Applied Mechanics and Materials Vols. 813-814

Abstract: Composites are being used in variety of applications ranging from defense and aircraft structures, where usage is profuse, to vehicle structures and even for repair and rehabilitation. Most of these composites are made of different laminates glued together with matrix for binding and now-a-days fibers of different types are embedded in a composite matrix. The characterizations of material properties of composites are mostly experimental with analytical modeling used to simulate the system behavior. But many times, the composites develop damage or distress in the form of cracking while they are in service and this adds a different dimension as one has to evaluate the response with the damage so that its performance during its remaining life is satisfactory. This is the objective of the present study where a hybrid approach using experimental results on damaged specimens and then analytical finite element are used to evaluate response. This will considerably help in remaining life assessment-RLA- for composites with damage so that design effectiveness with damage could be assessed. This investigation has been carried out on a typical composite with carbon fiber reinforcements, manufactured by IPCL Baroda (India) with trade name INDCARF-30. Experimental studies were conducted on undamaged and damaged specimens to simulate normal continuous loading and discontinuous loading-and-unloading states in actual systems. Based on the experimental results, material characterization inputs are taken and analytical studies were carried out using ANSYS to assess the response under linear and nonlinear material behavior to find the stiffness decay. Using stiffness decay RLA was computed and curves are given to bring the influence of type of damage and load at which damage had occurred.

Abstract: Surface coating is sharing the responsibility between coating and substrate, which enhances the surface properties such as strength, hot hardness and toughness, wear resistance, antifriction and chemical inertness. The present work is focused on wear behavior of Mild Steel substrate material deposited with Titanium dioxide-30 wt % of Inconel718 incorporating plasma spray process. These composite coatings were subjected to slurry erosion wear test by simulating the corrosive-erosive atmosphere by mixing of silica sand and 3.5 percent of NaCl in distilled water. Under identical conditions, coated mild steels gave better wear resistance compared to uncoated sample.

Abstract: Now a day’s Hybrid Metal Matrix composites has a large number of applications in automobiles, aircrafts and structural applications like brake rotors, engine parts and cylinder liners. The aim of this study is to determine the mechanical properties of boron carbide (B₄C) and zirconium silicate (ZrSiO₄) particulate reinforced with AA6063 alloy composites. In this experimental study, B₄C and ZrSiO₄ particulates reinforced with AA6063 composites were manufactured by stir casting technique. Mechanical properties of these composite materials were investigated by different weight percentages, 3%, 6%, 9% of boron carbide (B₄C) and 9%, 6%, 3% of zirconium silicate (ZrSiO₄) respectively. The mechanical properties evaluation reveals variations in hardness and the tensile strength values with the composite combinations investigated in this work. From the experimental studies, the optimum volume fraction of hybrid reinforcement in AA6063 alloy on the basis of mechanical properties and SEM analysis is also determined.

Abstract: In this study, B₄C and MoS₂ were taken as reinforcements and Al2219 as matrix material. The hybrid MMC’s were produced by stir casting technique and Mechanical,Tribological properties of aluminium metal matrix hybrid composites was studied. K₂TiF₆ halide salt with 0.4Ti/B₄C ratio were taken to improve the wettablity of composites.The hybrid composites were characterized by using SEM and XRD.The result reviles that, the fairly distribution of B₄Cp and MoS₂ right through the image and no clustering can be seen.XRD pattern shows the occurrence of B₄C and MoS₂ in prepared composites. The Physical and Mechanical properties were determined for Al2219 and hybrid composites. Micro Vickers Hardness of matrix material is low and for hybrid composite is high. Ultimate tensile strength and yield strength of prepared hybrid composites is low when compared to Al2219; it is generally due to crack propagation and particle pull out of MoS₂ particle.The dry sliding wear behavior were examine by pin-on disc tribometer for different sliding velocities and test result reviles the specific wear rate is minimum for 1.26 m/s and maximum for 6.30 m/s, as the sliding velocity increases the specific wear rate increases. Tensile fractured surface and worn surface pin samples of Al2219 and hybrid MMC’s were examine using SEM micrograph

Abstract: Abstract. The pipelines for offshore water applications are made of Polyurethane (PU) or polyurethane coated. Most of the shape memory polymer composites are made with polyurethane resin, which has poor mechanical properties. Thus it is blend with epoxy resin (EP), because epoxy resin has got good mechanical properties. So designing a suitable composite for shape memory application with improved mechanical properties has become important as it can be used in offshore pipelines for several years. Since epoxy resin has got good mechanical properties, the hardness of the Nanocomposite composed of the heat treated clay powder dramatically increased as a function of clay content, which is attributed to the homogeneous dispersion of the Nano fillers in the polymer matrix and strong filler–polymer interactions. Mechanical properties of the attapulgite clay reinforced polyurethane shape-memory Nanocomposite are strongly dependent on the pre-treatment of the Nano-powders.The energy consumption for actuation and ability to remember two or multiple shapes and the knowledge of the glass transition temperature are very important for the characterization of the composite materials. In this work, the developed composite material is compared with a existing polyurethane composite with the help of Tensile test. It has been observed that the developed composite material strength increases abruptly compared to pipelines made of polyurethane.

Abstract: In this present research work, corrosion behaviour of grit blasted AISI 410 steel substrate coated with NiCr/Al₂O₃,NiCr/ZrO₂ particles was investigated using salt spray test as per ASTM B117. Coatings were prepared using air Plasma spray process. Nickel chromium was used as bond coat for obtaining good fastening between the base metal and coated particles. The microstructures of the coated and un-coated specimens were characterized using scanning electron microscope and optical microscope. Distribution coated particle was found uniform throughout the steel substrate was revealed from SEM microphotographs. The obtained results shows significant improvement in corrosion resistance and micro hardness for NiCr/Al₂O₃ and NiCr/ZrO₂ coating deposited on steel by plasma spray process than the as sprayed base steel substrates.

Abstract: This paper focuses on characterization of Hydroxyapatite coated SS316 L using Pulse vapour deposition method. The target material (Hydroxyapatite) has been synthesised chemically in laboratory through the addition of (NH₄)2HPO₄ with Ca (NO₃)₂4H₂O solution. This mixture has been converted in to circular blocks through various processes as explained below and coated over the stainless steel substrate. The morphological characteristics of the coating and surface roughness analysis have done through SEM and AFM. Also the hardness and corrosion resistance of the coating are examined. It has been found that improved hardness when compared with SS316L (175 Hv) to Hydroxyapatite (245 Hv) coated SS316 L. Also the results of corrosion resistance test after 250 Hrs of experiment found that formation of red rust is attained for uncoated samples where as Hydroxyapatite coated samples remains unchanged.

Abstract: Various defects on the CNT wall have been reported, which are formed during the synthesizing process. CNTs have superior properties compared to the traditional engineering materials. However, these properties hold only for the ideal case of carbon nanotubes, where these are made of perfect hexagonal graphite honeycomb lattice of mono-atomic layer thickness. The advantages or disadvantages of the presence of defects in carbon nanotubes depend on their applications. Structural defects may increase the adhesion of other atoms and molecules to carbon nanotubes. It has also been found that the defects in CNT do cause a change in its resonant frequency as compared to that of a non-defective CNT. The defects that have been considered for the purpose of analysis in this research includes defects in the carbon nanotubes likewise Waviness, Vacancy Defect, Pinhole Defect, Fracture and Stone Wales Defect. It has been observed that with the increase in the number of defects in CNT, a reduction in the fundamental frequency is observed.

Abstract: Al6061 has immense use in manufacture of several internal combustion engine parts as well. However the internal parts of an IC engine manufactured using Al6061 are susceptible to corrosion. Water may condense on the cylinder walls or move across the piston rings owing to blow-by and thus be admitted into the crankcase. This usually occurs in cold environment or short duration drive since pertaining to these conditions the engine may still be not hot enough to get rid of this water by evaporation. Upon amalgamation of this condensed water with the sulphur present in considerable quantities especially in low-grade fuels, sulphuric acid is formed thereby leading to a localized corrosion enhancing corrosive environment. In this work, TiO₂ and Inconel 718 are plasma sprayed on Al6061 specimen and their ability to protect against corrosion is studied and observed that the corrosion resistance of specimen coated with TiO₂ has improved by a considerable margin.

Abstract: Sericin is a natural protein which is removed from silk in a process called degumming. In India, 250-300 tons of sericin is extracted per year and goes as waste, it has wide range of application because of its properties like antioxidant, antibacterial, UV resistant, anticoagulant and moisture retention capacity. This paper is concerned with the application of sericin on polyester fabrics using cross linking agents like di-methylol di-hydroxy ethylene urea (DMDHEU) and glutaraldehyde. The Polyester fabrics are pretreated with sodium hydroxide (NaOH) and low temperature plasma (Oxygen gas). This pretreated sericin applied polyester fabrics show the better improvement in the wicking (moistureabsorbency) and good dye uptake properties on acid dyed fabric and it will be used for medical application.