The current research is concerned with methods of formation and their effect on the sintering process of ceramic materials. The research is divided into a number of chapters. The first chapter addressed the research structure (the research problem, importance, objective, limits, and it also defined the terms used in the research). The second chapter addressed the theoretical framework, where the theoretical framework has been divided into three sections. The first section dealt with methods of formation of ceramic materials including: Plasticizing method 2- semi-dry pressing method 3- dry pressing method 4- extrusion method 5- casting method.
The researcher found that there is a clear difference between the methods through her formation of tables and as it is clear in the research body. As for the second section, it addressed studying the raw ceramic materials that the researcher has classified into: 1- plastic raw materials 2- non-plastic raw materials. In the third section, the researcher addressed types and divisions of sintering: First: sintering in the solid state and its stages. Second: sintering with the presence of an effective liquid. Third: sintering by pressing and hot compression.
The third chapter consists of the research procedures that addressed 1- preparing the raw material. 2- Examination of the raw material through a- chemical analysis b- metal composition c- thermal microscope examination. 3- Preparing the mixtures where four hypotheses have been put and in every hypothesis, the researcher dealt with what results from mixing the materials (Silica, crock, sodium carbonate, and kaolin under various temperatures and pressure). 4- preparing the laboratory models in which the researcher tackled 1- mixing the materials 2- forming the laboratory models 3- drying process 4-burning process 5- determining the general features for the models. The researcher has conducted some experiments to determine the features of the models after the burning process according to the following: Calculating the longitudinal contraction b- water suction c-virtual space. The fourth chapter addressed and discussed the research results. The researcher reached at the results through conducting the laboratory examinations for the samples within tables (4, 5) affixed in the research. The recommendations and suggestions put forth by the researcher to complete the scientific approach for the research are as follows: 1- not to start the research before finding the oven. 2- Conducting examinations using a thermal microscope before burning 3- burning at a slow timing rate to prevent the occurrence of distortions.
In Iraq, government contributions to the public companies have become a very important aspect which contributes to the survival and sustainability of these institutions as it consider one of the main sources of funding, if not it consider the basis of funding.
According to the vital roles assigned to these institutions to follow up, which usually include important activities in the national economy, the research focused on studying the field reality of the method used in evaluating the stock of total production and purchases of goods for the purpose of selling the strategic commodities of the General Company for Grain Trade. As a result, the aim of this study came to came to highlight&n
... Show MoreThe superconductor compound (YBa2Cu2.8Zn0.2O7+δ) is prepared by solid state reaction (SSR), Sol-gel (SG) and laser Pulse deposition (PLD) methods. We used the X-ray diffraction technique, which shows an orthorhombic crystalline system for all the samples, and increase in the high-phase (Y-123) and decrease in low-phase and vary in proportion according to the method of preparation with the emergence of some impurities. The behavior of the samples in terms of electrical resistance and critical temperature was investigated all samples showed superconducting behavior. The properties of the dielectric (real dielectric constant, imaginary dielectric constant, loss tangent, alternating electrical conductivity) were s
... Show MoreThe study aimed to clarify the meanings learned and inferred from reading books، letters and messages in Surat Al-Qur’an. The inductive method، the analytical method، and the deductive method، One of the most prominent results of the research: that the multiplicity of Qur’anic readings produces a variety and expansion in the meaning that has a clear impact on the interpretation by clarifying the meaning of the verse.
The regression analysis process is used to study and predicate the surface response by using the design of experiment (DOE) as well as roughness calculation through developing a mathematical model. In this study; response surface methodology and the particular solution technique are used. Design of experiment used a series of the structured statistical analytic approach to investigate the relationship between some parameters and their responses. Surface roughness is one of the important parameters which play an important role. Also, its found that the cutting speed can result in small effects on surface roughness. This work is focusing on all considerations to make interaction between the parameters (position of influenc
... Show MoreNowadays, university education stands in front of both students who feel they are weak and teachers who are addicted to using traditional and dependent teaching. This has led to have negative repercussions on the learner from different aspects, including the mental aspect and the academic achievement process. Therefore, the present research is concerned with finding a new teaching method that adopts the motivation by the fear of failure technique. Thus, the study aims to examine the effect of adopting this method on students’ academic achievement. To achieve this aim, an experimental method was used, and an achievement test was built for the curriculum material of level two students. The pretest test was applied on 17 male and female s
... Show MoreSol-gel method was use to prepare Ag-SiO2 nanoparticles. Crystal structure of the nanocomposite was investigated by means of X-ray diffraction patterns while the color intensity was evaluated by spectrophotometry. The morphology analysis using atomic force microscopy showed that the average grain sizes were in range (68.96-75.81 nm) for all samples. The characterization of Ag-SiO2 nanoparticles were investigated by using Scanning Electron Microscopy (SEM). Ag-SiO2 NPs are highly stable and have significant effect on both Gram positive and negative bacteria. Antibacterial properties of the nanocomposite were tested with the use of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria. The results have shown antibacteri
... Show MoreBackground: Ceramic veneers represent the treatment of choice in minimally invasive esthetic dentistry; one of the critical factors in their long term success is marginal adaptation. The aim of the present study is to evaluate the marginal gap of ceramic veneers by using two different fabrication techniques and two different designs of preparation. Material and methods: A typodont maxillary central incisor used in the preparation from which metal dies were fabricated, which were in turn used to make forty stone dies. The dies divided into four experimental groups, each group had ten samples: A1: prepared with butt-joint incisal reduction and restored with IPS e.max CAD, A2: prepared with overlapped incisal reduction and restored with IPS e.
... Show MoreBending effects on the transmission of optical signal are investigated on a single mode
optical fiber (SMOF) of 10 m length, core radius of 5 μm and optical refractive index difference
0.003. The bending radii (R) were between 0.08 and 0.0015 m. A great decrease in the amplitude is
shown for radii below 0.01 m. Sudden break down occurs for radii less than 0.0015 m. Birefringence
(B) is difficult to measure for long fibers. Meanwhile, B was found by comparing with calibrated
fiber of the same properties but of length of 0.075 m. The results show an increase in propagation
constant (Δβ) and the decrease in beat length (Lb), and show that bending decreases the critical radius
of curvature (Rc) related to B. The chang
Experiments were conducted to study axial liquid dispersion coefficient in slurry bubble column of 0.15 m inside diameter and 1.6 m height using perforated plate gas distributor of 54 holes of a size equal to 1 mm diameter and with a 0.24 free area of holes to the cross sectional area of the column. The three phase system consists of air, water and PVC used as the solid phase. The effect of solid loading (0, 30 and 60 kg/m3) and solid diameter (0.7, 1.5 and 3 mm) on the axial liquid dispersion coefficient at different axial location (25, 50 and 75 cm) and superficial gas velocity covered homogeneous-heterogeneous flow regime (1-10 cm/s) were studied in the present work. The results show that the axial liquid dispersion coeffic
... Show MoreThis research aims to examine the ability of impact of the cash flow statement indicators in the change in the market value of the industrial firms listed on the Palestine Stock Exchange. The research population consisted of (13) firms during the period (2015-2020). Data were collected from the annual financial statements of the firms. The research relies on the Pooled effects model to analyze the cross-section data (Panel Data), and the multiple regression method to test the hypotheses. The research finds a positive significant impact of (the ratios of cash flows from operating activities to sales, the return on assets from operating cash flows, and cash flows from operating activities to total current liabilities) in the change
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