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URN etd-0719106-164220 Statistics This thesis had been viewed 2893 times. Download 1488 times. Author Sheng-Ying Hsu Author's Email Address email@example.com Department Materials Engineering Year 2005 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 87 Title Preparation of Mn-Ni-Al system NTC Ceramics
Mixed difference Concentration Boron by the Chemical Coprecipitation
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Abstract It is well known that a material is acquired to produce small joule-heat only when it has low resistance according to the electricity rule. Therefore reduce the resistance of NTC in the match for the design of circuit gives more space in chosen. In addition, the stability of NTC resistance is a quite important factor for consideration. In order to improve the stability of low resistance NTC , coprecipitation is a suitable method to prepare the NTC powders. The powders obtained from the coprecipitation are mixed in solution. This method gives high homogeneous in compositions, low mean grain size, and high chemical activation , so reflects the reaction faster and more complete than the traditional solid state route. The powder compositions of this study are by Mn-Ni-Al mixed difference concentration Boron primarily . From the experimental results of coprecipitation process, there are several conclusions. The powder was weight loss approximately 55﹪in calcination process by the chemical coprecipitation . It is affects the Ag paste by the sample density .The density value must be higher than 2.7 g/cm3 , then the Ag can paste with sample . The sintering densification is enhanced as the content of Boron increased , and it can observation the densification is obvious enhanced at sintering temperature 900℃ .When the sample were mixes Boron at sintering process , the Boron was pastes on grain boundary , therefore it affects the electric properties by the grain boundary resistivity is increased . The resistivity of Mn-Ni-Al system NTC at 25℃ is enhanced while the content of Boron increased . When the Mn-Ni-Al system NTC mixed 0wt% Boron at sintering temperature 1100℃, the ΔR/R value is change not many while the aging increased , and it has well stability (ΔR/R＝0.17﹪、1.73﹪、0.1﹪) . Advisor Committee Yi-Hu - advisor
none - co-chair
none - co-chair
Files Date of Defense 2006-06-19 Date of Submission 2006-07-20