Microscopic analysis of Fe-Cr alloy produced by single roll strip casting

Das, S.,Seol, J.B.,Kim, Y.C.,Park, C.G. Maney Publishing 2011 Materials science and technology Vol.27 No.9

Structure and mechanical properties of Ni-Cr alloy produced by single roll strip casting

Das, S.,Seol, J.B.,Kim, Y.C.,Park, C.G. Scientific and Technical Press ; Elsevier Science 2010 MATERIALS AND DESIGN Vol.31 No.1

In the present investigation the microstructure and some mechanical properties of Ni-Cr alloy prepared by single roll strip casting (SRSC) were studied. The top surface (surface not in contact with the roll) of the as received sample was rough and lusterless. The grain size of the top surface was significantly larger compared to that of the bottom surface. Grain interior showed dendritic morphology. Etch-pits, formed by dislocation were observed on the top and bottom surfaces of the sample. Scanning electron microstructure revealed continuous corroded region along the grain boundaries. X-ray diffraction (XRD) study confirms the formation of chromium carbide at the grain boundary, which depletes Cr near the grain boundary. The hardness of the top surface is lower compared to the bottom surface. The cross-sectional surface shows much higher hardness compared to top and bottom surface, suggesting anisotropic nature of the alloy. The tensile properties of the sample were affected by chromium carbide precipitation at grain boundaries.

INTERACTION BETWEEN THREE MOVING GRIFFITH CRACKS AT THE INTERFACE OF TWO DISSIMILAR ELASTIC MEDIA

Das, S.,Patra, B.,Debnath, L. 한국전산응용수학회 2001 The Korean journal of computational & applied math Vol.8 No.1

The paper deals with the interaction between three Griffith cracks propagating under antiplane shear stress at the interface of two dissimilar infinite elastic half-spaces. The Fourier transform technique is used to reduce the elastodynamic problem to the solution of a set of integral equations which has been solved by using the finite Hilbert transform technique and Cooke’s result. The analytical expressions for the stress intensity factors at the crack tips are obtained. Numerical values of the interaction efect have been computed for and results show that interaction effects are either shielding or amplification depending on the location of each crack with respect to other and crack tip spacing. AMS Mathematics Subject Classification : 73M25.

Genetic Variation and Correlation Studies of Some Carcass Traits in Goats

Das, S.,Husain, S.S.,Hoque, M.A.,Amin, M.R. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.7

Three groups of wethers viz. Jamunapari ♂$\times$Black Bengal ♀ (JBB), Selected Black Bengal ♂$\times$Selected Black Bengal ♀ (SBB) and Random Black Bengal ♂$\times$Random Black Bengal ♀ (RBB) of 1 year old were evaluated for pre-slaughter traits and carcass characteristics. The correlations between pre-slaughter traits and carcass traits were computed. It was found that the preslaughter weights of JBB and SBB were almost similar in yielding hot and chilled carcass as well as dressing percentage (DP). RBB wethers were lighter (p<0.05) than JBB and SBB in pre- and post-slaughter weights and also inferior (p<0.05) in DP. SBB wethers were found to produce more visceral fat compared to JBB and RBB. Other variety meats appeared erratic in yield.l. Correlations were compared by Z statistic among three genetic groups and the value of Z did not differ (p>0.05) between groups.

Effect of the rolling speed on microstructural and mechanical properties of aluminummagnesium alloys prepared by twin roll casting

Das, S.,Lim, N.S.,Seol, J.B.,Kim, H.W.,Park, C.G. Scientific and Technical Press ; Elsevier Science 2010 MATERIALS AND DESIGN Vol.31 No.3

In the present investigation the microstructures and mechanical properties of Al-Mg alloys prepared by twin roll casting (TRC), varying rolling speed, (i.e., 3, 4, and 5rpm) were studied. Optical microstructures of the all the samples show dendritic morphology. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS) studies show segregation of alloying elements at the interdendritic regions. Transmission electron microscopy (TEM) observation confirms the presence of intermetallic phase (Mg<SUB>5</SUB>Al<SUB>8</SUB>) at the grain boundaries. It was observed that the secondary dendritic arm spacing (SDAS) increases (marginally) with rolling speed. Also the microhardness and tensile strength decreases with increase in rolling speed.

Metal-ion doped p-type TiO₂ thin films and their applications for heterojunction devices

Das, S.,Liu, D.,Park, J.B.,Hahn, Y.B. Elsevier Sequoia 2013 Journal of alloys and compounds Vol.553 No.-

Our study revealed that wet chemically processed metal-ion (i.e., Al<SUP>+3</SUP>, Cr<SUP>+3</SUP>, Ni<SUP>+2</SUP>) doped TiO<SUB>2</SUB> thin films could convert its conducting nature from n-type to extrinsic p-type. X-ray photoelectron spectroscopy (XPS) showed shifting of valence band edges with increasing doping concentration. The metal-ion doped TiO<SUB>2</SUB> films were employed as active component in bipolar heterojunction devices, which recorded low turn-on voltage and showed rectification behavior. These results were analyzed to conclude that the doped TiO<SUB>2</SUB> is p-type in nature. Temperature-dependent responses of field effect transistors (FETs) with the p-TiO<SUB>2</SUB> films as channel component revealed efficient features. Conclusive results revealed that reliable and reproducible p-type conductivity could be obtained with Ni<SUP>+2</SUP> doped TiO<SUB>2</SUB>.

Effect of rolling speed on microstructure and age-hardening behaviour of Al-Mg-Si alloy produced by twin roll casting process

Das, S.,Lim, N.S.,Kim, H.W.,Park, C.G. Scientific and Technical Press ; Elsevier Science 2011 Materials & design Vol.32 No.8

In the present investigation the microstructure and age-hardening behaviour of Al-Mg-Si alloy prepared by twin roll casting (TRC), varying rolling speed (i.e., 3, 4, and 5rpm), were studied. The as-cast samples were subjected to optical microscopy (OM) to understand the effect of rolling speed on the alloy microstructure. Significant difference in grain size and shape was observed for all the alloys in as-cast condition. The as-cast samples were solutionized at 540<SUP>o</SUP>C for 2h followed by isothermal heating at 180<SUP>o</SUP>C for different time intervals. Thereafter, the as-cast and solutionized samples were subjected to scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Segregation of solute atoms at grain boundaries were observed for both as-cast as well as solutionized samples. Age-hardening results show that time to attain peak hardness decreases for the alloy produced by higher rolling speed.

COMPENSATORY GROWTH AND NUTRIENT UTILIZATION IN CROSSBRED HEIFERS DURING REVIVAL PERIOD FED UREA MOLASSES LIQUID DIET

Dass, R.S.,Verma, A.K.,Mehra, U.R. Asian Australasian Association of Animal Productio 1996 Animal Bioscience Vol.9 No.5

Five crossbred heifers(Holstein Friesian $\times$ Hariana) aged about one year and average body weight 157.0 kg were used to observe the effect of UMLD with restricted amount of wheat straw (500 g/100 kg body weight) on body weight gain and nutrient utilization. After seven months feeding the animals were switched to a revival diet consisted of wheat straw and concentrate mixture, for an additional six months. Fortnightly body weights were recorded and metabolism trials were conducted at the end of the two experimental periods. Results indicated that the average daily gain were 57.0 and 413.3 g in two feeding systems. This showed a sub-optimum growth during UMLD feeding which was compensated when good quality revival diet was available. Though, the nutrients intake were significantly (p < 0.01) lower in UMLD feeding period as compared to revival diet feeding, but digestibility of all the nutrients were alike statistically. It can be concluded that UMLD with restricted amount of wheat straw can be fed as scarcity feed for a short period, without causing irreparable loss to the animals, provided sufficient feed nutrients are available after the scarcity period.

LOW-DENSITY CLOSE-CLOSED LOOP BURST ERROR DETECTING CODES

Dass, Bal-Kishan,Jain, Sapna 한국전산응용수학회 2002 The Korean journal of computational & applied math Vol.9 No.1

In this paper, we study cyclic codes detecting a subclass of close-closed loop bursts viz. low-density close-closed loop bursts. A subclass of CT close-closed loop berets called CT low-density close-closed loop bursts is also studied.

Nutrient Utilisation and Rumen Fermentation Pattern in Murrah Buffaloes (Bubalus bubalis) Fed Urea and Urea Plus Hydrochloric Acid Treated Wheat Straw

Dass, R.S.,Verma, A.K.,Mehra, U.R.,Sahu, D.S. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.11

Wheat straw was treated on laboratory scale with 4% urea at a moisture level of 50% along with different amount of HC1 to fix various levels of ammonia (30, 40, 50 and 60%) and stored for 4 weeks. Result, revealed a significant (p<0.01) increase in CP content of the samples where HC1 was added. The CP content of the straw was only 7.8%, which increased to 14.1, 16.0, 15.0 and 15.2% with the addition of acid. Similarly the concentrations of NDF, ADF and hemicellulose was significantly different due to HC1 addition. The level of HC1 recommended was to trap 30% ammonia as there was not significant difference in CP content of straw due to addition of 4 levels of acids. Results of in vivo experiment conducted on nine buffaloes divided randomly into three groups of three animals in each revealed no significant difference in the intake of DM, OM, NDF, ADF, cellulose and hemicellulose in group I (ammoniated straw), group II (HC1 treated ammoniated straw) and group III (HC1 treated ammoniated straw + 1 kg barley grain), but the intake of CP was significantly (p<0.01) more in group III as compared to other 2 groups. The digestibility of DM, OM and CP was significantly (p<0.01) more in groups where HCI treated straw was fed as compared to only ammoniated straw fed group, whereas there was no significant difference in the digestibility of NDF, ADF and cellulose in 3 groups. Intake was significantly higher of nitrogen (p<0.05), calcium (p<0.01) and phosphorus (p<0.01) in group III as compared to other two groups. Animals in all the 3 groups showed positive nitrogen, calcium and phosphorus balance, though the balances of all the 3 nutrients were significantly higher in group III as compared to other 2 groups. Rumen fermentation study conducted in 3 rumen fistulated buffaloes in $3{\times}3$ latin square design offering the same 3 diets as in group I to III revealed that rumen pH was alike statistically in 3 groups and at various time intervals. The mean ammonia-N concentration was significantly (p<0.01) more in group II and III as compared to group I. The mean TVFA concentration (mM/100 ml SRL) were 6.46, 7.84 and 8.47 in 3 groups respectively and different statistically (p<0.01). Results revealed no significant difference in the activities of carboxy methyl cellulase, urease or protease at both the time of sampling (0 h and 4 h) in all the 3 groups of animals.