Search results

With ion plated aluminium films, the film acted as the anode of the cell and was subject to chemical dissolution. The corrosion rates in NaCl, however, were comparatively lower than those detected for bulk aluminium. Figs. 8 and 9 show scanning electron micrographs for surface texture of a coated couple in comparison with the surface texture of uncoated couples.

The purpose of this paper is to fabricate composite nanogrease for tribological applications. Multi-walled carbon nanotubes (MWCNTs) with a size 10 nm average diameter and 5 μm in length were used as additives to calcium grease.

The tribological four-ball machine was used to evaluate calcium grease with carbon nanotubes (CNTs) as an additive. The interaction between CNT and calcium grease (nanogrease) were studied by transmission electron microscopy and X-ray diffraction.

MWCNTs composite nanogrease was manufactured for tribological applications. The effectiveness of the fabricated grease in improving the tribological performance at different concentrations and under different loads was tested. The results are summarized as follows. CNT nanoparticle additive dispersed in calcium grease significantly improve its anti-wear performance, reducing friction, increasing load-carrying capacity and extreme pressure (EP) property. The friction is reduced by about 50 per cent, the wear scar diameter (WSD) decreased to 32 per cent and the EP properties increases about 38 per cent, with only 3 wt.%. The modified grease with CNTs additives of 3 wt.% showed the most favorable results. Energy dispersive x-ray (EDX) analysis shows that C was present on the worn scar surface, with atomic concentration of about 22 per cent. The presence of C suggests that a lubricating film is likely formed because of the presence of CNTs and very likely prevented the steel-to-steel direct contact.

The results indicated that a 3 wt.% of MWCNT nanogrease is an excellent antiwear, with EP and low friction coefficient. It was also found that the friction coefficient was reduced to about 50 per cent, the WSD decreased by about 32 per cent and the EP properties increased about 38 per cent. The mating surfaces were investigated with scanning electron microscopy and EDX. The results show that a boundary film mainly composed of CNTs, Cr and Fe was formed on the rubbed surfaces.

It is now increasingly recognised that surface coating technology offers production engineers and designers significant opportunities to optimise the use of raw materials. Due to the forecasted shortage in a number of engineering metals, such as zinc, mercury, tin … etc., surface coating technology offers the most attractive finishing process, with material conservations. Suitable bulk materials may be selected for cost or structural reasons, whilst surface coating materials are chosen to meet specific surface properties, such as wear resistance, protection against corrosion, surface thermal and electrical conductance, optical reflections and decorative features. The recent design trends towards higher speeds, minimum airplane weight and maximum load capacity, however, encourage the use of light weight titanium fasteners in airplane aluminium alloy structures. This creates a serious galvanic corrosion problem to airplane skin sheets. In the following a new surface coating technique which is recently recognised as a growth of a new technology is applied to the problem of galvanic corrosion in air frame structures. The application of aluminium coatings for the protection of airplane skin sheets and fasteners against the galvanic corrosion in local environments is investigated. Both polarisation and galvanic tests are used for the evaluation of the potential of the new surface coatings. Furthermore both sodium chloride and sulphur dioxide electrolytes are used to simulate sea water and jet exhaust environments. Electrolyte saturation with either air or nitrogen are considered to compensate for the presence and lack of oxygen at different environments. It is concluded that the strong adhesion and the extensive graded interfaces of the ion plated films are responsible for the good protection of coated metallic couples.

The Ohio State University Libraries began the process of restructuring the Technical Services Department in early 1995. Changes that were introduced as a result of this process had a profound effect on the roles of professional and para‐professional staff in the organisation. The author of this paper will outline the process of revamping the organisational structure of a large department in an academic library and will discuss the impact it had on the traditional roles assigned to librarians and staff in such a setting. The study will concentrate on copy cataloguers and their changing role in Technical Services.

The purpose of this paper is to evaluate the influence of nanoparticles as an additive on the tribological properties of calcium grease.

The nano additives in this research are with different concentration of multi carbon nanotubes (MWCNTs) and Talc powder (1, 2, 3, 3 and 5 per cent). The ratio of MWCNTs to Talc powder is 1:1. The tribological properties of hyper MWCNTs/Talc powder to calcium grease were evaluated using a pin-on-disk wear testing. The results show that the nano additives MWCNTs/Talc to calcium grease exhibit good performance in anti-wear and friction reduction. The action mechanism was estimated through analysis of the worm surface with x-ray diffraction and transmission electron microscope.

The result indicates that boundary film mainly composed of MWCNT and Talc powder, and other organic compound was formed on the worm surface during the friction test. In addition, the wear rate and coefficient of friction of nanogreases have shown excellent improvement about 80.62 and 63.44 per cent, respectively, at 4 Wt.% of MWCNTs/Talc powder. Moreover, the thermal conductivity of nanogrease increased about 51.72 per cent.

This study describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

To enhance the tribological properties of nanogrease, one of the new technologies was used to synthesize a nanogrease having carbon nanotubes (CNTs) nanoparticles (NPs) with different concentrations. The microstructures of the synthesized NPs were characterized and evaluated by x-ray diffraction spectroscopy (XRD) and transmission electron microscopy (TEM). Tribological properties of the nanogrease were evaluated using a four-ball tester. The worn surface of four steel balls was investigated by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX).

Grease was dissolved in chloroform (10 Wt.%), at 25 °C for 1 h. In parallel, functionalized CNTs with different volume concentrations (0.5, 1, 2 and 3 Wt.%) were dispersed in N, N-dimethylformamide. The mixture was stirred for 15 min and then sonicated (40 kHz, 150 W) for 30 min. After that, the mixture was added to the grease solution and magnetically stirred for 15 min and then sonicated for 2 h.

The results suggested that CNTs can enhance the antiwear and friction properties of nanogrease at 0.5 Wt.% CNTs to about 57 and 48 per cent, respectively. In addition, the weld load of the base oil containing 0.5 Wt.% CNTs was improved by 17 per cent compared with base grease.

This work describes the inexpensive and simple fabrication of nanogrease for improving the properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

The purpose of this paper is to investigate the rheological characteristics of graphene nanoplatelets (GNPs) and hybridized nanocomposite consisting of multi-walled carbon nanotubes (MWCNTs) and GNPs as an additive on lithium-based grease. The experiments of nanogrease are examined in different values of shear stress, apparent viscosity, temperature and shear rate using Brookfield Programmable Rheometer DV-III ULTRA and characterized by high-resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD).

First, GNPs was mixed well with lithium grease using mechanical stirring at 3,500 rpm for 15 min at room temperature to form a homogenous composite at different concentrations (0.5, 1, 1.5, 2 and 2.5 Wt.%). Afterwards, MWCNTs and GNPs are mixed and dispersed well in the lithium grease using a sonication path for 30 min and mechanical stirring at 3,500 rpm for 15 min at 28°C to form a homogenous nanocomposite.

The results indicated that 1 Wt.% of GNPs is the optimum concentration. Subsequently, the weight percentage of additives varying between MWCNTs and GNPs are tested, and the result indicate that the grease containing GNPs had a 75 per cent increase in shear stress and 93.7 per cent increase in apparent viscosity over ordinary grease.

This work describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

Examines the outsourcing of Slavic original cataloguing at the Ohio State University libraries. It includes: the rationale for doing so; the evaluation and cost analysis; the advantages and disadvantages; and what we have learned.

This work describes the fabrication of composite nanogrease based on carbon nanotubes (CNTs) as an additive at different volume concentrations 0, 0.5, 1, 2 and 3 Wt.% and investigates the correlation between CNTs and grease rheological behaviour. In addition, study the influence of shear thinning rate at various temperatures and investigates the thermal conductivity of nanogrease. The results demonstrated that grease behaves like a Newtonian viscoelastic material with a narrow linear domain. The thermal conductivity of nanogrease was enhanced by about 31.58 per cent, and the thermal and mechanical stabilities improved. Moreover, the apparent viscosity and dropping point increased by about 93 and 27 per cent, respectively.

Grease was dissolved in chloroform (10 Wt.%), at 25°C for 1 h. In parallel, functionalized CNTs with different volume concentrations (0.5, 1, 2 and 3 Wt.%) were dispersed in N,N-dimethylformamide; the dispersion was stirred for 15 min, and then sonicated (40 kHz, 150 W) for 30 min. Grease solution was then added to the CNTs. The nanofluid was magnetically stirred for 15 min and then sonicated for 2 h. This ensured uniform dispersion of nanoparticles in the base fluid.

Inexpensive and simple fabrication of nanogrease. Thermal conductivity of nanogrease was typically enhanced compared to other reported studies. Apparent viscosity and dropping point increases with the increase the volume concentration.

This work describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.

Reliable grounding is an important condition for the stable operation of substations and cathodic protection is one of the electrochemical protection technologies for substation grounding grids. The purpose of this paper is to consider the design proposal, installation, construction requirements and monitoring methods for Hunan 220 kV substation grounding grid.

This paper treated Hunan 220 kV substation grounding grid as a research object. The physical and chemical data of three soil samples were measured, German DIN50929 evaluation criteria were used to assess its corrosion and a sacrificial anode cathodic protection design was selected, based on advanced concepts.

The design proposal, installation, construction requirements and monitoring methods for the 220 kV substation grounding grid were clearly explained and recommended for implementation.

This paper has some guidance on design ideas and the selection method for substation sacrificial anode cathodic protection.