scholarly journals Structure Formation of Polycarbide-Based TiC-VC(NbC)-WC/nano WC Hard Alloys

2019 ◽  
Vol 57 ◽  
pp. 35-40 ◽  
Author(s):  
Liudmyla Bodrova ◽  
Halyna Kramar ◽  
Yaroslav Kovalchuk ◽  
Sergiy Marynenko ◽  
Ihor Koval
Keyword(s):  
Chemical Composition ◽  
Tungsten Carbide ◽  
Optical Microscopy ◽  
Structure Formation ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Hard Alloys ◽  
Alloying Additions ◽  
The Core

The process of structure formation in the alloys of the system TiC-VC(NbC)-NiCr with the alloying additions of the fine or nano WC, depending on the chemical composition and sintering temperature using the optical microscopy, SEM and XRD analysis, is investigated in this paper. The core/rim structure alloys were found irrespective of the amount of tungsten carbide additions. The research suggests that the adding of nano WC causes decrease in carbide grains, redistribution of the elements in the core and rim, and decrease in sintering temperature by 50–100 °С. Tika pētīts struktūru veidošanas process sakausējumos TiC-VC(NbC)-NiCr ar smalku vai nano WC sakausējuma papildinājumiem atkarībā no ķīmiskā sastāva un saķepināšanas temperatūras, izmantojot optisko mikroskopiju, SEM un XRD analīzi. Centru/aptvērumu struktūras sakausējumi tika konstatēti neatkarīgi no volframa karbīda piedevu daudzuma. Pētījums liecina, ka nano WC pievienošana samazina karbīda graudus, elementu pārdali centros un aptvērumos, kā arī notiek saķepināšanās temperatūras samazināšanās par 50–100° С.

The character of the structure formation of model alloys of the Fe-Cr-(Zr, Zr-B) system synthesized by powder metallurgy

2020 ◽  
Vol 2 (100) ◽  
pp. 49-57
Author(s):  
Z.A. Duriagina ◽  
M.R. Romanyshyn ◽  
V.V. Kulyk ◽  
T.M. Kovbasiuk ◽  
A.M. Trostianchyn ◽  
...  
Keyword(s):  
Phase Composition ◽  
Powder Metallurgy ◽  
Chemical Composition ◽  
Structure Formation ◽  
Xrd Analysis ◽  
Model Alloy ◽  
Phase Identification ◽  
Laves Phases ◽  
Cr System ◽  
Sintered Alloys

Purpose: The purpose of the work is to synthesize and investigate the character of structure formation, phase composition and properties of model alloys Fe75Cr25, Fe70Cr25Zr5, and Fe69Cr25Zr5B1. Design/methodology/approach: Model alloys are created using traditional powder metallurgy approaches. The sintering process was carried out in an electric arc furnace with a tungsten cathode in a purified argon atmosphere under a pressure of 6·104 Pa on a water cooled copper anode. Annealing of sintered alloys was carried out at a temperature of 800°C for 3 h in an electrocorundum tube. The XRD analysis was performed on diffractometers DRON-3.0M and DRON-4.0M. Microstructure study and phase identification were performed on a REMMA-102-02 scanning electron microscope. The microhardness was measured on a PMT-3M microhardness meter. Findings: When alloying a model alloy of the Fe-Cr system with zirconium in an amount of up to 5%, it is possible to obtain a microstructure of a composite type consisting of a mechanical mixture of a basic Fe2(Cr) solid solution, solid solutions based on Laves phases and dispersive precipitates of these phases of Fe2Zr and FeCrZr compositions. In alloys of such systems or in coatings formed based on such systems, an increase in hardness and wear resistance and creep resistance at a temperature about 800°C will be reached. Research limitations/implications: The obtained results were verified during laser doping with powder mixtures of appropriate composition on stainless steels of ferrite and ferrite-martensitic classes. Practical implications: The character of the structure formation of model alloys and the determined phase transformations in the Fe-Cr, Fe-Cr-Zr, and Fe-Cr-B-Zr systems can be used to improve the chemical composition of alloying plasters during the formation of ferrite and ferrite-martensitic stainless steel coatings. Originality/value: The model alloys were synthesized and their phase composition and microstructure were studied; also, their microhardness was measured. The influence of the chemical composition of the studied materials on the character of structure formation and their properties was analysed.

Nanoprobe analysis of core–rim structure of carbides in TiC–20 wt% Mo2C–20 wt% Ni cermet

1999 ◽  
Vol 14 (11) ◽  
pp. 4129-4131 ◽  
Author(s):  
T. Yamamoto ◽  
A. Jaroenworaluck ◽  
Y. Ikuhara ◽  
T. Sakuma
Keyword(s):  
Electron Microscope ◽  
Chemical Composition ◽  
Sintering Temperature ◽  
Miscibility Gap ◽  
X Ray ◽  
The Core ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Discrete Change ◽  
Nanoscale Level

In order to get detailed information of the core–rim interface of carbides in TiC–20 wt% Mo2C–20 wt% cermet, chemical analysis in the vicinity of the interface was carried out by energy dispersive x-ray spectroscopy equipped with a high-resolution transmission electron microscope (HRTEM) with a field-emission-type gun. It was found that the chemical composition discretely changed across the core–rim interface at a nanoscale level, whereas HRTEM observation revealed that the interface is highly coherent. The discrete change in molybdenum content at the interface may suggest the existence of a miscibility gap between TiC and MoC systems at the sintering temperature.

Rapidly Solidified Melt-spun Bi-Sn Ribbons: Surface Composition Issues

2016 ◽  
pp. 3287-3297
Author(s):  
Tarek El Ashram ◽  
Ana P. Carapeto ◽  
Ana M. Botelho do Rego
Keyword(s):  
Chemical Composition ◽  
Optical Microscopy ◽  
Melt Spinning ◽  
Surface Composition ◽  
Electrochemical Process ◽  
Melt Spun ◽  
Bismuth Alloy ◽  
The One ◽  
Rapidly Solidified ◽  
Melt Spinning Technique

Tin-bismuth alloy ribbons were produced using melt-spinning technique. The two main surfaces (in contact with the rotating wheel and exposed to the air) were characterized with Optical Microscopy and AFM, revealing that the surface exposed to the air is duller (due to a long-range heterogeneity) than the opposite surface. Also the XPS chemical composition revealed many differences between them both on the corrosion extension and on the total relative amounts of tin and bismuth. For instance, for the specific case of an alloy with a composition Bi-4 wt % Sn, the XPS atomic ratios Sn/Bi are 1.1 and 3.7 for the surface in contact with the rotating wheel and for the one exposed to air, respectively, showing, additionally, that a large segregation of tin at the surface exists (nominal ratio should be 0.073). This segregation was interpreted as the result of the electrochemical process yielding the corrosion products.

CHARACTERIZATION OF HYDROXYAPATITE/TI6AL4V COMPOSITE POWDER UNDER VARIOUS SINTERING TEMPERATURE

2015 ◽  
Vol 75 (7) ◽  
Author(s):  
Amir Arifin ◽  
Abu Bakar Sulong ◽  
Norhamidi Muhamad ◽  
Junaidi Syarif
Keyword(s):  
Mechanical Properties ◽  
Composite Powder ◽  
Sintering Temperature ◽  
Physical And Mechanical Properties ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Different Temperatures ◽  
Two Phases ◽  
Work Interaction

Hydroxyapatite (HA) has been widely used in biomedical applications due to its excellent biocompatibility. However, Hydroxyapatite possesses poor mechanical properties and only tolerate limited loads for implants. Titanium is well-known materials applied in implant that has advantage in mechanical properties but poor in biocompatibility. The combination of the Titanium alloy and HA is expected to produce bio-implants with good in term of mechanical properties and biocompatabilty. In this work, interaction and mechanical properties of HA/Ti6Al4V was analyzed. The physical and mechanical properties of HA/Ti6Al4V composite powder obtained from compaction (powder metallurgy) of 60 wt.% Ti6Al4V and 40 wt.% HA and sintering at different temperatures in air were investigated in this study. Interactions of the mixed powders were investigated using X-ray diffraction. The hardness and density of the HA/Ti6Al4V composites were also measured. Based on the results of XRD analysis, the oxidation of Ti began at 700 °C. At 1000 °C, two phases were formed (i.e., TiO2 and CaTiO3). The results showed that the hardness HA/Ti6Al4V composites increased by 221.6% with increasing sintering temperature from 700oC to 1000oC. In contrast, the density of the composites decreased by 1.9% with increasing sintering temperature. 

Examination of Dust in AVR Pipe Components

2008 ◽  
Author(s):  
Johannes Fachinger ◽  
Heiko Barnert ◽  
Alexander P. Kummer ◽  
Guido Caspary ◽  
Manuel Seubert ◽  
...  
Keyword(s):  
Particle Size ◽  
Optical Microscopy ◽  
Phase 1 ◽  
Median Number ◽  
Primary Circuit ◽  
Pipe Surface ◽  
Dose Rates ◽  
The Core ◽  
Chemical Decontamination ◽  
Dust Surface

Pebble Bed HTGR’s like the AVR in Ju¨lich have the advantage of continuous fuelling. However the multiple passes of the fuel pebbles through the core have the disadvantage that the pebble’s movement through the fuelling system and the core produces graphite dust. This dust is transported from the core to other parts of the primary circuit and deposits on components. Although previous experiments performed during AVR operation have given some insight into the dust particle size and activity, there is little information on the behaviour of the dust that was deposited in the system. The decommissioning of the AVR has provided the opportunity to sample and characterise such dust from a number of components and gauge the adhesion strength. From the side of PBMR Pty Ltd this opportunity is considered important to enhance the knowledge about dust characteristics before the PBMR Demonstration Power Plant (DPP) is operational and able to produce specific plant information through sampling and analysis. AVR GmbH has provided a number of pipes and joints for investigation of loose and bound dust. Phase 1 of the analysis was used to determine the best techniques to be used on larger items. No measurable loose dust could be collected. Thereupon rings were cut from a T-section and subdivided into eight segments. The surface of the untreated segments were photographed and documented by optical microscopy, the dose rates were measured and gamma-spectrometry performed. Following this a mechanical or chemical decontamination was carried out to remove and isolate the bound dust. The average isolated dust amount was about 2 mg/cm2. Both decontamination processes indicates a strong bonding of the dust surface layer. In the case of mechanical decontamination about 60% and by chemical decontamination about 95% of the radionuclide inventory could be removed. The contribution of removed metal needs to be investigated in more detail. The median number related particle size measured by optical microscopy was found to be in the range of 0.2 to 0.7 μm whereas the median weight related size is in the range of 0.8 to 1.5 μm. The initial results indicate that this dust sticks very strongly to the pipe surface. Phase 2 will concentrate on longer pieces of piping where hopefully more loose dust can be obtained and analysed. If the same strong bonding is observed the reason for this phenomenon needs to be explained and perhaps tested with non-active dust.

scholarly journals Effect of the sintering temperature on the fabrication of alumina beads

2019 ◽  
Vol 16 (2) ◽  
pp. 125-135
Author(s):  
Ayse KALEMTAS
Keyword(s):  
Sintering Temperature ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Liquid Phase Sintering ◽  
Sintered Ceramic ◽  
Mullite Phase ◽  
Commercial Grade ◽  
Composite Beads ◽  
Sintering Additive ◽  
Dta Analysis

In this study, kaolin bonded alumina-alginate composite beads were fabricated via a facile one-step sol-gel process by using sodium alginate. In order to achieve sintering of the beads at lower sintering temperatures a limited amount of CC31 commercial-grade kaolin was used as a sintering additive (Al2O3:CC31 commercial-grade kaolin=14:1). Produced composite beads were heat treated at 1300°, 1400° and 1500°C for 1 hour to achieve partial densification of the beads. TG-DTA analysis of the CC31 commercial-grade kaolin showed that mullite phase formation took place approximately at 1000°C. However, XRD measurements revealed that there is only alumina phase in the sintered ceramic beads. Due to the low amount of CC31 commercial-grade kaolin, mullite formation was not detectable via XRD analysis. No significant grain growth was observed at the sintered samples depending on the increasing sintering temperature. However, when the sintering temperature was increased, densification ratio and mechanical properties of the produced beads were enhanced significantly. Microstructural investigations of the sintered beads shown that with the help of the liquid phase sintering process, a good chemical bonding was achieved between the alumina particles.

scholarly journals Titania powder activation and rutile ceramics structure formation

2009 ◽  
Vol 41 (1) ◽  
pp. 27-33 ◽  
Author(s):  
I.R. Ziganshin ◽  
S.E. Porozova ◽  
A.E. Stolina ◽  
M.F. Torsunov
Keyword(s):  
Raman Spectroscopy ◽  
Porous Materials ◽  
Optical Microscopy ◽  
Aqueous Medium ◽  
Structure Formation ◽  
Mechanochemical Activation ◽  
Organic Additives ◽  
X Ray Diffraction ◽  
X Ray ◽  
Titania Powder

Impact of mechanochemical activation (MCA) in aqueous medium with various organic additives on commercial titania powder and products made of it has been investigated by X-ray diffraction, optical microscopy and Raman spectroscopy. Agar-agar additive has been shown to offer promise for activation of titania powders used in obtaining both dense and porous materials.

scholarly journals Scanning Near-Field Optical Microscopy

2008 ◽  
Vol 8 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Dušan Vobornik ◽  
Slavenka Vobornik
Keyword(s):  
Molecular Structure ◽  
Chemical Composition ◽  
Optical Microscopy ◽  
Temporal Resolution ◽  
Dynamic Properties ◽  
Near Field ◽  
Medical Sciences ◽  
Human Eye ◽  
Nano Structures

An average human eye can see details down to 0,07 mm in size. The ability to see smaller details of the matter is correlated with the development of the science and the comprehension of the nature. Today’s science needs eyes for the nano-world. Examples are easily found in biology and medical sciences. There is a great need to determine shape, size, chemical composition, molecular structure and dynamic properties of nano-structures. To do this, microscopes with high spatial, spectral and temporal resolution are required. Scanning Near-field Optical Microscopy (SNOM) is a new step in the evolution of microscopy. The conventional, lens-based microscopes have their resolution limited by diffraction. SNOM is not subject to this limitation and can offer up to 70 times better resolution.

Hydrogeochemical and isotopic characterization of groundwater at Žitný Island (SW Slovakia)

2015 ◽  
Vol 46 (6) ◽  
pp. 929-942 ◽  
Author(s):  
Z. Ženišová ◽  
P. P. Povinec ◽  
A. Šivo ◽  
R. Breier ◽  
M. Richtáriková ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Surface Water ◽  
Danube River ◽  
Water Isotopes ◽  
Anthropogenic Contamination ◽  
The Danube River ◽  
The Core ◽  
Groundwater Reservoir ◽  
Isotopic Characterization

Hydrogeochemical investigations and spatial variations studies on the distribution of water isotopes and radiocarbon in the groundwater of Žitný Island (Rye Island) were carried out. Žitný Island represents the largest groundwater reservoir in Central Europe (about 10 Gm3). The chemical composition of the groundwater of Žitný Island depends mainly on the chemical composition of Danube water, as well as on the length of its infiltration from the Danube River. The groundwater is characterized by potamogenic mineralization, and its chemical composition is influenced by anthropogenic contamination. Sub-surface water profiles showed enriched δ18O levels up to around 20 m water depth, and depleted values for deeper waters. The observed isotopic composition of the groundwater is similar to Danube water, suggesting that the Danube River is the main source of the Žitný Island groundwater. The core of the sub-surface 14C profile represents contemporary groundwater with 14C values above 80 pMC.

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