PDF《博士学位论文公示材料》

266 MPa to

443 MPa, ?Tmax is increased by 22℃, tp is reduced by 89s, and the conversion ratio at

1 h increases from 91.59% to 94.92%. (4) Based on the optimized process parameters, with the increase of binder addition from 1% to 3%, the conversion ratio at 1h decreases from 92.90% to 89.80%. (5) The data points of the conversion rate and the nitriding time can be approximately fitted with the probability density function of the log-normal distribution. (6) Based on the optimized process parameters, with the increase of nitriding pressure from 0.2 MPa to 0.6 MPa, ?Tmax is increased from 55℃ to 159℃, tp is reduced from

324 s to

138 s, the final mass increase is increased from 6.46% to 8.09%, the maxium conversion rate is changed from 103* 10-3 s-1 to 726* 10-3 s-1 ;

(7) Based on the optimized process parameters, with the increase of intial temperature from 700℃ to 850℃, it was found that increasing temperature is beneficial for enhancing nitrogen content;

while from 850℃ to 950℃, there is no obvious difference among nitrogen content of different samples at different temperatures. When reaction temperature is too high, much heat will be released within short time due to the large reaction rate. Thus, sintering of manganese particles in pellet may happen which retards the further nitriding process. It was also concluded that keeping at the high temperature for a long time is no use in........