Study On Preparation Technology And Tribological Properties Of Cold-Pressed Sintered Cast Iron Based Wear-Resistant Bearing Bush

The crankshaft shaft tiles are used to support the crankshaft in its work and have very high accuracy requirements.After a long period of use,the shaft tiles will show material flaking and burning on their inner surface.Lubricant to the crankshaft journal surface of a good package,is one of the keys to improve the lubrication performance of the shaft shingle.Therefore,in-depth analysis and calculation of the bearing problems of the shaft shingles and effective protective measures to reduce or avoid their early abnormal wear are of great significance to enhance the safe serviceability of compressor units and are the main trends in the development of crankshaft shaft shingles.In this paper,a powder metallurgical method is used to prepare wear plates.The three main steps are: mixing of the powder,billet forming and vacuum sintering.Three different structures of press billets are designed to study the friction and wear reduction effect of different structures of press billets on the shaft shingles under different sintering temperatures.Firstly,the simulation experiment is carried out by using ANSYS simulation software.Based on ANSYS-Workbench finite element analysis,the temperature and pressure of oil film are solved by FLUENT finite element software,and the influence of rotational speed on oil film pressure and temperature is studied.Finally,the flow velocity and pressure field of the oil film are applied to the bearing contact surface,and the force-structure coupling analysis is carried out to analyze the bearing force characteristics.Secondly,in terms of preparation and characterisation,chilled-press sintered powders were formulated.The corrosion resistant cast iron material was selected as the matrix and WC was used as the strengthening phase for reasonable proportioning.Three press blanks were designed according to the requirements,and the suitable pressure and temperature ranges were designed through analytical calculations and prepared using a cold-pressure vacuum sintering process.The surface macro-and microstructure characterisation and mechanical properties of the three pressed blanks were analysed.It was found that the bonding of the clad billets with the carbide matrix was not high enough,the surface of the surface billets had more pores and the hybrid billets had the best performance.As the sintering temperature increases,the hardness of the substrate gradually increases and the hardness of the carbide gradually decreases.The surface microhardness of the superficial and hybrid billets increases and then decreases as the sintering temperature increases,and the microhardness of the cross-section of both billets does not fluctuate much as the distance from the sintering point increases,indicating that the overall dense billets are more uniform.However,the surface billets may have been sintered with Fe and Ni instead of the conventional binder,resulting in a lower sintering strength and more pores on the surface,resulting in a lower hardness.Both the superficial and hybrid billets have the highest microhardness at a sintering temperature of 1150℃,which is 2.358 and 2.556 times higher compared to the matrix.Overall,the surface properties of the hybrid billets were the best,the superficial type the second best and the clad type the worse.Finally,During dry friction wear,the friction coefficients of the three types of billets were higher for the clad and surface billets and lowest for the hybrid billets during the wear phase.As the sintering temperature increased,the average friction coefficient of the three types of billets showed a trend of decreasing and then increasing.The average coefficient of friction of all three types of billets is lowest at 1150℃.During the frictional wear process,the carbide plays a supporting role,which becomes more and more obvious as the carbide occupies a larger portion of the wear scar,and can significantly reduce the amount of wear.Both surface and hybrid pressed blanks showed the lowest wear at a sintering temperature of 1150℃.By observing the wear morphology and carrying out EDS spectroscopy,the wear mechanisms of the three pressed blanks are mainly abrasive wear,adhesive wear and oxidative wear.Under oil lubrication conditions,the surface and hybrid billets perform well,the clad billets have a higher coefficient of friction in the wear phase,the surface billets have the second highest coefficient of friction in the wear phase and the hybrid billets have the lowest coefficient of friction,which is around 0.1 after stabilisation.Within a certain temperature range,the coefficient of friction can be significantly reduced as the sintering temperature increases.In terms of wear volume,the mixed type press billets have better wear resistance than the surface type press billets.It can over play the obvious effect of anti-wear and friction reduction.In terms of wear volume and wear profile,the hybrid billets are better than the surface billets in terms of wear resistance.