Papers by Author: Mohammad M. Haque

Abstract: Two types of cast irons with Fe-C-Si and Fe-C-Al. alloy systems were investigated in the present study. In order to modify the microstructure and properties of cast iron, Al was added to low silicon pig iron that is in Fe-C-Al (Sorel metal) alloy system. Its effect was then studied with comparing to normal Fe-C-Si alloy system. Both cast irons were produced in sand mould of suitable design to provide all information regarding the structure and properties. The microstructure was analyzed using optical microscope which showed the distribution of graphite flakes in pearlite or ferro-pearlite matrix. The size of the graphite flakes in Fe-C-Al system was smaller and more evenly distributed compared to the Fe-C-Si alloy system. The cast product was also characterized by using XRD. The maximum hardness of the Fe-C-Al alloy was measured as 110.2 HRB compared to 89.32 HRB of the conventional Fe-C-Si alloy system. The impact test results showed that Fe-C-Al cast iron has higher impact property than Fe-C-Si cast iron.

Abstract: In order to study the wear properties of Fe-C-Si and Fe-C-Al alloy systems, castings were produced in resin bonded sand mould of suitable design, which provides information regarding various thicknesses of the castings. Gray cast iron is an inexpensive and readily available material used for manufacturing of roller, roller shell, piston rings, cylinder liners, etc. Its low melting point is characterized as unique combination of superior properties like good friction and wear properties and economic in manufacturing. In the present study, wear behavior of the Fe-C-Si and Fe-C-Al cast irons were investigated using a pin-on-disk type apparatus at room temperature. Alumina ball of 3 mm diameter was used as pin, while the cast sample served as the disk. The tests were carried out at a normal load of 5.0 N and a sliding velocity of 250 mm/s for 30 min. The Fe-C-Al cast iron showed a wear rate of 3.3203×10-5 mm3/m/N compared to 12.42×10-5 mm3/m/N of Fe-C-Si cast iron. The worn surfaces were analyzed using optical profilometer and SEM.

Abstract: Any useful object is commonly made from selected engineering materials with proper shape and dimension. The selection of materials and manufacturing processes is an important criterion towards the production of useable and affordable objects. The technologies behind this knowledge are needed to acquire through study, proper education, practical training and scientific research related to Materials and Manufacturing Engineering (MME). Allah (swt), the sources of all power and knowledge, has bestowed the Guide Book, the Holy Qur’an through His beloved Messenger Prophet Mohammad (pbuh) to the mankind. Allah (swt) narrated various stories in many Surahs of the noble Qur’an related to applied science and technology. This paper is an attempt to view the integration between the revealed knowledge and the science and technology based knowledge related to engineering materials and manufacturing processes. Finally, stresses have been given to acquire knowledge on science and technology based education and understanding, and disseminate it for the cause of humanity.

Abstract: Green sand casting and chill mould casting methods are representing the slow and fast cooling rates of the brass casting, respectively. The compositions of the raw material for this study were about Cu70 and Zn30, which falls under alpha (α) brass. Slow cooling rate casting shows coarse dendritric structures with large spacing between the dendrites. On the other hand, faster cooling rate casting shows finer grains with shorter dendrite spacing. The developed structure during solidification influences the properties of the cast samples. As grain size decreases, the strength of the cast brass increases; micro-porosity in the casting decreases and the tendency for the casting to fracture also decreases. However, the macro-examinations of fracture surfaces of these castings show the differences in the cast samples. Fracture surfaces of the sand cast specimen show larger dimples taking longer time to break indicating higher elongation. However, chill cast specimen shows smaller dimples and cleavage type fracture surface having higher strength and lower elongation.

Abstract: Aluminium-silicon alloys have low density, high electrical and thermal conductivity and high resistance to corrosion at ambient temperature. However, these alloys usually contain numerous alloying and impurity elements, which consist essentially of a fairly ductile matrix of alpha aluminium solid solution with a variety of non-ductile particles of silicon and various intermetallic compounds. The shape and distribution of these constituents largely control the deformation behaviour of the alloy. The addition of magnesium makes the alloys lighter and harder, but its hardening effect is fully responsive only after proper heat treatment. Therefore, in the present study, microstructures and properties of the alloys have been evaluated on the as-cast and heattreated conditions. Results show that the addition of magnesium to aluminium-silicon eutectic base alloy refines microstructure up to certain level and increases the strength and hardness at the expense of ductility.

Abstract: Aluminium-silicon alloys having different silicon contents (13, 20 and 27 percent) were used in the present study. The molten alloys were poured in to a mild steel die to cast tensile test bars. Then tensile and hardness tests were performed in order to analyze the properties and fracture surfaces of the cast specimens. Results show that as silicon content increases, the alloy becomes harder and less ductile. At the same time, the presence of alloying and impurity elements in the alloys forms complex compounds and intermetallic phases. They present deleterious effects on the strength of the alloys, causing a lowering of the energy required to fracture the test specimens with little permanent extension. However, heat treatment operations altered the structures and properties of the aluminium-silicon alloys. Heating to higher temperature, then quenching, ageing and tempering make the alloys stronger up to 13% silicon and beyond that limit the alloys become weaker, fracturing at lower load. The appearance of fracture surfaces after tensile testing showed these differences. This investigation also suggests that for the aluminium-silicon alloys containing 20% and 27% silicon do not require any expensive and time consuming thermal treatment operations, since properties do not improve with such treatments.