http://nopr.niscpr.res.in/handle/123456789/8821 2026-10-09T07:06:13Z http://nopr.niscpr.res.in/handle/123456789/30403 Title: Stabilising dimensions of brass powder components Authors: Ansari, Akhter H; Hameedullah, M; Asghar, M S J Abstract: <span style="mso-bidi-language:HI">Powder metallurgy components are manufactured by compacting metal powders. Hence, compaction pressure affects the properties of the components. In the present case, pre-alloyed cartridge brass (70:30) powder is employed for investigation and the effect of compaction pressure on dimensional properties of components is studied. A volumetric shrinkage is observed at various levels of compaction pressure. The shrinkage reduces with an increase in compaction pressure. It is 1.0% at 242 MPa, which reduces further to 0.4% at 725 MPa. At high level of compaction pressure, the <span style="mso-bidi-language:HI">shrinkage is found along the diameter. A swelling of 1.0% in diameter is exhibited at low level. </span></span> Page(s): 481-486 2004-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/9329 Title: Decolourisation of metal complex azo dyes and treatment of a dyehouse waste by modified photo-Fenton (UV-vis/ferrioxalate/H₂O₂) process Authors: Tripathi, Pooja; Chaudhuri, Malay Abstract: In a laboratory study, decolourisation of three metal complex azo dyes (Acidol Yellow, Acidol Grey and Acidol Scarlet) in mixture by the modified photo-Fenton (UV-vis/ferrioxalate/H₂O₂) process, and treatment of a dyehouse waste containing the three dyes were examined. From decolourisation of the dye mixture, process conditions for decolourisation were selected – <i style="">p</i>H 4, Fe(III) dose 12.5 mg/L, oxalic acid dose 50 mg/L, hydrogen peroxide dose 60 mg/L and irradiation time 90 min. Ninety-two percent decolourisation of the dye mixture (colour 120 SU) occurred in 90 min under irradiation with sunlight intensity in the range 0.5-0.8 kW/m². The process was found effective in decolourisation of highly coloured solutions. Modified photo-Fenton decolourisation of the synthetic dyehouse waste (<i style="">p</i>H 7.5, colour 120 SU, COD 260 mg O₂/L, BOD₅ 125 mg/L, turbidity 1.5 NTU, conductivity 1265 mmho/cm and total solids 875 mg/L) under selected process conditions and irradiation with sunlight or incandescent lamp, was also studied. Ninety-two percent decolourisation (residual colour ca 10 SU) was achieved under 90 min irradiation with sunlight (0.5-0.8 kW/m²) or incandescent lamp (6.5 kW/m²). A depth of 30 cm was found to be the maximum depth for decolourisation. The study has demonstrated that modified photo-Fenton is an effective process for decolourisation of dyehouse waste containing metal complex azo dyes. A scheme for oxidative treatment of the dyehouse waste was formulated and the treatment efficiency was evaluated – 90-92% or 90-92%, 69-70% or 63-73%, and 52-65% or 50-60% removal of colour, COD and BOD₅ were achieved under irradiation with sunlight or incandescent lamp. Page(s): 499-504 2004-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/9328 Title: Property analysis and mathematical modeling of machining properties of aluminium alloy hybrid (Al-alloy/SiC/flyash) composites produced by liquid metallurgy and powder metallurgy techniques Authors: Charles, S; Arunachalam, V P Abstract: Aluminium hybrid composites reinforced with silicon carbide and flyash particulates were fabricated by stir casting and powder metallurgy methods. Different volume fractions of SiC particles (10, 15 and 20 vol%) and constant volume fraction of flyash (10 vol%) were used for the synthesis. Wear, micro hardness, tensile and microstructural properties were studied. Results of the investigations indicated that wear resistance and hardness were enhanced on increasing the vol% of SiC. The tensile strength was high at 10 vol% of SiC and it decreased as the vol% increased. Microstructure showed a fairly uniform distribution of the dispersoids. Electric discharge machining was done on the composite specimens and mathematical models were developed for predicting the material removal rate and tool wear rate using design of experimentation with current, pulse duration and vol% of SiC as the process variables. Curves describing the direct and interaction effect of the process variables were drawn. It was found that the material removal rate and tool wear rate increased with increase in current and decreased with increase in pulse duration and vol% of SiC. The behaviour of the composites was similar both for powder metallurgy and stir casting, except the fact that stir cast specimens exhibited higher hardness, wear resistance and tensile strength. This increase can be attributed to the close interfacial bonding of stir cast specimens. Page(s): 473-480 2004-12-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/9327 Title: An investigation on the applicability of Cartesian grid approach to calculate flow over arbitrary terrain Authors: Vengadesan, S; Nakayama, A; Yokojima, S Abstract: An investigation is made on the applicability of method of representing by Cartesian grid to calculate flow over natural terrain. Model hill geometry with different maximum slope angles is chosen and calculations by both Cartesian and Boundary-fitted coordinate representations are made. Computations are performed for laminar flow at different Reynolds numbers and turbulent flow conditions. Results in terms of mean velocity distribution, streamline, vorticity distribution and velocity vector close to the surface are analyzed and discussed. The study indicates that to calculate flow over undulating natural terrain, rectangular coordinate method of representing the geometry is able to capture most of the flow phenomena and it can be a viable alternative. Page(s): 465-472 2004-12-01T00:00:00Z