A study on microstructural, mechanical properties and optimization of wear behavior of friction stir processed AlCrCoFeNi High Entropy Alloy reinforced SS410 using response surface methodology

The equimolar High Entropy Alloy (HEA) is incorporated on the surface of SS410 steel to enhance the mechanical properties for the current industrial scenario. The objective of the present work is to make a first attempt at surface modification of SS410 steel with gas atomization synthesized AlCrCoFeNi HEA powder through Friction Stir Processing (FSP). The microhardness and ultimate tensile strength of the FSP-HEA sample are increased by 41.3 % and 39.1 % respectively due to the high degree of refined grains with 2.84 μm and evenly distributed HEA particles. The wear rate of FSP-HEA samples is optimized by response surface methodology with process parameters including applied load, sliding distance, and sliding velocity. The most influential factor and regression model are derived from experimental results that predict the wear rate by the analysis of variance technique. The worn surface of FSP-HEA samples is evaluated by morphological analysis with corresponding induced wear mechanisms. The minimum wear rate is achieved by optimum process parameters along with higher hardness through particle-stimulated nucleation mechanism, Hall-Petch relation, and dynamic recrystallization. The grain refinement, barrier effect, and grain growth hindrance of HEA particles lead to enhancement in the strength of processed HEA samples.

Simulation of ground water quality for noyyal river basin of Coimbatore city, Tamilnadu using MODFLOW

In recent years groundwater modelling has become a major part of many projects dealing with groundwater exploitation, protection and remediation. Coimbatore city is located along the Noyyal River which is grown in size and population on either side of the river and the dumping of wastes very close to the river banks, leads to pollution of both surface and groundwater. Study on the quality of groundwater along the Noyyal River in Coimbatore city of Tamilnadu, is necessary to safeguard the interest of the people with respect to quality and quantity of water. The objective of the research is to develop Groundwater quality models to suggest ways and means to contain and remediate the polluted groundwater under various conditions. Data related to the groundwater quality, rainfall and well log were collected from the reputed government departments and fifteen sample well locations are identified near the noyyal river basin. The quality parameters such as pH, TDS, EC, TH, chlorides, alkalinity, sodium, calcium, magnesium, sulphates and nitrates are considered for the study. Groundwater quality modelling is attempted by using MODFLOW/MT3DMS with different scenarios. This study revealed that in all the scenarios the center portion of study area is more affected i.e. from P·N.Palayam to Kalangal. The groundwater flow is moving towards and along the river flow. Hence the pollutants are moving easily from upstream to the downstream side. necessary measures has to be taken to control the groundwater contamination.

Shewanella algae and Microbulbifer elongatus from marine macro-algae - isolation and characterization of agar-hydrolysing bacteria

Macro-algae are a good source of agar oligosaccharides, which can be obtained through bacterial enzymatic hydrolysis. The agarase enzyme secreted by the micro-organisms cleaves the cell wall of the algae and releases agar oligosaccharides as degradation products with various applications. Agarolytic bacteria were isolated from the marine algae Kappaphycus sp., and Sargassum sp., and studied for their agar-degrading properties. Among the 70 isolates, 2 isolates (A13 and Sg8) showed agarase activity in in vitro assays. The maximum agarolytic index was recorded in the isolate Sg8 (3.75 mm and 4.29 µg ml-1 agarase activity), followed by the isolate A13 (2.53 mm and 2.6 µg ml-1 agarase activity). Optimum agarase production of isolate Sg8 was observed at pH7 and at a temperature of 25 °C in 24-48 h, whereas for isolate A13 the optimum production was at pH7 and at a temperature of 37 °C in 48 h. The identities of the agarolytic isolates (Sg8 and A13) were confirmed based on microscopy, morphological, biochemical and molecular analysis as Shewanella algae [National Center for Biotechnology Information (NCBI) GenBank accession number MK121204.1] and Microbulbifer elongatus [NCBI GenBank accession number MK825484.1], respectively.