Preparation And Activation Process Of Antigorite Powder And Tribological Properties

The preparation and activation of mineral powders and the interaction mechanism between mineral powders and metal friction pair are the key technical and scientific issues that restrict and affect the efficiency,benefit and mechanism of mineral powders used as friction reducing and repairing materials for mechanical equipment.In this paper,the integration of micro nano-activation technology of antigorite,the interaction mechanism between antigorite and metal friction pair,and the extreme pressure resistance of micro nano grease containing antigorite were studied.The main achievements are as follows:(1)with the planetary mill as the main equipment,and through transform iron and polymer based ball mill can change the ball material ratio and process conditions such as time and rotational speed,and under the optimization of process preparation d₅₀=0.27?m and low crystallinity(54.57%)of micro-nano antigorite powder.It provides the experimental basis and technical support for the industrial preparation of micro-nano antigorite powder.(2)It was found that under the continuous action of mechanization,crystallinity of antigorite decreased significantly,cell parameters a₀,?-angle and cell volume increased,and b₀and c₀decreased.During the grinding process,the high speed motion of the medium ball endures the compressive stress perpendicular to the lamellar crystal,the shear force and the friction thermal energy oblique to the lamellar crystal,which results in the decrease of the order degree(crystallinity)of the antigorite structure.Concomitant with this,the wavy folds of the crystal in the direction of a₀undergo compression deformation(resulting in the increase of a₀),the crystal in the direction of c₀is compressed and becomes thinner(c₀decreases),and the crystal in the direction of b₀is associated with the increase of a₀and shrines(b₀decreases),but the total volume of the crystal cells increases.This study provides a new experimental basis for the mechanism analysis of mineral crystallinity reduction and crystal structure change under mechanization.(3)It was found that after mechanized mechanical activation,the dissolution amount of silicon and magnesium ions in micro and nano antigorite powder increased by 15 and 3 times respectively.It is believed that the order degree and binding force of siloxane tetrahedron and magnesite octahedron decrease under the combined action of mechanical energy and thermal energy,and the binding force of siloxane tetrahedron and magnesite octahedron is weakened,which is the main reason for the enhanced dissolution ability of siloxane and magnesite ions after activation.(4)The quantitative study on the quality and surface composition of steel balls in different ball grinding stages shows that the mass loss rate of steel balls in the early stage of ball grinding is large(the first 30 h mass loss rate is 1.11%),and the mass loss rate of steel balls in the late stage of ball grinding is significantly reduced(the last 150 h mass loss rate is 0.29%).It was also found that the modified layers of Si and Mg with a thickness of 5-100?m were formed on the surface of the ball after long period interaction with antigorite,which was the main reason for reducing the wear rate of the ball in the late grinding stage.(5)It is found that the extreme pressure resistance of lithium-based grease can be significantly improved by micro-nano antigorite,the sintering load is increased from 200kg(lithium-based grease)to 400 kg(grease with powder added),and the friction coefficient(average friction coefficient is reduced by about 5.8%)and spot diameter(decreased by 3.4%)can be reduced.(6)The influences of ball diameter,ball grinding speed and ball grinding tank material on grinding efficiency were analyzed by computer simulation.It was concluded that the maximum contact force between balls,average contact times and maximum kinetic energy of balls were the main factors affecting grinding efficiency.