Abstract: The Equal Channel Angular Extrusion (ECAE) process is a promising technique for imparting large plastic deformation to materials without a resultant decrease in cross-sectional area. The die consists of two channels of equal cross section intersecting at an angle of 110°C. The work piece is placed in one channel and extruded into the other using a punch. In the present study, Influence of equal channel angular extrusion on room temperature, the mechanical properties of Aluminum Alloy AA 6351 alloy was investigated. The results show that, the mechanical properties of Aluminum AA 6351alloy, such as yield strength, ultimate tensile strength and elongation, can be improved heavily by equal channel angular extrusion. Processing routes, processing temperature and extrusion passes have important influence on room temperature mechanical properties of processed Aluminum AA 6351alloy by equal channel angular extrusion. The mechanical properties such as yield strength and ultimate tensile strength can be enhanced when Aluminum AA 6351 alloy was processed by equal channel angular extrusion for single pass at route A at 303 K.

Abstract: Galena particles (concentrate) were analyzed by sedimentation method using conventional technique, appropriate apparatus and reagents. A critical evaluation of the relationship between effective particle depth and a consortium of factorials; settling time and particle diameter was carried out using a derived model which is two-factorial-quadratic in nature. Results of the sedimentation analysis show increased effective depth reached by the particles as a result of decrease in the descending particle diameter, and increased settling time. The validity of derived model; β = 2 x 10^-5 γ² - 5 x 10^-4 γ – 1.5 x 10^-3 α + 0.2176 is rooted on the core expression β - 1.5 x 10^-3 = 2 x 10^-5 γ² - 5 x 10^-4 γ + 0.2176 where both sides of the expression are correspondingly approximately equal to 0.2. The model validity was verified through comparative evaluation of the settling rates from experimental and model-predicted results. These settling rates are 0.002 and 0.0025 m/mins. respectively which are in proximate agreement. The standard error incurred in predicting the effective particle depth for each value of settling time & particle diameter considered as evaluated from experiment and derived model are 0.0018 and 0.0027 & 0.0005 and 0.0024 respectively. Maximum deviation of model-predicted results from experiment was less than 3%, implying a confidence applicability level of about 97%.

Abstract: Oven-dewatering of Otamiri clay designated for production of porcelain was carried out over a time and temperature range: 30-130 mins. and 80-110°C respectively, following a well strategize step-wise preparation of the clay in as-mine condition. Multi-factorial analysis of periodic water loss during the drying process was also carried out using a derived empirical model. Water loss at 100°C by evaporation through a rectangular surface was found to be least compared to other drying temperatures considered irrespective of the drying time. This was basically due to the fall-back of condensed part of the water leaving the drying clay as steam, since steam can re-convert to water without any change in temperature. Evaluations from generated results indicate that the evaporation rates of the Otamiri clay and the standard error incurred in predicting water loss for each value of the drying times considered, as obtained from experiment, derived model and regression model were 0.0770, 0.0733 and 0.0733g min^-1 as well as 0.8051, 2.1 x 10^-4 and 3.45 x 10^-5 % respectively. The maximum deviation of the model-predicted water loss (from experimental results) was less than 20%, implying a model confidence level above 80%.