Study Of Wear Mechanism Of Ceramic Materials In Hydrogen Peroxide Solutions

The moving parts (such as the turbo pump bearings) and seals of a new generation of non-toxic rocket propulsion system need to work under peroxide solution strong oxidizing environment. In the extreme working conditions of peroxide solutions, tribological behaviors of the rubbing pairs will become worse. Ceramic material is compatible with peroxide solution, due to its high temperature resistance, wear resistance, corrosion resistance and a series of excellent performances, engineering ceramic materials have wide prospects in the field of aerospace bearing application. Currently, the study on tribological behaviors and failure mechanisms of engineering ceramics in peroxide solutions is very limited. This study conducted the friction and wear behaviors, the electrochemical corrosion characteristics and failure mechanisms of the engineering ceramics in peroxide solutions. Based on the experimental results, the wear model and the corrosion model of the ceramic balls/1 Cr18Ni9Ti stainless steel rings in various concentrations of peroxide solutions have been established. It is believed that the knowledge obtained in this study will provide a guide for the choice of the rubbing pairs in the peroxide solutions.The tribological behaviors of the ceramics balls (ZrO2 AL2O3 Si3N4) against the 1Cr18Ni9Ti stainless steels rings in different concentrations of peroxide solutions had been studied on the tribo-tester, which equipped with electrochemical test device. The comparison analysis of the friction coefficients, wear mass loss, worn surface topographiesm, debris characteristics and corrosion electrochemical parameters was conducted. The wear model on wear mass loss-concentrations of peroxide solutions and corrosion model on corrosion mass loss-concentrations of peroxide solutions were established.The results showed that, with the increase of the concentrations of peroxide solutions, the average friction coefficients of AL2O3 ceramic/1Cr18Ni9Ti stainless steel ring rubbing pairs and ZrO2 ceramic/1Cr18Ni9Ti stainless steel ring rubbing pairs decreased, while the Si3N4 ceramic/1 Cr18Ni9Ti stainless steel ring rubbing pairs increased. Adsorption capacity of the ionic bond ceramic materials (ZrO2 Al2O3) was stronger than the covalent bond ceramic material (Si3N4) when mounted with 1Cr18Ni9Ti stainless steel ring. The stainless steel transfer film which formed on the surface of the ceramics made the wear mechanism be similar to adhesive wear between metal to metal and the friction coefficient was high. With the increase of the concentrations of peroxide solutions, the degree of adhesive wear weakened and the friction coefficient decreased. In high concentration of peroxide solutions, the main wear mechanism of ceramic materials was corrosive wear, abrasive wear and the friction coefficient increased. For the wear mass loss, in general, Si3N4 ceramics /1Cr18Ni9Ti stainless steel ring rubbing pairs was the most wear-resistant in peroxide solutions while ZrO2 ceramics/1 Cr18Ni9Ti stainless steel ring rubbing pairs was the worst wear-resistant and AL2O3 ceramics/1 Cr18Ni9Ti stainless steel ring rubbing pairs was in-between. For ZrO2 ceramic ball, the brittle fracture and furrow wear occurred in peroxide solutions and the wear mass loss was the maximum. For Si3N4 ceramic ball, corrosive wear occurred and the generated membrane played a protective role to the worn surface and the wear mass loss was the minimum. The surface topographies of the rubbing pairs had been examined, the results indicated that peroxide solution had the similar chemical polishing process to the stainless steel materials in the wear process, causing the wear surface to be smoother. The variations of the corrosion potential in the wear process had been examined. The results indicated that the corrosion potential was negative in pure water. With the increase of the concentrations of peroxide solutions, the corrosion potentials changed to be positive and then increased. The anode corrosion current densities of the lCrl8Ni9Ti stainless steel decreased. The stability and thickness of the passive film increased and the passive performance enhanced in the passive role of the peroxide solution. As a result, the corrosion potentials changed to be positive. The greater of the concentration, the stronger of the passive role and the corrosion potentials increased more. The corrosion potentials of the Si3N4 ceramics/ 1 Crl 8Ni9Ti stainless steel ring rubbing pairs increased with the least degree, while the ZrO2 ceramics/1Cr18Ni9Ti stainless steel ring rubbing pairs increased significantly and seriously fluctuated. The Al2O3 ceramics/1Cr18Ni9Ti stainless steel ring rubbing pairs was in-between. The passive film damaged, regenerated and then redamaged with the process of friction and wear in the peroxide solutions, which made the corrosion potentials change and fluctuate. The models on wear mass loss versus concentrations of peroxide solutions and corrosion mass loss-concentrations of peroxide solutions respectively followed the exponential and logarithmic relationship. The wear model and the corrosion model can provided a reference to analyze the friction and wear behaviors and the corrosion electrochemical properties of the the ceramics balls against the 1Cr18Ni9Ti stainless steels rings in different various concentrations of peroxide solutions, playing an important role in test guiding.