Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of t...Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of the copper alloys which has many applications in everyday life and the industry. In this work, the influence of the precipitation heat treatment temperature on the metallurgical microstructure, structure, thermal properties, and microhardness of an alpha brass is analyzed. Samples were heat treated by precipitation for 2 h at 300°C, 400°C, 500°C, 600°C, and 700°C. The best mechanical properties were found at 500°C of precipitation heat treatment temperature. Specimens were characterized by scanning electron microscopy, X-ray diffraction, Vickers microhardness, photothermal radiometry, and photoacoustic to study the thermal diffusivity and conductivity, as well as the heat capacity. The inverse of the full width at the half maximum analysis showed that the crystallinity decreased as the precipitation heat treatment temperature increased. Metallurgical microstructure and microhardness were correlated to the precipitation heat treatment temperatures to determine the effect on the metallurgical and mechanical properties, as well as the effect on the thermal properties of alpha brass.展开更多
Marine microplastics(MPs)are an increasingly important concern worldwide.This study aimed to investigate the occurrence and characteristics of microplastics in an intertidal sea snail,the common periwinkle(Littorina l...Marine microplastics(MPs)are an increasingly important concern worldwide.This study aimed to investigate the occurrence and characteristics of microplastics in an intertidal sea snail,the common periwinkle(Littorina littorea)sampled from Saint Martin's Island,Bay of Bengal.The results revealed that 100%of the common periwinkle snails ingested microplastics(MPs),with a mean abundance ranging from 2.63±1.07 to 23.89±3.53 MP/g(average:7.76±5.77 MP/g).Microplastic particles in the 100–1500μm size class were the most abundant(63%),whereas black and red fibers were the most abundant colors and shapes.Polypropylene(PP,34%)and polyethylene(PE,38%)were the major polymer types,followed by polystyrene(PS,15%)and polyethylene terephthalate(PET,13%).Although the polymer hazard index(PHI)showed risk categories Ⅲ to Ⅳ due to highly hazardous polymers such as PS and PE in the soft tissue of the common periwinkle snails,the pollution load index(PLI<10)revealed minor contamination across the sampling site of Saint Martin's Island.Gastropod feeding patterns and food items impacted MP abundance in the studied area.展开更多
文摘Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of the copper alloys which has many applications in everyday life and the industry. In this work, the influence of the precipitation heat treatment temperature on the metallurgical microstructure, structure, thermal properties, and microhardness of an alpha brass is analyzed. Samples were heat treated by precipitation for 2 h at 300°C, 400°C, 500°C, 600°C, and 700°C. The best mechanical properties were found at 500°C of precipitation heat treatment temperature. Specimens were characterized by scanning electron microscopy, X-ray diffraction, Vickers microhardness, photothermal radiometry, and photoacoustic to study the thermal diffusivity and conductivity, as well as the heat capacity. The inverse of the full width at the half maximum analysis showed that the crystallinity decreased as the precipitation heat treatment temperature increased. Metallurgical microstructure and microhardness were correlated to the precipitation heat treatment temperatures to determine the effect on the metallurgical and mechanical properties, as well as the effect on the thermal properties of alpha brass.
基金Research Cell,Noakhali Science and Technology University partially supported this study through project number NSTU/RC-OC-03/T-23/117.
文摘Marine microplastics(MPs)are an increasingly important concern worldwide.This study aimed to investigate the occurrence and characteristics of microplastics in an intertidal sea snail,the common periwinkle(Littorina littorea)sampled from Saint Martin's Island,Bay of Bengal.The results revealed that 100%of the common periwinkle snails ingested microplastics(MPs),with a mean abundance ranging from 2.63±1.07 to 23.89±3.53 MP/g(average:7.76±5.77 MP/g).Microplastic particles in the 100–1500μm size class were the most abundant(63%),whereas black and red fibers were the most abundant colors and shapes.Polypropylene(PP,34%)and polyethylene(PE,38%)were the major polymer types,followed by polystyrene(PS,15%)and polyethylene terephthalate(PET,13%).Although the polymer hazard index(PHI)showed risk categories Ⅲ to Ⅳ due to highly hazardous polymers such as PS and PE in the soft tissue of the common periwinkle snails,the pollution load index(PLI<10)revealed minor contamination across the sampling site of Saint Martin's Island.Gastropod feeding patterns and food items impacted MP abundance in the studied area.
