| Friction and wear have wasted a lot of energy in modern industrial. But most of the mechanicalfriction pairs are lubricated with oil, resulting in the shortage of oil resources. So finding analternative lubricant is the key to solving the problem. Water, as a kind of lubricant has a number ofadvantages. The traditional metallic material sliding in water will be corrosive. Therefore findingreasonable friction material is the key to solving the problem in water lubrication. Ceramic materialshave excellent lubricating properties in water, so that ceramic materials become the focus inresearching. But ceramic materials are difficult to overcome the shortage of brittleness and poorpossession of abrasive particles, so that their application has been limited. Metal-ceramic is composedof ceramic and metal, which has the both characteristics of metal and ceramic materials. A number ofresearchers are studying its lubricating properties in water conditions, found that the cermet hasexcellent lubricating properties in water, and has great potential with water lubrication.The main contents of this paper is to explore friction and wear properties of the Ti(C,N) cermetand SiC ceramic friction pair sliding at different loads, speeds, and lubricant. The lubricant includesdeionized water, seawater,2.453%NaCl solution,0.52%MgCl2solution and sea water without Na+ions. The experiments are finished on the pin-on-disk tribo-meter. Conclusions are as follows:1. In deionized water conditions, SiC/Ti(C,N) friction coefficient can’t be reduced to0.01or lessafter a long period of time, and friction coefficient has been maintained at0.1or even higher. In thiscondition, the friction pair can’t be in the fluid lubrication.2. In seawater conditions, SiC/Ti(C,N) friction coefficient can be reduced to0.025or even lowerafter a long period of time in both high speed-low load and high speed-high load conditions. In thiscondition the friction pair can enter the fluid lubrication. The friction coefficient only has falleninsignificantly at low speed condition, indicates that higher sliding speed increases the effects of fluidlubrication and carrying capacity of the friction pair. Although the friction pair’s total wear is largerthan the one in deionized water, but the amount of wear of the Ti(C,N) plate is about a half comparedwith the plate in deionized water. The high hardness and good corrosion resistance of Ti(C,N) materialresult in the least wear loss of the the friction pair in most conditions. And the plate’s wear loss at highload is less than that at low load. It is deduced that running-in process contained mechanical abrasionand chemical corrosion. The running-in process is as follows: metal and its oxide layers on the surfaceof the plate are removed gradually at first, then the inner ceramic layer is polished, finally the lubrication film produced by tribo-chemical reaction is accumulated on the surface and hence reducedthe friction coefficient. Because the seawater is corrosive and has dozens of chemicals mixed together,and the Ti(C,N) cermet material contains seven kinds of chemical compositions. These chemicals mayaccelerate the formation of lubricating film.3. In the seawater conditions, SiC/Ti(C,N) friction coefficient can be reduced to0.035in both2.453%NaCl solution and sea water without Na+ions. But there is no stable break-in period in highspeed-low load, which indicates that higher load increases the effects of water lubrication andcarrying capacity of the friction pair. It indicates that the Na+ions has affections on lowering thefriction coefficient of the process, but there are other ion affections. The SiC/Ti(C,N) has the samecurve after a long running-in in0.52%MgCl2solution, friction coefficient can hardly be reduced. Itindicates that the Cl-ions have little influence on the friction process. |
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