Wear of some F.C.C. metals during unlubricated sliding part II: effects of normal load,sliding velocity and atmospheric pressure on wear fragments

The effects were determined of normal load, sliding velocity and atmospheric pressure on the volume and the formation rate of wear fragments obtained by experiments with Ni, Cu and Au under unlubricated conditions. The results show that the volume and the formation rate change in different ways. The change of wear with normal load or sliding velocity is predominantly due to a change in the volume of fragments. The change in wear with atmospheric pressure is due to a change of the formation rate. It is concluded that the volume of wear fragments is governed mainly by some mechanical factors and that the formation rate is dependent on chemical factors such as the chemisorption of oxygen.     

正弦波交交变频调速系统的研究

交流变频调速是各种调速方法中最有前途的调速方法。在我国,交交变频调速还处于研制阶段,进入实际应用的还比较少.本文研究了用微机作为系统控制器的正弦波交交变频调速系统,精确设计了系统控制电路和控制软件.     

DMA242C动态机械热分析仪故障分析与维护

介绍了DMA242C工作原理、操作条件,并对在使用过程出现的lock\unlock问题,顶杆位移等问题进行了分析和应对,对使用过程中的某些注意事项进行了阐述.     

高效液相色谱法测定维生素C片中V_C含量

目的:建立维生索C片中Vc的高效液相色谱测定法(HPLC).方法:以甲醇-0.015mol/L醋酸钠(体积比5:95)为流动相,用ExformmaC18柱(4.6×250mm,5μm)进行分离,于波长254nm处检测.结果:线性范围为37.6～601.6ng(r=0.9999,n=7),平均回收率为99.51%,RSD为0.53%(n=9).结论:用该方法测定Vc含量,结果稳定,重现性好,可操作性强,适于维生素C片的质量控制.