Using Iraqi materials to produce lining refractories with international standards
In this study dense high alumina refractories were manufactured according to DIN51053 standards and characterizations (physical, mechanical, and thermal) of fired specimens were investigated. The mixtures of specimens were prepared from different weight percentages of (kaolinite, bauxite with additives of alumina to all mixture ratio). The aims of this study was to benefit of local raw materials to produced high alumina refractory characterized by low porosity, in addition to manufacture thermal insulation to use as lining in different industrial furnaces, and enhance the thermal insulation, thermal stability, and mechanical properties of high alumina refractory by adding alumina. From the results it have been obtained high alumina refractory with high compressive strength, high thermal stability, and thermal insulation also have characterized by low porosities and high bulk density.
Production of High Alumina Fire Brick from Iraqi Clay
The importance of refractory materials in various industries such as lining of kilns, furnaces and the need for exploitation of raw materials which are available in Iraqi industries. So this work deal with the exploitation of Iraqi kaolin from Dewechla deposits, as a raw material in the manufacturing of high alumina fire brick. High alumina fire brick specimens (alumina content about 70%) were prepared by semi-dry pressing, then drying and burned at different temperatures 1200,1300, 1400,1500Cᵒ for 2hr soaking time and 100Cᵒ/hr firing rate. Investigations of these specimens show that, the increasing alumina content will increase the strength, the porosity of the fire products, while the hardness, apparent density, water absorption and permanent linear change will decrease. These properties affected by the firing temperature, where the formations of the mullite phase play a governed role in the behavior and properties of the final products. In addition, the results reveal that the fire brick products appear to withstand thermal shock resistance; it can be used as thermal insulator in various industries. The thermal conductivity and density behavior of products containing alumina ˃ 70% are vary as a function of porosity. Thus, the insulating property of the end product can be improved through the porosity and its distribution.
Influence of filler addition, storage medium and evaluation time on biaxial flexure strength and modulus of adhesive systems
Abstract Objective. This study evaluated the effects of filler addition, storage medium and time on biaxial flexural strength and flexural modulus of six adhesive systems. Materials and methods. The adhesives were either unfilled resins: Single Bond, Prime&Bond 2.1 and One-Step; or filled resins: Single Bond Plus, Prime&Bond NT and One-Step Plus. Resin discs of each product (0.5 mm thick × 6.0 mm diameter) were prepared using silicon molds (n = 10). The discs were stored dry, in water, mineral oil or ethanol for 1 week or 3 months before biaxial flexural testing. Data were statistically analyzed by 3-way ANOVA and Tukey's post-hoc test (α = 0.05). The specimens were tested in a universal testing machine at 1.27 mm/min until failure occurred. Results. In general, the storage in ethanol led to significantly lower flexural strength and flexural modulus values than the other storage conditions for all adhesives in both storage periods. Filler addition increased flexural strength and flexural modulus for Prime&Bond NT, when it was stored dry or in water for 1 week. For Single Bond Plus, the filler addition resulted in higher flexural modulus, when it was stored for 1 week in oil and in ethanol. No significant differences in flexural modulus were observed between One-Step and One-Step Plus in any storage medium. Conclusions. Results suggested that filler addition does not necessarily have to increase the flexural strength and flexural modulus. Ethanol and oil storages tended to yield opposite effects.