Tribological evaluation of solid lubricant enriched in modified Jatropha-Based Oil as Minimum Quantity Lubrication (MQL) oil for composite material

The use of lubricant during the machining process plays an important role to reduce friction and wear. Mineral-based oil is the most widely used lubricant that provided high-quality lubrication properties. However, mineral-based oil has poor biodegradability and causes long-term pollution to the environment and harmful to human. Implementation of environmental-friendly lubricant was encouraged to achieve sustainable manufacturing practices. The inherent biodegradability of vegetable-based oil with solid particle offers greater benefit to the environment and lubrication performance. The study aims to evaluate the influence of green solid particle (hexagonal boron nitride, hBN) enriched in the modified jatropha oil (MJO) through tribology testing using four-ball tribotestermachine. hBN particlewas added inMJOat various concentration ratio; 0.05wt% and 0.5wt%. TheMJOsamples were compared with the crude jatropha oil and commercial synthetic ester. The tribology testing was conducted according to ASTM D4712. The value of coefficient of friction, wear scar diameter, worn surface analysis and surface roughness were evaluated. The lowest concentration of hBN particles in MJO (MJO + 0.05 wt% hBN) has reduced the coefficient of friction with smaller wear scar diameter and better surface roughness quality. The worn surface analysis from the ball lubricate byMJO + 0.05 wt% hBN had light and shallow grooves. The study proved that MJO + 0.05 wt% hBN exhibits better lubrication ability and suitable as an alternative for the environmental-friendly lubricant especially for minimum quantity lubrication (MQL) oil

External sulphate attack on recycled concrete: Assessment of the influence of recycled aggregate

The performance of recycled aggregate concrete (RAC) under external sulfate attack (ESA) has not been fully clarified yet. The attached mortar on recycled aggregate particles increases the content of hydration products from Portland cement that are able to react with external sulfates. In addition, it increases the porosity of the resulting material, facilitating the penetration of ions.In this paper, we present experimental results focusing on the evaluation of the potential reactivity of recycled aggregates themselves. Weight and length variations of mortar bars made with fine recycled aggregates obtained from crushing concretes containing high and low C3A Portland cements were determined after exposure to sulfate solution at 38ºC. In addition, concrete cores with 25 mm and 75 mm in diameter exposed to sulfate solution at 20ºC were also evaluated. The results show no indication of significant reactivity of recycled aggregates with external sulfate.Fil: Santillan, Lautaro Rodolfo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Área Tecnología del Hormigón; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Villagrán Zaccardi, Yury Andrés. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Área Tecnología del Hormigón; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Zega, Claudio Javier. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Área Tecnología del Hormigón; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaRILEM Final Workshop of TC 251-SRTMadridEspañaInstituto de Ciencias de la Construcción Eduardo TorrojaThe International Union of Laboratories and Experts in Construction Materials, Systems and Structure