RESUMO
This study evaluates the effect of treated and untreated jute fiber/eggshell particulate reinforced cement-paper matrix composites for ceiling board application. Treated jute fiber (TJF) was obtained by immersing untreated jute fiber (UJF) into 1.25 M sodium hydroxide (NaOH) solution in a shaker water bath maintained at 40 °C for 4 h. Eggshells (ESP) were pulverized and sieved to -75µm. Samples were prepared by varying the fiber volume fraction from 0.5 to 2.5 wt.% in the composites. While other constituents such as the binder (cement) and eggshell were kept constant. An hydraulic press cold compaction molder was utilized in the production of the hybrid composites in a predetermined mix ratio designed based on previous research. The samples produced were cured for 7 and 14 days, then sundried for 36 h. The physical, thermal, mechanical and wear behaviour of the produced composites were evaluated while the surface morphology of the fractured splitting tensile samples were analyzed. The result reveals that TJF/ESP hybrid composites had better performance than UJF/ESP hybrid composites in most of the tests carried out. Increase in the number of curing days was found to also enhance the properties of the composite produced in majority of the test evaluated. The 0.5 wt.% UJF/ESP gave the least performance of all the composites developed. While 2.5 wt. % TJF/ESP showed an optimum properties among the composites tested. When compared with standard, it is concluded that the hybrid composites developed can be suitable for ceiling boards and also find possible application in wall partitioning.
RESUMO
Quenching is one of the major processes of heat treatment of medium carbon steel that aims at improving its mechanical properties. However, the effectiveness of this process is dependent on several control factors that must be maximized to obtain optimum results in terms of hardness, yield strength, ultimate tensile strength among others. This study aims at optimizing the process of improving the mechanical properties of medium carbon steel by varying some key factors like the quenchant used (A), heat treatment temperature (B), and soaking time (C). The measured responses in this study were the hardness, yield strength (YS), and ultimate tensile strength (UTS). Optimization was conducted in two stages. The first stage dealt with the mono-optimization of process parameters using Taguchi's Signal-to-Noise (S/N) ratio. A total of nine (9) experiments were performed based on standard L9 orthogonal array because each of the three control factors has three (3) levels. The second stage was multi-objective optimization using Taguchi-based grey relational analysis (GRA). The optimal conditions for hardness, YS, and UTS were obtained at A2B3C3, A3B2C3, and A3B3C3, respectively. Using ANOVA as statistical analysis, it was observed that the soaking time was the main control factor for all three measured responses (31.95% contribution ratio for hardness, 62.46%, and 66.76% for YS and UTS, respectively), while the quenchant had the least contribution. Analysis of the Taguchi-based GRA revealed that the results obtained are in total conformance to that of the Taguchi method, with soaking time having the highest contribution ratio of 69.41%.
