Tribological Properties Of The Carbonized AISI882 Steel And Research On The Self-repairing Process On The Modified Surface Layers

The wear of materials brings about a large number of losses in the industry. In present study, the characteristics of sliding and rolling friction of carbonized AISI8822 steel were investigated by using MM-200 friction and wear tester under different loads and time. The surface images during the friction process were analyzed qualitatively and quantitatively by SEM and OPM. Self-repair technology of wear of materials is an innovation technology in the field of surface engineering. The technology can evidently improve the physic-chemical and mechanical properties of friction pairs and reduce the wear loss by selected repairing the worn surface. Tribological characteristics of carbonized and nitrided steel pairs were investigated under lubricated condition with and without hydroxyl silicate additives.The following conclusions were obtained:(1) The sliding friction including two stages of "running-in" and "stable wear". With increase of the load, the friction coefficient is reduced gradually; The width of wear track increases continuously. The surface becomes more and more even and smooth. With increase of time, the surface topography looks smooth gradually. Roughness and friction coefficient reduced. In the first stage weight loss increases very fast, the wear rate is relatively big. The wear rate in the second stage is very small. The tribological characteristics keep stable during friction and wear test.(2) The experimental results of rolling friction show that: In the early stage, there are many scratch, fatigue pits and surface cracks. With the increase of time, the size of the fatigue pits will enlarge and appears exfoliation wear. With the increase of load, the size and quantity of the fatigue pits increase greatly, and scratches will disappear gradually. The friction process turned into rolling friction when load reaches to a certain level. In this stage, the size and quantity of the fatigue pits reduce greatly.(3) The self-repairing coating can be generated on the carbonized steel surface lubricated with silicate additive oil during friction and wear. The self-repairing surface is very smooth and the protective coating can prohibit the crack or void nucleation and initiation in the deformed layers. Therefore, this avoids the occurrence of delamination wear. Formation of the self-repairing coating on the worn surface can compensate the mass loss to some extent.(4) The self-repairing coating can not be generated on the nitrided steel surface lubricated with silicate additive oil during friction and wear. It can only improve the wear resistance of the metals to a certain extent.