Defence Metallurgical Research Laboratory

About: Defence Metallurgical Research Laboratory is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 1208 authors who have published 2662 publications receiving 51663 citations.

Erosion-oxidation interaction in Ni and Ni-20Cr alloy

Abstract: The solid-particle erosion of metals and alloys at elevated temperatures is characterized by different mechanisms of material removal, depending on the temperature of exposure, impact velocity, impact angle, and flux rate of the eroding particles. The objective of this article is to delineate the prevalent erosion mechanisms in nickel and a nickel-20 chromium alloy over a large range of temperatures, impact velocities, impact angles, and particle feed rates. For this purpose, a specialized elevated-temperature erosion rig has been utilized. Nickel and a Ni-20Cr alloy have been chosen as the test materials, in view of their substantially different oxidation behaviors. Results from the present study indicate that while the erosion rate generally increases with increasing temperature, an increased particle feed rate causes a reduction in the erosion rate, especially at higher temperatures beyond 650 K. On the basis of a detailed examination of the morphology of the eroded surfaces and the subsurface features beneath the eroded surfaces, four different material removal mechanisms have been identified in the nickel, while only three material removal mechanisms were operative in the Ni-20Cr alloy. Utilizing the aforementioned information, erosion-oxidation (E-O) interaction mechanism maps (herein, termed E-O maps) delineating the regions of dominance of the various erosion mechanisms in an impact velocity-test temperature space have been constructed for Ni and a Ni-20Cr alloy. Finally, the differences in erosion behavior between the Ni and Ni-20Cr alloy have been identified and rationalized.

Biochemical alterations induced by nickel oxide nanoparticles in female Wistar albino rats after acute oral exposure.

Abstract: Context: Nickel oxide (NiO) nanoparticles (NPs) with appropriate surface chemistry have been widely used for their potential new applications in biomedical industry. Increased usage of these NPs, enhances the chance of exposure of personnel involved in the work place.Objective: This study was designed to assess the ability of NiO NPs to cause biochemical alterations post-acute oral exposure in female Wistar rats.Materials and methods: Rats were administered with 125, 250, and 500 mg/kg doses of NiO NPs for haematological, biochemical and histopathological studies. Biodistribution patterns of NiO NPs in female Wistar rats were also monitored.Results: NiO NPs caused significant (P < 0.01) inhibition of RBC and brain AchE of treated rats at the high dose. Activation of the hepatotoxicity marker enzymes, aminotransferases was recorded in serum and liver, whereas inhibition was observed in kidney. The activity of antioxidant enzymes was also altered by NiO NPs in a dose-dependent manner and found to be...

Dielectric and piezoelectric properties of SrBi4−xHoxTi4O15 (x=0.00, 0.02, 0.04 and 0.06) ceramics

Abstract: The dielectric and piezoelectric properties of SrBi4−xHoxTi4O15 (x=0.00, 0.02, 0.04 and 0.06) ceramics were investigated. SrBi4−xHoxTi4O15 (x=0.00, 0.02, 0.04 and 0.06; SBHT-x) ceramics were synthesized by the conventional solid state reaction sintering method. An X-ray diffraction measurement indicated that a single phase layered perovskite was obtained for all compositions. Studies of dielectric properties with temperature at different frequencies and piezoelectric properties have been carried out.