
Qingfeng Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxygen Diffusion ◽  
Area Ratio ◽  
Modulus Of Rupture ◽  
Thermal Shock Test ◽  
X Ray Diffraction ◽  
Shock Test ◽  
X Ray ◽  
The Matrix ◽  
Scanning Electron

Additions of andalusite aggregates (19 wt%) were shown in previous literature to enhance the antioxidation of Al2O3-SiC-C (ASC) castables. This work aims to investigate whether micronized andalusite has a greater influence on antioxidation improvement than andalusite aggregates. Various low contents (5 wt% and below) of micronized andalusite (≤5 μm) were introduced as a substitute for brown fused alumina in the matrix of ASC castables. The antioxidation of castable specimens was estimated by the oxidized area ratio on the fracture surface after a thermal shock test. The microstructure and phases of micronized andalusite and the castable specimens were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results suggest that the antioxidation effects of ASC castables with a low addition of micronized andalusite are effectively enhanced. The heat-induced transformation of andalusite produces SiO2-rich glass, favoring the sintering of the castable matrix and impeding oxygen diffusion into the castable’s interior. Therefore, the castable antioxidation is enhanced without deteriorating the hot modulus of rupture.

Effects of graphene on the microstructure and properties of MAO coatings formed on AA7050

2020 ◽  
Vol 111 (6) ◽  
pp. 463-468
Author(s):  
Bo Xu ◽  
Yafeng He ◽  
Xiangzhi Wang ◽  
Weimin Gan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Composite Coatings ◽  
Ceramic Coatings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Scanning Electron

Abstract Ceramic coatings were prepared on the surface of 7050 highstrength aluminum alloy using micro-arc oxidation in an aluminate electrolyte with added graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron, and electrochemical measurements were used, respectively. The addition of 9 g · L-1 of graphene to the electrolyte decreased the micro-pore size of the composite coatings and improved the density. In addition, with the addition of graphene, the roughness was the lowest, and the corrosion resistance was significantly improved.

Metallography, Microanalysis & Corrosion of the Athlit Ram

2011 ◽  
Vol 1319 ◽  
Author(s):  
M. R. Notis ◽  
M. Hoban ◽  
D-N. Wang
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Optical Metallography ◽  
Metal Corrosion ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Wood Analysis ◽  
Maritime Museum ◽  
Scanning Electron

ABSTRACTThe Athlit ram, a bronze warship ram from a 2nd Century BCE Roman-era galley, was found in 1980 off the coast of Israel at Athlit, and is now displayed at the National Maritime Museum, Haifa, Israel. It meant to fit on the prow of a medium-sized oared warship. This ram is the only known surviving example of this ancient naval weapon. Inside the bronze ram some of the ship’s wood is still preserved. We have recently studied a piece of the ram removed during early conservation. Remnant metal, corrosion products, and mineralized and pseudomorphed wood have all been found and examined by light optical metallography, x-ray diffraction, scanning electron microscopy, and microanalysis using energy dispersive x-ray mapping. The main corrosion product on the Athlit Ram is identified as covellite (CuS), and the entrained material is pseudomorphed cedar wood. Analysis indicates the lumen to be replaced by calcium carbonate and the cell walls to be replaced by covellite, consistent with the matrix.

Microstructure Evolution of In Situ Synthesized VC Reinforced Iron Matrix Composites

2012 ◽  
Vol 217-219 ◽  
pp. 71-74
Author(s):  
Jing Wang ◽  
Si Jing Fu ◽  
Shu Yong Jiang ◽  
Hong Cheng
Keyword(s):  
Electron Microscopy ◽  
In Situ Synthesis ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
Iron Matrix ◽  
X Ray ◽  
Matrix Microstructure ◽  
The Matrix ◽  
Scanning Electron

Iron matrix composite reinforced with VC reinforcements was produced by in situ synthesis technique. The microstructure of the composites was characterized by X-ray diffraction and scanning electron microscopy. The micrographs revealed the morphology and distribution of the reinforcements. The results show that the composite consists of VC carbide as the reinforcing phase and α-Fe as the matrix. The distribution of spherical VC particulates in iron matrix is uniform, and the matrix microstructure of Fe-VC composite is pearlite.

Effect of Nd Addition on Microstructure of Mg-Zn-Nd Master Alloys

2012 ◽  
Vol 500 ◽  
pp. 646-650 ◽  
Author(s):  
Zhen Wei Zhao ◽  
Xin Ying Teng ◽  
Guo Rong Zhou
Keyword(s):  
Electron Microscopy ◽  
Growth Process ◽  
Energy Dispersive Spectrometer ◽  
X Ray Diffraction ◽  
Growth Morphology ◽  
X Ray ◽  
Nd Addition ◽  
Master Alloys ◽  
The Matrix ◽  
Scanning Electron

Mg-Zn-Nd master alloys containing spherical quasicrystal phase were prepared under conventional casting conditions. The microstructures and phases of Mg-Zn-Nd ternary alloy have been investigated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The results show that the microstructure of Mg-Zn-Nd master alloys has been changed significantly with the addition of Nd. When adding 5wt% Nd, it is clear that a lot of spherical I-phase with high roundness and size below 10μm distributed evenly in the matrix. With the increase of Nd, the number of spherical I-phases is reduced and rod-like phases increased. The growth process and the final growth morphology of quasicrystal phase are restricted by the element Nd, thus the growth rates of all quasicrystal growth surfaces tend to be consistent, which contributes to the formation of spherical quasicrystal phase.

Sign in / Sign up

Export Citation Format

Share Document