氮气压力对锰球氮化反应的影响(Ⅰ)

INFLUENCE OF NITROGEN PRESSURE ON NITRIDING REACTION OF Mn PELLET(Ⅰ)

利用自制的密闭氮化系统研究了不同压力下的锰球氮化反应。锰球的制备条件为:锰粉重量100 g、锰粉粒度16~20目、粘结剂添加量质量分数为2%和成球压力354 MPa。氮化炉温为900℃,氮化时间3 600 s。实验记录了在不同的氮气压力下锰球氮化实时增重和温度曲线。实验结果显示,当氮气压力从0.2 MPa升高至0.6 MPa时:(1)反应速率峰值时刻由266 s缩短至86 s,球心温度峰值时间由324 s缩短至138 s,球心温度恢复至炉温时由1 310 s缩短至642 s;(2)球心温度峰值由945℃升高至1 049℃,球心最大温升由55℃升高至159℃;(3)氮化3 600 s时的增重率由6.46%增至8.09%,转化率由81.34%增至93.62%;(4)增重速率峰值由8.15×10^(-3)s^(-1)增至62.7×10^(-3)s^(-1),转化速率峰值由103×10^(-3)s^(-1)增至726×10^(-3)s^(-1);(5)增重率达到6.46%的时间由3 600 s缩短为555 s,缩短84.6%。

Nitriding reaction of Mn pellets at different nitrogen pressures was investigated with the self-made air-proofed nitriding system. The research conditions of Mn pellet were 100 g of Mn particle, 16-20 mesh of particle size,mass fraction 2.0% of binder content and 354 MPa of pelletizing pressure. The initial fianace temperature and the nitriding time were set to 900 ℃ and 3 600 s respectively. The real-time variation curves of temperature and weight of Mn pellet at different nitrogen pressures were measured and recorded by the nitriding system. The experimental results show that, with the increasement of nitrogen pressure from 0.2 MPa to 0.6 MPa, （ 1 ） the timing of reaction rate peak is shifted from 266 s to a earlier time of 86 s, the timing of peak temperature of pellet center is shifled from 324 s to 138 s, and the timing for the peak temperature of pellet center recovering to 900 %℃ is moved up from 1 310 s to 642 s; （2） the peak temperature of pellet center is increased from 945 ℃ to 1 049℃, and the maximum increment of pellet center temperature is from 55℃to 159 ℃; （3） the weight gain ratio after 3 600 s nitriding is increased from 6.46% to 8.09%, and the conversion ratio is enhanced from 81.34% to 93.62%; （4） the peak value of weight gain rate is increased from 8.15 × 10.3 s^-1 to 62.7× 10^-3 sl, and the peak value of conversion rate is improved from 103×10^03 s-1 to 726×10^-3 s^-1, （5） the time needed for weight gain ratio of 6.46% is reduced from 3 600 s to 555 s by 84.6%.