The effects of high-energy ball milling and subsequent calcination on the formation of barium aluminate cementing phases using mixtures of Al2O3 and BaCO3 were investigated. Silica fume was further added in the raw mixtures to observe its role on the cementing phase formation. Results indicated that the decomposition temperature of BaCO3 lowered remarkably with the increase of milling time. X-ray diffraction (XRD) results confirmed the presence of several crystalline barium-silicate and barium-aluminate phases. Barium-Aluminate cements with grain size in nanometer range were obtained from high-energy ball milled raw mixtures. Formation of crystalline BaAl2O4 phase was observed between 1000-1100°C in the raw mixtures, which were obtained in amorphous state after milling for 5h. This temperature is at least 300°C lower than that used in the traditional solid-state method. Fume SiO2 additions resulted in BaAl2Si2O8 (celsian) formation which acted as a retarder providing more workability and mechanical strength.
1. Introduction
Researches are being carried out to obtain better performance of high temperature cements to be applied for refractory castables and monolithic refractory products [1-8]. Efforts are also being done to minimize the furnace lining cost by using unconventional processes for high temperature cement production [9-20]. The new developments in high temperature cements have provided better innovations in castable preparation and significant improvement in product performance in the steel and foundry industries [21-23]. The calcium aluminate cements (CACs) are the most widely used high temperature cement for concretes based on aggregates of quartz, cordierite, alumina, spinel, zirconia and magnesia [24-50]. It is obse...
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...ling process has been applied to mixtures of Al2O3 and BaCO3. The reaction between Al2O3 and BaCO3 towards single phase BaAl2O4 formation is obtained at much lower temperatures (~ 1000°C). High energy ball milling process has a significant effect to obtain high reactivity of mixes prepared by commercial raw materials, that reaction of the oxides is initiated at temperature as low as 900°C. The effect of high-energy ball milling on the fineness of the mixtures, microstructure development of the milled powders, cementing properties and phase analysis was investigated. Further addition of fume silica in various amounts in ground mixtures of Al2O3 and BaCO3 was done. Formation of barium aluminate-celsian composite cement was observed and this phase increased setting time of the barium aluminate cement and thus an improvement in workability of cement pastes was observed.
Die-forming of sheet metal has been around for thousands of years. Originally the metal was manipulated by hand and hammered into the depression, by utilizing crude grooves carved into wood or stone. This technique was used to make spouts, handles, and other forms. Since then, however; they have undergone a remarkable technological evolution. Mate-female conforming dies to create hollow forms by using hydraulic pressure or drop hammer pressure, changed die-forming forever (Paisin, 2013).
Ceramics have high hardness and wear resistance, making them suitable for applications such as the articulating surfaces in joints and bone bonding surfaces in implants. Ceramics like alumina and zirconia are more appropriate to use in joint replacements and dentistry whereas hydroxyapatite or calcium phosphate cements are useful for bone bonding applications which is assist with bone growth and implant integration with surrounding natural bone and tissues (http://www.azom.com/article.aspx?ArticleID=108).
There are many different types of sanders in our world that vary from random orbit, spindle, belt, disc, hand, vibrating, drum, detail, and so forth. A sander is a power tool that is used for smoothing a surface with sandpaper or other abrasive materials. Each woodworking sander serves a certain purpose so that you may be able to complete your task more efficiently. They vary from being a manual sander to being an electrically powered sander. Typically in the world of carpenters and woodworkers they will usually stick with power sanders just because they are more time consuming and there is less manual labor that is necessary.
Milling offers the advantages of being highly precise and having much smoother surface finish (surface roughness of easily around 1 µm ) compared to powder bed fusion additive manufacturing (layer thickness in the range of 20 µm and above; surface roughness of 15 µm and above ). Flat surfaces and sharp corners can be obtained with CNC milling. Similarly, features such as threads and holes are more accurately created through
In this experiment, we will look at the concentration of sodium bicarbonate in the light reaction of photosynthesis. This will be carried out using three different colored filters to identify the effect on the light reaction of photosynthesis. Since, photosynthesis is the process whereby light energy is captured by plant, algal, or bacterial cells and is used to synthesize organic molecules from carbon dioxide and water. Although, photosynthesis is atmospheric carbon dioxide is removed and transformed into oxygen and carbohydrates. Elodea is an aquatic plant of a genus that includes the ornamental waterweeds. Sodium bicarbonate is commonly known as baking soda. On the other hand, there are four primary photosynthetic pigments found in the chloroplast
Investigating the Thermal Decomposition Of Metal Carbonates Aim: To investigate a range of metal carbonates and see if they thermally decompose. Thermal Decomposition INVESTIGATION [IMAGE] ------- Written By Tauqir Sharif ------------------------ Research: When a metal is thermally decomposed the bond between the metal and its carbonate (carbon and oxygen) is removed and the carbonate is released as carbon dioxide. Metal Carbonate = Metal Oxide + Carbon Dioxide Malachite is an ore of copper.
In order to gain strong insight into the surface chemistry of silica we have perform a thorough literature search. Our goal is to identify the pioneer research performed on silica and silica supported catalyst. Particular interest lies in silica-water-cobalt and silica-alcohol-cobalt systems. This study is both on macro and micro level so that a complete theoretical base can be established. From this theoretical knowledge, key areas to look upon will be identified and a design of experiments will be established. The goal is to develop a both efficient and effective product (catalyst) using a novel methodology developed from past research.
Baking Powder is a crucial ingredient in baking and is more commonly used than Baking Soda because of its soft texture. It is made up of Sodium Bicarbonate, Monocalcium Phosphate, and Carbon Dioxide. Baking Powder is more compacted and naturalized than Baking Soda. It is used to help with the cupcakes' leavening- which means to rise. Without the Baking Powder the cupcakes would be dense, flat and very hard.
The micro hardness of the prepared samples were obtained by using a Vickers Micro hardness Tester (Model : Leco LV 700, USA). 5 readings were taken for each sample to calculate the average hardness. An indentation load of 5gf was used. After calculating the average hardness for each sample, mean variance and standard deviation (S.D.) was calculated to check the consistency of the data.
The Synthesis of Alum from Aluminum lab centralized on the creation of potassium aluminum sulfate dodecahydrate from a set amount of aluminum, and using quantitative analysis to then compare the actual yield to the theoretical yield. The synthesis of alum was conducted through a series of steps involving aluminum foil, potassium hydroxide, and sulfuric acid. Given that aluminum is amphoteric, meaning it can dissolve in both strong acids and strong bases, potassium hydroxide and sulfuric acid were both suitable for the dissolution of aluminum. There are multiple applications to synthesizing alum; from eliminating waste in the environment by repurposing, to utilizing alum as a medical treatment, the practicality of alum is immense.
Concrete is a composite material used widely in the construction industry. Concrete is basically a mixture of cement, water, aggregates and admixture (sometimes). Cement is a fine gray powder that consists of oxidizes calcium, silicon and aluminum. The aggregate used is normally gravel, crushed stone or sand. Admixture is a solid or liquid substance that gives a certain characteristics of the concrete. The cement reacts with water chemically and binds the aggregates together through a process called hydration during hardening or curing of concrete. It means that water helps in the hardening of the concrete while the cement bind the aggregate and also react with water to form a solid mass.
The basis for the understanding of the heat treatment of steels is the Fe-C phase diagram. Because it is well explained in earlier volumes of Metals Handbook and in many elementary textbooks, the stable iron-graphite diagram and the metastable Fe-Fe3 C diagram. The stable condition usually takes a very long time to develop, especially in the low-temperature and low-carbon range, and therefore the metastable diagram is of more interest. The Fe-C diagram shows which phases are to be expected at equilibrium for different combinations of carbon concentration and temperature. We distinguish at the low-carbon and ferrite, which can at most dissolve 0.028 wt% C at 727 oC and austenite which can dissolve 2.11 wt% C at 1148 oC. At the carbon-rich side we find cementite. Of less interest, except for highly alloyed steels, is the d-ferrite existing at the highest temperatures. Between the single-phase fields are found regions with mixtures of two phases, such as ferrite + cementite, austenite + cementite, and ferrite + austenite. At the highest temperatures, the liquid phase field can be found and below this are the two phase fields liquid + austenite, liquid + cementite, and liquid + d-ferrite. In heat treating of steels the liquid phase is always avoided. Some important boundaries at single-phase fields have been given special names. These include: the carbon content at which the minimum austenite temperature is attained is called the eutectoid carbon content. The ferrite-cementite phase mixture of this composition formed during cooling has a characteristic appearance and is called pearlite and can be treated as a microstructural entity or microconstituent. It is an aggregate of alternating ferrite and cementite particles dispersed with a ferrite matrix after extended holding close to A1. The Fe-C diagram is of experimental origin. The knowledge of the thermodynamic principles and modern thermodynamic data now permits very accurate calculations of this diagram.
Cement is a finely ground compound of limestone and clay or marl (Chandigarh, 2001). It is used in hydraulic binding since it hardens and binds together aggregates and becomes waterproof thereafter. The most popular use of sand is in building and construction where it is used to bind sand and gravel to obtain concrete used in constructing houses, roads, water channels, among others. Yanbu Cement company produces different types of cement such as Portland cement types I, II, III and IV.
During the past two decades significant research effort has been made to develop a better understanding of the crystallization mechanisms like nucleation, growth etc, as well as on the modeling and control of crystallization systems. The advancement in process analytical technology and computing power has made this task much easier. The key developments have occurred in novel crystallization concepts, modeling, monitoring and control. A major development in the modeling area is the use of multi-dimensional population balance models which gives the morphological model of crystallization processes, as well as in the better understanding of crystallization in impure media. Developments in...