scholarly journals INVESTIGATION OF TUNGSTEN SURFACE CARBIDIZATION UNDER PLASMA IRRADIATION

2022 ◽  
pp. 37-43
Author(s):  
G. K. Zhanbolatova ◽  
A. Z. Miniyazov ◽  
T. R. Tulenbergenov ◽  
I. A. Sokolov ◽  
O. S. Bukina
Keyword(s):  
Phase Composition ◽  
Surface Temperature ◽  
Test Temperature ◽  
Irradiation Time ◽  
Sample Surface ◽  
Literature Analysis ◽  
Optimal Parameters ◽  
Experimental Conditions ◽  
Plasma Irradiation ◽  
Tungsten Surface

This paper presents the results of a study of the formation of a carbidized layer under various experimental conditions and the choice of optimal parameters for carbidization of a tungsten surface under plasma irradiation. To study the effect of the surface temperature of a tungsten sample and the duration of plasma irradiation, experiments were carried out at a sample surface temperature of 1300 °C and 1700 °C with an irradiation duration of 300–2400 s. Analysis of the research results showed that the maximum formation of W2C on the surface is observed at a test temperature of 1700 °C. At a temperature of 1300 °C, the phase composition of the carbidized layer depends on the duration of plasma irradiation. According to the literature analysis, the formation of WC occurs on the surface of tungsten, from which C diffuses into the particle and forms the underlying layer of W2C. With an increase in the ion fluence, depending on the irradiation time and the temperature of the sample surface, the diffusion of C into W accelerates, the WC content decreases, and W2C becomes the dominant carbide compound.

scholarly journals Investigation of tungsten surface carbidization under plasma irradiation

2021 ◽  
Vol 2064 (1) ◽  
pp. 012053
Author(s):  
A Z Miniyazov ◽  
M K Skakov ◽  
T R Tulenbergenov ◽  
I A Sokolov ◽  
G K Zhanbolatova ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Phase Analysis ◽  
Experimental Work ◽  
Irradiation Time ◽  
Sample Surface ◽  
Optimal Parameters ◽  
Experimental Conditions ◽  
X Ray ◽  
Plasma Irradiation ◽  
Tungsten Surface

Abstract This paper presents the results of studying the formation of a carbide layer under various experimental conditions and the choice of the optimal parameters for carbidization of the tungsten surface under plasma irradiation in methane. Therefore, to assess the effect of the surface temperature of a tungsten sample during experimental work, the surface temperature of the sample was 1300-1700°C, and to assess the effect of the irradiation time, a range within 300-2400 s was selected. From the results of X-ray phase analysis of the surface of tungsten samples, concluded that the temperature of the sample surface and the duration of irradiation have a significant effect on the formation of a carbidized layer on the tungsten surface during plasma irradiation on plasma-beam installation.

scholarly journals Effect of ion irradiation on structural state and mechanical properties of naturally-aged hot-pressed D16 (Al-Cu-Mg) alloy profiles

2021 ◽  
Vol 2064 (1) ◽  
pp. 012060
Author(s):  
N V Gushchina ◽  
V V Ovchinnikov ◽  
L I Kaigorodova ◽  
D Y Rasposienko ◽  
D I Vichuzhanin
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Intermetallic Compounds ◽  
Ion Irradiation ◽  
Irradiation Time ◽  
Ion Beam ◽  
Sample Surface ◽  
Strength Properties ◽  
Stable Phase ◽  
Subgrain Structure

Abstract The effect of irradiation with 20 keV argon ions on the mechanical properties, structure, and phase composition of quenched and then naturally aged, hot-pressed profiles (6 mm thick) from the D16 alloy of the Al-Cu-Mg system has been studied. It was found that short-term irradiation with Ar+ ions (E = 20 keV, j = 200 μA/cm2, F = 1×1016 cm-2, irradiation time 8 s) leads to transformation of the microstructure and phase composition of the alloy. The coarsening of the initial subgrain structure occurs near the sample surface. Both in the surface layer and at a distance of ∼ 150 μm from it, partial dissolution and fragmentation of complex intermetallic compounds of crystallization origin located along grain boundaries are observed, as well as a decrease in the size and change in the morphology of Al6(Fe, Mn) intermetallic compounds of crystallization origin are observed too: the distribution density of lamellar precipitations decreases, and equiaxial precipitations disappear. Under the influence of irradiation, the decomposition of the supersaturated solid solution is activated with the formation of a more stable phase S’. As a result of ion-beam treatment in this mode, the plasticity of the alloy increases while maintaining the strength properties.

Assessment of Decimal Reduction of Pathogens in Frozen Chicken Products Using Surface Pasteurization

2007 ◽  
Vol 3 (4) ◽  
Author(s):  
Aluck Thipayarat
Keyword(s):  
Surface Temperature ◽  
Temperature Profile ◽  
Sample Surface ◽  
Steam Treatment ◽  
Minimal Processing ◽  
Large Size ◽  
Food Borne ◽  
Similar Temperature ◽  
Page Equation ◽  
Heating Up

The focus of this study involved the application of an effective methodology to estimate decimal reduction of two main food-borne pathogens (i.e., Salmonella and Listeria) in frozen cooked chicken products using surface pasteurization. A quick and effective approach to estimate the surface temperature of the product was proposed using the Page equation and the evaluation of pathogenic destruction on the large-size and small-size frozen steamed chicken products. The samples were in the frozen form and treated as if they were post-contaminated by Salmonella and Listeria. The pasteurization temperatures in the steam oven were varied at 70, 75, 80, 90 and 100 degree Celsius. The Page equation performed well to accurately predict the surface temperature profile of the different product sizes. The steam treatment was very effective in heating up the pasteurized products and resulted in similar temperature profiles regardless of product size. The relationship between the model constant coefficient and pasteurization temperature followed the Arrhenius expression. The substitution of the predicted surface temperature profile to the process lethality equation facilitated quick estimation of pathogenic destruction on the sample surface. The different sizes of the chicken products only slightly affected the pasteurization time. However, the pasteurization time to achieve that same decimal reduction varied significantly between the two different target pathogens. The simplicity and effectiveness of this approach did not only eliminate multiple experimental repetitions and simplify the estimation of pathogenic destruction, but also provided and effective minimal processing procedure for frozen cooked chicken pasteurization of two sizes of steamed products while retaining the desirable quality of end products after surface pasteurization.

The mechanism of the production of atomic hydrogen by hot tungsten

1936 ◽  
Vol 32 (4) ◽  
pp. 653-656 ◽  
Author(s):  
J. K. Roberts ◽  
G. Bryce
Keyword(s):  
Temperature Variation ◽  
Atomic Hydrogen ◽  
Hydrogen Molecule ◽  
Hydrogen Pressure ◽  
The Other ◽  
Square Root ◽  
Important Process ◽  
Experimental Conditions ◽  
Tungsten Atom ◽  
Tungsten Surface

The fact that the rate of production of atomic hydrogen at a tungsten surface at a given temperature is proportional to the square root of the hydrogen pressure means either that the important process is the evaporation of atoms from an adsorbed film which over the whole range of experimental conditions is sparsely occupied, or that the production of atoms is in the main due to a process in which a hydrogen molecule strikes a bare tungsten atom in the surface, one atom being adsorbed and the other evaporating and the surface being almost completely covered over the whole range of experimental conditions. Either process leads to a temperature variation in the rate of atom production in agreement with experiment. A definite decision between the two processes cannot yet be made.

Photo-Thermal Spectroscopic Imaging of MEMS Structures with Sub-Micron Spatial Resolution

2012 ◽  
Vol 1415 ◽  
Author(s):  
Robert Furstenberg ◽  
Christopher A. Kendziora ◽  
Michael R. Papantonakis ◽  
Viet Nguyen ◽  
R. A. McGill
Keyword(s):  
Spatial Resolution ◽  
Thermal Emission ◽  
Imaging System ◽  
Chemical Vapor ◽  
Sample Surface ◽  
Laser Wavelength ◽  
Ir Detector ◽  
Experimental Conditions ◽  
Emission Signal ◽  
Polyimide Membrane

ABSTRACTWe are developing a new non-contact and non-destructive imaging technique which requires no sample preparation and provides similar content information as FTIR or Raman spectroscopy while being immune to fluorescence and offers a potentially faster scan rate and/or higher spatial resolution. It utilizes photo-thermal heating of the sample with a quantum cascade laser (or other suitable infrared laser) and measuring the resulting increase in thermal emissions by either an infrared (IR) detector or a laser probe consisting of a visible laser reflected from the sample. The latter case allows for further increases in the spatial resolution from ∼10 μm to ∼1 μm or better, with suitable experimental conditions. Since the thermal emission signal is proportional to the absorption coefficient, by tuning the wavelength of the IR laser we can directly measure the IR spectrum of the sample. By raster scanning over the surface of the sample we can obtain maps of the chemical composition of the sample surface. We demonstrate this technique by imaging the surface of a micro-fabricated flow-through chemical vapor preconcentrator consisting of a silicon frame and a suspended-perforated polyimide membrane with a pair of platinum heater traces, coated with a custom sorbent polymer for selective sorption of analyte. We measure the spatial resolution of our photo-thermal imaging system as well as discuss the conditions under which the spatial resolution can be further increased from the far-field diffraction limited resolution given by the combination of the imaging optic and IR excitation laser wavelength.

Study on the Fabrication and Properties of Ni-P Composite Coating

2013 ◽  
Vol 537 ◽  
pp. 265-268
Author(s):  
Zhao An ◽  
Ming Ya Li ◽  
Nian Hao Ge ◽  
Xiao Ying Li ◽  
Qiu Fan Li ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Phase Composition ◽  
Surface Morphology ◽  
Composite Coating ◽  
Electroless Deposition ◽  
Sample Surface ◽  
Reducing Agent ◽  
Experimental Results ◽  
Complexing Agent

In this paper, the method of electroless deposition of nickel-phosphorous composite coating on the sample surface is employed. The effect of the complexing agent ratio on the surface morphology and phase composition of nickel-phosphorus coating when the main salt and reducing agent concentration unchanged has been studied. The influence of heat treatment on properties and microstructure of coatings are also investigated. Experimental results show that in the case of salt and reducing agent concentration unchanged, complexing agent concentration has strong effect on the morphology of the coatings and the crystal structure of the composite coating. During heat treatment, the morphology of the composite coating changed significantly, and the hardness was improved a certain degree for all the samples, which is related to the precipitation of Ni3P.

scholarly journals Establishing adequate conditions for mercury determination in environmental samples by INAA

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Caroline Perez ◽  
Eliane Conceição Dos Santos ◽  
Mitiko Saiki
Keyword(s):  
Environmental Samples ◽  
Gamma Ray ◽  
Irradiation Time ◽  
Certified Reference Materials ◽  
Nuclear Research ◽  
Tree Bark ◽  
Good Precision ◽  
Experimental Conditions ◽  
Synthetic Standard ◽  
Adequate Method

Mercury (Hg) is a toxic element released into the environment mainly by anthropic activities. Consequently, the improvement for Hg determination in environmental samples is of great interest. Instrumental Neutron Activation Analysis (INAA) is considered an adequate method to determine several elements. However, Hg determination by INAA is often hampered by its volatility, which causes losses. The aim of this study was to establish adequate irradiation conditions for Hg determination in environmental samples by INAA. The following parameters were evaluated: irradiation time, container for irradiation and spectral gamma ray interferences. For the study, aliquots of certified reference materials (CRMs) and tree bark samples were irradiated together with Hg synthetic standard at the IEA-R1 nuclear research reactor. Gamma ray activities of 197Hg and 203Hg were measured in a spectrometer coupled to a HGe detector. Obtained results indicated that polyethylene capsules or envelopes can be used as container for sample irradiation and the Hg impurities in these containers were negligible. Irradiation time of one hour was adequate for Hg determination and in long irradiations of 8 h problems of spectral interference of 198Au and 75Se were observed. In addition, Hg loss during the irradiation of 1 h and after irradiation was not observed. Quality control of Hg results, obtained in the CRMs analyses using one hour of irradiation, indicated good precision and accuracy with HORRAT < 2 and |Z score| < 2. The experimental conditions established in this study were applied to tree bark samples. Detection limits in these analyses were between 0.14 and 1.9 µg g-1.

scholarly journals Otimização da produção de biodiesel a partir de óleo de coco babaçu com aquecimento por microondas

2018 ◽  
Vol 39 (4) ◽  
pp. 37
Author(s):  
Ulisses Magalhães Nascimento ◽  
Antonio Carlos Sales Vasconcelos ◽  
Eduardo Bessa Azevedo ◽  
Fernando Carvalho Silva
Keyword(s):  
Microwave Heating ◽  
Irradiation Time ◽  
Reaction Times ◽  
Coconut Oil ◽  
Microwave Oven ◽  
Raw Material ◽  
Biodiesel Production ◽  
Experimental Conditions ◽  
Domestic Microwave Oven ◽  
Central Composite

Reactions under microwave heating present reduced reaction times and larger yields. Therefore, this work is aimed at adapting a domestic microwave oven and optimizing the transesterification reaction used in biodiesel production with microwave heating, using babaçu coconut oil as raw material. It was used a central composite design for varying irradiation time, KOH concentration, and oil:methanol ratio. Statistical analyses were performed in orderto assess the significance of the model used. The optimized experimental conditions were: oil:methanol ratio, 8.59; KOH concentration, 2.19 %; and irradiation time, 70 seconds, givingan yield of approximately 100% regarding esters formation.

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