Study of the Temperature Effect on the Structure and Thickness of Hot-Dip Zinc Coatings on Fixing Products

2014 ◽  
Vol 698 ◽  
pp. 355-359 ◽  
Author(s):  
Olga Bondareva
Keyword(s):  
Coating Thickness ◽  
Elevated Temperatures ◽  
Zinc Coating ◽  
High Strength ◽  
Bath Temperature ◽  
X Ray ◽  
Minimal Thickness ◽  
Galvanized Coating ◽  
Zinc Coatings ◽  
Scanning Electron

Hot-dip galvanizing of steels is usually performed by immersing the metal in a bath with molten zinc in the temperature range from 450 to 460 °C. In some cases it is necessary to obtain a minimal coating thickness. For example, high-strength bolts and other fixing products require a minimal thickness of the coating because a too thick zinc coating requires additional work on re-threading, which leads to spalling of coatings, a loss of corrosion resistance and, consequently, failure of the entire product. The main aim of this work was to study the influence of elevated temperatures of hot-dip galvanizing on the thickness and microstructure of zinc coatings on bolts and nut preform. The microstructure and elemental composition of the coating were studied by scanning electron microscopy and energy dispersion X-ray microanalysis. It was found that the coating thickness obtained in the range between 475 and 535°C decreases with temperature and reaches a minimum at 535°C. The structure of the coating after high-temperature hot-dip galvanizing was fundamentally different from the structure of the coating made at standard temperatures 450-460°C. This coating formed at 535°C was dense, homogeneous, non-porous and composed of a mixture of the δ and ζ-phases without distinct phase boundaries. That’s why it was recommended to maintain the bath temperature in the range between 533°C and 537°C. It allows us to obtain a hot-dip galvanized coating of a minimal thickness and a good quality on fixing products.

Study on Linear Segregation of ZL205A Alloy

2021 ◽  
Vol 1020 ◽  
pp. 8-12
Author(s):  
Wu Hu ◽  
Ke Zhu ◽  
Meng Wang ◽  
Wei Dong Huang ◽  
Jian Min Zeng
Keyword(s):  
Aluminum Alloy ◽  
Wall Thickness ◽  
Hot Spots ◽  
Energy Dispersive Spectrometer ◽  
High Strength ◽  
X Ray ◽  
Thermal Cracks ◽  
Zl205a Alloy ◽  
Solidification Speed ◽  
Scanning Electron

Linear segregation of high strength aluminum alloy ZL205A castings were studied by X-ray Nondestructive testing, scanning electron microscope and energy dispersive spectrometer. It is found that the linear segregation occurs at the large wall thickness of the casting and/or at the place where the wall thickness is in transition. Segregation element is mainly Cu, which exists as compound θ (Al2Cu) phase. The formation of linear segregation is related to the flow of Cu-rich melt in the late solidification period, while the occurrence of thermal cracks promotes the formation of linear segregation. The formation of linear segregation of the casting can be effectively prevented by eliminating hot spots of the casting, refining crystal grains and increasing solidification speed of the casting.

Effect of Bismuth on the Microstructure and Corrosion Resistance of Galvanized Coating

2011 ◽  
Vol 391-392 ◽  
pp. 1183-1188 ◽  
Author(s):  
Jian Hua Wang ◽  
Xing Ming Wang ◽  
Chun Mei Liu ◽  
Xu Ping Su ◽  
Chang Jun Wu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electrochemical Corrosion ◽  
Energy Dispersive ◽  
Phase Layer ◽  
Corrosion Tests ◽  
X Ray ◽  
Galvanized Coating ◽  
Scanning Electron

The microstructure of the galvanized coating was investigated using scanning electron microscope equipped with energy dispersive X-ray spectroscope. The immersing and electrochemical corrosion tests were carried out to study the corrosion resistance of the galvanized coating. The addition of Bi in Zn-bath affects remarkably the morphology of the galvanized coating. The thickness of δ + ζ phase layer in the coating reaches the maximum when the content of Bi in Zn-bath is 0.5 wt.%. The corrosion resistance of the galvanized coating declines with the increase of the content of Bi.

scholarly journals Application of Bonded Joints for Quantitative Analysis of Adhesion

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Jarmila Trpčevská ◽  
Mária Kollárová ◽  
Eva Zdravecká ◽  
Jana Tkáčová
Keyword(s):  
Steel Substrate ◽  
Zinc Coating ◽  
Experimental Tests ◽  
Coated Steel ◽  
Bonded Joints ◽  
Steel Sheets ◽  
Galvanized Coating ◽  
Zinc Coatings ◽  
Peel Tests

The performance of hot-dip coated steel sheets is associated with properties of the zinc coatings on steel substrate. For the characterization of the adhesion behaviour of zinc coating on steel various tests were employed. The study was focused on quantification assessment of galvanized coating adhesion to substrates. Methods for evaluation of the bonding strength of zinc coating by the shear strength and the T-peel tests applying four special types of adhesives were used. The experimental tests of bonded joints show that the adhesion of the zinc coating to the substrate was higher than that of the applied adhesive with the highest strength.

Influences of Fe2O3 Doping on the Crystallization of SiO2-Al2O3-MgO-K2O-ZrO2-F Glass-Ceramics

2009 ◽  
Vol 79-82 ◽  
pp. 1503-1506 ◽  
Author(s):  
Qing Bo Tian ◽  
Li Na Xu ◽  
Li Yang ◽  
Yan Sheng Yin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Elevated Temperatures ◽  
Glass Ceramics ◽  
X Ray Diffraction ◽  
Crystallization Peak ◽  
X Ray ◽  
Microstructural Morphology ◽  
Microscopy Techniques ◽  
Scanning Electron

The influences of Fe2O3 doping on crystallization characteristics and microstructural morphology in the SiO2-Al2O3-MgO-K2O-ZrO2-F glass were investigated by using differential scanning calorimeter, X-ray diffraction and scanning electron microscopy techniques. The results indicate that the addtions of Fe2O3 shift the crystallization peaks to higher temperatures and the crystallization peaks increases in magnitude and the gap values between two crystallization peak temperatures boarden with the increment of Fe2O3 contents.The star-shaped crystals of cordietite by dendritic-manner growths are homogeneously precipitated in the rusidual glass. The mica phases, which are precipitated at interdendritic cordietite phases and formed the plate shapes at the elevated temperatures. The mica crystals grow at the expense of cordietite phases and finally form the composites of mica/cordietite uniformly distributed.

Corrosion resistance of zinc electrodeposited from acidic and alkaline electrolytes using pulse current

2009 ◽  
Vol 63 (5) ◽  
Author(s):  
Matilda Zemanová
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Test ◽  
Pulse Current ◽  
Zinc Coating ◽  
Accelerated Corrosion ◽  
X Ray ◽  
Before And After ◽  
Alkaline Electrolytes ◽  
Zinc Coatings ◽  
Chrome Iii

AbstractCorrosion resistance of zinc coatings was investigated in an accelerated corrosion test in a condensation chamber. Zinc was electrodeposited from alkaline and acidic electrolytes using direct current (DC) or pulse current (PC). The zinc coating was subsequently protected against corrosion with a chrome (III) layer. Morphology and structure of the coatings was investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD) before and after the corrosion test. Corrosion resistance of alkaline zinc coatings electrodeposited with DC and PC under test conditions was found to be comparable. The corrosion resistance of zinc coatings deposited from acidic electrolytes by PC was lower in comparison with corrosion resistance of zinc coatings deposited using DC.

Experimental Research on High-Strength Super Sulphate Cement Paste Mixed with Superfine Mineral Admixtures

2014 ◽  
Vol 629-630 ◽  
pp. 150-155
Author(s):  
Jun Wang ◽  
Bao Ying Yu ◽  
Long Yang ◽  
Yu Xin Gao ◽  
Jia Yu Xiang
Keyword(s):  
Silica Fume ◽  
High Strength ◽  
Hydration Product ◽  
Mineral Admixtures ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Cement Ratio ◽  
X Ray ◽  
Early Strength ◽  
Scanning Electron

Aimed at the performance affect of high-strength super sulphate cement (SSC) paste mixed with superfine mineral admixtures, influence of microbead and silica fume replacing SSC quantity on high-strength SSC paste compression strength were studied under water-cement ratio 0.18; Hydration product morphology and phase were further compared by scanning electron microscopy and X-ray diffraction analyzer in this paper. Results show that, compared with sample HS-1, 3-day strength of HS-2 and HS-3 were increased by 5% and 10%, 28d strength basically unchanged; Furthermore, early strength of HS-7 sample slightly higher and late strength basically unchanged. SSC by adding 5% microbead and 3% silica fume (HS-11) has compressive strength 50.8MPa at 3 days and 86.1MPa at 28 days is significantly higher than other samples. Early strength of HS-11sample mainly depends on hydration reaction of SSC and particle filling effect of admixtures, later strength is due to accelerating consumption of gypsum and promoting formation of ettringite.

scholarly journals QUALITY REINFORCEMENT OF ELECTROPLATING ZINC COATINGSELECTRODEPOSITED FROM CYANIDE FREE ALKALINE SOLUTION BY POLYAMINE 70.000 AND POLYVINYL ALCOHOL 16.000

2018 ◽  
Vol 55 (5B) ◽  
pp. 18
Author(s):  
Truong Thi Nam
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Polyvinyl Alcohol ◽  
Zinc Coating ◽  
Alkaline Solutions ◽  
Zinc Ions ◽  
Sem Images ◽  
Zinc Coatings ◽  
Scanning Electron ◽  
Good Agreement

Zinc coatings have been deposited electrochemically from cyanine free alkaline solutions containing zinc ions with the presence of polyamine 70.000 and polyvinyl alcohol at different contents. The scanning electron microscope (SEM) images showed that the size of zinc grains decreased with the presence of polyamine 70.000 and polyvinyl alcohol with smoother surface of zinc coating. The polarization measurements also revealed that the coatings with the presence of polyamine or polyvinyl alcohol possessed higher value of polarity degree. This result is in good agreement with the result obtained from SEM images.

scholarly journals SEM and EDAX Evaluation of Al-Fe Alloy

2019 ◽  
Vol 9 (1) ◽  
pp. 2651-2654 ◽  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
Exothermic Reaction ◽  
Bath Temperature ◽  
Molten Bath ◽  
X Ray ◽  
Fe Alloys ◽  
Scanning Electron

The scanning electron microscopy (SEM) and energy dispersive X-Ray analysis of the Al-Fe alloy revealed the formation of varying ironaluminide intermetallic compounds. The Al-Fe alloys were produced by varying the composition of Fe. The pure ‘Al’ billets were heated up to 750о c and in the molten condition of aluminium ‘Fe’ powder was added resulting in an exothermic reaction. The exothermic reaction raised the molten bath temperature to ~ 1400о c which activated the formation of intermetallic compound.

Effect of Aluminum Insertion Material on the Properties of AAC

2016 ◽  
Vol 703 ◽  
pp. 406-410
Author(s):  
Yun Feng Pan ◽  
Wan Ming Huang ◽  
Ya Qing Jiang ◽  
Qiang Song
Keyword(s):  
Volume Ratio ◽  
High Strength ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Hydration Degree ◽  
Scanning Electron Microscope Analysis ◽  
X Ray ◽  
Electron Microscope Analysis ◽  
Aerated Concrete ◽  
Scanning Electron

Study on the compressive strength, shrinkage and effect of aluminum insertion materials on the hydration products of Autoclaved Aerated Concrete (AAC). The types and properties of hydration products are studied by X-Ray Diffraction Analysis (XRD), Differential Thermal Analysis (DTA), Scanning Electron Microscope analysis (SEM) and so on. The results showed that the strength and the shrinkage resistance capability of the product could be improved effectively. Al3+successfully doped into C-S-H gel and tobermorite crystals, then replaced si4+of tobermorite and formed the system of C-A-S-H. Tobermorite in aluminum insertion aerated concrete is smaller and more compact. All hydration products interlace to form a whole, then the structure turns denser. Low porosity, high crystal gel volume ratio and high hydration degree are the key of the high strength aluminum insertion aerated concrete. Aluminum insertion materials improve the performance of the products.

Microstructural Characterization of Sm-Co Magnets

2014 ◽  
Author(s):  
Patricia Iglesias Victoria ◽  
Weimin Yin ◽  
Surendra K. Gupta ◽  
Steve Constantinides
Keyword(s):  
Magnetic Properties ◽  
Permanent Magnets ◽  
Elevated Temperatures ◽  
Microstructural Characterization ◽  
Particle Accelerators ◽  
X Ray ◽  
Aerospace Applications ◽  
Electron Microscopes ◽  
Demagnetizing Fields ◽  
Scanning Electron

Samarium cobalt permanent magnets have been widely used for their excellent intrinsic magnetic properties such as very high Curie temperature, high anisotropy fields and most importantly excellent temperature coefficients of induction and coercivity. These materials have continuing industrial interest especially for applications operating at elevated temperatures and in the presence of high demagnetizing fields, such as particle accelerators, high frequency traveling wave tubes (TWTs), servo-motors and automotive and aerospace applications. An area of opportunity for improving performance of SmCo magnets is increasing magnet toughness — resistance to fracture. Like all other sintered rare earth magnetic materials, SmCo magnets are based on intermetallic compounds which are intrinsically brittle and can crack in the course of fabrication, machine work, and installation in the application. Increased toughness would also reduce handling sensitivity of magnetized magnets. For many years, studies on SmCo magnets have been focused on their magnetic properties, but the mechanical characteristics, strengthening and toughening mechanisms have been rarely reported. Understanding the phase and structural transformations induced in the SmCo magnets during the manufacturing process offers insight into potential modifications — chemical or processing-related. In this study, microstructural characterizations of 1:5 and 2:17 Sm-Co magnets were carried out using optical and scanning electron microscopes. In scanning electron microscopy (SEM), backscattered electron imaging and energy dispersive X-ray (EDX) microanalysis were used to investigate different phases and oxides. Finally, crystal structure of the magnets was studied using an X-ray diffractometer (XRD). The study correlates the microstructure characterization with the thermal processing history of different grades of SmCo magnets.

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