جستجوی مقالات مرتبط با کلیدواژه "granulation" در نشریات گروه "فنی و مهندسی"

In this research, the production process of YSZ powder for thermal spraying by co-precipitation method is presented, which is divided into two main stages. In the first stage, YSZ material is obtained through a series of processes, including preparing a soluble precursor from the salts that make up the YSZ powder based on stoichiometric ratios, hydrolyzing the precursor, filtering the precipitates, drying the precipitates, and calcining them. After various tests and confirmation of the chemical composition, phase composition, and purity of the synthesized YSZ powder, the first stage is completed. In the second stage, the produced powders undergo the granulation process to increase their flowability and thermal sprayability. Following the completion of the second synthetic stage, YSZ powder is ready for use in thermal barrier coatings. The synthesized powder closely resembles the highly regarded Metco 204NS-G powder, known for its superior performance and final coating structure.

Nowadays, concrete has received special attention due to reasons such as the ease of preparation of constituent components, low costs compared to other materials, favorable engineering properties, extraordinary durability, formability, and most importantly, positive interaction with the environment. Although the construction of concrete with the main components of cement, aggregate and water is very simple and conventional, but the addition of new materials such as fibers causes the fragility of concrete to be significantly reduced and it shows ductile behavior under different loads. Fibrous concrete is actually a type of composite that, with the use of reinforcing fibers in the concrete mixture, does not easily fall apart under the impact of impact loads, and its tensile strength increases above normal.Concrete gains very little strength at very low temperatures, so when the degree of saturation of the concrete is not sufficiently reduced by the dewatering action, it is necessary to protect the concrete against damage caused by freezing. The use of polyolefin fibers and the effect of appropriate granulation in the concrete mixing plan is one of the effective factors in reducing the effect of freezing. In this article, the reason for the use of polyolefin fibers, the manufacturing method, mechanical properties, fiber concrete applications, and the effect of mixing design granulation on the compressive strength and abrasion percentage of fiber concrete samples in the normal environment and freezing, according to the results of applications and researches has been discussed.

Methylene blue and crystal violet dyes are the most widely used dyes in some industries such as textiles, silk, and wood. Accumulation of cationic dyes in water resources is harmful to humans, animals, and the environment, so their removal from the effluents of the dyeing industry is essential. Among all the treatment methods, adsorption is one of the most attractive routes for the treatment of polluted water due to its low cost and simplicity of design. According to the studies, it can be seen that zeolites modified with iron nanoparticles show a high adsorption capacity in the removal of dyes. However, the use of adsorbents in the form of fine powders is still difficult and their use in continuous systems is limited due to the cracking and the pressure drop.

To solve the problems of adsorbents in powder form, the ionic gelation method was used to prepare a granular adsorbent based on natural zeolite clinoptilolite modified with Fe3O4 nanoparticles. In order to prepare granules with suitable appearance and high adsorption percentage, the effect of various parameters such as initial pH of the solution, type and concentration of the crosslinking solution and initial ratio of alginate to nanocomposite was investigated. The synthesized granules were investigated by XRD, SEM-EDX and BET analysis.

The results showed that the pH was ineffective and the iron (III) chloride solution was optimal with a concentration of (2 w/v%) and an initial ratio of 1:4 alginate to nanocomposite. The maximum adsorption capacity of the prepared granules towards methylene blue and crystal violet adsorption was determined as 12.484 mg/g and 11.904 mg/g by Langmuir isotherm, respectively, which indicated to a high ability of the prepared granules to remove these cationic dyes.