scholarly journals Influence of activators on constitutes of diffusion layer at boronizing pressed samples from iron powder

2008 ◽  
Vol 62 (3) ◽  
pp. 164-169 ◽  
Author(s):  
Emina Pozega ◽  
Svetlana Ivanov
Keyword(s):  
Experimental Investigation ◽  
Chemical Composition ◽  
Iron Powder ◽  
Ammonium Chloride ◽  
Diffusion Layer ◽  
Potassium Fluoride ◽  
Mixture Composition ◽  
Ammonium Bifluoride ◽  
Mathematical Processing ◽  
Quantitative Changes

In this paper, results of experimental investigation which contributes to study of quantitative changes of porosity during chemical-thermical process, apropos boronizing of pressed samples from iron powder, with variation of boronizing mixture composition are presented. The basic mixture is modified by the addition of activators with different chemical composition and in different percentage rate (0-4 wt%). Mixtures with ammonium chloride, ammonium bifluoride and boron potassium fluoride were investigated. According to the results of the experiments it is found that the content of activators has an influence on the porosity of pressed samples from iron powder. In order to obtain better boride layers it was necessary to choose a mixture for boronizing and to determine the most useful activators and their ratio. The results of research and mathematical processing enable the choice of optimal mixture composition for boroning. .

scholarly journals The possibility of the boronizing process on the pressed samples of iron powder

2009 ◽  
Vol 63 (3) ◽  
pp. 253-258
Author(s):  
Emina Pozega ◽  
Svetlana Ivanov ◽  
Vesna Conic ◽  
Branislav Cadjenovic
Keyword(s):  
Experimental Investigation ◽  
Thermal Treatment ◽  
Iron Powder ◽  
Ammonium Chloride ◽  
Treatment Process ◽  
Polynomial Function ◽  
Potassium Fluoride ◽  
Volume Changes ◽  
Fourth Degree ◽  
Powder Samples

The paper presents results of the experimental investigation of the boronizing process on nonsintering iron powder samples (NC100.24, H?gan?s, Sweden). Experiments are planned within the limits of applicability of simultaneous sintering at chemical-thermal treatment process (boronizing). The simlex plan of 15 experimental points was used for the experiment, while a polynomial function of fourth degree was employed in the modeling of a mixture composition based on the volume changes, porosity and the depth layer changes. Boronizing was carried out in mixture with born carbide by addition of ammonium bifluoride, ammonium chloride and boron potassium fluoride as activators, by proportion definited plan.

Diffusion Niobizing of Titanium Grade 2 by Gas-Contact Method

2015 ◽  
Vol 669 ◽  
pp. 158-166
Author(s):  
Dariusz Bartkowski ◽  
Andrzej Mlynarczak ◽  
Adam Piasecki ◽  
Waldemar Matysiak ◽  
Michal Hatala ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Diffusion Layer ◽  
Powder Mixture ◽  
Diffusion Processes ◽  
Contact Method ◽  
Niobium Content ◽  
Structure Quality ◽  
Pure Niobium ◽  
Titanium Grade ◽  
Geometric Surface

The work presents results of diffusion niobizing of titanium Grade 2 by gas-contact method. Microhardness, thickness, chemical composition and microstructure were investigation. Diffusion processes was carried out in a two powder mixture. First consisted of ferro-niobium, kaolin and ammonium chloride, second mixture contained pure niobium instead ferro-niobium. The processes were carried out at 950°C, 1000°C and 1050°C for 2, 4 and 6 hours. Due to the geometric surface structure quality and other properties like thickness or microhardness, the best diffusion layer was obtained using first powder mixture and following parameters: temperature 950°C and time of diffusion equal 2 hours. The diffusion layer established in these conditions, had structure of niobium solution in titanium, and niobium content of about 10%. Its hardness was 550 HV0.05 while thickness was 120 μm.

Distribution of chemical composition of statistical copolymers from the conversion dependences of copolymer or residual monomer mixture composition

1986 ◽  
Vol 19 (6) ◽  
pp. 1575-1580 ◽  
Author(s):  
Jaroslav Stejskal ◽  
Pavel Kratochvil ◽  
Dagmar Strakova ◽  
Ondrej Prochazka
Keyword(s):  
Chemical Composition ◽  
Mixture Composition ◽  
Monomer Mixture ◽  
Residual Monomer

scholarly journals Chemical composition fluctuations in roots of Plumbago scandens L. in relation to floral development

2011 ◽  
Vol 83 (4) ◽  
pp. 1165-1170 ◽  
Author(s):  
Selma R. Paiva ◽  
Lucilene A. Lima ◽  
Maria Raquel Figueiredo ◽  
Maria Auxiliadora C. Kaplan
Keyword(s):  
Chemical Composition ◽  
Palmitic Acid ◽  
Developmental Stage ◽  
Floral Development ◽  
Developmental Stages ◽  
Quantitative Changes ◽  
Composition Fluctuations ◽  
Subtropical Species

Plumbago scandens L. is a Brazilian tropical/subtropical species that occurs along the coast. Chemically it is mainly represented by naphthoquinones, flavonoids, terpenoids and steroids. The aim of the present work is to study quantitative changes in the root metabolic production of Plumbago scandens during different physiologic developmental stages relative to floration. The results indicated the presence of four substances in the extracts: plumbagin, epi-isoshinanolone, palmitic acid and sitosterol, independent on developmental stage. The naphthoquinone plumbagin has always showed to be the major component of all extracts. Naphthoquinones exhibited their highest content during floration, while the content of the two others components decreased during this stage, revealing an inverse profile. The chemical composition changed depending on the plant requirements.

Chemical, sorptive and morphological properties of montmorillonite treated with ammonium bifluoride (NH4HF2) solutions

Clay Minerals ◽  
1985 ◽  
Vol 20 (1) ◽  
pp. 81-92 ◽  
Author(s):  
J. Fijal ◽  
M. Zyla ◽  
M. Tokarz
Keyword(s):  
Electron Microscope ◽  
Chemical Composition ◽  
Crystal Surface ◽  
Bulk Sample ◽  
Morphological Properties ◽  
Surface Layers ◽  
Electron Microscopic ◽  
Ammonium Bifluoride

AbstractThe fluorination of montmorillonite by aqueous ammonium bifluoride solution (NH4HF2) has been investigated by chemical, sorptive, porosimetric and electron microscopic methods. Changes in the chemical composition of the montmorillonite during the fluorination were compared both in the crystal surface and in the bulk sample. The accumulation of fluorine was distinctly zonal, being present mainly in the surface layers. The electron microscope studies showed that the 300–400 nm thick macrodomains in the initial montmorillonite were cracked into small microdomains 20–30 nm in thickness, this resulting from disruption in the continuity of the octahedral sheets. These distinct changes in morphology of the montmorillonite aggregates particularly influenced the porosity and sorptive properties.

scholarly journals DILATANCY OF CEMENT SLURRIES WITH CHEMICAL ADMIXTURES

2004 ◽  
Vol 10 (3) ◽  
pp. 227-233 ◽  
Author(s):  
Gintautas Skripkiūnas ◽  
Mindaugas Daukšys
Keyword(s):  
Experimental Investigation ◽  
Chemical Composition ◽  
Rheological Properties ◽  
Disperse Medium ◽  
Coaxial Cylinder ◽  
Structural System ◽  
Chemical Admixtures ◽  
Rotation Viscometer

The results of experimental investigation of plasticising, air‐entraining and viscosity‐modifying admixtures with different chemical composition influence on rheological properties and dilatancy of cement slurries are presented in the article. Rheological properties of cement slurries were tested by a rotation viscometer with coaxial cylinder, at different gradients of velocity. Dilatancy of cement slurries was determined by the distortion of the rheological curve and index of dilatancy D was calculated according to proposed methods. The results of investigation show that the properties of liquid disperse medium of structural system influence slightly the dilatancy of cement slurries. Plasticising admixtures with a different chemical composition slightly increases but air-entraining and viscosity-modifying admixtures slightly reduces the dilatancy of cement slurries.

scholarly journals Volume contraction in the process of combustion of various fuels in combustion engines

2013 ◽  
Vol 154 (3) ◽  
pp. 72-78
Author(s):  
Barbara WORSZTYNOWICZ
Keyword(s):  
Chemical Composition ◽  
Theoretical Calculations ◽  
Combustion Process ◽  
Mixture Composition ◽  
Combustion Engines ◽  
Volume Contraction ◽  
Gaseous Fuels ◽  
The Individual

The paper discusses the issues related to the change of volume of the reagents during the process of combustion. The formulas that were necessary to make the calculations were derivedfor liquid and gaseous fuels. Based on the formulas, theoretical calculations of the change of the kilo-mole number for various fuels depending on the mixture composition were performed. The results of the calculations were presented in the tables. Further, the influence of volume contrac­tion on the parameters of the combustion process was analyzed. In the conclusions, a comparison of the influence of the previously described phenomena on the individual fuels was performed in relation to their chemical composition and the composition of the mixture.

Sign in / Sign up

Export Citation Format

Share Document