RESUMO
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.
RESUMO
This study investigates the possibility of multi-objective optimization in the transesterification of mahogany seed oil (MSO). The Taguchi method together with Grey relational analysis (GRA) was used to maximize both percent fatty acid methyl ester (FAME) yield and heat transfer coefficient (HTC). It was found that methanol to oil molar ratio was the factor that contributed the most in obtaining high percent FAME (ester) yield and HTC. Employing the following conditions: 32.6 wt% methanol (9:1 methanol to oil molar ratio), 0.5 wt% catalyst, 60 °C temperature and 300 rpm agitation was found to offer an improved percent ester yield and HTC. A confirmatory test resulted in an ester yield of 90.1 % and HTC up to 153.0 W/m2K. The structure of the optimized transesterified mahogany seed oil (TM) was confirmed by FTIR analysis. In the event of comparison, TM, raw mahogany seed oil (FM) and SAE40 were analyzed by cooling curve analyses. TM identified to have superior quenching performance.
RESUMO
The present study examined wear characteristics of A356/melon shell ash particulate composites. Dry-sliding the stainless steel ball against specimen disc revealed the abrasive wear behavior of the composites under loads of 2 and 5N. The composite showed lower wear rate of 2.182 × 10-4 mm3/Nm at 20 wt% reinforced material under load of 5N. Results showed that wear rate decreased significantly with increasing weight percentage of melon shell ash particles. Microstructural analyses of worn surfaces of the composites reveal evidence of plastic deformation of matrix phase. The wear resistance of A356 increased considerably with percentage reinforcement. In other words, the abrasive mass loss decreased with increasing percentage of reinforcement addition at the both applied loads. The control sample suffered a highest mass loss at 5 N applied load.