scholarly journals The Relaxation Behavior of High Chromium- Ni Base Superalloys

2011 ◽  
Vol 278 ◽  
pp. 321-326 ◽  
Author(s):  
Mohamed Nazmy ◽  
Claus Gerdes
Keyword(s):  
Thermal Analysis ◽  
Residual Stress ◽  
Differential Thermal Analysis ◽  
Test Temperature ◽  
Intermetallic Phase ◽  
Relaxation Behavior ◽  
High Chromium ◽  
Different Temperatures ◽  
Nimonic 80A ◽  
Negative Creep

The relaxation behavior of wrought high chromium Ni-base alloys Nimonic 80A, Nimonic 101 and Nimonic 105 was studied at different temperatures. All of these alloys exhibited increase in the residual stress during the relaxation tests e.g. at 450°C for Nimonic 80A and 650°C for Nimonic 105. The observed increase in the residual stress is a manifestation of the known phenomenon of “negative creep”. The stress free aging of specimens of these alloys exhibited dimensional contraction at different temperatures ranging from 450°C to 650°C. The abnormal relaxation behavior of these alloys and the observed contraction were attributed to the precipitation and ordering of the intermetallic phase Ni2(Cr,Mo) at the test temperature. The differential thermal analysis i.e. DTA results, demonstrated endothermic peaks to correspond with the order–disorder reaction of Ni2(Cr,Mo).

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.

Functional Modification of Xylan-Rich Hemicelluloses in Ionic Liquid

2011 ◽  
Vol 391-392 ◽  
pp. 950-954 ◽  
Author(s):  
Xin Wen Peng ◽  
Jun Li Ren ◽  
Lin Xin Zhong ◽  
Yan Bo Huang ◽  
Run Cang Sun
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Ionic Liquid ◽  
Differential Thermal Analysis ◽  
Nmr Spectroscopy ◽  
Thermal Behavior ◽  
Succinic Anhydride ◽  
Different Temperatures ◽  
Thermal Stability Of ◽  
C Nmr

Xylan-rich Hemicelluloses (XH) isolated from wheat straw were converted to functional biopolymers by modification using succinic anhydride (SA) as reactant without catalyst in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid. The reaction was performed under various conditions such as different temperatures, different times, and the different amounts of SA, and the effect of reaction factors on the degree substitution (DS) of products were discussed. The product had the maximum DS of 1.80. The structure of modified hemicellulosic derivatives (MD) was actually confirmed by13C NMR spectroscopy. The thermal behavior of MD was monitored by means of thermogravimetry (TG) and differential thermal analysis (DTA), and the thermal stability of MD was lower than XH.

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.

scholarly journals Purification of Aluminium Cast Alloy Melts through Precipitation of Fe-Containing Intermetallic Compounds

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 796 ◽  
Author(s):  
Marina Gnatko ◽  
Cong Li ◽  
Alexander Arnold ◽  
Bernd Friedrich
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Intermetallic Compounds ◽  
Cast Alloy ◽  
Intermetallic Phase ◽  
Temperature Ranges ◽  
Fe Intermetallics ◽  
Alloy Properties ◽  
Secondary Materials ◽  
Scanning Electron

Aluminium secondary materials are often contaminated by impurities such as iron. As the alloy properties are affected by impurities, it is necessary to refine aluminium melts. The formation of Fe intermetallics in aluminium melts can be used to develop a purification technology based on the removal of intermetallic compounds. In this study, the temperature range for effective separation of intermetallics was determined in an industrial-relevant Al–Si–Fe–Mn system with 6 to 10 Si wt. %, 0.5 to 2.0 Fe wt. %, and 0 to 2.0 Mn wt. %. Based on DTA (Differential Thermal Analysis) and SEM (scanning electron microscope) results and following the rules of phase boundary drawing, isopleths were drawn. This method allows to derive the temperature ranges of intermetallic phase stability and can be applied for the assessment of melt-refining parameters.

Zeolites Fit For A Crown: Probing Host-Guest Interactions with Thermogravimetric Methods

2018 ◽  
Author(s):  
Asel Sartbaeva ◽  
Paul R. Raithby ◽  
Remi Castaing ◽  
Antony Nearchou
Keyword(s):  
Mass Spectrometry ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Petrochemical Industry ◽  
Rational Use ◽  
New Methodologies ◽  
First Time ◽  
Kinetics Of

Through a combination of thermogravimetry, mass spectrometry and differential thermal analysis, we demonstrate for the first time that all four zeolites show experimental differences in their host-guest interactions with 18C6. In addition, we have estimated the kinetics of 18C6 decomposition, which is a technique that has not been applied to zeolites previously. Using these findings as a toolkit, a more rational use of OSDAs can be utilised to prepare designer zeolites. Furthermore, the new methodologies presented herein can be applied to current zeolites, such as MFI-type zeolites used in the petrochemical industry.

PHASE EQUILIBRIUM IN THE AS2TE3-TM2TE3 SYSTEM.

2020 ◽  
Vol 5 (8(77)) ◽  
pp. 65-68
Author(s):  
Teymur Mammad Ilyasly ◽  
Rahman Hasanaga Fatullazade ◽  
Zakir Islam Ismailov ◽  
Nigar Nadir Jafarova
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Differential Thermal Analysis ◽  
Phase Equilibrium ◽  
Physicochemical Properties ◽  
Thermal Effects ◽  
Isothermal Annealing ◽  
Intermediate Phase ◽  
Physicochemical Analysis ◽  
Two Phases

The synthesis of alloys of the system was carried out stepwise in rotary furnaces. The synthesis mode was selected based on the physicochemical properties of the elementary components. For homogenization, the alloys were subjected to isothermal annealing at 750 and 1275 K, depending on the Tm2Te3 concentration, for 250 h after homogenization of the alloys, they were subjected to physicochemical analysis. The results of differential thermal analysis showed that reversible thermal effects are observed in the alloys of the system. In alloys in a 1: 1 ratio, a new intermediate phase is formed with a composition corresponding to the TmAsTe3 compound. The homogeneity area is observed in the concentration range 52.5-47.5. It was found that in the concentration range 98.5-52.5 Tm2Te3 there are two phases - a mixture of β and of the solid solution, and in the concentration range of 47.51 mol% Tm2Te3 phases and α are in equilibrium. ) 66 The eutectic has coordinates of 11.5 mol Tm2Te3 at a temperature of 575 K.

PENINGKATAN LAJU DISOLUSI ACYCLOVIR DENGAN METODE SISTEM DISPERSI PADAT MENGGUNAKAN POLOXAMER 188

2016 ◽  
Vol 5 (1) ◽  
pp. 6
Author(s):  
Budi Setiawan ◽  
Erizal Zaini ◽  
Salman Umar
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Scanning Electron Microscopy ◽  
Fourier Transform ◽  
Differential Thermal Analysis ◽  
Fourier Transform Infrared ◽  
X Ray Diffraction ◽  
Poloxamer 188 ◽  
X Ray ◽  
Scanning Electron

Sebuah penelitian tentang sistem dispersi padat dari asiklovir dengan poloxamer 188 telah dilakukan formulasi dengan pencampuran secara fisika dengan rasio 1 : 1, 1 : 3, 1 : 5 dan dispersi padat 1 : 1, 1 : 3, 1 : 5 dan penggilingan 1:1 sebagai pembanding. Dispersi padat dibuat menggunakan metode pencairan (fusi), yang digabung dengan poloxamer 188 pada hotplate kemudian asiklovir dimasukkan ke dalam hasil poloxamer 188 lalu di kocok hingga membentuk masa homogen. Semua formula yang terbentuk termasuk asiklovir poloxamer 188 murni dianalisis karakterisasinya dengan Differential Thermal Analysis (DTA), X-ray Diffraction, Scanning Electron Microscopy (SEM), dan Fourier Transform Infrared (FTIR), kemudian pengambilan dilakukan  (penentuan kadar) mengunakan spektrofotometer UV pada panjang gelombang 257,08 nm dan uji laju disolusi dengan aquadest bebas CO2 menggunakan metode dayung. Hasil pengambilan  (penentuan kadar) menunjukkan bahwa semua formula memenuhi persyaratan farmakope Amerika edisi 30 dan farmakope Indonesia edisi 4 yaitu 95-110%. Sedangkan hasil uji laju disolusi untuk campuran fisik 1: 1, dan dispersi padat 1: 1, dan penggilingan 1: 1 menunjukkan peningkatan yang nyata dibandingkan asiklovir murni. Hal ini juga dapat dilihat dari hasil perhitungan statistik  menggunakan analisis varian satu arah  SPSS 17.

Kinetics of temperature-programmed reactivation of a hydrodesulphurization catalyst

1983 ◽  
Vol 48 (12) ◽  
pp. 3340-3355 ◽  
Author(s):  
Pavel Fott ◽  
Pavel Šebesta
Keyword(s):  
Carbon Dioxide ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thin Layer ◽  
Kinetic Parameters ◽  
Diffusion Region ◽  
Reaction Heat ◽  
Gaseous Products ◽  
Temperature Programmed ◽  
Kinetics Of

The kinetic parameters of reactivation of a carbonized hydrodesulphurization (HDS) catalyst by air were evaluated from combined thermogravimetric (TG) and differential thermal analysis (DTA) data. In addition, the gaseous products leaving a temperature-programmed reactor with a thin layer of catalyst were analyzed chromatographically. Two exothermic processes were found to take part in the reactivation, and their kinetics were described by 1st order equations. In the first process (180-400 °C), sulphur in Co and Mo sulphides is oxidized to sulphur dioxide; in the second process (300-540 °C), in which the essential portion of heat is produced, the deposited carbon is oxidized to give predominantly carbon dioxide. If the reaction heat is not removed efficiently enough, ignition of the catalyst takes place, which is associated with a transition to the diffusion region. The application of the obtained kinetic parameters to modelling a temperature-programmed reactivation is illustrated on the case of a single particle.

Effect of experimental conditions on the differential thermal-analysis of karnallite type hydrates

1984 ◽  
Vol 49 (12) ◽  
pp. 2770-2775
Author(s):  
Vladimir Z. Poilov ◽  
Jana Ederová ◽  
Antonín Blažek
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Experimental Conditions

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