Although the lubrication systems for internal combustion engines have been designed to prevent engine wear and friction, their configuration does not contemplate the maximum use of each load of lubricant; because of this limitation, lubricant consumption is currently an environmental and economic problem. In this work, the performance of lubrication systems to form the tribological film that prevents wear is simulated and optimized, through the mass balance of the lubricant precursors contained in the oil and the implementation of optimal control techniques. Optimization results indicate that regulating the flow of lubricant passing through the engine prevents excessive degradation of lubricant precursors, maximizing the life of each lube oil charge, giving the possibility to increase the sustainability of internal combustion engines.

DYNA es una publicación científica general del área de las ciencias tecnológicas, fundada en 1933, es el medio de expresión de los trabajos en el área de ingeniería, ciencias y tecnología de la Facultad de Minas de la Universidad Nacional de Colombia.

Los motocompresores elevan la presión del gas después de una caída de presión y temperatura generada durante el acondicionamiento. El paro no programado eleva los costos, pues se deja de dar servicio y percibir ingresos. Para este estudio se analizaron 11 equipos, instalados en 3 plantas de bombeo, se usaron dos criterios: las fallas frecuentes y las fallas críticas, para determinar qué tipo de fallas tienen mayor impacto en la operación de los motocompresores; bajo el criterio de las fallas que generan más tiempo fuera de servicio, las fallas críticas resultaron más relevantes para mejorar la calidad del proceso. Tres fallas críticas representaron el 51.3% del tiempo de mantenimiento correctivo, al prevenirlas mediante un plan de mantenimiento basado en confiabilidad, se redujo el tiempo medio entre fallas (MTF) y el servicio de bombeo se interrumpió por menos tiempo.

The wear reducing properties of aqueous solutions of ammonium thiomolybdate and ammonium thiotungstate were evaluated using a frontal cylinder-on-cylinder test tribometer on an AISI 304 steel–steel contact. The antiwear characteristics of the lubricating solutions of thiomolybdate and thiotungstate were evaluated at 24.5, 30, and 40 N keeping fixed the entrainment speed, sliding distance, temperature, and additive concentration. Although there was a reduction in wear for the two salts compared to fluid reference, it is worth mentioning that the thiotungstate additive was slightly more effective under tested lubricating contact conditions than thiomolybdate additive. Energy-dispersive X-ray spectroscopy (EDS) analysis of a wear track lubricated with thiomolybdate showed Mo and S elements and for the track lubricated with thiotungstate W and S were detected. Raman spectra of the wear track showed peaks at 373, 404 and 208, 253, 280, 353 cm⁻¹ corresponding to 2H-MoS₂ and FeS, respectively. Ammonium thiomolybdate releases sulfur atoms that also react with the freshly exposed surface, forming FeS, which takes part in reducing wear.

General-purpose polystyrene (GPPS) is widely used in packaging and insulation, although its recyclability poses environmental challenges that require circular economy strategies. The objective of this study was to evaluate the mechanical and tribological behavior of virgin GPPS (100%N), a 50% virgin–50% recycled blend (50N–50R), and 100% recycled GPPS (100%R), processed in Mexico under controlled injection molding conditions. Micro-tensile, flexural, surface roughness, and sliding wear (pin-on-disk) tests were conducted in accordance with ASTM/ANSI standards. The results show that virgin GPPS exhibited the highest strength (micro-tensile: 31.1 MPa; flexural: 87.8 MPa), while the 50N–50R blend maintained comparable tensile strength (27.5 MPa) with greater ductility, making it viable for secondary applications. Recycled GPPS exhibited a significant reduction in strength (micro-tensile: 18.6 MPa; flexural: 41.1 MPa), although with greater deformability. In tribological tests, the coefficients of friction were 0.480 (100%N), 0.128 (50N–50R), and 0.143 (100%R), all with relative errors of less than 4%, confirming statistical validity. Surface roughness analysis showed that the virgin material had the most uniform surface (Ra = 1.0 µm), while the blends exhibited greater variation (Ra ≈ 1.2 µm). In conclusion, although recycled GPPS has limitations compared to virgin material, it retains acceptable mechanical and tribological properties for non-structural applications. These findings support its potential in circular economy strategies in Mexico and provide a framework for countries with similar recycling infrastructure conditions.

El presente trabajo tiene como propósito analizar la micro dureza al poliestireno cristal HF555 [1], con máster batch negro para hallar las diferencias entre utilizar diferentes porcentajes de material nuevo-reciclado, las 5 muestras que se utilizaron para el estudio fueron de ramas obtenidas por el proceso de inyección colada fría, estas mezclas van desde el 100% de material reciclado hasta el 100% de material nuevo (virgen) con intervalos de 25% entre cada muestra. Después de realizar 50 indentaciones bajo el método de micro dureza Vickers los resultados demuestran que, si existe diferencia en utilizar más del 50% de material reciclado contra utilizar el 100%, por lo tanto, se puede concluir que utilizar una mezcla con el 75% de material reciclado o más se obtiene una menor resistencia a la penetración del poliestireno coloreado y que a partir de utilizar una mezcla con el 50% reciclado-50% virgen se obtiene una mayor resistencia a la penetración, pues al principio del trabajo se propone que la mezcla ideal sea del 75% reciclado-25% virgen, pero con base a los datos obtenidos no es posible.