CR-437-2008-end - National institute of Technology Rourkeia...

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Unformatted text preview: National institute of Technology, Rourkeia - 769008 . Autumn Semester Examination, (End Semester)» 2008 Session: 2008-09 Semester . B. Tech: 7"1 Semester _ Subject: Sensor Technology (CR-437) ' Department Code: Ceramic Engineering CU!) Full Marks: 10!) marks Answer Any four Questions Figures at the right hand margin indicate marks Duration of Examination: 3 Hours All parts of a question should be answered to the point at one place (Symbols have their usual meanings) QHNo (a) What are the merits and demerits of ceramic ferroeleotric .1. materials over metals in application as PTC material? (b) Donor doped BaTi03 is more conducting than acceptor doped BaTiO; at room temperature. - Explain. . (c) How grain boundary plays a crucial role in ceramic thermistor.- Whether single crystal BaTiO3can be used for PTC application? '(d) Suggest a basic composition for a PTC thermistor that will switch at 30°C and can be sintered below 1100°C. _ (e) How NTC material can be used to delay in attaining maximum power on a load resistance? (a) Discuss the operating mechanism of ceramic oxide based '- moisture sensor (high moisture and trace moisture condition)? _ :(b) What are the advantages and disadvantages of ceramic oxide '2 based moisture sensor over that of polymeric material? '- (c) How porosity plays a major role in oxide based ceramic- humidity sensor? (d) How will you prepare anodic aluminimn oxide for moisture ' sensor-application? Briefly discuss the'stability of difi'erent phases of alumina. Write few applications of moisture sensor. - -(e) Write the advantages and disadvantages of PZT over BaTiO; as a piezoelectrics Page 1 of 2 3+3 +(5+2)+7+5 6+3+3+(3+2+3}r5 _(a) Write the operating principle of Lamda sensor. - (b) Writelthe characteristics and composition of electrolyte required for Lamda sensor. - - _ (c) What is the shortcoming of lamda sensor and mention the measure to tackle the problem? (d) How ppm level of oxygen content can be measured in molten metal? - - (a) Write the operating- mechanism of different gas sensor available in market? ' (b) What are the advantages and disadvantages of ceramic semiconductor gas sensor? (0) How the sensitivity and selectivity of polycrystalline ceramic gas sensing material can be controlled? (d) What is the importance of hydrogen sensor? (6) What is LEL and UEL ' '- (a) Describe 'the difierence between type I and type II superconductor. (b) If - vanadium has an H; value of 0.081" and is superconductive, ' = ;. what must its temperature be? Critical superconducting temperature of vanadium is 5.3K and critical field in Tesla at 0K is 0.102. (c) What-are the merits and demerits of the new high temperature oxide superconductor? (d) Explain briefly the BCS theory of superconductivity. - (3) Write the operating principal of Josephson Junction. How ceramic superconductor can be utilized as a magnetic sensor? (i) Write-the merits and demerits of polymer piezoelectric material? Give one example of polymer piezoelectric. Page20f2_ 7+3+{2+6)+7 12+3 +6+2+2 S+3+3+3+4+4+3 ' ...
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