Fractions of β-HMX(β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane) have been used to demonstrate the mutual relationship between friction and impact sensitivities.Inclusion of an additional twelve nitramines into this sce...Fractions of β-HMX(β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane) have been used to demonstrate the mutual relationship between friction and impact sensitivities.Inclusion of an additional twelve nitramines into this scenario resulted in a series of partial relationships,which were determined from the molecular structure of these substances.It was also found that there is a relation between increasing heats of fusion of the nitramines studied and their decreasing friction sensitivities.Comparison of friction sensitivity with heats of fusion,ΔHm,tr of the studied nitramines shows that the increase in ΔHm,tr values is more or less connected with a decrease in friction sensitivity.展开更多
Ultrasonic treatment of the solidifying metal is a promising method for improving the quality of fusion welding. A method to combine the ultrasonic waves to the welding process using arc excited ultrasonic emissio...Ultrasonic treatment of the solidifying metal is a promising method for improving the quality of fusion welding. A method to combine the ultrasonic waves to the welding process using arc excited ultrasonic emission, called arc ultrasonic, was high frequency modulation of the arc plasma. The effects of arc ultrasonic on the weld including the fusion zone, the partially melted zone and the heat affected zone are described. The arc ultrasonic energy changes the weld microstructure. In the fusion zone, the primary dendrite arm spacing decreases significantly and more acicular ferrite appears. In the partially melted zone, a large amount of fine grains appear. In the heat affected zone, the width of the tempered zone increases with increasing modulation frequency and the microstructure is refined. The results show that arc ultrasonic is a new and effective way for improving weld quality. 展开更多
基金the project of the Ministry of Education,Youth and Sports of the Czech Republic,No.MSM 0021627501
文摘Fractions of β-HMX(β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane) have been used to demonstrate the mutual relationship between friction and impact sensitivities.Inclusion of an additional twelve nitramines into this scenario resulted in a series of partial relationships,which were determined from the molecular structure of these substances.It was also found that there is a relation between increasing heats of fusion of the nitramines studied and their decreasing friction sensitivities.Comparison of friction sensitivity with heats of fusion,ΔHm,tr of the studied nitramines shows that the increase in ΔHm,tr values is more or less connected with a decrease in friction sensitivity.
基金Supported by the National Natural Science Foundation of China ( No.5 9775 0 61)
文摘Ultrasonic treatment of the solidifying metal is a promising method for improving the quality of fusion welding. A method to combine the ultrasonic waves to the welding process using arc excited ultrasonic emission, called arc ultrasonic, was high frequency modulation of the arc plasma. The effects of arc ultrasonic on the weld including the fusion zone, the partially melted zone and the heat affected zone are described. The arc ultrasonic energy changes the weld microstructure. In the fusion zone, the primary dendrite arm spacing decreases significantly and more acicular ferrite appears. In the partially melted zone, a large amount of fine grains appear. In the heat affected zone, the width of the tempered zone increases with increasing modulation frequency and the microstructure is refined. The results show that arc ultrasonic is a new and effective way for improving weld quality.
