Calcium aluminates

About: Calcium aluminates is a research topic. Over the lifetime, 490 publications have been published within this topic receiving 9200 citations.

A Study on Calcium Transfer from Slag to Steel and its Effect on Modification of Alumina and Spinel Inclusions

Abstract: Aluminum deoxidized steel tends to form solid inclusions (alumina, spinel, partially modified calcium aluminates). These solid inclusions are known to present challenges during casting, cause slivers during mechanical working and act as crack initiation sites for mechanical failure. Calcium injection practice has been used by the industry to transform these solid inclusions into liquid inclusions for several decades. There has been a significant amount of study to understand the mechanism of calcium modification of alumina/spinel inclusions. However, there has been little attempt to understand calcium transfer from slag to steel to inclusions that may modify alumina inclusions. In this study, laboratory deoxidation experiments were conducted using an induction furnace, physically simulating a ladle furnace; samples were taken during these experiments to study the extent of calcium transfer through inclusion analysis. This study shows that in the presence of silicon, there can be significant amount of calcium transfer from slag. Also, as the rate of calcium transfer from slag is limited by mass transfer in steel and slag, it is difficult to modify a large concentration of inclusions. However, an appreciable extent of calcium transfer was found in the case of lower concentration of inclusions (less than 150 ppm area fraction).

Quick setting agent and spraying material

Abstract: PROBLEM TO BE SOLVED: To provide a quick setting agent which can be suitably used for forming a spraying material having high initial strength. SOLUTION: The quick setting agent is characterized by containing amorphous calcium aluminates and crystalline calcium aluminates. COPYRIGHT: (C)2009,JPO&INPIT

Strength Properties and Micro-structure of Steel Slag Based Hardened Cementitious Composite with Graphene Oxide

Abstract: For the rapid hardening of concrete, various types of calcium aluminate composite have been used for special purpose as shotcrete or rapid repairing in construction field. However, high cost of calcium aluminates is demerit in the point of expanding usage. In recent years, a new binder for rapid hardening has been introduced as the pulverized ladle furnace slag (RC-LFS) with main components of C 12 A 7 and β-C 2 S. Like other traditional cementitious materials, it’s use will preserve natural resources and has high environmental advantage with economic efficiency, by transferring the industry byproducts into high value materials. Even though flake state, graphene oxide has high tensile strength and electric conductivity. Then, it can be used to increase strength and thermal properties of concrete and its efficiency depends on the dispersion in the cement matrix. In this paper, we used graphene oxide for increasing the engineering properties in RC-LFS concrete with GGBFS. Test results showed that the 0.05w% of graphene oxide increase the flexural strength to 26% and compressive strength to 16%.

Mechanochemical Synthesis of Tricalcium Aluminum Hydrate from Calcium Hydroxide-Boehmite Mixtures by Room Temperature Grinding

Abstract: Tricalcium aluminum hydrate (3CaO·Al2O3·6H2O：C3AH6) is synthesized mechanochemically from mixtures composed of calcium hydroxide (Ca(OH)2) and pseudo-boehmite (γ-AlO(OH)) powders by room temperature grinding using a planetary ball mill. Use of the boehmite sample with inferior crystallinity is more favorable for the mechanochemical synthesis rather than that with well crystalline one. The time required to form C3AH6 from the Ca(OH)2-γ-AlO(OH) mixture is much longer than that from the Ca(OH)2-gibbsite (Al(OH)3) one. Adsorbed water from air during grinding plays a significant role in the formation of C3AH6 from the former mixture. After water addition to Ca(OH)2-γ-AlO(OH) mixtures ground for various times, excess hydrated calcium aluminates such as C2AH8, C3AH8-12 and C2A0.5H6.5 are formed in the starting and the short time ground mixtures, while a few amount of these compounds is formed in these hydrated mixtures after prolonged grinding. Formation of these excess hydrated compounds, which belong to layered structural materials, is enhanced in the presence of free Ca, Al compounds and water.

Characterization of W-Ir Mixed Metal Matrix Scandate Cathode

Abstract: In this paper development and characterization of W-Ir mixed metal matrix scandate cathodes prepared by impregnating W-Ir (80% - 20% by weight) mixed metal matrices with 3% scandium oxide doped 5:3:2 barium calcium aluminates are discussed Emission characterization, Auger electron spectroscopy and life test results are discussed