Experimental Study on the Oxide Scale of Steel Slab under Oxygen-Enrichment Combustion

2013 ◽  
Vol 395-396 ◽  
pp. 327-330
Author(s):  
Li Ying Qi ◽  
Da Qiang Cang ◽  
Liu Hong

In this paper, A test furnace design for use in oxygen-enriched combustion to investigate the oxide scale of steel slab. The heating time, oxygen content and temperature were investigated, and the structure of oxides formed on the slab was characterized. The results show that magnetite film formed on the slab increases in thickness with oxygen enrichment which restricts the diffusion of oxygen and make oxide scale decreased, the oxidation loss of billet has reduced by approximately 37% and the fuel has a 26% fuel savings because of the heating time is decreased

2020 ◽  
Vol 10 (1) ◽  
pp. 49
Author(s):  
Suharto Suharto ◽  
Muhammad Amin ◽  
Muhammad Al Muttaqii ◽  
Syafriadi Syafriadi ◽  
Kiki Nurwanti

Experimental study on the use of basalt stone originated from Lampung has been conducted to evaluate its potential for a partial substitute of raw material in production of cement clinker. The basalt stone contains minerals of anorthite, augite, and albite phases that are required for clinker formation. In this study, the main raw materials were 80% limestone, 10% silica sand, 9% clay and 1% iron sand. The raw material in these experiments were mixtures 90% or 80% of the main raw material and 10% or 20% of basalt stone. The effect of adding coal to raw materials was also studied to see the possibility of an increase in clinkerization temperature inside the raw material mixture, and at the same time to see the effect of coal ash on clinker composition. Clinker obtained from heating of raw materials at a temperature of 1100oC had LSF of 94.1% and 95.1% (heating time of 1 and 3 hours). If heating is carried out at 1200oC, the clinker had LSF of 97.7% and 98.0% (heating time of 2 and 3 hours, respectively). Depending on the temperature and duration of heating, the clinker mostly had SM in the range of 2.18-2.40% , and AM in the range of 0,78-1.80%. Characterization using XRD showed that the clinker consisted of larnite and gehlenite phases, and dominated by CaO.Batu basalt Lampung telah diuji potensinya sebagai pengganti sebagian bahan baku utama pembuatan klinker semen. Batu basalt tersebut memiliki mineral-mineral dalam fase anorthite, augite, dan albite yang diperlukan pada pembentukan klinker. Pada penelitian ini, bahan baku utama adalah batu kapur 80%, pasir silika 10%, tanah liat 9% dan pasir besi 1%. Campuran bahan baku klinker adalah 90% atau 80% bahan baku utama dan 10% atau 20% batu basalt. Efek penambahan batubara ke dalam bahan baku klinker juga dipelajari untuk melihat kemungkinan kenaikan temperatur klinkerisasi di dalam campuran bahan baku, dan sekaligus untuk melihat efek abu batubara terhadap komposisi klinker. Klinker hasil pemanasan bahan baku pada temperatur 1100oC memiliki LSF 94,1% dan 95,1% (lama pemanasan 1 dan 3 jam). Jika pemanasan dilakukan pada 1200oC, klinker memilik LSF 97,7% dan 98,00% (lama pemanasan 2 dan 3 jam). Tergantung pada temperatur dan lama pemanasan, klinker hasil percobaan ini umumnya memiliki SM 2,18-2,40%, dan AM antara 0,78-1,80%. Karakterisasi dengan XRD menunjukkan bahwa klinker terdiri dari fase larnite dan gehlenite, dan didominasi CaO.


2013 ◽  
Vol 27 (10) ◽  
pp. 6191-6197 ◽  
Author(s):  
Nazim Merlo ◽  
Toufik Boushaki ◽  
Christian Chauveau ◽  
Stéphanie de Persis ◽  
Laure Pillier ◽  
...  

2020 ◽  
Vol 321 ◽  
pp. 06009
Author(s):  
Dominique Poquillon ◽  
Coralie Parrens ◽  
Alessandro Pugliara ◽  
Maxime Perrais ◽  
Benoit Malard

Titanium alloys are widely used in many applications thanks to their good corrosion resistance and to their high specific modulus. However, at temperatures above 450°C, oxidation must be taken into account to improve life assessment of components. Especially for long-term exposures, oxidation leads to an oxide scale along with an oxygen enrichment in the metal below this oxide scale. In this study, the oxidation behaviour of Ti– 6Al–4V is investigated between 450 and 600°C for a maximum duration of about 6800 h. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) are used to characterize the oxide layer and the layer affected by oxygen uptake. The local oxygen content is quantified. Vibration tests are performed to determine elastic properties on thin specimens with different thicknesses affected by oxygen enrichment. Creep tests are also carried out to quantify the influence of this oxygen uptake on viscoplastic behaviour. An oxygen-enriched zone occupying 5% of the cross-section of a specimen is sufficient to induce detectable changes in its creep behaviour.


Vestnik IGEU ◽  
2019 ◽  
pp. 16-24
Author(s):  
G.A. Perevezentsev ◽  
V.A. Gorbunov ◽  
O.B. Kolibaba

One of the effective ways to intensify heat exchange processes in the bulk tank is organization of gas filtration through the tank. However, it is necessary to compare the positive effect obtained by reducing the heating time and, hence, the required amount of heat input with the resistance of the bulk tank, which affects the choice of equipment. The existing formulas for determining tank layer resistance, as a rule, have a limited application range due to a number of structural parameteres. Thus, obtaining the value of the aerodynamic resistance of bulk tanks of different structures is an important task for determining the amount of energy consumed for the organization of the filtration process. The work employed the data obtained in the experimental study of fluid filtration through a porous medium in the range of porosity values. The method of nonlinear regression analysis was used to approximate the desired dependence. Based on the data on the resistance of bulk tanks of different porosity obtained in the experimental study, the authors have derived an empirical polynomial dependence of the resistance of bulk tanks on the fluid mass flow rate and porosity. This equation can be applied for the filtration rate values from 2 to 8 m/s and porosity values from 0,345 to 0,888 regardless of the structural parameters of the bulk tank layer. The authors carried out mathematical modeling of the air filtration process through the tank by replacing the real structure with a fractal-like model. The obtained results allow optimizing the operating parameters of the equipment in thermal heating furnaces, and the presented dependence can be used to determine the aerodynamic resistance of bulk tanks, affecting the choice of traction equipment in the reconstruction of furnaces. The accuracy of the obtained results is determined by the experiment error, which does not exceed 7 %.


2010 ◽  
Vol 158 ◽  
pp. 71-75 ◽  
Author(s):  
Xiu Juan Su ◽  
Wei Mo ◽  
Shao Jian Ma ◽  
Jin Lin Yang ◽  
Mei Qun Lin

The microwave pretreatment of a typically refractory flotation gold concentrate was investigated. The results demonstrated that a maximum gold recovery of 97% was achieved, and that gold recoveries of the refractory gold concentrate quickly increased to the maximum with microwave heating time. Adding additives during microwave heating process was helpful to improve the leaching rate of gold, and the effect of microwave heating with single NaOH on the leaching rate of gold is not better than that of NaOH combined with other additives.


ACS Omega ◽  
2020 ◽  
Vol 5 (47) ◽  
pp. 30495-30501
Author(s):  
Fahui Wang ◽  
Jingning Chen ◽  
Xiaoping Wen ◽  
Qiang Hu

2019 ◽  
Vol 142 (3) ◽  
pp. 1275-1286 ◽  
Author(s):  
S. Madhankumar ◽  
M. Jerome Stanley ◽  
S. Thiyagarajan ◽  
V. Edwin Geo ◽  
V. Karthickeyan ◽  
...  

Author(s):  
B. Öztürk ◽  
L. Mengis ◽  
D. Dickes ◽  
U. Glatzel ◽  
M. C. Galetz

AbstractThe Ti-6Al-4V alloy is extensively used in aerospace, automotive and biomaterial applications. In the aerospace industry, the service temperature of Ti-6Al-4V is currently limited to 350 °C due to its insufficient oxidation resistance. Oxidation at higher temperatures causes the formation of a fast-growing oxide scale and an oxygen-enriched subsurface layer, which is known as the “alpha-case.” Additionally, the effect of water vapor on the oxidation behavior is critical. In the present study, the oxidation behavior of Ti-6Al-4V in dry air and air containing 10 vol.% H2O at 500, 600 and 700 °C for up to 500 h has been investigated. The main focus of this study is the examination of the different oxide scale morphologies along with the oxygen enrichment in the subsurface zone. It has been observed that spallation of the oxide scale is more severe in a water vapor-containing environment. In dry air, the oxide morphology shows the typical layered TiO2/Al2O3 structure after exposure at 700 °C for 300 h, while Al2O3 precipitates are present in the outermost part of the TiO2 scale when oxidized in wet air. This indicates that the solubility and diffusivity of Al3+ ions in TiO2 are influenced by water vapor. In addition, the extent of oxygen enrichment in the subsurface zone (alpha-case) as a function of temperature and time is determined by nanoindentation profiles. It was shown that in contrast to the scale formation, the alpha-case thickness is not affected by the presence of water vapor in the atmosphere.


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