Effects Of Mechanical Stirring And Short Heat Treatment On Thixoformed Of Carbon Nanotube Aluminium Alloy Composite

The present work aimed to determine the effects of thixoforming and short T6 heat treatment processes on the microstructure and mechanical properties of thixoformed A356 alloy reinforced with 0.5 wt% multi-walled carbon nanotube (A356-MWCNT). The semisolid composite feedstock was produced by a mechanical stirring route followed by thixoforming, and finally, it was heat treated with a shorter solution treatment and artificial ageing hours. A premix of 0.5 wt% magnesium (Mg) as wettability agent and MWCNT was injected into molten A356 alloy at 650 °C. Mixing and stirring were performed by a using three-blade impeller at 500 rpm for 10 min, and the mixture was poured into a preheated mould. Microstructure studies show the mechanical stirring effects on the transformation of dendritic arms to mostly globular and rosette structures of α-Al. The formations of more spheroidised structure of eutectic silicon (Si) were predominant after the heat treatment, thereby revealing the effectiveness of shorter T6 heat treatment. Results of field emission scanning electron microscopy images showed uniform distribution and pull-out structures of MWCNT throughout the matrix, thereby justifying the effective load transfer and wettability between reinforcement and alloy matrix. Subsequently, the mechanical properties of the composite shown significant improvements after each stage. The yield strength (YS), ultimate tensile strength (UTS) and elongation to fracture of cast A356 alloy increased from 115 MPa, 132.9 MPa and 1.8% to 135 MPa, 178.3 MPa and 3.1% respectively, in the A356-MWCNT. Consequently, these properties were further improved to 180 MPa, 255.8 MPa and 5.7% after the thixoforming process. The highest attainment of yield strength (YS), ultimate tensile strength (UTS) and elongation to fracture after short T6 of A356-MWCNT were 215 MPa, 277.0 MPa and 7.6%, respectively. The hardness of the samples was improved from 59.5 HV in as-cast alloy to 106.4 HV in thixoformed short T6 A356-MWCNT

Homogenous Dispersion And Interfacial Bonding Of Carbon Nanotube Reinforced With Aluminum Matrix Composite: A Review

Recent developments in the field of carbon nanotube (CNT) have attracted attentions on a new development of aluminum matrix composite (AMC). Homogenous dispersion and interfacial bonding of CNT/metal matrix are the two main problems yet to have sound solutions.In general, to ensure uniform dispersion, the overall process can be divided into three steps: preprocessing, mixing and post processing. This paper summarizes previousworks on solid and liquid processing techniques which some are more successful than others by looking at the improvement of the composite tensile strengths. On the other hand the interfacial bonding depends on the existance of Al4C3 phase and physical conditions of CNT. Both elements must be controlled for the optimized results. The review presented here would be used as references in the future works to fabricate higher strength CNT/aluminum composite

Two parameters weibull analysis on mechanical properties of kenaf fiber under various conditions of alkali treatment

This paper present two parameters Weibull analysis result on mechanical properties of kenaf fiber under different condition of alkali treatment. The mechanical properties of kenaf fiber that as focused in this study was fiber matrix interfacial shear strength (IFSS) and fiber tensile strength (TS). Kenaf fiber were treated under various conditions alkali concentration at 2, 6 and 10 (w/v%), immersion duration at 30, 240 and 480 minute and immersion temperature at 27, 60 and 100oC. Unsaturated polyester matrix was used in this study to determine the interfacial shear strength (IFSS). The result shows that Weibull modulus of kenaf fiber interfacial shear strength (IFSS) at 30 minutes immersion duration value was 2.59 to 3.12 with characteristic strength, σo-IFSS value range was 0.29MPa to 0.37MPa. The highest Weibull modulus was at room temperature and 6% alkali concentration. For kenaf fiber tensile strength Weibull modulus, the range was 2.40 to 3.07 with characteristic strength value range from 345MPa to 597MPa. The highest Weibull modulus also was measured at room temperature and 2% alkali concentration. The characteristic strength value shows a degrading pattern with the increment on immersion temperature and alkali solution concentration

Two parameters Weibull analysis on mechanical properties of kenaf fiber under various conditions of alkali treatment

This paper present two parameters Weibull analysis result on mechanical properties of kenaf fiber under different condition of alkali treatment. The mechanical properties of kenaf fiber that as focused in this study was fiber matrix interfacial shear strength (IFSS) and fiber tensile strength (TS). Kenaf fiber were treated under various conditions alkali concentration at 2, 6 and 10 (w/v%), immersion duration at 30, 240 and 480 minute and immersion temperature at 27, 60 and 100oC. Unsaturated polyester matrix was used in this study to determine the interfacial shear strength (IFSS). The result shows that Weibull modulus of kenaf fiber interfacial shear strength (IFSS) at 30 minutes immersion duration value was 2.59 to 3.12 with characteristic strength, σo-IFSS value range was 0.29MPa to 0.37MPa. The highest Weibull modulus was at room temperature and 6% alkali concentration. For kenaf fiber tensile strength Weibull modulus, the range was 2.40 to 3.07 with characteristic strength value range from 345MPa to 597MPa. The highest Weibull modulus also was measured at room temperature and 2% alkali concentration. The characteristic strength value shows a degrading pattern with the increment on immersion temperature and alkali solution concentration

Accommodating student's learning experience through personalized learning style adaptation in computer programming course at Centre for Foundation Studies, IIUM

Teaching and learning computer programming can be difficult, especially for beginners. Since they are not exposed to any computer programming experience, they may face difficulties if the teaching approaches do not match with their learning styles. Computer programming requires the students to understand logical reasoning and syntax and be able to apply them practically for solving programming problems in nearly all disciplines. Mitra [1] claims that most students feel computer programming is a challenging intellectual exercise. At Centre for Foundation Studies, foundation students encounter difficulties in learning and applying computer programming concepts. Some of them perform better in other science subjects, but find difficulties in grasping the computer programming concepts. In this research, we have used Felder-Solomon Learning Style Inventory to identify C Programming’s students for their preferred learning styles. The result of the survey shows that the Engineering/Computer Science students came from mixed learning styles. Therefore, we have adapted Felder-Solomon’s learning style model, and come out with a model of three hybrid categories. This paper will provide detail suggestions for an online learning system based on a selected topic in C Programming. The system will accommodate the students’ learning style in accordance to the modified Felder-Solomon’s learning style model. As a significant contribution to programming educations, our suggestions may further be adopted for designing personalized learning for other disciplines

Bat echolocation-based algorithm for device discovery in D2D communication

Proximal device discovery is an essential initial phase in the installment of a device-to-device communication system in cellular networks. Therefore, an efficient device discovery scheme must be proposed with characteristics of minimum latency, discover maximum devices, and energy-efficient discovery in dense areas. In this paper, a bat echolocation-based algorithm derived from the bat algorithm is proposed and analyzed to fulfill the requirement of a proximal device discovery procedure for the cellular networks. The algorithm is applied to multiple hops and cluster devices when they are in a poor coverage zone. In this proposed algorithm, devices are not required to have prior knowledge of proximal devices, nor device synchronization is needed. It allows devices to start discovering instantly at any time and terminate the proximal device discovery session on completion of the discovery of the required proximal devices. Finally, device feedback is utilized to discover the hop devices in the clusters and analyze proximal discovery in a multi-hop setting. Along with this, a random device mobility pattern is defined based on human movement, and the device discovery algorithm is applied. The device discovery probability is calculated based on the contact duration and meeting time of the devices. We set up an upper bound less than 10 ms in long-term evolution of running time of the bat echolocation-based algorithm; this upper bound signifies the maximum degree of device discovery (more than 75% of the system) and the total number of devices. The outcomes thus imply that the proposed bat echolocation-based algorithm upper bound is better than 10 ms

Growing Teratoma Syndrome: A Rare Case Report and Review of the Literature

Growing teratoma syndrome is rare and usually it occurs in the younger aged group. The use of chemotherapy following initial surgical resection will yield the diagnosis following tumour enlargement. Complete resection is usually curative and renders better prognosis

Collapsibility of PMMA based material in direct investment casting

Over recent years, the rapid growth of Additive manufacturing (AM) has benefits the Direct Investment Casting (DIC) process for intricate design in which significantly reduces the cost when associated with low volume production. Nevertheless, ceramic shells cracking has been recognized as critical problem when involved direct casting in which leads to incomplete collapsibility. Therefore, this study presents a numerical and experimental on poly(methyl) methacrylate (PMMA) pattern collapsibility for investment casting process and the stress analysis study on the ceramic shells. Study revealed that there were significant average of 5.8 % reduction of stress between square and polygon patterns. This study was conducted to examine the collapsibility of AM materials in the IC process

Spatial and temporal variations of water quality and trophic status in Bukit Merah Reservoir, Perak

A study of spatial and temporal variations on water quality and trophic status was conducted twice a month from December 2012 to January 2014 in four sampling stations at Bukit Merah Reservoir (BMR). The concentration of dissolved oxygen (DO), water temperature, conductivity, total dissolved solids (TDS), total phosphorous (TP), PO4-, NO2-, NO3-, NH4+ and net primary productivity had significant differences temporally (p<0.05) except for pH, total suspended solids (TSS) and chlorophyll-a. Based on correlation analysis, the amount of rainfall and rain days has negatively correlated with secchi depth and chlorophyll-a (p<0.01). The water level has significantly decreased the value of the temperature, pH, conductivity, TP and NO2- but it has positive correlation with NO3- and NH4+. Discharged from Sungai Kurau increased the value of conductivity, TSS, TP and NO2- as a result from runoff and erosion, thus decreasing the secchi depth values, NO3- and NH4+. The water quality of BMR is classified in Class II and TSI indicates that the BMR has an intermediate level of productivity (mesotrophic) and meets the objective of this reservoir which was to provide water for paddy irrigation