No abstract

No abstract

This paper reports a systematic study which examines the use of solid lubricants in the sequential deposition and machining of wire and arc additive manufactured parts and characterises the effects of solid lubricants on the microstrucure. This paper also describes the microstructure developed and the effect on micro hardness by manual cleaning of deposited layers with acetone. Mild steel wire consumable electrode G3Si1 with the diameter of 0.8mm was used. The use of graphite and molybdenum disulphide as solid lubricant in machining was also studied and a scanning electron microscope was used in detecting any form of lubricants contamination. A systematic study shows that a significant amount of solid lubricant contamination can be found in the deposited material. Furthermore, the results indicate that even cleaning of the wire and arc additive manufactured surfaces with acetone prior to the weld deposition can affect the microstructure of the deposited material.

This paper reports the effects of local cooling media (groundnut oil, palm oil, shea butter and air) on the mechanical properties of heat treated mild steel. Tensile test, hardness test and microstructural analysis were carried out on the heat treated and as-purchased specimens. The results show significant differences in the mechanical properties of the heat treated specimens. The hardness profile showed higher values for palm oil-cooled, shea butter-cooled, and the groundnut oil-cooled specimens in an increasing of order respectively when compared with as-purchased specimen with 194.9 VHN, while a decrease in hardness was recorded for the air-cooled specimen. Furthermore, the yield strength and ultimate tensile strength of the heat treated specimens obtained through the tensile test analysis showed an increase in yield strength for the groundnut oil-cooled (464.4 MPa) and the shea butter-cooled (412.9 MPa) specimens, and a decrease in yield strength for the air-cooled (358.3 MPa) and palm oil-cooled (307.7 MPa) specimens when compared with the as-purchased specimens (376.9 MPa). Also, the same trend was observed in the ultimate tensile strength (UTS) of the specimens. In contrast, the ductility improved in air-cooled specimen (40.28) while decreased in the specimen cooled in the media when compared with as-purchased specimens (34.22). Furthermore, microstructural analysis revealed that the groundnut oil-cooled specimens gave a microstructural quality than the other heat treated specimens.

This research investigated the effects of addition of ethanol to gasoline with the aim of improving the performance and emission characteristics of Spark Ignition (SI) engine. Four samples of gasoline-ethanol blend were prepared, namely 100% ethanol, 100% gasoline, 95% gasoline + 5% ethanol and 90% gasoline+10% ethanol, and were labeled sample A, B, C and D respectively. Physicochemical analysis was carried out on the four samples while sample B, C, and D were used to run a single cylinder, two stroke, air cooled SI engine to determine the performance characteristics of the engine at four engine speeds of 800rpm, 1000rpm, 1200rpm, and 1400rpm. An exhaust gas analyzer was used to analyze the exhaust emission to determine its constituents at no load. The research concluded that blending gasoline with ethanol not only improved the performance of the engine, it also yielded a friendlier emission. It also solves the problem of sole dependence on petroleum products to run SI engines with its attendant cost and environmental implications.