scholarly journals Application of sacrificial coatings and effect of composition on Al-Al3Ni ultrafine eutectic formation

2014 ◽  
Vol 50 (1) ◽  
pp. 31-36 ◽  
Author(s):  
L. Celko ◽  
L. Klakurková ◽  
B. Smetana ◽  
K. Slámecka ◽  
M. Zaludová ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Substrate Surface ◽  
Intermetallic Phase ◽  
Hvof Spraying ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Initial Substrate ◽  
Constant Heating ◽  
Image Analysis Techniques

This paper introduces an unconventional method designed for forming hypereutectic alloys via coating deposition onto the substrate surface and subsequent heat treatment of such systems. The coating was produced from 99.7 wt% nickel powder by means of high velocity oxyfuel (HVOF) spraying onto the surface of 99.999 wt% aluminium sheet. The specimens were manufactured immediately after the spraying. Specimens were heat-treated using a differential thermal analysis (DTA) apparatus up to a temperature of 900?C and then cooled down to the room temperature in an argon atmosphere with constant heating and cooling rates, under which the NiAl3 intermetallic phase formed within the initial substrate. Two different alloy microstructures consisting of a coarse eutectic and an ultrafine well-dispersed eutectic were produced. The formation processes and resultant microstructures were studied by means of differential thermal analysis, metallography, scanning electron microscopy, energy dispersive microanalysis, and image analysis techniques.

Effect of Heat Treatment on Formation of Al-Al3Ni Hypereutectic Alloys

2013 ◽  
Vol 592-593 ◽  
pp. 513-516
Author(s):  
Ladislav Čelko ◽  
Lenka Klakurková ◽  
Karel Slámečka ◽  
Bedřich Smetana ◽  
Tomasz Płociński ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Hvof Spraying ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Initial Substrate ◽  
Constant Heating ◽  
Image Analysis Techniques ◽  
Intermetallic Layers

The paper deals with the mechanism of eutectic formation in a nickel coated aluminium system after heat treatment. The initial coating was produced from a nickel powder by means of high velocity oxyfuel (HVOF) spraying onto an aluminium sheet substrate. Specimens for investigations were manufactured immediately after the spraying. The specimens were heat-treated using a differential thermal analysis (DTA) apparatus up to the temperature of 700 or 900 °C and then cooled down to room temperature in argon atmosphere with a constant heating and cooling rate of 5 °C / min, under which Al-Al3Ni + Al3Ni hypereutectic alloys were formed within the initial substrate. Two different alloy microstructures consisting of intermetallic layers and coarse eutectic or an ultrafine well-dispersed eutectic were formed. Formation processes and resulting microstructures were studied by means of DTA, metallography, scanning electron microscopy, focused ion beam, energy dispersive microanalysis and image analysis techniques.

High-Temperature Modifications of Thorium Dicarbide

1964 ◽  
Vol 8 ◽  
pp. 78-85 ◽  
Author(s):  
P. K. Gantzel ◽  
S. Langer ◽  
N. L. Baldwin ◽  
F. L. Kester
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
High Temperature ◽  
Thermal Effects ◽  
Room Temperature ◽  
Thermal Analyses ◽  
Tetragonal Modification ◽  
X Ray ◽  
Space Groups ◽  
Heating And Cooling

AbstractThermal analyses of samples of thorium dicarbide in equilibrium with graphite show arrests which indicate phase transitions at 1427 ± 21°C arid 1481 ± 28°C. These thermal effects have been observed on heating and cooling both in standard thermal analysis and in differential thermal analysis using graphite as a reference material. The microstructure of thorium dicarbide samples shows the characteristic “herringbone” pattern of a material which has undergone a martensitic-type transition.A high-temperature X-ray investigation has revealed that the observed thermal arrests correspond to erystallographic transformations. The monodinic modification found at room temperature is stable to 1427°C, at which temperature a tetragonal modification with a0 = 4.235 ± 0.002Å and c0 = 5.408 ± 0.002Å is formed. At 1481°C, the tetragonal is transformed to cubic with a0 = 5.809 ± 0.002 Å. The best agreement between observed and calculated intensities has been obtained with C-C units of 1.5-Å assumed bond length in space groups P42/mmc and Pa3 for the tetragonal and cubic modifications, respectively.

Synthesis of Ultra-Fine ZrB2 Powder by Borothermal Reaction under High Heating Rate

2009 ◽  
Vol 66 ◽  
pp. 77-80 ◽  
Author(s):  
Ge Sun ◽  
Hao Wang ◽  
Wei Min Wang ◽  
Yu Cheng Wang ◽  
Zheng Yi Fu
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Heating Rate ◽  
Zirconium Oxychloride ◽  
Reduction Reaction ◽  
Average Crystalline Size ◽  
High Heating Rate ◽  
Heat Treated ◽  
High Heating ◽  
Borothermal Reduction

Ultra-fine zirconium diboride (ZrB2) powders have been synthesized by borothermal reduction reaction, using zirconium oxychloride (ZrOCl2•8H2O) as the precursors of zirconia. The thermodynamic variation in the amorphous ZrO2-B system was studied by thermogravimetric and differential thermal analysis (TG-DTA). The precursors containing amorphous ZrO2 and B were heat-treated under a high heating rate. It is shown that the borothermal reaction can be completed at a relatively low temperature (~950 °C) and short duration (~5 min) under a heating rate of 200 °C/min. The synthesized powders have an average crystalline size of 300 nm with oxygen content less than 2.62 wt%.

Differential thermal analysis of AlgFeMnSi2 intermetallic phase particles

1994 ◽  
Vol 30 (4) ◽  
pp. 435-439 ◽  
Author(s):  
A. Flores-Valdes ◽  
M.I. Pech-Canul ◽  
M. Méndez-Nonell ◽  
M. Sukiennik
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Intermetallic Phase

A DTA Study on HVOF Thermally Sprayed WC–M Coatings

2007 ◽  
Vol 566 ◽  
pp. 155-160
Author(s):  
M. Heydarzadeh Sohi ◽  
Shahin Khameneh Asl ◽  
Kazuyuki Hokamoto ◽  
M. Rezvani
Keyword(s):  
Heat Treatment ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
High Temperature ◽  
Amorphous Phase ◽  
Exothermic Reaction ◽  
Intermetallic Phase ◽  
Chemical Compositions ◽  
Crystalline Phases ◽  
Sprayed Coatings

Five types of tungsten carbide based powders with different chemical compositions (WC-12Co, WC-17Co, WC-10Ni, WC-10Co-4Cr and WC- 20Cr-7Ni) were deposited onto ST37 mild steel substrate using high velocity oxy fuel (HVOF) spray technique. The feedstock powders and sprayed coatings were studied by using X-ray diffraction (XRD), and differential thermal analyzing (DTA). The results were shown during HVOF thermal spraying, WC-M powders become partially melted before being sprayed on the surface of the substrate with supersonic speed. In these types of coatings, the crystallographic structures are normally non equilibrium, because the cooling rates of the deposited splats are very high due to the cold substrate acting as a thermal sink. These partially melted powders are then rapidly solidified to an amorphous phase. XRD analysis showed that the amorphous phase was existed in all of the as sprayed coatings. The amorphous phase in WC-12Co, WC-17Co and WC-10Ni coatings was transformed to crystalline phases by heat treatment at high temperature. Heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. In cobalt base coatings, the new phases were eta carbide phases like Co6W6C and Co3W3C but in WC-10Ni coating a NiW intermetallic phase was formed. Heat treatment of WC-10Co-4Cr and WC-20Cr-7Ni coatings did not change the amorphous phases in these coatings. Differential thermal analysis of cobalt containing coatings revealed an exothermic reaction at approximately 880°C. This exothermic reaction may be related to the transformation of the amorphous phase to eta phases. On the contrary, DTA analysis of feedstock powders of these coatings showed an endothermic reaction at approximately 1000°C. DTA analyses of nickel containing cermets also showed similar results. Differential thermal analysis of chromium containing cermets did not show any noticeable exothermic or endothermic reactions.

scholarly journals Электрические взаимодействия в смесях сегнетоэлектрических порошков хлорида диизопропиламмония и титаната свинца

2021 ◽  
Vol 63 (6) ◽  
pp. 772
Author(s):  
С.В. Барышников ◽  
А.Ю. Милинский
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Phase Transitions ◽  
Cooling Mode ◽  
Powder Mixtures ◽  
Heating And Cooling ◽  
Additional Phase

The results of studies of phase transitions in mixtures of C6H16NCl (DIPAC) powders with PbTiO3 by the method of differential thermal analysis (DTA) are pre-sented. The measurements were carried out in the heating and cooling mode in the tem-perature range from 300 to 440 K. It was found that electrical interactions between ferroelectric particles lead to the appearance of additional phase transitions for DIPAC in powder mixtures.

Differential Thermal Analysis Apparatus for Heating and Cooling Data

1958 ◽  
Vol 30 (4) ◽  
pp. 492-494 ◽  
Author(s):  
D. D. Williams ◽  
R. D. Barefoot ◽  
R. R. Miller
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Heating And Cooling

Effect of pressure on reversible solid-solid transitions in nepheline and carnegieite

1976 ◽  
Vol 40 (313) ◽  
pp. 487-492 ◽  
Author(s):  
Lewis H. Cohen ◽  
William Klement
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Transition Temperature ◽  
Initial Slope ◽  
Temperature Transition ◽  
Effect Of Pressure ◽  
Reversible Transition ◽  
Heating And Cooling ◽  
Higher Temperature ◽  
Reversible Transitions

SummaryDifferential thermal analysis of a rapidly reversible transition in carnegieite to 7 kbar shows the transition temperature increases from ⪝ 707°C (on heating) at I bar with initial slope ≈ 8·0 deg kbar−1 and anomalous curvature (d2T/dp2 > o), with hysteresis between heating and cooling signals that decreases with pressure. DTA of rapidly reversible transitions in nepheline shows the very subtle transition near 185°C (on heating) at 1 bar decreases with pressure to ≈ 170°C near 2-3 kbar and hardly varies in temperature up to 6 kbar; and the higher temperature transition increases from ≈ 872°C (on heating) at 1 bar with slope ≈ 25 deg kbar−1, to 5 kbar, with the hysteretic interval remaining essentially unchanged in the investigated range.

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