Tribological performance of glass/epoxy composites filled with MWCNTs

The effect of addition of multi-walled carbon nanotubes (MWCNTs) on the wear behaviour of glass/epoxy composites manufactured using the pre-preg method was investigated. The MWCNT filling rates were 0.5, 1, and 2 wt.%, and unfilled composite samples were used for comparison. The worn surfaces were characterised by means of scanning electron microscopy for evaluating the wear mechanisms. The experimental results showed that all the composites filled with MWCNTs have a lower wear loss than the unfilled composite sample, and the wear resistance increased with increase in the amount of MWCNTs. It is revealed that the abrasive wear resistance of the glass/epoxy composites is mainly related to the adhesion at the matrix and fibre interface. © Carl Hanser Verlag GmbH & Co. KG

process

The effects of burnishing and other conventional machining processes (grinding, reaming, drilling, turning, and honing) on the surface characteristic properties of mild steel were investigated and compared in terms of surface roughness, circularity (roundness), and cylindricity in this study. The effect of these processes on the microstructures was also examined to understand the relationship between the machining process and surface characteristic properties. All surface machining processes were performed under constant depth of cut, cutting speed, and feed rate. The highest hardness was obtained on the burnished surface. Experimental results also showed that the roller burnishing method is the most favorable post-machining process method for obtaining optimum surface topography on mild steel

Production of surface chilled ductile iron

Surface chilled ductile iron has become a promising material for machine parts exposed the wearing and impact because of good combination of high wear resistance and toughness. In this study, the effect of the chemical composition, mold wall thickness and sample diameter on the chill formation, chill depth, and carbide precipitation in the ductile iron were studied. The casting having four different chemical compositions were carried out to copper molds having various samples diameter (empty set 10-50mm) and mold wall thickness (5, 15, 20, 30 and 50 mm). Microstructural and hardness profile evaluation were carried out from surface to center of part in order to define the effects of cooling rate on the chill formation. Experimental results showed that the production of surface chilled ductile iron having various chill depths can be achieved with controlling of the cooling rate. Hardness profile increases with increasing of mold wall thickness (cooling rate). High chromium content increases chill depth and decrease graphite formation. High silicon content promotes graphite formation while it decreases carbide precipitation. Chill formation on the ductile iron can be optimized with controlling mold wall thickness and sample diameter (cooling rate)

Investigation of tribological behaviours of graphene-coated journal bearing

In this study, we investigated macro- and nano-scale tribological behaviours of single-layer graphene on steel parts. Single layer graphene was synthesized via Chemical Vapour Deposition (CVD) on copper foil and then transferred onto commercial journal bearing that has a considerable rough surface. Nanotribological tests were carried out by using Atomic Force Microscopy (AFM) under loadings differs from 5 to 30 nN, and macrotribological experiments were done using pin on disc type tribometer at three different loads of 10, 15 and 30 N within 90, 120 and 250 s sliding cycle durations. The results exhibited that graphene effectively diminish the wear rate of substrate material, whereas it has no significant improvement in coefficient of friction due to high asperity of surface. The worn surface analyses were characterized by scanning electron microscopy for the evaluation of wear mechanisms. © 2018, © 2018 Institute of Materials, Minerals and Mining and Informa UK Limited, trading as Taylor & Francis Group

of an AISI 52100 steel

The effects of repeated tempering process on the microstructure and machinability of AISI 52100 steel in terms of cutting force, cylindricity and surface roughness were investigated in the present study. Specimens were annealed at 850 degrees C for 60 minutes. The specimens were then rapidly quenched in oil. Quenched samples were tempered at various tempering temperatures (175, 225, 300 and 400 degrees C) and numbers of passes (1 and 2) in a tempering furnace. Machining tests were carried out at various cutting speeds (30, 45, 60 and 70 m x min(-1)), various feed rates (0.15, 0.20 and 0.25 mm x rev(-1)) and at a constant depth of cut at 0,4 mm after repeated tempering. The experimental results show that repeated tempering temperature and number of passes significantly affect microstructure and machinability of AISI 52100 steel. The hardness of the AISI 52100 steel decreases with increasing number of temperings and temperature. The lowest cutting force was obtained at the highest cutting speed and the lowest feed rates. The machinability of AISI 52100 can be optimized by repeated tempering heat treatment

Effect of ecological surface treatment method on friction strength properties of nettle (urtica dioica) fibre yarns

Over the last few decades, more attention is given to lignocellulose based fibres as reinforcement material in the polymer composites owing to the environmental pollution caused by the extensive usage of synthetic and inorganic fibres. Developing new natural fibre reinforced composites is the focus of many researches nowadays. They are made from renewable resources and they have less environmental effect in comparison to inorganic fibre reinforced composites. The interest of consumers in eco-friendly natural fibres and textiles has increased in recent years. Unlike inorganic fibres, natural fibres present light weight, high strength/density ratio and are readily available, environmentally friendly and biodegradable. Many different types of natural fibres are exploited for the production of biodegradable polymer composites. The nettle (Urtica dioica L.) is a well-known plant growing on rural sites of Europe, Asia, and North America. Nettle plant contains fibre similar to hemp and flax. However, similar to other natural fibres, nettle fibres are poorly compatible with the thermoplastic matrix of composites, due to their hydrophilic character which reduces mechanical properties of nettle fibre reinforced thermoplastics. In order to improve the fibrematrix adhesion of the natural fibre reinforced composites, surface treatment processes are applied to the lignocellulose fibres. In this study nettle (urtica dioica) fibre yarns were treated with NaOH by using conventional, ultrasonic and microwave energy methods. After treatment processes tensile strength, elongation, friction strength and SEM observations of the nettle fibre yarns were investigated. All treatment processes were improved the tensile strength, elongation and friction strength properties of the nettle fibre yarns. Also higher tensile strength, elongation and friction strength properties were obtained from treated nettle fibre yarns which treated by using microwave energy method. © Published under licence by IOP Publishing Ltd

Congenital sialidosis

Congenital sialidosis is a rare disease resulting from the absence of neurominidase and presenting with hydrops fetalis, hepatosplenomegaly, dysmorphic features, vacuolated lymphocytes and extensive vacuolation of the connective tissue. Elevated levels of sialooligosaccharides in the urine is characteristic. We describe a newborn baby with congenital sialidosis and discuss the difficulties in reaching the diagnosis