Enhancing mechanical and structural properties of pewter alloy using microwave sintering

97%Sn 2%Cu 1%Sb (pewter) alloys were examined to determine the effect of green density, sintering time and sintering temperature on the mechanical and structural properties of the conventional and microwave sintered compacts. Two compaction loads; 30kN and 40kN were used to produce the samples with different green densities. Eight different time-temperature combinations were used for each heat treatment. Samples with a higher green density resulted in a higher sintered density and higher hardness. Longer sintering time and higher sintering temperatures resulted in higher densities, larger grain size and higher hardness for both sintering methods. However, the microwave sintered samples in general have finer microstructures, higher densities and higher hardness compared to the conventional sintered samples in a much shorter duration. Better mechanical and structural properties were achieved by microwave sintering in 15 minutes compared to conventional sintering which took 120 minutes

Mechanical and Structural Properties of Microwave Sintered Tin-Copper-Antimony Alloys

Tin-copper-antimony (pewter) alloys have been traditionally produced by a casting process which consumes large amounts of energy, time and as a result is expensive. This research aims to investigate the possibilities of implementing powder metallurgy for pewter production through a sintering process using microwave energy. The optimum sintering conditions using microwave sintering are also of interest. Pewter alloys were examined to determine the effect of green density, sintering time, and sintering temperature on the mechanical and structural properties of the sintered compacts. Samples were prepared by hydraulic pressing of a well mixed and blended tin alloy powder with three different compositions; 97wt%Sn 2wt%Cu 1wt%Sb, 94wt%Sn 4wt%Cu 2wt%Sb and 91wt%Sn 6wt%Cu 3wt%Sb. Two compaction loads were used to produce the samples with different green densities. Pellets pressed at 96 MPa had an average relative density of 80.7%, while those pressed at 129 MPa had an average green density of 84.6%. Sixteen different time-temperature combinations were used for the heat treatments at 160 and 220 C for both conventional and microwave sintering. However, the sintering times had to be restricted to 15 and 30 minutes for microwave heating. Meanwhile, 60 and 120 minutes were used for conventional heating. It was found that for all three compositions, samples with a higher green density had a higher sintered density, compared to samples with lower green density, for the same sintering time and temperature. The relative density of sintered pewter alloys increased on average by 13% after conventional sintering and by about 14% after microwave sintering, when the sintering was carried out for the longer of the two sintering times and at the higher of the sintering temperatures selected, for all three compositions. Moreover, the hardness increased by 25.6%, 23.5% and 7.0% when microwave sintered relative to the conventional sintering for 97Sn2Cu1Sb, 94Sn4Cu2Sb and 91Sn6Cu3Sb alloys respectively. Nevertheless, the grain size remained similar for all three compositions under the same sintering conditions. The degree of grain growth in microwave sintered samples was marginally smaller (up to 23-24 μm) than in conventionally sintered samples which reached a grain size of 26-27 μm. In terms of strength, microwave sintering produced samples with similar properties to those conventionally sintered under the same sintering conditions for all three compositions. The tensile strengths obtained compared well with the strengths obtained from the casting process. Nonetheless, tensile strengths for both conventionally and microwave sintered material was higher in the transverse direction than in the longitudinal direction. In conventionally sintered material, there was an increase in transverse strength of about 6.9%, 5% and 4%, while for the microwave sintered material, the strength increase was 9.1%, 5.6% and 4.5% for 97Sn2Cu1Sb, 94Sn4Cu2Sb and 91Sn6Cu3Sb alloys respectively when compared to the longitudinal direction. The microwave sintered samples in general have improved hardness, better densification and a finer microstructure compared with the conventionally sintered samples and traditionally cast pewter. Increasing the Cu and Sb content increases the hardness and strength but in return, decreases its ductility. Hence, a pewter alloy with a moderate amount of Cu and Sb, i.e. 97Sn2Cu1Sb, microwave sintered at 220 C for 30 minutes would be the best choice for optimum mechanical properties

Effect of microwave sintering on the mechanical and structural properties of pewter alloy

97%Sn 2%Cu 1%Sb (pewter) alloys were examined to determine the effect of green density, sintering time and sintering temperature on the mechanical and structural properties of the conventional and microwave sintered compacts. Two compaction loads; 30kN and 40kN were used to produce the samples with different green densities. Eight different time-temperature combinations were used for each heat treatment. Samples with a higher green density resulted in a higher sintered density and higher hardness. Longer sintering time and higher sintering temperatures resulted in higher densities, larger grain size and higher hardness for both sintering methods. However, the microwave sintered samples in general have finer microstructures, higher densities and higher hardness compared to the conventional sintered samples in a much shorter duration. Better mechanical and structural properties were achieved by microwave sintering in 15 minutes compared to 120 minutes by conventional sintering

An integral equation for conformal mapping of multiply connected regions onto a circular region

Abstract. An integral equation is presented for the conformal mapping of multiply connected regions of connectivity m+1 onto a circular region. The circular region is bounded by a unit circle, with centre at the origin, and m number of circles inside the unit circle. The development of theoretical part is based on the boundary integral equation related to a non-homogeneous boundary relationship. An example for verification purpose is given in this paper for the conformal mapping from an annulus onto a doubly connected circular region with centres and radii are assumed to be known

Reckless formalin injection in the eyelid instead of local anesthetic: case report

Accidental injection of formalin is certainly rare, but it has serious consequences in terms of morbidity and mortality. We report a case of severe ophthalmic damage due to an accidental formalin's injection in the eyelid of a three-year-old child presenting with congenital ptosis's surgical repair of her left eye. This accident has damaged the orbital region and led to upper left eyelid's necrosis, eyeball's deformation and ipsilateral cataract. In terms of our observation, we discussed consequences of this rare type of accident, and its systematic and loco-regional effects. We tried also to explain these manifestations by analyzing the metabolism process of formalin in the human body. Finally, a medico-legal implication of such accident has been illustrated according to the Tunisian law (Penal Code of the Tunisian republic 'PCT').The Pan African Medical Journal 2016;2

Economic analysis of using e-glass composite wrap repair system for pipelines in Malaysia

One of the biggest problems faced by the oil and gas industries is transmitting gas when there is a damaged pipeline. This damage may be a result from corrosion, crack or a burst pipe. Damaged pipelines need a safe, quick and efficient repair mechanism to prevent any further extensive damage. There are various methods and repair systems that offer different advantages and limitations to the oil and gas industries. Composite wrap repair system is a new technology that is being used in the United States of America and some European countries. However, this technology has not penetrated into the South East Asian region yet. This study is done with the aim of determining the feasibility of implementing this repair system into the Malaysian oil and gas industries. E-Glass fiber was selected since it is the most suitable and appropriate type of composite that can be adapted for the composite wrap. Then, cost analysis was done for this composite repair system and compared with the welding repair and pipeline replacement methods. Calculations for the result of every repair system were performed to compare the most efficient method. E-Glass fiber composite wrap has shown to be the most economical technique when compared with the welding and pipe replacement methods

Wear analysis of Silicon Nitride (Si3N4) cutting tool in dry machining of T6061 Aluminium Alloy

Dry machining is an eco-friendly machining process and its importance in the manufacturing industries should be taken seriously. Machining without the use of any cutting fluid is becoming increasingly more popular due to concerns regarding the safety of the environment and reducing cost. Dry and wet turning of T6061 aluminium alloy was performed on a lathe by using Silicon Nitride (Si3N4) inserts as the cutting tool. Tool wear behaviour of Si3N4 cutting tool were studied with the aim of finding the optimum cutting conditions for both dry and wet machining. Machining was performed at four different cutting speeds; 292, 388, 518 and 689 m/min using two different cutting parameters (feed rate, f = 0.2 mm/rev, depth of cut, d = 0.1 mm and f = 0.4 mm/rev, d = 0.2 mm). Material removal rate (MRR) was also obtained and the temperature at the tool-chip interface were measured using an infrared (IR) thermometer as to see the effect of temperature rise during machining. Dry machining with smaller cutting parameters resulted in lower wear rates by 37 to 48% for all four cutting speeds. Nevertheless, reduction of wear rate by 38 to 57% was found from wet machining. The optimum cutting speed for both dry and wet machining of T6061 aluminium alloy using Si3N4 cutting tool was found to be 518 m/min for both cutting parameters. However, the optimum cutting parameters are apparently with the feed rate of 0.4 mm/rev and depth of cut of 0.2 mm. At the optimum cutting speed, the tool tip temperature for dry machining was higher than wet machining by 40 and 51% for f = 0.2 mm/rev and f = 0.4 mm/rev respectively. Dry machining of T6061 Aluminium alloy can be more suitable particularly at higher cutting speed with interrupted cutting operations

Study of TiC cutting tool insert using microwave synthesis

Microwave processing ceramics is emerging fast as a new field of ceramic processing and material synthesis. The past year has witnessed significant progress in the aspects of commercialization and application of the technology to new areas. Further research states that Titanium Carbide (TiC) is the best cutting tool due to its high melting point and by that reason this project aims to show the difference between conventional sintering, microwave sintering and Hot Isostatic Pressing (HIP). Two different compositions consisting of 97TiC3Ni and 93TiC7Ni were sintered using conventional furnace, microwave furnace and HIP. Density, hardness and microstructure analysis were carried out on these TiC inserts. 97TiC3Ni produced higher density and hardness values compared to 93TiC7Ni for all three different methods. Microwave sintering produced the highest density and hardness values compared to conventional sintering and HIP. Microwave produced samples with improved density and hardness in a shorter processing time which is 93% faster than conventional sintering and 50% faster than HIP