Influence of Powder Structure on Decarburization and Microstructure of HVOF Sprayed WC-12wt.%Co Coatings

2013 ◽  
Vol 834-836 ◽  
pp. 609-612 ◽  
Author(s):  
Ning Ma ◽  
Zhen Xiong Cheng ◽  
Huan Tao Wu ◽  
Fu Xing Ye
Keyword(s):  
Particle Size ◽  
Tungsten Carbide ◽  
Carbide Particle ◽  
Volume Fraction ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Spray System ◽  
Hvof Spray ◽  
Steel Substrates ◽  
Sprayed Coatings

In order to examine the influences of tungsten carbide particle size on decarburization behavior and microstructure of HVOF sprayed WC-Co coating, four kinds of agglomerated WC-12wt.%Co powders were deposited on mild steel substrates by using a high velocity oxy-fuel (HVOF) spray system. The phase compositions and microstructure of the feedstock powders and sprayed coatings were investigated by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM), respectively. The results showed that the decarburization became more serious with the decreasing of tungsten carbide particle size in the starting powder. W phase was detected in the as-sprayed nanocomposite WC-12wt.%Co coating. All the coatings showed very compact microstructure with the hard phases embedded in Co matrix. The microstructure of HVOF sprayed WC-12wt.%Co coatings depended on the feedstock powder structure. The shape of tungsten carbide particles was rounder and the volume fraction of carbide phase decreased in coatings as the tungsten carbide particle size decreased.

Direct Write Assembly of 3-Dimensional Structures with Aqueous-Based Piezoelectric Inks

2012 ◽  
Vol 512-515 ◽  
pp. 390-394 ◽  
Author(s):  
Ya Yun Li ◽  
Bo Li ◽  
Jing Bo Sun ◽  
Kun Peng Cai ◽  
Ji Zhou ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Xrd Analysis ◽  
Direct Write ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
3 Dimensional ◽  
Direct Ink Writing ◽  
Shaping Process ◽  
Piezoelectric Devices ◽  
Sintering Condition

A kind of aqueous based suspensions of lead lanthanum zirconnate titanate (PLZT) was developed for direct ink writing (DIW) assembly. Piezoelectric ceramic woodpile structures with diameter of 315-470μm were fabricated from these inks by using DIW. The preparation of aqueous based piezoelectric inks, the principle of DIW and the sintering process were systematically discussed. The ink with solids volume fraction over 70% by 1 day aging reveals shear-thinning behavior and proper viscoelastic properties, which ensures a feasible extrusion in the whole shaping process. The PLZT samples sintered at varying temperatures between 1150 oC and 1250 oC for 2h or 4 h in either air or a lead-rich atmosphere yielded various microstructures observed by scanning electron microscopy (SEM). Choosing the optimum sintering condition, the sintered products were densified with relative density exceed 98%. The test of X-ray diffraction (XRD) analysis reveals that the main phase of sintered samples is rhombohedral Pb0.93La0.07(Zr0.65Ti0.35)0.9825O3. The direct ink writing technique has advantages of good design ability and rapid forming capability, which opens up a potential route for the design and fabrication of piezoelectric devices.

Semiquantitative Analysis by X-Ray Powder Diffraction (SQXRD) of the < 2 mm to 0.002 mm and < 0.002 mm Fractions of Soil

1988 ◽  
Vol 3 (3) ◽  
pp. 144-152 ◽  
Author(s):  
G. A. Raab
Keyword(s):  
Particle Size ◽  
Clay Fraction ◽  
Internal Standard ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Freeze Dried ◽  
Strict Protocol ◽  
Attention To Detail

AbstractThe method described in this paper is a strict protocol for X-ray diffraction (XRD) analysis of mineral phases found in soils. Its application is not restricted to soils and is an attempt to standardize XRD sample preparation and analysis. The protocol requires the particle size of the < 2 mm - 0.002 mm fraction be reduced to 0.002 mm before analysis. In die qualitative section, the clay fraction ( < 0.002 mm particle size) is prepared as oriented slides. The suspended clay fraction is saturated with ethylene glycol, K +, and Mg+2; pipeted; air-dried; heat-treated at 110°C, 350°C, and 550°C; and X-rayed at each step in order to properly identify the clay minerals. In the quantitative section, the method employs a matrix-flushing agent, corundum (Al2O3). The corundum acts also as an internal standard, a calibration standard, and a reference standard. The suspended clay fraction is freeze-dried and corundum is added to each sample. Randomly oriented powder mounts are prepared from the < 2 mm - 0.002 mm fraction, and the < 0.002 mm fraction, and X-rayed. A series of reference standards are prepared based on the existing mineralogy, corundum is added, and each mixture is X-rayed. The software integrates the area under specific peaks (chosen for intensity and no overlap) in each sample, calculates the reference intensity ratios (RIRs) and calculates the percentage of each mineral based on the equation of Chung (1974). The attention to detail allows documentation and verification of the results yielding data of known quality.

Study of Corrosion Behavior of Conventional and Nanostructured WC-Ni High Velocity Oxy Fuel (HVOF) Sprayed Coatings

2011 ◽  
Vol 673 ◽  
pp. 167-172 ◽  
Author(s):  
Shahin Khameneh Asl ◽  
Mohammad Reza Saghi Beyragh ◽  
Neda Faale Noori
Keyword(s):  
Heat Treatment ◽  
High Velocity ◽  
Electrochemical Impedance ◽  
Heat Treating ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
Chemical Test ◽  
Hvof Spray ◽  
Ni Powder ◽  
Sprayed Coatings

The current study is focused on WC-Ni cermet coatings, materials that are extensively used in applications requiring wear resistance. In this work, WC-10%Ni powder was thermally sprayed onto mild steel using High Velocity Oxy Fuel (HVOF) spray technique. The nanostructured specimen was produced from sprayed samples by heat-treating at 1100°C in a vacuum chamber. Their structures were studied by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Polarization and electrochemical impedance spectroscopy (EIS) tests were performed on both types of coated samples in 3.5% NaCl solution. The amorphous phase in WC-10%Ni coating was transformed to crystalline phases by heat treatment at high temperatures. Heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. Generation of these phases produced the nanostructured coating with better mechanical properties. Comparative electro chemical test results showed that, the heat treatment could improve corrosion resistance of the nanostructured WC-10%Ni coating than the as sprayed coatings.

Effect of energy, temperature, and Cu-doped coatings on crystallinity of Hydroxyapatite thin films obtained by pulsed laser deposition

2021 ◽  
Author(s):  
Nooshin Kashi ◽  
Mahdi Momeni ◽  
Habib Hamidinezhad
Keyword(s):  
Pulsed Laser Deposition ◽  
Laser Energy ◽  
High Surface ◽  
Pulsed Laser ◽  
Xrd Analysis ◽  
Laser Deposition ◽  
Laser Source ◽  
X Ray Diffraction ◽  
Crystalline Films ◽  
Steel Substrates

In this work, a pulsed laser deposition (PLD) technique with an Nd:YAG laser source was used to produce pure Hydroxyapatite (HA) and Cu-substituted HA (Cu-HA) coatings on stainless steel substrates in vacuum at room temperature. It is observed that the combined effects of percentages of Cu dopants and laser energy as well as annealing temperature significantly modify the crystallinity of the films. The morphology and structural properties of the deposited HA films were analyzed by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Raman spectroscopy. FESEM images displayed various shapes of nanoparticles with high-surface density throughout the area of the substrate and with typical sizes around 26–208 nm. XRD analysis confirmed that post-deposition annealing is essential to achieve the desired crystallinity and uniformity of coatings. The Raman spectrum of HA has peaks at 958.22, 437.48, and 587.05 cm[Formula: see text] attributed to the [Formula: see text] PO[Formula: see text], [Formula: see text] PO[Formula: see text], and [Formula: see text] PO[Formula: see text], respectively. The synthesized HA and Cu-HA crystalline films are nanostructures with dense and compact microstructures. Finally, irregular surface and crystalline structure of fabricated films lead to the extension of the surface and enhance the cell’s proliferation in medical uses and biomedical applications.

Effect of HVOF Gas Velocity and Fuel to Oxygen Ratio on the Wear Properties of Tungsten Carbide Coating

1996 ◽  
Author(s):  
K. Korpiola ◽  
P. Vuoristo
Keyword(s):  
Wear Rate ◽  
Tungsten Carbide ◽  
Particle Temperature ◽  
Gas Velocity ◽  
Spray Process ◽  
High Particle ◽  
Carbide Coatings ◽  
Hvof Spray ◽  
Thermally Sprayed ◽  
Sprayed Coatings

Abstract The high quality of the thermally sprayed tungsten carbide coatings has been attributed to high particle velocity and relatively low particle temperature. Such thermal spray conditions can be obtained with the HVOF spray process. In comparison to the plasma spray process, in the HVOF spray process the high particle velocity and optimum particle temperature have been associated with very high gas velocity (&gt;1000 m/s) and a relatively low gas temperature (&lt; 2700 °C). In this work tungsten carbide coatings (WC-17Co) were sprayed by the HVOF process with a low and a high gas velocity of 1050 and 1560 m/s, respectively. The spray tests were carried out also with different hydrogen/oxygen ratios. The coatings were abrasion tested in order to find out how gas velocity and the fuel/oxygen ratio affect the coating quality and wear rate. Wear rates of the HVOF sprayed coatings were found to decrease with the higher combustion gas velocity. The coating quality and wear rate became also less sensitive to gas parameters with the increasing gas velocity. The coating microhardness and wear rate were also compared to hot isostatic pressed (HIP) reference material from the same spray powder lot. The HIP sintered test piece was found to be less wear resistant than the corresponding thermally sprayed coatings.

Effect of Dispersants on Microstructures of Nano Alpha Alumina Developed from Aluminium Dross Waste

2015 ◽  
Vol 1115 ◽  
pp. 378-381 ◽  
Author(s):  
S. Anis Sofia ◽  
Noorasikin Samat ◽  
Meor Yusoff Meor Sulaiman
Keyword(s):  
Particle Size ◽  
Xrd Analysis ◽  
Planetary Mill ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Particle Size Analyzer ◽  
Milling Method ◽  
Aluminium Dross ◽  
Alpha Alumina

This paper compares the effect of dispersants which are Sodium Laureth Sulfate (SLS) and distilled water (DW) on the crystallization, particle size distribution and morphological behavior of nanoalpha Alumina (α-Al2O3) synthesized from Aluminium (Al) dross waste. The synthesizing of nanoα-Al2O3 via wet milling method was performed using a planetary mill for 4 hours at a speed of 550 rpm. The nanoα-Al2O3 powders with dispersants were characterized with x-ray diffraction (XRD), particle size analyzer (PSA) and transmission electron microscopy (TEM). XRD analysis shows the broadening and shifting of peaks after the sample was calcined at 1300 °C, indicating high crystallinity. The crystallite size of α-Al2O3 milled with SLS is also smaller than the α-Al2O3 milled with DW. These results are consistent with the PSA analysis in which the graphs displayed a symmetrical trend. Then, the PSA analysis is validated with TEM observation up to 100000x magnification, particularly for α-Al2O3 milled with SLS.

X-Ray Diffraction Study of Cold Sprayed Ni-20Cr and Ni-50Cr Coatings on Boiler

2012 ◽  
Vol 620 ◽  
pp. 257-262 ◽  
Author(s):  
Niraj Bala ◽  
Harpreet Singh ◽  
Satya Prakash
Keyword(s):  
Chemical Composition ◽  
Xrd Analysis ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Xrd Study ◽  
Non Destructive ◽  
Sprayed Coatings ◽  
Boiler Steels ◽  
Better Than

X-ray diffraction (XRD) is a versatile, non-destructive technique that reveals detailed information about the chemical composition and crystallographic structure of materials. In this work Ni-20Cr and Ni-50Cr coatings were deposited on two boiler steels namely T22 and SA 516 steel. The measurement of residual stresses of these cold sprayed coatings was done with the help of X-ray diffraction technique. This paper discussed the XRD study of the as-sprayed coatings. Further the XRD technique was used to study the uncoated and coated steels after cyclic exposure to air, molten salt [Na2SO4-60%V2O5], and actual boiler environments. The results obtained from the XRD analysis have been shown. The weight change results showed that the coated steels performed better than their uncoated counterparts which might be attributed to the formation of protective phases.

Influence of Citric Acid on the Formation of Hydroxyapatite Powders by Using Ca(NO3)2-P2O5 Ethanol Solution System

2010 ◽  
Vol 152-153 ◽  
pp. 1248-1252
Author(s):  
Qing Chang ◽  
Hong Qiang Ru ◽  
Liang Yu ◽  
Ji Guang Li
Keyword(s):  
Particle Size ◽  
Citric Acid ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Transformation Process ◽  
Ethanol Solution ◽  
X Ray Diffraction ◽  
Solution System ◽  
Ca Addition ◽  
Xrd Patterns

In this study, nano-hydroxyapatite (HA) powders were synthesized via a simple sol-gel method using Ca(NO3)2•4H2O and P2O5 as starting materials. Two different precursors, with and without citric acid (CA), were prepared. The transformation process of HA from precursors, purity and particle size of the obtained HA powders were evaluated. HA derived from the precursor with CA showed a different transformation process from that without CA. It was observed that the content of CaO as an unavoidable major impurity was reduced due to the addition of CA. In the calcined powders from the CA-free precursor, X-ray diffraction (XRD) patterns revealed an intense CaO peak. For the calcined powders from the CA-addition precursor, XRD analysis showed a very weak CaO peak. It was also found that the synthesized HA powders from precursor with CA were finer than those without CA. The mechanism of the influence of CA on the formation, purity and particle size distribution of HA powders was discussed.

X-Ray Diffraction Study of High Velocity Oxy-Fuel (HVOF) Sprayed Cr3C2-NiCr Coating

2012 ◽  
Vol 620 ◽  
pp. 186-192
Author(s):  
Manpreet Kaur ◽  
Harpreet Singh ◽  
Satya Prakash
Keyword(s):  
Molten Salt ◽  
Diffraction Study ◽  
High Velocity ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Characterization Techniques ◽  
Xrd Study ◽  
Hvof Spray ◽  
Boiler Steels

Among the various characterization techniques, X-ray diffraction (XRD) analysis is a key method which reveals various phases and protective oxides formed on the surfaces of exposed specimens. This paper discusses the XRD study of two boiler steels, namely ASTMSAE213-T22 and SAE-347H with and without High Velocity Oxy-fuel (HVOF) spray Cr3C2-NiCr coating, which were exposed to air, molten salt [Na2SO4-82%Fe2(SO4)3], and actual boiler environments. XRD analysis has been discussed and the results obtained from the analysis are shown. The performance of the steels was found to improve after the deposition of the coating, which may be attributed to the formation of protective phases.

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