Analysis of high-temperature materials for application to electric weapon technology

Abstract

High-power and temperature pulsed-power electronics can be exploited by future military combat systems using advanced electric weapon concepts such as electrothermal-chemical (ETC) and electromagnetic (EM) gun technologies. The results of experiments conducted demonstrate the electrical behavior of SiC and metal ohmic-contact layers as a function of thermal stress. It has been determined from these experiments that both titanium (Ti) and tantalum (Ta) metalization structures will provide a stable electrical ohmic-contact with n-type SiC at elevated temperatures for short bursts that are considered relevant for pulsed-powered electric weapon technologies. The Ti-SiC structure exhibited a stable current-voltage (I-V) characteristic to as much as 800/spl deg/C for a 10-min burst, while Ta metalizations provided a stable I-V characteristic on SiC even after a temperature burst of 1000/spl deg/C for as long as a 3-min interval. For samples of n-type, 4H SiC, metalized with (Ti), the standard deviation in resistance (resistivity) of the measured samples is less than 0.17 ohms for a sample having an average resistance of 4.45 ohms. The Ti-SiC sample was exposed to an elevated temperature range of 300-1,120/spl deg/C. For the Ta contact on SiC, the standard deviation in resistance is 0.05 ohms for a sample having an average resistance of 4.25 ohms over a temperature range of 600-1120/spl deg/ C. The experiments showed that for both Ti and Ta metalized SiC samples, the change in resistivity of annealed samples is between 3.8% and 1.2% compared to the average values of sample resistance based upon the I-V measurement technique used.