Taguchi method has been employed to investigate the effects of cutting fluids on surface roughness in turning AISI 1330 alloy steel, using manually operated lathe machine. Experiments have been conducted using L27 (3 4 ) orthogonal array and each experiment was repeated three times and each test used a new cutting tool, High Speed Steel (HSS), to ensure accurate readings of the surface roughness. The statistical methods of Signal-to-Noise (S/N) ratio and the Analysis of Variance (ANOVA) were applied to investigate effects of cutting speed, feed rate and depth of cut on surface roughness under different cutting fluids. Minitab 14 software was used to analyze the effect of variables on the surface roughness. Results obtained indicated that optimal variables for the minimum surface roughness were cutting speed of 35 m/min (level 2), feed of 0.124 mm/rev (level 1), depth of cut of 0.3 mm (level 1) and a cutting fluid with a viscosity of 2.898 mm 2 /s (level 3). Hence, the optimal parameters to obtain better surface roughness of the workpiece material were obtained when groundnut oil based cutting fluid was used. Analysis of variance shows that feed rate has the most significant effect on surface roughness.

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A comparative study was carried out to investigate the suitability of some selected Nigerian vegetable oils as alternative quenchant to SAE40 engine oil for industrial heat treatment of Medium Carbon steels. The study involved the characterization of physicochemical properties and fatty acid profile of cotton seed oil, palm kernel oil, neem seed oil and palm oil. The quenching performance of these vegetable oils was conducted at quenchant bath temperatures of 34˚C, 50˚C, 70˚C, and 100˚C. SAE40 engine oil (Standard quenchant) and tap water served as control. The effect of cooling rates of the quenching media on mechanical properties and microstructure of the quenched steel samples were investigated. The results obtained show that the different vegetable oils have different viscosity and viscosity-temperature behavior just as their molecular structures were different. The mechanical properties of the as-quenched specimens in these oils show that the hardness of steel quenched in palm kernel oil was highest 40.85HRC. As received sample absorbed the highest amount of energy (183 J) before fracture while sample quenched in water absorbs least energy (28 J). Hence vegetable oil is suitable as alternative quenchant to petroleum based SAE40 engine oil for quenching medium carbon steels, without cracking or distortion, the most suitable among them being palm kernel oil.

Insulation of the combustion chambers has continued to gain prominence over time because of the desire to improve the thermal efficiency of the systems. The present study investigated the suitability of scoria as an insulating material. Three different batches of scoria, clay and naphthalene were mixed. Scoria served as the matrix, clay served as the binder and naphthalene as the pore creator. The first batch contained 17.6% clay, the second contained 30%, while the third batch contained 39.1%. From each batch, test samples were prepared at varying percentage naphthalene content. Test samples were moulded into different shapes, depending on the test to be carried out on them. They were then allowed to dry under ambient air. This process was followed by oven-drying for 2 hours at 110 o C to further reduce the moisture content of the test samples. The test samples from batch 1 disintegrated during the drying stage leaving only batches 2 and 3. The test samples were thereafter fired in an electric kiln to a temperature of 1000 ºC. Following the firing process, test samples from batches 2 and 3 were subjected to apparent porosity, bulk density, thermal shock resistance and thermal conductivity tests. At 40% naphthalene addition, the percentage apparent porosity values obtained for batch 2 and 3 test samples were 73.13% and 63.23%. Bulk density values at the same naphthalene addition were 1.27 and 1.36 gcm-3 respectively. Between 0% and 40% naphthalene addition, the thermal conductivity values for batches 2 and 3 test samples steadily reduced from 0.14-0.04 W/m.K and 0.27-0.09W/m.K. The thermal shock resistance of the test samples from batches 2 and 3 also decreased from 12 to 7 and 13 to 6.5 cycles respectively. Test samples produced from batch 2 produced better results overall, which proved scoria to be suitable for use as a thermal insulating material.

The quenching ability of modified and unmodified cottonseed oils was investigated using AISI 1070 steel. In the event of the quenching, the steel samples immersed in each of five distinct quench media, namely epoxidized cottonseed oil (EC), epoxidized-transesterified cottonseed oil (ETC), transesterified cottonseed oil (TC) and fresh cottonseed oil (FC). Tests and analysis conducted determined mechanical properties and microstructures of the quenched samples. The data obtained showed that ETC outperformed other quench media with hardness value of the quenched sample; 407 HVN (hardness value from the FC-quenched sample) increased to 746 HVN indicating an 83.29% improvement. Notably, in the microstructure of ETC-quenched sample, a unique homogeneous microstructure containing a mixture of lath and plate martensite observed with largest martensite per cent of 95.