Characterization of n-type β-SiC as a piezoresistor

SiC is currently being investigated for device applications involving high temperatures. The properties of n-type β-SiC relevant to piezoresistive devices, namely the gauge factor (GF) and temperature coefficient of resistivity (TCR), are characterized for several doping levels. The maximum gauge factor observed was -31.8 for unintentionally doped (10¹⁶-10¹⁷/cm³) material. This gauge factor decreases with temperature to approximately half its room-temperature value at 450°C. Unintentionally doped SiC has a roughly constant TCR of 0.72%/°C over the range 25-800°C and exhibits full impurity ionization at room temperature. Degenerately doped gauges (N_d=10²⁰/cm³) exhibited a lower gauge factor (-12.7), with a more constant temperature behavior and a lower TCR (0.04%/°C). The mechanisms of the piezoresistive effect and TCR in n-SiC are discussed, as well as their application towards sensors     

Standardization of parameters of the state of used engine oils

Translated from Khimiya i Tekhnologiya, Topliv i Masel, No. 10, pp. 16–18, October, 1990.     

The elongation of viscose cord at a load of 4.5 kgf

Conclusions 1. It is impossible to achieve an increase in the intermediate elongation by changing the parameters of the technological conditions in the formation of cord with a breaking length of 34–36 km.2. On passing to the technological conditions for obtaining fibre with a higher strength, fatigue properties improve and the intermediate elongation decreases.3. The intermediate elongation of the cord depends on the type of dynamometer and the clamps with which the determination is carried out. Consequently, it cannot characterise the fatigue properties of both raw and rubber-treated cord.4. To determine the physicomechanical characteristics of cord thread it is necessary to use the same dynamometers, clamps and materials for them.Krasnoyarsk Branch of All-Union Synthetic Fibre Research Institute (VNIIV). Translated from Khimicheskie Volokna, No. 3, pp. 65–67, May–June, 1969.