Fluid In The Pulse Discharge Preparation Tic Ceramic Coating And Sliding Wear Behavior Study

The author has made an experimental researches firstly on a new technology called EDC(electric discharge coating). A TiC ceramic layer about 30 μm thickness was obtained by EDC with a Ti powder green compact electrode in kerosene on 45 carbon steel surface. The hardness of the layer reaches 1800HV above, and is 6 times than the base metal's. The phase structure of the layer was determined by X-ray Diffraction (XRD). The surface morphology of the layer were observed by Scan Electron Microscope (SEM). The variation of the elements in the layer were analyzed by Electron Probe. The result shows that: the layer mostly comprises TiC. there are many heaves and concaves which can be observed on the surface of the layer, and so they make the surface of the layer rough. The surface of the layer is rich in Ti, but gradually the Ti decreases. It shows that The combine of the layer with the base is good, which result from the heat diffusing and chemical metallurgy reaction.The paper has discussed the effect of the parameter on the layer. The discussion shows that peak current and pulse on-time are the primary factor, pulse off-time and depositing time have almost no effect on the hardness but thickness of the layer. Orthogonal experiment shows that a good layer can be obtained on condition that the small current and short pulse are chosen.The formation mechanism of the layer was also discussed. The main formation mechanism of the layer are electrochemistry reaction and micro-electro-spraying. During pulse discharge, kerosene was decomposed and Ti metal from electrode was molten by the high temperature of the plasma, then, C from kerosene combined with Ti, and TiC was created on the surface of the workpiece finally.In the end, the sliding abrasion properties of the layer were tested. The result shows the tribology properties are good, the kinetic friction coefficient are under 0.1. In the same conditions of wearing test, the weight loss of surface treated with EDC is about one tenth of the weight loss without treatment, and is about one sixth of the weight loss treated with electroless composite coating. The abrasion morphology shows that abrasion mechanism is mostly grain abrasion.