Preparation of near net size porous alumina‐calcium aluminate ceramics by gelcasting‐pore‐forming agent processs

2020 ◽  
Vol 103 (8) ◽  
pp. 4602-4610
Author(s):  
Bian‐Lei Hao ◽  
Ying Lang ◽  
Da‐Qian Bian ◽  
Chang‐An Wang
Keyword(s):  
Calcium Aluminate ◽  
Porous Alumina

An HREM study of superstructures in Ca4Al6SO16

1990 ◽  
Vol 48 (4) ◽  
pp. 1066-1067
Author(s):  
Y.G. Wang ◽  
H.Q. Ye ◽  
K.H. Kuo
Keyword(s):  
Calcium Aluminate ◽  
Structural Model ◽  
Bright Spot ◽  
Sulphur Atom ◽  
Synthetic Compound ◽  
Space Group ◽  
Lattice Images ◽  
Cubic Structure ◽  
Good Agreement

A synthetic compound Ca4Al6SO16 (usually abbreviated as C4A3S) obtained by mixing CaO, A12O3 and CaSO4 powders and finally sintered at 1380°C is a cement with excellent hydraulicity and greatly expanding in application. It is hydralysed rapidly by water to form predominatly calcium aluminate hydrates and therefore unlikly to occur naturally, although structurally it may be regarded as an end member of the sodalite-hauynite series of naturally occuring minerals. C4A3S has a cubic structure with ao=9.19Å and space group . Fig.1 is the projection viewed down axis, in which there are two sets of 8C position in , namely CaI and CaII, occupied by the calcium atoms, respectively, and the ratio of occupations in these two sets of positions is about 3:1. This suggests that the calcium atoms can freely occupy these sites in various degrees and usually they almost locates on the CaI positions. A through-focus series of the lattice images were found in good agreement with the simulated ones. Each bright spot in the image taken at Scherzer defocus correspounds to a colunm of sulphur atom in the structural model (Fig.1).

Porous Alumina Ceramic Prepared by HEMA-TBA Gelcasting System

2017 ◽  
Vol 32 (7) ◽  
pp. 731 ◽  
Author(s):  
XIE Yu-Zhou ◽  
PENG Chao-Qun ◽  
WANG Xiao-Feng ◽  
WANG Ri-Chu ◽  
LUO Feng
Keyword(s):  
Porous Alumina ◽  
Alumina Ceramic

Quick Setting Property and Hydration of Portland Cement with Accelerating Agent Based on Calcium Aluminate.

2000 ◽  
Vol 49 (2) ◽  
pp. 209-214
Author(s):  
Minoru TAKEHIRO ◽  
Seishi GOTO ◽  
Koji IOKU ◽  
Hirotaka FUJIMORI
Keyword(s):  
Portland Cement ◽  
Calcium Aluminate ◽  
Agent Based

Catalytic wet air oxidation of dyeing and printing wastewater

1997 ◽  
Vol 35 (4) ◽  
pp. 311-319 ◽  
Author(s):  
L. Lei ◽  
X. Hu ◽  
H. P. Chu ◽  
G. Chen ◽  
P. L. Yue
Keyword(s):  
High Pressure ◽  
Reaction Time ◽  
Textile Industry ◽  
Porous Alumina ◽  
Supported Catalyst ◽  
Metal Salts ◽  
Treated Wastewater ◽  
Catalytic Wet Air Oxidation ◽  
Air Oxidation ◽  
Wet Air Oxidation

The treatment of dyeing and printing wastewater from the textile industry by oxidation was studied. The reaction was carried out in a two-litre high pressure reactor. In order to promote the oxidation of organic pollutants present in the wastewater, experiments were conducted using various catalysts including metal salts, metal oxides, and porous alumina supported metals. All catalysts tested were able to enhance the conversion of organic compounds in wastewater, shorten the reaction time, and lower the reaction temperature. The alumina supported catalyst has an advantage over other catalysts in that it can be easily separated from the treated wastewater by filtration and recycled. The conditions in preparing the catalyst supported by porous alumina were experimentally optimised.

scholarly journals Study by DTA/TG of the formation of calcium aluminate obtained from an aluminium hazardous waste

2009 ◽  
Vol 99 (3) ◽  
pp. 999-1004 ◽  
Author(s):  
A. López-Delgado ◽  
F. A. López ◽  
L. Gonzalo-Delgado ◽  
S. López-Andrés ◽  
F. J. Alguacil
Keyword(s):  
Hazardous Waste ◽  
Calcium Aluminate

scholarly journals Physicochemical, Mineralogical, and Mechanical Properties of Calcium Aluminate Cement Concrete Exposed to Elevated Temperatures

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3855
Author(s):  
Amirmohamad Abolhasani ◽  
Bijan Samali ◽  
Fatemeh Aslani
Keyword(s):  
Temperature Rise ◽  
Calcium Aluminate ◽  
Elevated Temperatures ◽  
Ultrasonic Pulse Velocity ◽  
Pulse Velocity ◽  
Calcium Aluminate Cement ◽  
Cement Concrete ◽  
Sem Images ◽  
Strength Deterioration ◽  
Aluminate Cement

One commonly used cement type for thermal applications is CAC containing 38–40% alumina, although the postheated behavior of this cement subjected to elevated temperature has not been studied yet. Here, through extensive experimentation, the postheated mineralogical and physicochemical features of calcium aluminate cement concrete (CACC) were examined via DTA/TGA, X-ray diffraction (XRD), and scanning electron microscopy (SEM) imaging and the variation in the concrete physical features and the compressive strength deterioration with temperature rise were examined through ultrasonic pulse velocity (UPV) values. In addition, other mechanical features that were addressed were the residual tensile strength and elastic modulus. According to the XRD test results, with the temperature rise, the dehydration of the C3AH6 structure occurred, which, in turn, led to the crystallization of the monocalcium dialuminate (CA2) and alumina (Al2O3) structures. The SEM images indicated specific variations in morphology that corresponded to concrete deterioration due to heat.

scholarly journals Laboratory Test to Evaluate the Resistance of Cementitious Materials to Biodeterioration in Sewer Network Conditions

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 686
Author(s):  
Amr Aboulela ◽  
Matthieu Peyre Lavigne ◽  
Amaury Buvignier ◽  
Marlène Fourré ◽  
Maud Schiettekatte ◽  
...  
Keyword(s):  
Calcium Aluminate ◽  
Standardized Test ◽  
Performance Indicator ◽  
Cementitious Materials ◽  
Test Method ◽  
Sustainable Construction ◽  
Public Health Issue ◽  
Sulfur Source ◽  
Test Protocol ◽  
Wide Range

The biodeterioration of cementitious materials in sewer networks has become a major economic, ecological, and public health issue. Establishing a suitable standardized test is essential if sustainable construction materials are to be developed and qualified for sewerage environments. Since purely chemical tests are proven to not be representative of the actual deterioration phenomena in real sewer conditions, a biological test–named the Biogenic Acid Concrete (BAC) test–was developed at the University of Toulouse to reproduce the biological reactions involved in the process of concrete biodeterioration in sewers. The test consists in trickling a solution containing a safe reduced sulfur source onto the surface of cementitious substrates previously covered with a high diversity microbial consortium. In these conditions, a sulfur-oxidizing metabolism naturally develops in the biofilm and leads to the production of biogenic sulfuric acid on the surface of the material. The representativeness of the test in terms of deterioration mechanisms has been validated in previous studies. A wide range of cementitious materials have been exposed to the biodeterioration test during half a decade. On the basis of this large database and the expertise gained, the purpose of this paper is (i) to propose a simple and robust performance criterion for the test (standardized leached calcium as a function of sulfate produced by the biofilm), and (ii) to demonstrate the repeatability, reproducibility, and discriminability of the test method. In only a 3-month period, the test was able to highlight the differences in the performances of common cement-based materials (CEM I, CEM III, and CEM V) and special calcium aluminate cement (CAC) binders with different nature of aggregates (natural silica and synthetic calcium aluminate). The proposed performance indicator (relative standardized leached calcium) allowed the materials to be classified according to their resistance to biogenic acid attack in sewer conditions. The repeatability of the test was confirmed using three different specimens of the same material within the same experiment and the reproducibility of the results was demonstrated by standardizing the results using a reference material from 5 different test campaigns. Furthermore, developing post-testing processing and calculation methods constituted a first step toward a standardized test protocol.

Joining of Porous Alumina with a CaO-Al2 O3 -SiO2 Glass-Ceramic

2013 ◽  
Vol 96 (6) ◽  
pp. 1738-1744 ◽  
Author(s):  
Weiwei Zhu ◽  
Jichun Chen ◽  
Chunhai Jiang ◽  
Chuanyong Hao ◽  
Jinsong Zhang
Keyword(s):  
Glass Ceramic ◽  
Porous Alumina ◽  
Sio2 Glass
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