scholarly journals Characterization of Cobalt-Based Stellite 6 Alloy Coating Fabricated by Laser-Engineered Net Shaping (LENS)

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7442
Author(s):  
Tomasz Durejko ◽  
Magdalena Łazińska
Keyword(s):  
Elevated Temperatures ◽  
Protective Coatings ◽  
Alloy Coating ◽  
Chemical Homogeneity ◽  
X Ray ◽  
Laser Engineered Net Shaping ◽  
Stellite 6 ◽  
Manufacturing Techniques ◽  
Net Shaping ◽  
Corrosive Environments

The results of microstructure and mechanical properties evaluation of a Stellite 6 (Co-6) alloy deposited on X22CrMoV12-1 substrate by the laser-engineered net shaping (LENSTM) technology are presented in this paper. The Stellite 6 alloy is widely used in industry due to its excellent wear resistance at elevated temperatures and corrosive environments. Specific properties of this alloy are useful in many applications, e.g., as protective coatings in steam turbine components. In this area, the main problems are related to the fabrication of coatings on complex-shaped parts, the low metallurgical quality of obtained coatings, and its insufficient adhesion to a substrate. The results of recently performed investigations proved that the LENS technology is one of the most effective manufacturing techniques of the Co-6 alloy coatings (especially deposited on complex-shaped turbine parts). The microstructural and phase analyses of obtained Stellite 6 coatings were carried out by light microscopy techniques and X-ray diffraction analysis. A chemical homogeneity of Co-6 based layers and a fluctuation of chemical composition in coating–substrate zone after the laser deposition were analyzed using an energy dispersive X-ray spectrometer coupled with scanning electron microscopy. The room temperature strength and ductility of the LENS processed layers were determined in static bending tests.

Comparison of Corrosion Performance of Zn and Zn/Al 85/15 Coatings Produced by TWEA

2011 ◽  
Vol 312-315 ◽  
pp. 325-330
Author(s):  
Ahmet Güleç ◽  
Fevzi Yilmaz ◽  
Ahmet Türk ◽  
Fatih Üstel
Keyword(s):  
Ductile Iron ◽  
Protective Coatings ◽  
Weight Ratio ◽  
Industrial Applications ◽  
Optimum Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anticorrosion Protection ◽  
Different Diameters ◽  
Corrosive Environments

Zn and Zn/Al 85/15 coatings are produced at optimum conditions by twin wire electric arc (TWEA) spraying technique and are used in various industrial applications to improve corrosion protection. As an alternative for Zn coating, Zn/Al 85/15 alloys coating show very good corrosion resistances and can protect substrate materials against harsh corrosive environments. The weight ratio of 85 Zn and 15 Al is regarded as optimum value. The forms of coating material are wires with different diameters. The aim of this study is comparison of anticorrosion performance of Zn and Zn/Al 85/15 coatings on ductile iron pipe surfaces as protective coatings against corrosion. Test samples were prepared from Zn and Zn/Al 85/15 coated ductile iron pipes. Coatings were investigated by optical microscopy, scanning electron microscopy (SEM) and have been analyzed by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). They were compared according to protection performance against corrosion in salt spraying test according to ASTM B117. As a result of this study, Zn/Al 85/15 coating showed clear anticorrosion protection capacity against Zn coatings.

scholarly journals Hot Corrosion Behaviour of Detonation Gun Sprayed Stellite-6 and Stellite-21 Coating on Boiler Steel SAE 431 at 900°C

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
N. K. Mishra ◽  
A. K. Rai ◽  
S. B. Mishra ◽  
R. Kumar
Keyword(s):  
Hot Corrosion ◽  
Gas Turbines ◽  
Elevated Temperatures ◽  
Protective Coatings ◽  
Total Duration ◽  
Boiler Steel ◽  
Stellite 6 ◽  
Stellite 21 ◽  
Wide Range ◽  
Detonation Gun

Hot corrosion is the serious problem in gas turbines, superheaters, and economizers of coal-fired boilers. It occurs due to the usage of wide range of fuels such as coal, oil, and so on at the elevated temperatures. Protective coatings on boiler steels are used under such environments. In the present investigation, Stellite-6 and Stellite-21 coatings have been deposited on boiler steel SAE 431 by detonation gun method. The hot corrosion performance of Stellite-6 and Stellite-21 coated as well as uncoated SAE 431 steel has been evaluated in aggressive environment of Na2SO4-82%Fe2(SO4)3under cyclic conditions at an elevated temperature of 900°C for total duration of 50 cycles. Thermogravimetric technique was used to approximate the kinetics of hot corrosion. Stellite-6 coating imparted better hot corrosion resistance than Stellite-21 coating in the given environment. Scanning electron microscopy was used to characterize the surface of hot corrosion products.

Electron microscopy of crystalline structure in thermotropic random copolymers

1991 ◽  
Vol 49 ◽  
pp. 1054-1055
Author(s):  
Afzana Anwer ◽  
S. Eilidh Bedford ◽  
Richard J. Spontak ◽  
Alan H. Windle
Keyword(s):  
Electron Microscopy ◽  
Crystalline Structure ◽  
Liquid Crystalline ◽  
Elevated Temperatures ◽  
Random Copolymers ◽  
Molecular Characteristics ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Identical Monomer ◽  
Periodic Layer

Random copolyesters composed of wholly aromatic monomers such as p-oxybenzoate (B) and 2,6-oxynaphthoate (N) are known to exhibit liquid crystalline characteristics at elevated temperatures and over a broad composition range. Previous studies employing techniques such as X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) have conclusively proven that these thermotropic copolymers can possess a significant crystalline fraction, depending on molecular characteristics and processing history, despite the fact that the copolymer chains possess random intramolecular sequencing. Consequently, the nature of the crystalline structure that develops when these materials are processed in their mesophases and subsequently annealed has recently received considerable attention. A model that has been consistent with all experimental observations involves the Non-Periodic Layer (NPL) crystallite, which occurs when identical monomer sequences enter into register between adjacent chains. The objective of this work is to employ electron microscopy to identify and characterize these crystallites.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals Protection of Stone Monuments Using a Brushing Treatment with Ammonium Oxalate

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 379
Author(s):  
Domagoj Mudronja ◽  
Frederik Vanmeert ◽  
Stjepko Fazinic ◽  
Koen Janssens ◽  
Darko Tibljas ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Treatment Time ◽  
Protective Coatings ◽  
Ammonium Oxalate ◽  
Protective Layer ◽  
Thick Layer ◽  
Calcite Dissolution ◽  
X Ray ◽  
Stone Monuments ◽  
Surface Corrosion

Stone monuments and buildings are susceptible to weathering. Carbonate-based stones are especially vulnerable in acidic environments, whereas magmatic acidic stones are more susceptible to chemical weathering in basic environments. To slow down surface corrosion of limestone and marble artworks/buildings, protective coatings which inhibit calcite dissolution have been proposed. In this work, samples from two stone types with different porosity were treated with ammonium oxalate (AmOx) to create a protective layer of calcium oxalate (CaOx) using the previously developed brushing method. Two different synchrotron microscopy experiments were performed to determine its protective capability. X-ray powder diffraction (SR-μ-XRPD) in transmission geometry allowed visualization of the distributions of calcium carbonate and oxalates along the sample depths. In a second step, X-ray fluorescence (SR-μ-XRF) was used to check the efficiency/integrity of the protective surface coating layer. This was done by measuring the sulfur distribution on the stone surface after exposing the protected stones to sulfuric acid. XRPD showed the formation of a protective oxalate layer with a thickness of 5–15 µm on the less porous stone, while a 20–30 µm thick layer formed on the more porous stone. The XRF study showed that the optimal treatment time depends on the stone porosity. Increasing the treatment time from 1 to 3 h resulted in a decreased efficiency of the protective layer for the low porosity stone. We assume that this is due to the formation of vertical channels (cracks) in the protective layer.

An in situ microtomography apparatus with a laboratory x-ray source for elevated temperatures of up to 1000 °C

2021 ◽  
Vol 92 (3) ◽  
pp. 033704
Author(s):  
Rongqi Zhu ◽  
Zhaoliang Qu ◽  
Shuo Yang ◽  
Daining Fang
Keyword(s):  
Elevated Temperatures ◽  
X Ray

Oxidation of Alloy-X in Subcritical, Transition, and Supercritical Water

CORROSION ◽  
10.5006/3881 ◽  
2021 ◽  
Author(s):  
Zachary Karmiol ◽  
Dev Chidambaram
Keyword(s):  
Supercritical Water ◽  
Photoelectron Spectroscopy ◽  
Focused Ion Beam ◽  
Elevated Temperatures ◽  
Subcritical Water ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Based Superalloy ◽  
Before And After

This work investigates the oxidation of a nickel based superalloy, namely Alloy X, in water at elevated temperatures: subcritical water at 261°C and 27 MPa, the transition between subcritical and supercritical water at 374°C and 27 MPa, and supercritical water at 380°C and 27 MPa for 100 hours. The morphology of the sample surfaces were studied using scanning electron microscopy coupled with focused ion beam milling, and the surface chemistry was investigated using X-ray diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy before and after exposure studies. Surfaces of all samples were identified to comprise of a ferrite spinel containing aluminum.

Sign in / Sign up

Export Citation Format

Share Document