Search results

The mechanical properties of Sn/Ag/Cu solder joints in combination with different component lead coating materials (Ni/Pd/Au, Sn/15 per cent Pb, Sn/2 per cent Bi, and Sn) are studied in this work using a lead pull test and free fall drop test. The results of this study show that the Sn/2 per cent Bi coated components provide the best performance under the drop impact loading followed by the Sn/15 per cent Pb, Sn and Ni/Pd/Au coated components. Failure modes and the structure of the coating surfaces were examined from cross‐sectioned samples using a scanning electron microscope. Furthermore, the wetting of the leads by the solder and thickness of the IMC layers were studied.

The purpose of this paper is to propose a novel wireless sensor node (SN), with impact resistant capability, for launch deployment into closed areas. In disaster areas, gathering disaster area information is crucially important to prevent secondary disasters. However, gathering information is usually associated with the risk of death and/or accident for rescue workers in closed areas. The authors propose the SN for gathering information in dangerous places, inaccessible to rescue workers and robots, by utilizing launch deployment.

Buffer material is essential when designing an impact‐resistant structure. The authors adopted the air cushion as general buffer material when considering the directional characteristics of sensor mounting and wireless communication quality and developed the expression for determining the thickness of the air cushion using the parameters of SN size, mass, air pressure and acceleration. The authors developed a sensor node with impact resistant structure by utilizing the proposed determination method of air cushion thickness.

In the evaluation of impact resistant structure in free fall, launch deployment, the authors verified that the impact resistant structure protected the SN, and the performance of configured devices on the SN. Then, the authors examined the effect of the impact‐resistant structure on wireless communication between SNs. The structure had no effect on electric field intensity, throughput, or packet jitter, which confirmed that the wireless communication capacity was unaffected by the structure.

In this paper, a new design method is stated for a sensor node with an impact‐resistant structure by utilizing an air cushion as a general buffer material.

The aim of this paper was to investigate the possibility of reusing frying oil, obtained during thermal treatment of food in fast-food restaurants for production of plastic greases.

In accordance with the proposed research concept, the used frying oil was to be the base oil of biodegradable plastic greases thickened with calcium 12-hydroxystearate and lithium 12-hydroxystearate. These studies included the determination of the effect of variable amounts of used oil component in the base oil on the properties of the resultant plastic greases.

It was found that the optimum amount of the component in the base oil is 10-15 per cent. Calcium and lithium greases prepared in such a way possess a quality to that of greases prepared with fresh rapeseed oil.

Higher concentrations of used frying oil in the base oil adversely affect the degree of thickening, thixotropic properties and dropping point of the grease, as well as, creating technological problems.

The investigations, beside their research goals have also a practical character – recycling waste material in place of its present method of disposal.

One of the least expensive material, and most commonly used to produce biodegradable lubricants are vegetable oils. In recent years, besides introducing biodegradable lubricating oils, increasing interest is observed in the use of plastic greases of high biodegradability. Now, it is possible to obtain such greases with additive of used frying oils. Biodegradable greases are used as lubrication of open gear, food production equipment, central lubrication system in cars and railway engineering.

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.

Parts One and Two in this series, which appeared in our February and March issues, dealt with Viscosity, Penetrometers, Rheometers, Penetration Methods, Limits and Variations, etc. The fourth part will cover miscellaneous properties, tests for which are included in modern specifications. Readers are reminded that Mr. Ellis's book, “Lubricant Testing—Introducing Recent Developments in Testing Technique” will be published very shortly.

This paper reports on the preparation of six formulations (G1‐G6) containing mixed soap greases based on cotton soap stock, aromatic extract, heavy alkylate and lube base oil. The physicochemical properties of these ingredients were characterised. The consistency, dropping point and mechanical stability of the formulated greases were assessed and tested in accordance with the National Laboratory for Grease Institute standards, and compared with the Egyptian Standards. The properties of the formulated grease G4 proved to be the best. The work reported also includes preparation of itaconyl‐o‐tolidine‐, itaconyl bisaniline‐ and itaconyl m‐phenylene‐ amide polymers. The structure of these polymers was investigated using infrared spectroscopy, micro analysis and gel permeation chromatography. The polymers prepared were evaluated as antioxidants for the optimum formulated grease G4. The study revealed that the itaconyl m‐phenylene amide polymer was a weak antioxidant, while itaconyl bisaniline‐ and itaconyl‐o‐tolidine amide polymers showed good anti‐oxidation property.

The purpose of this paper is to conduct research on the possibility of improving the tribological and utilization properties of lard and rapeseed oil bio-based greases by mixing it with ethanol and selection of thickener and modification with special biological additives.

Rapeseed oil- and lard-based greases with sodium and lithium soap thickeners were mixed with either water or ethanol and modified with a special biological anti-wear additive. Tribological properties of modified lubricants evaluated on a four-ball machine.

Rapeseed oil- and lard-based greases suspended in ethanol and modified with bio-additive have the same wear resistance as the industrial non-biological lubrication grease and much higher wear resistance as bio-based reference grease. The tribological efficiency of the additives is higher in greases of rapeseed oil and less efficient in lard-based greases. Oxidation and wear tests show that investigated bio-based greases have comparatively stable tribological properties also after their aging. Modified greases have sufficient consistence according penetration measurements and high thermal resistance according drop-point temperature measurements. All produced experimental greases pass within the category of the easily degradable materials.

The greases mixed with the ethanol make possible to form more homogeneous and stable grease mixture. Modified bio-based greases have significantly higher wear resistance as bio-based reference grease, their lubrication properties are stable also after the aging and are categorized as easily degradable materials.

Decreasing energy demand due to improved building standards requires the development of new biomass combustion technologies to be able to provide individual biomass heating solutions. The purpose of this paper is, therefore, the development of a pellet water heating stove with minimal emission at high thermal efficiency.

The single components of a 10 kW water heating pellet stove are analysed and partly redesigned considering the latest scientific findings and experimental know‐how in combustion engineering. The outcome of this development is a 12 kW prototype which is subsequently down‐scaled to a 6 kW prototype. Finally, the results of the development are evaluated by testing of an accredited institute.

Based on an existing pellet water heating stove, the total excess air ratio was reduced, a strict air staging was implemented and the fuel supply was homogenized. All three measures improved the operating performance regarding emissions and thermal efficiency. The evaluation of the development process showed that the CO emissions are reduced by over 90 per cent during full load and by 30‐60 per cent during minimum load conditions. Emissions of particulate matter are reduced by 70 per cent and the thermal efficiency increased to 95 per cent.

The result represents a new state of technology in this sector for minimal emissions and maximal thermal efficiency, which surpasses the directives of the Eco label “UZ37” in Austria and “Blauer Engel” in Germany, which are amongst the most stringent performance requirements in the European Union. Hence this design possesses a high potential as heating solution for low and passive energy houses.