Analysis of super-low friction mechanisms of carbon nitride in nitrogen gas lubrication and development of low frictiioon tribo-system

以氮化碳涂层为例，氮化碳涂层在氮气中与自身或氮化硅摩擦时，可获得0.001量级的超低摩擦系数。本文研究了沉积氮化碳涂层后的暴露条件和磨合工艺对氮化碳涂层与自身滑动或氮化硅涂层在氮气中滑动摩擦性能的影响，以阐明其超低摩擦机理，并开发出具有氮化碳涂层的低摩擦系统。此外，还研究了氮化碳涂层与氮化硅涂层的摩擦性能本研究的主要结果如下：(1)氮化碳涂层沉积后，在氮气条件下与氮化硅球摩擦的摩擦系数平均值在0.003~0.6之间变化。(2)氮化碳涂层沉积后，先将氮化碳涂层暴露在氧气中100秒，然后暴露在相对湿度为40-60%的环境空气中30分钟，(3)在环境空气中预滑500次后，摩擦因数由0.07降至0.004，磨球比磨损率也由1.0×10~(-1)/L降至0.004；氮化碳在氮气气流中滑动时，摩擦因数小于0.01。(4)在氮气气流中，给出了在环境空气中预滑50~1000次的最佳范围，摩擦系数小于0.01。

In case of carbon nitride coatings, super-low friction coefficient on the order of 0.001 is achieved in sliding against itself or silicon nitride in the stream of nitrogen gas.In this study, effect of exposure condition after deposition of carbon nitride coatings and running-in process on friction properties of carbon nitride coatingssliding against itself or silicon nitride in nitrogen gas is investigated to clarify the super-low friction mechanisms and to develop low friction system with carbon nitride coatings.Furthermore, possibility of further lower friction and necessary surface conditions for stable and low friction coefficient as low as 0.03 are investigatedFollowing are main results of this research.(1) The average values of friction coefficient of carbon nitride coating sliding against silicon nitride ball in nitrogen gas condition varied from 0.003 to 0.6 by exposure condition after deposition of the carbon nitride coating.(2) When carbon nitride coatings are exposed to oxygen gas first for 100 seconds after deposition of carbon nitride coatings, and then exposed to ambient air with 40-60% RH for 30 minutes, the friction coefficient in nitrogen gas condition shows as low as 0.003.(3) By introducing 500 cycles of pre-sliding in ambient air, friction coefficient reduces from 0.07 to 0.004 and specific wear rate of ball also reduces from 1.0×10^<-7>mm^3/Nm to 1.0×10^<-10>mm^3 on sliding of carbon nitride against itself in nitrogen gas stream.(4) Friction coefficient of lower than 0.01 is observed in nitrogen gas stream by giving optimum range of 50 to 1,000 cycles of pre-sliding in ambient air.