NOPR Collection:

Compressive stress-strain curves of natural fibre reinforced concrete

2016-07-20T06:16:59Z

Title: Compressive stress-strain curves of natural fibre reinforced concrete Authors: Siddique, R Abstract: The effects of addition of various percentages and lengths of natural san (Crotoralia Juncea) fibre on the compressive stress-strain curves of concrete are determined. From the compressive stress-strain curves, modulus of elasticityof fibre reinforced concrete is obtained. Three volume percentages of fibres, viz., 0.25, 0.50 and 0.75% and three different lengths, viz., 20, 25 and 30 mm are used. Presence of fibres increases the ductility of concrete and does not significantly affect the modulus of elasticity of concrete. The values of modulus of elasticity are compared with a theoretical model based on the law of mixtures. Page(s): 237-239

A comparative study of LaCoO₃ prepared by various wet chemical methods

2016-07-20T06:16:06Z

Title: A comparative study of LaCoO₃ prepared by various wet chemical methods Authors: Keshavaraja, A; Ramaswamy, A V Abstract: A comparative study off our different methods of preparation of LaCoO₃ by precipitation as oxalates, carbonates, citrates and hydroxides of La and Co followed by calcination at different temperatures to form LaCoO₃ is presented. The extent of formation of the LaCoO₃ phase from the precursors as a function of temperature is systematically followed using XRD, TG-DTA, and FT-IR techniques. Higher surface area (20 m²/g) samples of LaCoO₃ with no oxide impurities and with smaller particle size are formed from the citrate complex and the mixed hydroxides on calcination at 873 K. These are found to be more active in the oxidation of C₂-C₄ hydrocarbons at 573 K than the samples prepared from other mixed precipitates or by the ceramic route. Page(s): 229-236

Carburization of steels-An overview

2016-07-20T05:37:39Z

Title: Carburization of steels-An overview Authors: Prasannan, P C Abstract: A high carbon upper layer is produced by diffusing carbon and the carburized steel is used in gears, crankshafts where high ware and tare occurs. The thermodynamic, kinetic and transport phenomenon occurring during carburization is studied. Importance of thermochemical phase diagrams to determine the stability region of the oxides and carbides is illustrated. The relationship between the composition of the carburizing atmosphere and the carbon content of the steel is brought out Development of a suitable heat treating environment for obtaining the correct penetration depth is attempted. Mechanism of carburization, kinetic and reaction mechanism of decomposition of gas mixture on the steel surface is described. Models for predicting carburization depth are reviewed. A diffusion model is proposed which is applicable to any diffusion-cum-reaction process. Application and hazards of carburization are explained. Page(s): 221-228

Wear of grinding media and order of wear laws in tumbling ball mills

2016-07-20T06:15:13Z

Title: Wear of grinding media and order of wear laws in tumbling ball mills Authors: Raju, K R Abstract: In order to distinguish between Davis' volume law and Bonds' surface law for short duration tests for wear of balls, the test duration has been extended beyond a certain cross over point. The results of Menacho have been utilized for the determination of these cross-over points as affected by the wear order. The cross over point values for the dimensionless time (t*), diameter (d*) and mass (m*) as a function of wear order have also been determined to test the validity of orders of wear laws. Page(s): 217-220

NOPR Collection:

Compressive stress-strain curves of natural fibre reinforced concrete

A comparative study of LaCoO3 prepared by various wet chemical methods

Carburization of steels-An overview

Wear of grinding media and order of wear laws in tumbling ball mills

A comparative study of LaCoO₃ prepared by various wet chemical methods