NOPR Collection:

Instrumentation for a retarding potential analyzer for measurement of electron parameters

2016-07-20T06:22:20Z

Title: Instrumentation for a retarding potential analyzer for measurement of electron parameters Authors: Rajput, S S; Garg, S C Abstract: Various design considerations and their implementation in an instrument, designed for measurement of electron parameters on-board Indian satellites SROSS-C2, along its orbital path are presented. The proposed instruments measures the electron density in the range 5x10² - 5x10⁶ cm^-3 electron temperatures from 500 K to 4000 K, and photoelectron flux of energy 3-30 eV of the order 10⁸ cm^-s^-1 with full -scale instrument sensitivity 0.2%. Experimental results obtained during testing and flight demonstrate the instrument performance. Page(s): 315-322

Wear behaviour of titanium alloy GTM-900 under dry sliding

2016-07-20T06:24:10Z

Title: Wear behaviour of titanium alloy GTM-900 under dry sliding Authors: Pathak, J P; Mohan, S; Singh, V Abstract: Dry sliding wear behaviour of titanium alloy GTM-900 was investigated using a pin-on-disc wear testing machine. The alloy was solution treated in the α+β and β phase fields separately and cooled in air to produce duplex microstructure of primary α and transformed β and fully transformed β in the respective heat treated conditions. The sliding wear rate of the alloy in both of above heat treated conditions was observed to increase with the applied load. However, at a constant load, the rate of wear decreased with an increase in the sliding speed, to a minimum and then increasing trend was observed. Examination of wear debris by stereomicroscope and SEM and analysis of the worn surface by SEM revealed formation and smearing of oxides as well as distortion and removal of the metallic material from the mating surface. Microploughing on the sliding surface of the alloy, and dislodging of the material were also quite evident. The rate of wear was found to be higher in the β- treated than that in the α+ β treated condition. Page(s): 351-358

X-ray diffraction study on sulphur for rubber vulcanization

2016-07-20T06:27:35Z

Title: X-ray diffraction study on sulphur for rubber vulcanization Authors: Barali, K L; Bhattacharya, B Abstract: Identification of allotropic forms of sulphur present in commercial sulphur to be used for rubber vulcanization and the estimation of the percent content of each form present are essentially required for desirable performance characteristics of good quality rubber products. For these purposes x- ray diffraction technique has been chosen as the other conventional methods are incapable of distinguishing different forms of sulphur, viz .. normal α-type (orthorhombic) and insoluble ω-type(white sulphur or supersublimation sulphur). The ω-type (atleast 90% by weight) is most suitable, as it remains insoluble in rubber even at very high temperature. In this investigation pure α-type and ω-type as well as a sample of commercial type of sulphur have been thoroughly analyzed. This commercial sulphur is found to contain only 60% of in soluble sulphur, which does not at all fulfil the specific requirement. This analysis is very much helpful for quality improvement of rubber products. Page(s): 390-392

Relationship between the breakage and wetting characteristics of lignite

2016-07-20T06:19:42Z

Title: Relationship between the breakage and wetting characteristics of lignite Authors: Yekeler, M; Ozkan, A Abstract: This paper reports the findings of an investigation of the breakage values of lignite to relate the wettability properties. The breakage values, obtained from grinding, are the specific rates of breakage (S_i) and the γ of value the primary breakage function (B_i,J), and the wettability parameter, which is also easily obtained from contact angle measurements and flotation tests, is the critical surface tension of wetting value of solid (γ_c). The grindings were carried out as dry, wet and wet with kerosene aided tests in a laboratory size porcelain ball mill. The products (-212 μm) of the feed sizes of -600+425, -425+300 and -300+212 μm of lignite ground in the mill have been tested to obtain the γc values by contact angle goniometer and our new designed micro-flotation column cell. It is proposed that a relationship exists between the S_i and γ_c value of the lignite sample studied, i.e .. higher the Si value from the breakage process, lower the γc value in wetting processes, indicating less wettability in the physical-chemistry based separation methods. There is also another relatio nship found between the γ value of B_i,j (the fineness factor) and the γ_cvalue, where γ value increases with increasing γ_c value, except in the kerosene aided grindings. This means, coarser particles produced by grinding will behave more hydrophilic (i.e., water wets the solid completely) in the wetting operations. Page(s): 383-389