scholarly journals Physicochemical Interaction Processes in the Carbon (Diamond)–Silicon System

2021 ◽  
Vol 47 (3) ◽  
pp. 197-208
Author(s):  
V. Ya. Shevchenko ◽  
S. N. Perevislov ◽  
V. L. Ugolkov
Keyword(s):  
Thermal Analysis ◽  
Reaction Diffusion ◽  
Chemical Processes ◽  
Physicochemical Interaction ◽  
Reaction Sintering ◽  
Minimal Energy ◽  
Subsequent Reaction ◽  
Periodic Surfaces ◽  
Interaction Processes ◽  
Silicon System

Abstract The chemical processes occurring during the interaction of carbon (diamond) with silicon are experimentally investigated. Thermal analysis of the interaction of diamond with silicon is carried out. This made it possible to determine the mechanism of the synthesis of silicon carbide and subsequent reaction sintering of diamond particles based on Turing’s reaction-diffusion process and the formation of a microstructure consisting of triple periodic surfaces of the minimal energy.

A BGK MODEL FOR CHEMICAL PROCESSES: THE REACTION-DIFFUSION APPROXIMATION

1994 ◽  
Vol 04 (01) ◽  
pp. 35-47 ◽  
Author(s):  
RENATO SPIGLER ◽  
DAMIÁN H. ZANETTE
Keyword(s):  
Kinetic Model ◽  
Diffusion Approximation ◽  
Reaction Diffusion ◽  
Chemical Processes ◽  
Reaction Diffusion Equations ◽  
The Other ◽  
Diffusion Equations ◽  
Bgk Model ◽  
Chemical Substances ◽  
Chemical Effects

A BGK-type kinetic model is derived for describing the interaction of chemical substances. The ensuing equation is then solved asymptotically on certain space-time scales on which an appreciable interplay between kinetic and chemical effects, or the prevailing of one on the other, can be observed. The description of the interaction at the macroscopic level consists of a hierarchy of reaction-diffusion equations satisfied by the densities. Comparison is made with similar results previously obtained from certain phenomenological models, and illustrative examples are given.

Physical and Mechanical Properties of Mullite-Whisker Reinforced Alumina Composites

2007 ◽  
Vol 334-335 ◽  
pp. 325-328 ◽  
Author(s):  
Wei Kong Pang ◽  
Nobuo Tezuka ◽  
It Meng Low ◽  
E.G. Mehrtens ◽  
Bruno A. Latella
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Hot Isostatic Pressing ◽  
Physical And Mechanical Properties ◽  
Reaction Sintering ◽  
Alumina Matrix ◽  
Young’S Moduli ◽  
Solid Density ◽  
Alumina Composites

Reaction sintering and hot-isostatic-pressing (HIP) have been used for the compaction and densification of mullite-whisker-reinforced alumina composites. The effect of alumina matrix constraints on the in-situ transformation sequence in alumina-halloysite-AlF3 system was studied using differential thermal analysis. The physical and mechanical properties of the HIPed samples have been characterized in terms of bulk density, apparent solid density, porosity, Young’s moduli, flexural strength, hardness and the fracture toughness.

scholarly journals Study of a Waste Kaolin as Raw Material for Mullite Ceramics and Mullite Refractories by Reaction Sintering

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 583
Author(s):  
Pedro José Sánchez-Soto ◽  
Dolores Eliche-Quesada ◽  
Sergio Martínez-Martínez ◽  
Luis Pérez-Villarejo ◽  
Eduardo Garzón
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Relative Proportion ◽  
Raw Material ◽  
High Alumina ◽  
Size Analysis ◽  
Hammer Mill ◽  
Reaction Sintering ◽  
X Ray ◽  
Maximum Value

A deposit of raw kaolin, located in West Andalusia (Spain), was studied in this work using a representative sample. The methods of characterization were X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size analysis by sieving and sedimentation, and thermal analysis. The ceramic properties were determined. A sample of commercial kaolin from Burela (Lugo, Spain), with applications in the ceramic industry, was used in some determinations for comparison purposes. The kaolin deposit has been produced by alteration of feldspar-rich rocks. This raw kaolin was applied as an additive in local manufactures of ceramics and refractories. However, there is not previous studies concerning its characteristics and firing properties. Thus, the meaning of this investigation was to conduct a scientific study on this subject and to evaluate the possibilities of application. The raw kaolin was washed for the beneficiation of the rock using water to increase the kaolinite content of the resultant material. The results indicated that the kaolinite content of the raw material was 20 wt % as determined by XRD, showing ~23 wt % of particles lower than 63 µm. The kaolinite content of the fraction lower than 63 µm was 50 wt %. Thus, an improvement of the kaolinite content of this raw kaolin was produced by wet separation. However, the kaolin was considered as a waste kaolin, with microcline, muscovite and quartz identified by XRD. Thermal analyses by Thermo-Dilatometry (TD), Differential Thermal Analysis (DTA) and Thermo-Gravimetry (TG) allowed observe kaolinite thermal decomposition, quartz phase transition and sintering effects. Pressed samples of this raw kaolin, the fraction lower than 63 µm obtained by water washing and the raw kaolin ground using a hammer mill were fired at several temperatures in the range 1000–1500 °C for 2 h. The ceramic properties of all these samples were determined and compared. The results showed the progressive linear firing shrinkage by sintering in these samples, with a maximum value of ~9% in the fraction lower than 63 µm. In general, water absorption capacity of the fired samples showed a decrease from ~18–20% at 1050 °C up to almost zero after firing at 1300 °C, followed by an increase of the experimental values. The open porosity was almost zero after firing at 1350 °C for 2 h and the bulk density reached a maximum value of 2.40 g/cm3 as observed in the ground raw kaolin sample. The XRD examination of fired samples indicated that they are composed by mullite, from kaolinite thermal decomposition, and quartz, present in the raw sample, as main crystalline phases besides a vitreous phase. Fully-densified or vitrified materials were obtained by firing at 1300–1350 °C for 2 h. In a second step of this research, it was examined the promising application of the previous study to increase the amount of mullite by incorporation of alumina (α-alumina) to this kaolin sample. Firing of mixtures, prepared using this kaolin and α-alumina under wet processing conditions, produced the increase of mullite in relative proportion by reaction sintering at temperatures higher than 1500 °C for 2 h. Consequently, a mullite refractory can be prepared using this kaolin. This processing of high-alumina refractories is favoured by a previous size separation, which increases the kaolinite content, or better a grinding treatment of the raw kaolin.

Lime-Mediated Sewage Sludge and Gas Ash use as Metallurgy Sintering Ingredients

2013 ◽  
Vol 779-780 ◽  
pp. 1623-1628
Author(s):  
Chen Hong ◽  
Yi Xing ◽  
Yan Xiao Si ◽  
Zhi Qiang Wang ◽  
Guang Wei Yu ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Weight Loss ◽  
Differential Thermal Analysis ◽  
Sewage Sludge ◽  
Integration Method ◽  
Reaction Sintering ◽  
Analysis Method ◽  
Pyrolysis Process ◽  
Indoor Temperature ◽  
Air Atmosphere

The thermogravimetry - differential thermal analysis (TG-DTA) and theoretical analysis method of Coats-Redfern were employed to study the pyrolysis process and kinetics characteristics of mixture containing lime-mediated sewage sludge and gas ash, then sintering cup test the different proportion of mixture ball. It was found that the pyrolysis process of mixture from indoor temperature 1200°Ccould divided into 4 the weight loss stages, which brings a large number of heat and CaO, Fe2O3. Base on the results of Coats-Redfem integration method, the pyrolysis process of mixture under air atmosphere was belongs to two-class reaction. Sintering cup test show that lime-mediated sewage sludge and gas ash replacing part of the sintering ingredients is feasible.

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