NOPR Collection:

An experimental investigation on wear test parameters of metal matrix composites using Taguchi technique

2013-09-04T16:35:41Z

Title: An experimental investigation on wear test parameters of metal matrix composites using Taguchi technique Authors: Kumar, T R Hemanth; Swamy, R P; Chandrashekar, T K Abstract: This study evaluates the influence of wear test parameters such as sliding speed and normal load on dry sliding wear performance of Al-Cu-Mg/titanium dioxide particle reinforced composites. Three different weight percentages of titanium dioxide reinforced composite materials are used to conduct the test. Experiments are performed based on the plan of experiments generated through Taguchi technique. A mathematical model is developed relating wear rate and the test parameters using multiple regressions and the model is checked for adequacy. The experimental results and the developed model show that higher sliding speed and titanium dioxide reinforcement will favor for reducing the wear rate of composites. Page(s): 329-333

Efficient ammonia sensing over zinc oxide/polyaniline nanocomposite

2013-09-09T16:35:52Z

Title: Efficient ammonia sensing over zinc oxide/polyaniline nanocomposite Authors: Shukla, S K; Singh, N B; Rastogi, R P Abstract: Zinc oxide/polyaniline (ZnO/PANI) nanocomposite film is prepared by a chemical method using CuSO₄ as redox initiator. The nanocomposite is characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and TG techniques. X-ray diffraction studies of the composite show the reflection of ZnO nanoparticles along with a broad peak of PANI. FTIR and UV-visible spectra show interaction between ZnO and PANI. Current-voltage measurements (I-V curves) show that ZnO/ PANI has much higher electrical conductivity than pure PANI. The ammonia gas sensing behavior of the ZnO/PANI nanocomposite films is studied and the results show that it is a promising candidate for ammonia sensing with response time of 15 s and recovery time 45 s. Page(s): 319-324

High calcium fly ash geopolymer containing diatomite as additive

2013-09-14T16:34:52Z

Title: High calcium fly ash geopolymer containing diatomite as additive Authors: Phoo-ngernkhama, Tanakorn; Chindaprasirt, Prinya; Sata, Vanchai; Sinsiri, Theerawat Abstract: This paper studies the influence of the addition of diatomite on the properties of high calcium fly ash geopolymer pastes. Diatomite is calcined at 800°C and used to partially replace fly ash at the rate of 0, 10, 20, 30 and 40% by weight of binder. Sodium silicate (Na₂SiO₃), sodium hydroxide (NaOH) solution and curing at temperature of 60°C for 24 h are used to activate the geopolymerization. The NaOH concentration of 10 M and Na₂SiO₃/NaOH ratio of 2.0 by weight are used for all mixes. The results revealed that the use of diatomite to replace part of fly ash delayed the setting time of fresh geopolymer paste and also resulted in the reduction of density of hardened paste which is highly desirable for lightweight structure member. However, the strength and modulus of elasticity of the paste are reduced. Another positive effect is the increase in the strain capacity of the paste. The increase in strain capacity is significant and reflects in the ability of the paste to withstand increased strain before cracking. Page(s): 310-318

Tensile, compressive and shear properties of unidirectional glass/epoxy composites subjected to mechanical loading and low temperature services

2013-09-04T16:35:29Z

Title: Tensile, compressive and shear properties of unidirectional glass/epoxy composites subjected to mechanical loading and low temperature services Authors: Torabizadeh, Mohammad A Abstract: Composite materials are subjected to low temperatures in service and this has induced the need for a proper knowledge of low temperature behavior of composites. Most of the research in this field is focused on applying different types of loading and laminated configurations. This paper discusses the experimental study on the tensile, compressive and in-plane shear behavior of unidirectional (UD) glass fiber reinforced polymeric composite under static and low temperature loading conditions. Since UD composite is the basic building block of a composite structure and can be used to make general laminates. In order to fully characterize UD laminate, several experimental tests are performed using an environmental test chamber and a universal testing machine. Thermo-mechanical loads are applied to glass/epoxy unidirectional laminates at room temperature (25°C), -20°C and -60°C. The results of the present study indicate that low temperatures have a significant effect on composite failure mode. It is also found that the strength and modulus of UD composites both increased with decreasing the temperature in all cases including tensile, compressive and shear loads. On the other hand, the results show that strain to failure decreased by decreasing the temperature. Page(s): 299-309