Preparation Of Zirconia Oil-containing Self-lubricating Bearing Materials

Bearing is the indispensable basic part of all kinds of machines, whose performance directly influences and determines the performance of mechanical equipment. While self-lubricating ceramic bearing prepared by porous ceramic materials, combines the characteristics of self-lubricating bearing and ceramic materials, which provides a foundation for further application.In this paper, taking ZrO2 as raw material, Al2O3 as sintering aids and starch as pore-forming agent, porous ZrO2 ceramic was prepared by using the traditional dry pressing molding and atmospheric sintering method. And then ZrO2 self-lubricating bearing material was prepared by vacuum-impregnation process. The influences of the preparation procedure(the milling time, sintering temperature) and formulation(concentration of Al2O3 and starch respectively) on the properties of ZrO2 self-lubricating bearing material were invested. The main conclusions were as follows:1. Sintering temperature affects the microstructure and the final performance of samples. ZrO2 self-lubricating bearing material with the mass ratio of 20 wt% of Al2O3 and 30 wt% of starch was perfect under the best sintering temperature of 1500 ℃, which reached a oil content of 15 %, a Rockwell hardness of 85 HRB and a bending strength of 308 MPa. 2. Due to the incompatibility of ZrO2 and Al2O3, the particles of the same substance aggregated and the grains grew with the increase of Al2O3 concentration, which increased the oil content of the samples. Appropriate amount of Al2O3 evenly distributed in ZrO2, which increased the Rockwell hardness, while with the increase of Al2O3 concentration, the increase of the porosity led to the decrease of the Rockwell hardness. Rockwell hardness got the maximum when the content of the Al2O3 was 20 wt%. When the content of the Al2O3 was less than 20 %, with the increase of Al2O3 concentration, the bending strength decreased but remained above 300 MPa. Tetragonal-ZrO2 saved at the room temperature because of the addition of Al2O3 phase strengthened the effect of the transformation toughening. The friction coefficient of the samples first increased and then decreased, which was not presenting the relevant relation with the oil content.3. The less content of starch plays a role of binding agent, while with the increase of its content, starch can exert a good property of pore forming agent. When the sintering temperature was 1500 ℃ and the mass ratio of Al2O3 was 20 wt%, the oil content of the samples increased with the increase of starch concentration, but the Rockwell hardness and the bending strength decreased. The friction coefficient of the samples first decreased and then increased, it possessed minimum friction coefficient of 0.14 when the content of starch was 30 wt%. In practical applications, proper content of starch will be added into the raw materials according to the using request, to obtain high oil content and good mechanical property of the ZrO2 self-lubricating bearing material.