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Home > Role of Carbon Nanotubes Reinforcement and Processing Parameters on Mechanical Properties of Alumina Based Nanocomposites

Role of Carbon Nanotubes Reinforcement and Processing Parameters on Mechanical Properties of Alumina Based Nanocomposites

Thesis Info

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External Link

Author

Nabi Bakhsh

Program

PhD

Institute

Ghulam Ishaq Khan Institute of Engineering Sciences and Technology

City

Topi

Province

KPK

Country

Pakistan

Thesis Completing Year

2014

Thesis Completion Status

Completed

Subject

Applied Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/1284

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727111369

Similar


Along with other oxide ceramics, alumina is an important and widely used industrial material. Its applications include prostheses and dental implants used as bio-medical replacements, wear- resistant components and speedy cutting tools, thermal and electrical insulations and coatings for high temperature use. The effectiveness of alumina for such uses is credited to its excellent corrosion resistance, high hardness, good electrical and thermal insulating properties and high compressive strength. However, regardless of its excellent potentials and properties, its use for structural applications has significantly been limited due to its low-fracture toughness and low- fracture strength. The potential use of carbon nanotubes reinforced ceramic nanocomposites for various engineering applications has unlocked an interesting area of research. In the current work, two kinds of sintering routes, namely pressureless and spark plasma sintering are used for the synthesis of multiwalled carbon nanotube reinforced alumina matrix nanocomposites. The characterization of the resulted nanocomposites is carried out and their comparison with the sintering behavior of monolithic alumina is presented. Two types of composites were prepared by using pressureless and spark plasma sintering techniques both contained 1, 2 and 3 wt% of as-received and functionalized carbon nanotubes. The mixing and dispersion of carbon nanotubes in alumina was done by a novel technique of gas purging sonication. Varying percentages of carbon nanotubes in the composites were compacted using a uniaxial press followed by pressureless sintering at 1600°C in flowing argon with a dwell time of 15 minutes and spark plasma sintering at 1400°C under a pressure of 60 MPa for a holding time of 10 minutes. Pressureless sintered nanocomposites with 1 wt% carbon nanotubes gave 98.5% relative density with no degradation of carbon nanotubes. Moreover, it also resulted in an increase in fracture toughness from 8.1% and 9.4% and Young’s modulus by 5% and 7% when compared to as-received and functionalized carbon nanotube nanocomposites respectively with respect to pure alumina. This investigation has shown that the densification can be achieved without degradation of carbon nanotubes at elevated temperatures in the carbon nanotube-alumina nanocomposites sintered by conventional route. vWell-dispersed carbon nanotube-reinforced alumina nanocomposites have been synthesized successfully having a high density by spark plasma sintering. At 1 wt% functionalized carbon nanotubes addition in alumina, a near full density is achieved that contributes to the improvement in mechanical properties of the nanocomposites. On addition of 1wt% CNTs, fracture toughness values increased by approximately 18.6% and 14% for functionalized and as-received CNT-alumina nanocomposites respectively. However further addition of CNTs up to 3 wt % slightly decreased the hardness and the fracture toughness. Young’s modulus was improved by 6.5% for functionalized and 4% for as-received CNT-alumina nanocomposites over monolithic alumina. Average grain size of monolithic alumina is observed as 2.0 ± 0.5 μm while that of 1wt% CNT-alumina nanocomposite was less than 1 μm. The well-dispersed carbon nanotubes within the alumina matrix enhanced the pullout resistance, bridged the gaps between cracks and held up the crack propagation by using elasticity that lead to improved fracture toughness.
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پرنس نجم الدین

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تصوف کے غیر مشہور سلاسل کا تحقیقی جائزہ

Human being is the combination of two elements (body and soul). Soul is the eternal element in human being. Body of human is subordinate to disease and illness. Similarly soul can also get illness and inner disease. Human being visits doctors for cure and getting better physical health of body, likewise for the care and cure of the soul of human needs to have spiritual attachment, which is called tasawof. In Muslim society, it is believed that Tasawoof is confined to four categories (Salasil) i.e. Naqashbandiya, Chishtiya, Saharwardiya and Qadariya. In the same context it is also accepted that some other names of different salasil exist in different societies and books, which made the confusion in the  real picture and concept of Tasawof. This article is an attempt to find  these unfamiliar Salasil of tasawof and clarify their legal status. The researcher studied in this context which stated that tasawof is not restricted to the above mentioned four categories. The reason of less familiarization in the society is that the it was practiced by less followers at the time.

Combining Ability and Gene Action Studies of Maize Zea Mays L. under Water Deficit Conditions

Sixty inbred lines of maize (Zea mays L) were screened in the green house at seedling stage both under normal and water deficit conditions. The layout of design was complete randomized desidn (CRD) with two replications. Six water deficit tolerant inbred lines were selected on the basis of dry root weight, root/shoot ratio and relative leaf water content. These inbred lines were sown in the field conditions to attempt all possible crosses in a diallel fashion. The layout of the design was randomized complete block design (RCBD). F1 crosses, their reciprocal crosses along with their parental lines were planted under both normal and water deficit conditions. Normal irrigations(8) were applied to normal set of experiment whereas 50% of yhe normal irrigations(4) were applied to water deficit condition. The data pertaining to various morpho-physiological parameters was recorded at physiological maturity of the crop. The data was subjected to statistical analysis. The coefficient correlation among seedling traits like fresh root weight, dry root weight, root/shoot ratio and relative leaf water contents showed strong association with each other in both normal and water deficit conditions. Mean squares for all the parameters were significant under both conditions, indicating the presence of sufficient genetic variability. Relative general combining ability, specific combining ability and reciprocal effects were calculated for all the characters (Griffing, 1956, Method I, Model I). Estimates of variance components for general combining ability (GCA), specific combining ability (SCA) and reciprocal effects for all the parameters i.e., plant height, leaf temperature, days taken to tasseling, days taken to silking, anthesis-silking interval, no kernels per ear,100 grain weight, grain yield per plant, no of kernel per row, ear height, relative leaf water content, no of ears per plant under normal and water deficit regimes. These components were computed in order to obtain an estimate of relative importance of additive and non-additive or dominance type of gene action. Estimation of components of variation indicate larger values of GCA variance as compared to SCA variance depicting the preponderance of additive genetic effects for all the traits except number of kernels per ear having greater SCA variance than GCA variance 15 showing non additive genetic effects under normal conditions. Heritability estimates for grain yield and yield related parameters shoed maximum ability to transfer the genes to the next generation. Inbred lines W-10× W64SP proved to be best grain yielders on mean basis under normal and water deficit conditions. Hence, these inbred lines might be exploited in future breeding programs.Under water deficit condition, best performing cross was N-18×W-64SP. Hence this cross can be utilized for future breeding program under water deficit conditions.