The interfacial reaction in Cr3C2/Al2O3 composites

1999 ◽  
Vol 14 (3) ◽  
pp. 817-823 ◽  
Author(s):  
Ding-Fwu Lii ◽  
Jow-Lay Huang ◽  
Jin-Jay Huang ◽  
Horng-Hwa Lu
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Interfacial Reaction ◽  
Experimental Analysis ◽  
Computer Assisted ◽  
Sintering Atmosphere ◽  
Gas Concentration ◽  
Equilibrium Oxygen ◽  
Equilibrium Oxygen Partial Pressure ◽  
Good Agreement

This study investigates the effects of sintering atmosphere and temperature on the interfacial properties of Cr3C2/Al2O3 composites. Thermodynamic considerations and calculations with computer-assisted methods for the equilibrium compositions in the Al–O–Cr–C system were used to simulate the interfacial reaction in Cr3C2/Al2O3 composite during sintering. The results were in good agreement with the experimental analysis. Cr3C2 is more stable during sintering in a system with carbon due to the lower equilibrium oxygen partial pressure. Controlling CO and O2 gas concentration, Cr3C2 first oxidized, decarbonized, and then transformed to Cr7C3 before reacting with Al2O3. An interfacial reaction between Cr3C2 and Al2O3 was not observed.

Thermodynamic analysis of oxidation during selective laser melting of pure titanium

2020 ◽  
Vol 26 (8) ◽  
pp. 1401-1404
Author(s):  
Won-Hyuk Lee ◽  
Tae-Wook Na ◽  
Kyung-Woo Yi ◽  
Seung-Min Yang ◽  
Jang-Won Kang ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Concentration ◽  
Oxidation Behavior ◽  
Pure Titanium ◽  
Initial Powder ◽  
Laser Melting ◽  
Content Type ◽  
Equilibrium Oxygen ◽  
Equilibrium Oxygen Partial Pressure

Purpose When a pure titanium component is fabricated in a selective laser melting (SLM) process using titanium powder, the oxygen concentration of the SLM sample increases compared to the initial powder. The purpose of this paper is to study the reason for increasing oxygen concentration after SLM. Design/methodology/approach To understand this phenomenon, the authors analyzed the oxidation behavior during the SLM process thermodynamically. Findings Based on the laser parameters used in this study, the temperature of the Ti melt during the SLM process was expected to rise to 2,150°C. Based on the thermodynamic analysis, the equilibrium oxygen partial pressure for oxidation was 2.32 × 10−19 atm at 2,150°C when the dissolved oxygen concentration in the titanium is 0.2 wt.%. However, the oxygen partial pressure inside the SLM chamber was 1 × 10−3 atm, which is much higher than the equilibrium oxygen partial pressure. Therefore, oxidation occurred during the SLM process, and the oxygen concentration of the SLM sample increased compared to the initial powder. Originality/value Most studies on fabricating Ti components using additive manufacturing (AM) have been focused on how the changes in the microstructures and mechanical properties depend on the process parameters. However, there are a few studies that analyzed the oxygen concentration change of Ti during the AM process and its causes. In this study, the authors analyzed the oxidation behavior during the SLM process thermodynamically.

Ionic transport in LiNbO3

1991 ◽  
Vol 6 (4) ◽  
pp. 851-854 ◽  
Author(s):  
Apurva Mehta ◽  
Edward K. Chang ◽  
Donald M. Smyth
Keyword(s):  
Ionic Conductivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Ionic Transport ◽  
Ionic Transport Number ◽  
Cell Measurement ◽  
Experimental Validity ◽  
Pressure Independent ◽  
Temperature Equilibrium ◽  
Good Agreement

The high temperature equilibrium conductivity (950 °C–1050 °C) of congruent LiNbO3 can be resolved into two components: an electronic portion that is dependent on the oxygen partial pressure and an ionic portion that is pressure independent. It is shown that the two components can be obtained from an analysis of the total equilibrium conductivity measured as a function of oxygen partial pressure. The ionic transport number (fractional ionic conductivity) thus obtained is compared with that obtained from an oxygen concentration cell measurement. The two techniques are found to be in excellent agreement, confirming the experimental validity of the defect chemistry method. From the temperature dependence of the ionic conductivity, the activation energy (138 kJ/mol [1.43 eV]) for the ionic transport is obtained. The results are in good agreement with the value previously obtained for the oxygen chemical diffusivity.

scholarly journals Wet Oxidation of Dairy Sewage

2012 ◽  
Vol 19 (1) ◽  
pp. 29-38
Author(s):  
Klara Piotrowska ◽  
Mirosław Imbierowicz ◽  
Andrzej Chacuk
Keyword(s):  
Kinetic Model ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Organic Compounds ◽  
Reduction Rate ◽  
Kinetic Studies ◽  
Wet Oxidation ◽  
Tank Reactor ◽  
Good Agreement

Wet Oxidation of Dairy Sewage Results of kinetic studies on the process of wet oxidation of dairy sewage are presented. Experiments were carried out in a stirred batch tank reactor at the oxygen partial pressure equal to 1 MPa and at temperature ranging from 473 to 523 K. Dairy sewage was subjected to oxidation at a natural pH close to 4. The efficiency of decomposition of organic compounds was estimated on the basis of TOC measurement. The highest TOC reduction rate reached 79.6%. A kinetic model of the process was proposed and its parameters were determined experimentally. Good agreement of the experimental and calculated results was obtained.

The Oxygen Defect Chemistry of La2−xSrxCuO4−x/2+δ

1990 ◽  
Vol 209 ◽  
Author(s):  
Elizabeth J. Opila ◽  
Harry L. Tuller
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Content ◽  
Defect Chemistry ◽  
Oxygen Stoichiometry ◽  
Oxygen Defect ◽  
Defect Model ◽  
Strontium Concentration ◽  
Partial Pressures ◽  
Equilibrium Oxygen

ABSTRACTThe equilibrium oxygen stoichiometry of La2−xSrxCuO4±y (x=O, 0.2, 0.4, and 1.0) has been determined by TGA at temperatures between 800 and 1050°C and oxygen partial pressures between 1 and 10−4 atmospheres. The changes in oxygen content with temperature, oxygen partial pressure, and strontium concentration are evaluated in terms of a defect model.

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