Yüksek sıcaklıklarda metallerin özdirencini ölçen bir sistemin geliştirilmesi
Küçük Resim Yok
Tarih
1990
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
ÖZET Metallerin özdirenci yüksek sıcaklıklarda T ile, 5 alçak sıcaklıklarda T ile orantılıdır. Mott teorisine göre, yüksek sıcaklıklarda geçit metallerin özdirenci lineeri ikten sapar. Ferromanyetik metallerin faz değişimi Curie sıcaklığı ile belirlenir. Bu çalışmada, metal ve alaşımların özdirencini ölçen bir sistem geliştirilmiştir, özdirenç 10-3 torr basınçta oda sıcaklığı ile 1300 K arasında ölçülmüştür. Sistem; ölçüm odası, fırın ve sıcaklığı ölçen kontrol eden dijital bir sistemden oluşmaktadır. ölçüm odası 300 cm çelik tüpten yapılmış olup ve basıncı 10 torra kadar düşürülebilir. özdirenci ölçülecek örnek ölçüm odasının merkezine yerleştirildi. 1350 W lık bir 3 güç ile 1300 K sıcaklığa çıkabilen fırın llxl4x22 cm3 çalışma hacimine sahiptir. Kantal tel, seramik fibre ve mikanit sırasıyla ısıtma elemanı, ısı yalıtım malzemesi ve refrakter olarak kullanılmıştır. Sıcaklığı ölçme ve kontrol sistemi TSC 7107 ve LM 358 entegreleri kullanılarak yapıldı. Sıcaklığı ölçmek için, Ni - NiCr termoçifti sensör olarak kullanılmıştır. Yüksek sıcaklıklarda sıcaklık stabilitesi 4 derecedir. Elektriksel özdirenç four probe metodu kullanılarak belirlendi. Fe, Ni ve A1 alaşımının özdirenci sıcaklığın fonksiyonu olarak ölçüldü. Yükseksıcaklıklarda termal genleşmeden dolayı özdirenç düzeltilmesi yapıldı. Fe ve Ni ' in özdirenç eğrisi lineer değildir. Ni ve Fe ' in Curie sıcaklığı sırasıyla 631^3 K ve 1043^5 K olarak belirlendi. ölçümler litaratürle uyum içindedir. Al(AlgÜ3) alaşımının özdirenci artan sıcaklık ile lineer arttığı gözlendi. özdirenç eğrisinden, eğrinin eğimi 0.00847 + 0.00007 pilcm/K olarak bulunmuştur. 39
SUMMARY Electrical resistivity of metals is proportional with g T at high temperature and with T at low temperatures. According to the Mott theory, the resistivity of transtion metals at high temperature deviates from linearity. The magnetic phase change of ferromagnetic metals is determined by Curie temperature. In this study, a system to measure the resistivity of metals and alloys at high temperature is developed. The resistivity has been measured between the room -3 temperature and 1300 K at a pressure of 10 torr. The system contains a measuring chamber, oven and a digital system which controls and measures the temperature. The 3 measuring chamber is made of a steel tube of 300 cm and -3 the pressure in this can be decreased down to 10 torr. the samples were placed in the centre of it. The oven, capable of achieving a temperature of 1300 K with a power of 1350 W, has a working volume which is roughly 11x14x22 3 cm. Kantal wire, ceramics fibre and micanite were used as heating element, thermal insulation and refractory respectively. The temperature measuring and controlling system was made by using TSC 7107 and LM 358 integrated circuits. To measure the temperature, Ni- NiCr was used as a thermocouple sensor. Temperature stability was about ^:4 degrees at high temperatures. 40The electrical resistivity was determined by using four probe method. The resistivities of Ni, Fe and AMAI2O3) alloy were measured as a function of temperature. The resistivity was corrected to the thermal expansion at high temperatures. The resistivity curves of Ni and Fe are not linear. Curie temperatures of Ni and Fe were determined as 631 ?3 K ve 1043^5 K respectively. The measurements were a good in agreement with the literature. It is observed that the resistivity of Al(Alg03> alloy increases linearly with inceasing temperature. From the resistivity curve, it was found that the slope of the curve was 0. 008^7^ 0.00007 nQcm/K. 41
SUMMARY Electrical resistivity of metals is proportional with g T at high temperature and with T at low temperatures. According to the Mott theory, the resistivity of transtion metals at high temperature deviates from linearity. The magnetic phase change of ferromagnetic metals is determined by Curie temperature. In this study, a system to measure the resistivity of metals and alloys at high temperature is developed. The resistivity has been measured between the room -3 temperature and 1300 K at a pressure of 10 torr. The system contains a measuring chamber, oven and a digital system which controls and measures the temperature. The 3 measuring chamber is made of a steel tube of 300 cm and -3 the pressure in this can be decreased down to 10 torr. the samples were placed in the centre of it. The oven, capable of achieving a temperature of 1300 K with a power of 1350 W, has a working volume which is roughly 11x14x22 3 cm. Kantal wire, ceramics fibre and micanite were used as heating element, thermal insulation and refractory respectively. The temperature measuring and controlling system was made by using TSC 7107 and LM 358 integrated circuits. To measure the temperature, Ni- NiCr was used as a thermocouple sensor. Temperature stability was about ^:4 degrees at high temperatures. 40The electrical resistivity was determined by using four probe method. The resistivities of Ni, Fe and AMAI2O3) alloy were measured as a function of temperature. The resistivity was corrected to the thermal expansion at high temperatures. The resistivity curves of Ni and Fe are not linear. Curie temperatures of Ni and Fe were determined as 631 ?3 K ve 1043^5 K respectively. The measurements were a good in agreement with the literature. It is observed that the resistivity of Al(Alg03> alloy increases linearly with inceasing temperature. From the resistivity curve, it was found that the slope of the curve was 0. 008^7^ 0.00007 nQcm/K. 41
Açıklama
Bu tezin, veri tabanı üzerinden yayınlanma izni bulunmamaktadır. Yayınlanma izni olmayan tezlerin basılı kopyalarına Üniversite kütüphaneniz aracılığıyla (TÜBESS üzerinden) erişebilirsiniz.
Anahtar Kelimeler
Fizik ve Fizik Mühendisliği, Physics and Physics Engineering, Metaller, Metals, Yüksek sıcaklık, High temperature, Öz direnç, Resistivity
