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The purpose of this paper is to report on the tribological properties of beef tallow grease and improvements therein through modification with special processing, polymeric compounds and additives.

Pure original beef tallow grease was used as a biological lubricating grease reference material for the tribological research. Beef tallow was modified and synthesized by adding special biological anti-oxidant additives, LZ anti-wear additives, waste polyethylene terephthalate (PET) polymer compounds and thermally processed graphite.

Rheometric measurements indicate that the beef tallow grease modification technology used in this study enables control of the synthesis process to produce lubricants with the required microstructure. Investigation results of the tribological properties of differently modified greases show that beef tallow synthesized with polymer additives efficiently operates together with anti-wear additives to reduce friction and wear. The grease compound with thermally processed graphite has good tribological properties at 300 N load levels. The critical load level of lubricating greases could be significantly increased through the use of anti-wear additives and thermally processed graphite.

Investigation results of the tribological properties of differently modified beef tallow greases show that beef tallow synthesized with polymer additives efficiently operates together with anti-wear additives to reduce friction and wear. The critical load level of lubricating beef tallow greases could be significantly increased using anti-wear additives and thermally processed graphite.

Coupled metallographic examination and heat transfer numerical simulation are applied to reveal the laser sintering mechanisms of Ti powder of 63‐315 μm particle diameter. A Nd:YAG laser beam with a diameter of 2.7‐5.3 mm and a power of 10‐100 W is focused on a bed of loose Ti powder for 10 s in vacuum. The numerical simulation indicates that a nearly hemispherical temperature front propagates from the laser spot. In the region of α‐Ti just behind the front, heat transfer is governed by thermal radiation. The balling effect, formation of melt droplets, is not observed because the temperature increases gradually and the melt appears inside initially sintered powder which resists the surface tension of the melt.

This paper aims to present the influence of glass bead concentration in a matrix of polyamide on wear and several three-dimensional (3D) parameters of the surface texture when the composite is sliding on steel in dry contact.

There were mold disks with the following concentrations in glass beads: 2.5, 5.0, 10, 20, 30 and 50 per cent. The mix of glass beads has diameters in the range of several microns to 50 microns. Tests were done on a pin-on-disk tribotester, in dry regime, for the following parameters: average pressure (1, 2 and 3 MPa) and sliding speed (0.5, 1.0 and 1.5 m/s). Zones of 500 × 500 μm were investigated from worn tracks generated on the composite disks, and the average values of several 3D texture parameters were analyzed.

The authors plotted maps indicating no correlation between the glass bead concentration and the parameters characterizing the surface quality (amplitude parameters and functional parameters). Composites with concentrations of 10[…]30 per cent glass beads generated worn surfaces with better quality as compared to composites with extreme concentrations: low (2.5 and 5 per cent) and high (50 per cent).

This set of parameters allows for evaluating the influence of regime parameters on the surface quality, by comparing the obtained values before and after sliding, and this evolution of roughness parameters could give recommendations for selecting the friction couple of materials for particular contacts that function with repeated starts and stops.

The results encourage the researchers to use a set of 3D texture parameters instead of “classical” two-dimensional parameters, the arithmetic mean deviation of the profile, Ra, because this set of parameters better evaluate the surface quality, especially for worn surfaces.